Tecnologias de Produção

Prévia do material em texto

Victor Neto 
UNIVERSIDADE DE AVEIRO | 2018 
ADVANCED PRODUCTION 
TECHNOLOGIES 
Index 
 
1. Fundamentals of Modern Manufacturing Technologies. 3 
2. Innovation in Manufacturing Technologies. 10 
3. Solidification Manufacturing Processes - metal and polymeric solidification processes. 18 
4. Industrial Powder processing manufacturing 35 
5. Metal Forming & Sheet Metalworking 37 
6. Additive Manufacturing Processes 44 
7. Micro & Nanotechnology fundamentals 48 
8. Microtechnology processing technologies 53 
8.1 Thin film deposition 53 
8.1.1. Chemical Vapor Deposition (CVD) of Diamond 54 
8.1.2. Physical Vapor Deposition 58 
Vacuum Deposition (Vacuum Evaporation) 59 
Sputter Deposition 59 
Arc Vapor Deposition 60 
lon Plating 60 
8.2. Photochemical machining 61 
8.2.1. Wet etching and photolithography 61 
8.2.2. LIGA Process 62 
8.3. Micromachining 63 
8.3.1. Ultra-High Precision tooling 63 
8.3.2. Laser Micromachining 64 
8.4. Molding 64 
8.4.1. Soft Lithography 64 
8.4.2. Micro Injection Molding 66 
9. Nanotechnology processing technologies 70 
9.1. Trends in Nano-based products commercial production and use 72 
9.2. Engineered nanomaterial manufacturing processes 72 
9.3. Nanomaterials for industrial applications 77 
9.3.1. Carbon based 78 
9.3.2 Metals and Metal Alloys 82 
9.3.3. Ceramic 82 
9.3.4. Semi-metal/semiconductor 83 
9.3.5. Organic/inorganic 84 
9.3.6. Polymers 84 
9.3.7. Composites 84 
9.3.8. Quantum dots 86 
9.3.9. Nanofluids 86 
10. Nanotechnology Usability Tool (NTU) 87 
10.1. Data acquisition stage 88 
10.2. Evaluation stage 91 
11. Ecological Production and Sustainability 100 
12. Advanced techniques for Material Characterization 112 
 
1. Fundamentals of Modern Manufacturing Technologies. 
Advanced production technologies are all the innovative forms of transforming raw materials or 
components in new products, whatever applying conventional processes or making use of the most 
recent and cutting-edge science breakthroughs. 
The fundamental points of Modern Manufacturing Technologies are: Product Requirements 
Assessment; Materials and Material Properties; and Manufacturing Technologies 
There are the issues to be developed whenever a product is to be produced. What are the product 
requirements? For this requirements, what materials have the properties to fit them and what 
manufacturing technologies can be used to process this materials and attain the product. 
In the product development process, product requirements – materials – production technologies form 
a triple helix that cannot be separated. The definition of the “client” requirements for the product are 
fundamental for the selection of materials to be used, and when we think on materials to do a product, 
we need to think that those materials need to be transformed or shaped in to the product, and the way 
that we can transform or shape the materials depend very much on their properties. 
 
 
 
 
 
Product requirements 
Typical components of a product requirements document (PRD) are: 
 
 
Product 
Requirements 
 Materials 
 
 
Production 
Technologies 
• Title & author information 
• Purpose and scope, from both a technical and business perspective 
• Stakeholder identification 
• Market assessment and target demographics 
• Product overview and use cases 
• Requirements, including: 
⚫ functional requirements (e.g. what a product should do) 
⚫ usability requirements 
⚫ technical requirements (e.g. security, network, platform, integration, client) 
⚫ environmental requirements 
⚫ support requirements 
⚫ interaction requirements (e.g. how the product should work with other systems) 
• Assumptions 
• Constraints 
• Dependencies 
• High level workflow plans, timelines and milestones (more detail is defined through a project 
plan) 
• Evaluation plan and performance metrics 
Have a look to the following paper: Requirements management: a representation scheme for product 
specifications, Alison McKay, Alan de Pennington, Jim Baxter, Computer-Aided Design, 33-7, June 2001, 
511-520, ISSN 0010-4485, http://dx.doi.org/10.1016/S0010-4485(01)00050-1 
 
Materials 
Materials that are used as raw material for any sort of construction or manufacturing in an organized 
way of engineering application are known as Engineering Materials. 
Everything we use in our daily life can be tailored to use for specific cases. This can be done efficiently if 
we know the property of each material. Hence, materials have been extensively tested for their 
properties and classified into broad groups. Engineering materials are classified into the following broad 
groups: 
 
 
 
Another organization of them, not far from the last is: 
 
 
 
As referred, what distinguish materials, their applications and, very much, the way that they are 
processed are their properties. Physical, mechanical, thermal, electrical and other properties are the 
details that we need to fit with the product requirements. 
 
 
You can look in databases for lists of materials, that include aboard range of properties, application 
information and recommendations, suppliers, data-sheets, etc. My favorites are: 
The most complete database – MatWeb: http://matweb.com/ 
Special for polymers information – Omnexus: https://omnexus.specialchem.com/ 
With some extra environmental information – Matbase: https://www.matbase.com/ 
The best payed database – Granta: http://www.grantadesign.com/ 
For a good product development project, one needs to define very well the: product requirements; 
materials; and production technologies. The three are dependent form one another. The definition of 
the product requirements for the product are fundamental for the selection of materials to be used, and 
when we think on materials to do a product, we need to think that those materials need to be 
transformed or shaped in to the product, and the way that we can transform or shape the materials 
depend very much on their properties. 
This is a good paper to you to read about this topic: Selection strategies for materials and processes, 
M.F. Ashby, Y.J.M. Bréchet, D. Cebon, L. Salvo, Materials & Design, 25-1, February 2004, 51-67. 
http://dx.doi.org/10.1016/S0261-3069(03)00159-6 
 
Manufacturing processed 
Broadly speaking, if one considers only the shaping processes, one can divide them in solidification 
processes, particulate processes, deformation processes and material removal processes. Solidification 
processes involves the melting of the raw material, the pouring the melt in a mold, the solidification of 
the raw material and the demolding of the part. Polymers and metals are commonly shaped by 
solidification processes. Particulate processing is typically used when the raw material is not easily 
melted, as is the case of ceramics and some metals that have high melting temperatures. Particles are 
pressed to a geometry and then sintered. Deformation process make use of high pressure presses to 
shape materials. Material removal process are all the operations that removes material from a block in 
order to give it the desired shape. 
 
 
 
 
In a boarder perspective, one can organize manufacturing processes in a bigger family, such as the one 
presented below. 
 
 
 
In this diagram, you can already notice that material properties are indirectly present. Each process as 
its own attributes also, such as shape, size range, finishing, etc. Therefore, by combining product 
requirements, with material and processes attributes, one attains the production planning.2. Innovation in Manufacturing Technologies. 
As seen in the last class, we have a triple helix of manufacturing: Matching product requirements; 
Materials; and Manufacturing Technologies. It is from this that we can say how it is made and why with 
this materials and manufacturing technologies. 
Let’s now think of a under-the-hood plastic cover of a diesel car. What should be the product 
requirements for this product? What’s the propose of it? Manufactures started placing this parts in 
diesel car to reduce the noise of the car. So it need to absorb or isolate the engine noise and vibrations. 
But it also need to be lightweight, withstand the engine temperature and gases moistures. It should be 
eco-product, of course. 
 
 
Having defined some product requirements, what materials and production technologies to use to 
produce the product? I’ve already said that it is a plastic cover, but what type of plastic? For these 
requirements, maybe a ABS thermoplastic is fine and it will be produced by injection molding. Cannot 
forget to see it the material is automobile accepted by the manufacture and by car norms legislation. 
Let’s think of another example, a motorcycle helmet. How is a helmet made? Simplifying it, it is 
something such as: 
 
 
 Outer shell mold 
 ABS outer shell injection 
 Outer shell painting 
 Outer shell decoration and varnish 
 
 
 
 
 
And, what can go wrong? 
 
 
The product is subjected to quality tests, and if it fails, one need to analyze what went wrong. Could it 
be a product requirement badly defined? A problem with the materials? Or processing parameters? 
Sometimes it is from problems that innovation appears. Innovation can be a result of solving or avoiding 
problems. A very short list of potential methods of innovating can be by up-to-date operations 
management, application of TRIZ process, lean production setup or application of strategies such as six 
sigma quality insurance. 
TRIZ is a problem-solving method based on logic and data, not intuition, which accelerates the project 
team's ability to solve these problems creatively. TRIZ also provides repeatability, predictability, and 
reliability due to its structure and algorithmic approach. 
 
Lean production intends to do more work with fewer resources, yet achieving higher quality in the final 
product. The core idea of lean manufacturing is actually quite simple: persistently work on eliminating 
waste from the manufacturing process. Waste is any activity that does not add value from the 
customer’s perspective. According to research conducted by the Lean Enterprise Research Centre 
(LERC), fully 60% of production activities in a typical manufacturing operation are waste – they add no 
value at all for the customer. 
 
Quality strategies are also important, and Six Sigma is a systematic approach for quality implementation. 
It is a quality-focused program that utilizes worker teams to accomplish projects aimed at improving an 
organization’s organizational performance 
 
Integrated approaches for performance enhancements 
In the field of manufacturing technology development, integrated approaches for process performance 
enhancements are increasingly focused. New solutions in manufacturing technology enhancements 
often represent an integration of knowledge from different technology domains. The knowledge of 
technology is represented in different kinds of technology models. Thus in interdisciplinary solutions, 
different technology models are brought together, so that a new solution can be described or explained. 
In order to increase the probability of interdisciplinary solutions in production technology research and 
development, the linking of different technology explanation models is vital. Although experimentation 
remains the most essential tool for manufacturing technology development, a systematic use of known 
models prior to experimentation can improve the efficiency of the development process. Assuming that 
the technology knowledge that is necessary for finding and modelling new technology solutions already 
exists; this knowledge has to be made available for solving specific technology problems or limits. Due to 
the fact that the manufacturing technology knowledge needed for technology enhancements is 
contained in models, these models are classified into different model types as shown in bellow image. 
 
 
 
Analytical-physical models are based on physical laws or functions. The original type of physical models 
is the fundamental-analytical model, which is mainly based on basic physical equations and only to a 
minor extent on empirical interrelations. Since the age of computers has found its way into the 
modelling of manufacturing processes, numerical simulation methods have been used based on finite 
element models, kinematic-geometric models or molecular dynamic approaches. These approaches are 
among physical models. 
The empirical models are based on experimental data that is analyzed statistically. The most common 
empirical model is the regression model, which describes the relations between a dependent variable 
and one or several independent variables. An empirical model type developed of late is described by an 
artificial neural network. It is used for the prediction of output variables depending on input variables 
and the system model of the process. While the relations between input and output are hidden in this 
model, the model is created “automatically”. 
The third model type is represented by heuristic models. This type of models is based on experiences 
that often cannot be described in the form of exact quantities but by a rule based link between process 
characteristics. With help of fuzzy logic, the information can be transformed to mathematical 
expressions and thus be used for statistically reliable prediction of process results. Usually, current 
heuristic models often describe relations between input and output of a technical system or setting 
parameters and machining results in the case of a manufacturing process respectively. Besides, 
technology specific knowledge of an expert concerning the causes and effects of technology behaviour 
and mechanisms is also often described by heuristic models. 
Have a look on the following research articles for a deeper insight> 
● Andreas Roderburg, Fritz Klocke, Philip Koshy, Principles of technology evolutions for 
manufacturing process design, Procedia Engineering 9 (2011) 294–310, 
doi:10.1016/j.proeng.2011.03.120 
● Zhang Yingjie, Energy efficiency techniques in machining process: a review, Int J Adv Manuf 
Technol (2014) 71:1123–1132, doi:10.1007/s00170-013-5551-3 
● R. Venkata Rao, V. D. Kalyankar, Optimization of modern machining processes using advanced 
optimization techniques: a review, Int J Adv Manuf Technol (2014) 73:1159–1188, 
doi:10.1007/s00170-014-5894-4 
 
Cloud manufacturing 
Cloud manufacturing is associated with the capability of producing products in different environments, 
this is, one can develop a product without having the physical facilities to materialize it. Cloud 
manufacturing is a new manufacturing paradigm developed from existing advanced manufacturing 
models and enterprise information technologies under the support of cloud computing, Internet of 
Things, virtualization and service-oriented technologies, and advanced computing technologies. It 
transforms manufacturing resources and manufacturing capabilities into manufacturing services, which 
can be managed and operated in an intelligent and unified way to enable the full sharing and circulating 
of manufacturing resources and manufacturing capabilities. 
 
Industry 4.0 
We have been witness of afundamental transformation in our daily life through the emergence of 
Information and Communication Technologies (ICT). Computers are getting so small they seem to vanish 
inside nearly all of our technical devices. Beyond all this, things communicate in a world-wide network: 
the Internet. This trend will certainly find its way also into industrial production, which will benefit 
increasingly from the advances in ICT and computer sciences. In Germany, this trend is called the 4th 
Industrial Revolution, in shorthand, Industry 4.0. It is a synonym for the transformation of today's 
factories into smart factories, which are intended to address and overcome the current challenges of 
shorter product lifecycles, highly customized products and stiff global competition. 
A high product variability and at the same time shortened product-life-cycles require agile and flexible 
production structure, which can be reconfigured rapidly for new product demands. This degree of 
flexibility cannot be achieved by traditional automation. Instead, modular factory structures composed 
of smart devices – the so-called Cyber-Physical Systems (CPS) – that are network in an Internet of Things 
(IoT), are key elements to overcome the currently rigid planning and production processes. The 
challenge and key to the success of highly modular factory structures is multi-vendor interoperability of 
automation technology, which can only be achieved through coordinated standardization actions 
between the relevant technology providers, integrators and end-users. 
The vision of Industry 4.0 
Industry 4.0 is a strategic initiative of the German government that was adopted as part of the “High-
Tech Strategy 2020 Action Plan” in 2011. In Germany, a major debate on Industry 4.0 has started, which 
in the meanwhile has spread also to other countries, like the US or Korea. The idea behind this term is 
that, the first three industrial revolutions came about as a result of mechanization, electricity and IT. 
Now, the introduction of the IoT and CPS into the manufacturing environment is ushering in a 4th 
Industrial Revolution. In Industry 4.0, field devices, machines, production modules and products are 
comprised as CPS that are autonomously exchanging information, triggering actions and controlling each 
other independently. Factories are developing into intelligent environments in which the gulf between 
the real and digital world is becoming smaller. The strong bias of the electro-technical and hierarchical 
world of factory automation will transition to smart factory networks, that enable dynamic re-
engineering processes and deliver the ability to respond flexibly to disruptions and failures. 
Key paradigm of Industry 4.0 
Central aspects of the Industry 4.0 can be further specified through three paradigms: the Smart Product, 
the Smart Machine and the Augmented Operator. The guiding idea of the Smart Product is to extend the 
role of the work piece to an active part of the system. The products receive a memory on which 
operational data and requirements are stored directly as an individual building plan. In this way, the 
product itself requests the required resources and orchestrates the production processes for its 
completion. This is a prerequisite to enable self-configuring processes in highly modular production 
systems. 
The paradigm of the Smart Machine describes the process of machines becoming Cyber-Physical 
Production Systems (CPPS). The traditional production hierarchy will be replaced by a decentralized self-
organization enabled by CPS. They depict autonomic components with local control intelligence, which 
are able to communicate to other field devices, production modules and products through open 
networks and semantic descriptions. In this way, machines are able to self-organize within the 
production network. Production lines will become so flexible and modular that even the smallest lot size 
can be produced under conditions of highly flexible mass production. Additionally, a CPS-based modular 
production line allows an easy plug-and-play integration or replace of new manufacturing unities, e.g. in 
case of reconfiguration. 
The third paradigm mentioned above, the Augmented Operator, targets at the technological support of 
the worker in the challenging environment of highly modular production systems. Industry 4.0 is not 
gravitating towards worker-less production facilities (unlike the CIM-approach of the 80s): Human 
operators are acknowledged as the most flexible parts in the production system being maximally 
adaptive to the more and more challenging work environment. As the most flexible entity in the 
production systems, workers will be faced with a large variety of jobs ranging from specification and 
monitoring to verification of production strategies. By the same token, s/he will manually intervene in 
the autonomously organized production system, if required. Optimum support when tackling the 
versatile range of problems is provided by the mobile, context-sensitive user interfaces and user-
focused assistance systems. Proven, forward-looking solutions are provided by established interaction 
technologies and metaphors from the consumer goods market (e.g. tablets, smart glasses and smart 
watches), which do, however, need to be adapted to industrial conditions. Through technological 
support it is guaranteed that workers can realize their full potential and adopt the role of strategic 
decision-makers and flexible problem-solvers. As a result, the steadily rising technical complexity can be 
handled. 
The image bellow represents the need to integrate a full scope of competences and skills to be able to 
deliver a high personalized product, with reduced waste and therefore, higher productivity rates. 
 
 
Get more information about Industry 4.0 at: 
● Towards Industry 4.0 - Standardization as the crucial challenge for highly modular, multi-vendor 
production systems https://doi.org/10.1016/j.ifacol.2015.06.143 
● Collaboration Mechanisms to increase Productivity in the Context of Industrie 4.0 
https://doi.org/10.1016/j.procir.2014.05.016 
● Industria 4.0 http://www.victorneto.net/industria40 
 
 
3. Solidification Manufacturing Processes - metal and polymeric 
solidification processes. 
 
 
METAL CASTING PROCESSES. Metals for Casting. Sand Casting. Other Expendable-Mold Casting 
Processes. Permanent-Mold Casting Processes. Casting Quality. Product Design Considerations. 
 
 
Sand casted air compressor frame 
 
 
 
Production sequence in sand casting 
 
 
 
Types of patterns used in sand casting: (a) solid pattern, (b) split pattern, (c) match-plate pattern, (d) 
cope and drag pattern 
 
 
 
 
 
(a) open mold and (b) closed mold for more complex mold geometry with gating system leading into the 
cavity 
 
 
 
A pure metal solidifies at a constant temperature equal to its freezing point (same as melting point) 
 
Characteristic grain structure in a casting of a pure metal, showing randomly oriented grains of small size 
near the mold wall, and large columnar grains oriented toward the center of the casting 
 
 
 
Most alloys freeze over a temperature range 
Phase diagram for a copper‑nickel alloy system and cooling curve for a 50%Ni‑50%Cu composition 
 
Characteristic grain structure in an alloy casting, showing segregation of alloying components in center 
of casting 
 
 
(0) starting level of molten metal immediately after pouring; (1) reduction in level caused by liquid 
contraction during cooling. (2) reduction in height and formation of shrinkage cavity caused by 
solidification; (3) further reduction in volume due to thermalcontraction during cooling of solid metal 
 
 
 
Shell Molding 
 
 
 
 
Expanded Polystyrene Process 
 
 
 
Investment Casting 
 
 
Permanent Mold Casting 
 
 
Die Casting - Hot-Chamber 
 
Die Casting - Cold‑Chamber 
 
 
 
GLASSWORKING. Raw Materials. Shaping Processes in Glassworking. Heat Treatment and Finishing. 
Product Design Considerations 
(1) preparation of raw materials and melting, (2) shaping, and (3) heat treatment 
 
 
Spinning 
 
 
Pressing 
 
Press-and-Blow 
 
Continuous Glass Fibers 
 
 
Rolling of Flat Plate Glass 
 
 
Float Process for Producing Sheet Glass 
 
Drawing Glass Tubing 
 
 
 
 
 
 
 
SHAPING PROCESSES FOR POLYMERS. Properties of Polymer Melts. Extrusion. Production of Sheet and 
Film. Fiber and Filament Production (Spinning). Injection Molding. Compression and Transfer Molding. 
Blow Molding and Rotational Molding. Thermoforming. Casting. Polymer Foam Processing and Forming. 
Rubber Processing and Shaping. Product Design Considerations 
 
Thermoplastics and Thermosets 
 
 
 
 
Extruder 
 
 
 
 
 
 
Calendering 
 
 
Melt Spinning 
 
 
Injection Molding 
 
 
 
 
 
 
 
 
 
 
 
Compression Molding 
 
Transfer Molding 
 
 
Extrusion Blow Molding 
 
Injection Blow Molding 
 
 
Vacuum thermoforming 
 
 
 
 
 
 
 
 
 
COMPOSITES. Materials for PMCs. Open Mold Processes. Closed Mold Processes. Filament Winding. 
Pultrusion Processes. Other PMC Shaping Processes. 
 
 
 
 
 
4. Industrial Powder processing manufacturing 
 
PARTICULATE PROCESSING OF METALS AND CERAMICS. Engineering Powders. Processing of New 
Ceramics and Cermets. Pressing and Sintering. Design Considerations in Powder. 
 
(1) Blending, (2) Compacting, (3) Sintering 
 
 
Sintering Sequence 
 
Powder Materials 
Iron 
Aluminum 
Copper 
Stainless steels 
Certain copper alloys 
High speed steel 
Cemented Carbides (WC-Co) 
 
 
 
 
 
5. Metal Forming & Sheet Metalworking 
 
 
METAL FORMING. Material Behavior, Temperature, Friction and Lubrication in Metal Forming. 
 
Average flow stress in relation to Flow stress Yf and Yield strength Y 
 
 
Three temperature ranges in metal forming: 
- Cold working 
- Warm working 
- Hot working 
 
 
 
 
 
 
 
 
BULK DEFORMATION PROCESSES IN METALWORKING. Rolling. Forging. Extrusion and Wire and Bar 
Drawing. 
(a) Rolling and (b) forging 
 
(c) Extrusion and (d) wire and bar drawing 
 
 
 
 
 
 
 
 
(a) Open-die forging, (b) impression-die forging, and (c) flashless forging 
 
 
 
 
 
 
 
SHEET METALWORKING. Cutting and Bending Operations. Drawing. Other Sheet-Metal-Forming 
Operations. Dies and Presses for Sheet-Metal Processes. Sheet-Metal Operations Not Performed on 
Presses. Bending of Tube Stock. 
 
(a) Bending and (b) deep drawing 
 
 
 
 
 
 
 
 
 
 
 
 
Springback 
 
 
(c) Shearing: (1) punch first contacting sheet and (2) after cutting 
 
 
 
Roll Bending 
 
 
Spinning 
 
 
 
Roll Forming 
 
 
6. Additive Manufacturing Processes 
Additive Manufacturing processes include technologies such as Fused Filament Fabrication (FFF), 
Stereolithography (SLA), Selective Laser Sintering (SLS), Laminated Object Manufacturing (LOM), among 
others. 
If one takes the word “additive manufacturing” straight, technologies such as thin film deposition can 
also be consider. Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), Painting, among 
others can also be consider “additive” since they add material to a substrate or object. Nonetheless, 
PVD, CVD and other such technologies will be covered later when we speak about micro and 
nanotechnologies. 
One of the key features of additive manufacturing is that it enables new geometries and design that are 
not possible to be produced with conventional fabrication techniques. Additive manufacturing must be 
seen as a set of technologies that will open the scope of design and manufacturing capabilities and not 
as replacement of conventional technologies such as injection molding or machining. 
Product design can be further optimized when additive manufacturing is also considered, and concepts 
as computer generative design can create new solutions as the example presented below. 
 
 
From conventional to optimized, by using additive manufacturing and generative design 
 
The different types of additive manufacturing processes can be organized according to the material 
processes or the initial state that this material presents. The below diagram gives an example of such 
organization. 
 
 
Different Types of Additive Manufacturing (Noah Fram-Schwartz) 
 
Different organization of additive manufacturing technologies can be accomplished. The standard ASTM 
F2792 organizes additive manufacturing in 7 families: VAT Photopolymerization, Powder Bed Fusion, 
Binder Jetting, Material Jetting, Sheet Lamination, Material Extrusion, and Direct Energy Deposition. 
 
Bibliography 
● Different Types of Additive Manufacturing 
https://www.linkedin.com/pulse/different-types-additive-manufacturing-noah-fram-schwartz 
● 7 Families of additive manufacturing 
http://www.hybridmanutech.com 
● Additive manufacturing: technology, applications and research needs 
https://doi.org/10.1007/s11465-013-0248-8 
● Additive manufacturing: opportunities and constraints 
http://www.raeng.org.uk/AM 
● A Review of Additive Manufacturing 
https://doi.org/10.5402/2012/208760 
● Advancing Manufacturing - Advancing Europe, Report of the Task Force on Advanced 
Manufacturing for Clean Production (2013) 
https://doi.org/10.2769/87036 
 
 
 
 
7. Micro & Nanotechnology fundamentals 
The first important thing to understand when staring to work with micro and nanotechnologies is scales. 
We are used to the macroscopic scale: a tree, a house, a building, a mosquito, a water droplet. 
Engineers need to work with accuracies bellow 0.1 mm when doing plastic injection molds, for example. 
Sometimes the tolerances go to 0.01 mm. Do you imagine what 0.01 mm is? Do you know the length of 
a human hair? It is about 100 µm. This is 0.1 mm. Mold can be very accurate. 
In the figure bellow you can get an idea about scales, examples, terminology, how to observe and 
manipulate to fabricate useful devises. An interesting website to get a better insight of the very little 
and very big scales can be find here: http://htwins.net/scale2/ 
 
 
Manufacturing macro, micro and nano-scales 
 
Also important for this is the comprehension of the electromagnetic spectrum, because it is due to it 
that most of the techniques work. 
 
Electromagnetic spectrum 
 
A question that one can place is why develop microsystem or nanosystem products? Well, less material 
usage, lower power requirements, greater functionality per unit space, accessibility to regions that are 
forbidden to larger products, and in most cases, smaller products should mean lower prices because less 
material is used. 
See the example of a gyroscope. A gyroscope is a device used for measuring or maintaining orientation 
and angular velocity. It is a spinning wheel or disc in which the axis of rotation is free to assume any 
orientation by itself. Airplanes where equipped with several gyroscopeswith the size of a small shoebox. 
Today, you can find a micro-gyroscope inside a small smartphone. 
 
 
 
Airplane Gyroscope vs Smartphone Gyroscope 
So, how is a micro-gyroscope manufactured? A micro-gyroscope is what can be called a 
Microelectromechanical system (MEMS), a miniature systems consisting of both electronic and 
mechanical components. 
 
Different classification of micro devices 
 
To develop such device, three stages are required to be analyzed: 
1. Required feature 
2. Physics/Mechanics artifact to attain the feature 
3. Materials / technologies to produce it 
 
Let’s think on the micro-gyroscope. 
1. Required feature 
 
A gyroscope is a device that uses Earth's gravity to help determine orientation 
 
2. Physics/Mechanics artifact to attain the feature 
 
The paper “The development of micromachined gyroscope structure and circuitry technology” 
(http://www.mdpi.com/1424-8220/14/1/1394) presents various tuning fork gyroscope 
proposals. 
 
 
Various Tuning fork gyroscope.(a) SIMIT. (b) PKU. (c) Georgia Tech. (d) CEA-LETI. (e) National University of Defense Technology 
(NUDT). (f) SIMIT. 
 
3. Materials / technologies to produce it 
 
This is when Advanced Manufacturing Technologies comes in. 
 
Scanning Electron Microscopy image of a micro gyroscope. 
 
 
To produce a micro device, several techniques are available in the world. Thin film deposition, Bulk & 
Surface Micromachining, LIGA Process, Soft Lithography, Micro-injection molding, etc. 
The list of industrial applications of microsystems is increasing day by day. Ink-jet printing heads, Thin-
film magnetic heads, Compact disks, Automotive components, Medical applications, and Chemical and 
environmental applications are just a few of already old technologies. 
Nanomanufacturing processes incorporate the same principle. Once you attain the required feature and 
the physics/mechanics artifact to attain the feature, you need to be aware of the different technologies 
and possibilities to build it. Top-down techniques (nanomachining), bottom-up techniques 
(nanodeposition), nanolithography, particle and surface functionalization or self-assembly process are 
just a few of the available technology families. 
 
Bibliography 
● The Development of Micromachined Gyroscope Structure and Circuitry Technology 
http://www.mdpi.com/1424-8220/14/1/1394 
 
 
8. Microtechnology processing technologies 
The trend for micro-manufacturing at the present time is focused on miniaturizing or down-scaling both 
conventional and non-conventional methods to produce micro-products. Additionally, there are also 
emerging methods, such as the hybrid manufacturing methods, which combine two or more processes 
together. Manufacturing processes can be categorized according to the type of energy used in the 
process itself, such as mechanical, chemical, electrochemical, electrical and laser processes. The working 
principles behind each process include consideration of mechanical forces, thermal effects, ablation, 
dissolution, solidification, re-composition, polymerisation/lamination, and sintering. According to the 
way in which components/products are to be made, general manufacturing processes can also be 
classified into subtractive, additive, forming, joining and hybrid processes. The classification is equally 
applicable to micromanufacturing. Typical manufacturing methods against the way of producing 
components/products are: 
Subtractive processes: Micro-Mechanical Cutting (milling, turning, grinding, polishing, etc.); Micro-EDM; 
Micro-ECM; Laser Beam Machining; Electro Beam Machining; Photo-chemical-machining; etc. 
Additive processes: Surface coating (CVD, PVD); Direct writing (inkjet, laser-guided); Micro-casting; 
Micro-injection molding; Sintering; Photo-electro-forming; Chemical deposition; Polymer deposition; 
Stereolithography; etc. 
Deforming processes: Micro-forming (stamping, extrusion, forging, bending, deep drawing, incremental 
forming, superplastic forming, hydro-forming, etc.); Hot embossing; Micro/Nano-imprinting; etc. 
Joining processes: Micro-Mechanical-Assembly; Laser-welding; Resistance, Laser, Vacuum Soldering; 
Bonding; Gluing; etc. 
Hybrid processes: Micro-Laser-ECM; LIGA and LIGA combined with Laser-machining; Micro-EDM and 
Laser assembly; Shape Deposition and Laser machining; E-Fab; Laser-assisted-micro-forming; Micro 
assembly injection molding; Combined micro-machining and casting; etc. 
The definition of what constitutes a micro product or part can be placed as: 
- parts possessing a weight in the range of few milligrams; 
- parts possessing features where dimensions are in the micrometer range; 
- or, parts exhibiting dimensional tolerances in the micrometer range but without dimension limit. 
We will now explore some of this micromanufacturing methods. 
 
8.1 Thin film deposition 
Thin film deposition involves processing above the substrate surface. Material is added to the substrate 
in the form of thin film layers, which can either be structural layers or act as spacers later to be 
removed. MEMS deposition techniques fall into two categories, depending on whether the process is 
primarily chemical or physical. In chemical deposition, films are deposited via a chemical reaction 
between the hot substrate and inert gases in the chamber at low or atmospheric pressure. Depending 
on the phase of the precursor, chemical deposition is further classified into plating, spin coating, 
chemical vapor deposition (CVD) (e.g. low pressure CVD, plasma-enhanced CVD, and very low pressure 
CVD), and atomic layer deposition. In physical deposition, the raw materials (solid, liquid or vapor) are 
released and physically moved to the substrate surface, e.g. thermal evaporation, sputtering and ion 
plating. The choice of deposition process is dependent upon several factors, e.g. substrate structure, 
operating temperature, rate of deposition and source. These film layers are deposited and subsequently 
patterned using photolithographic techniques, then etched away to release the final. 
8.1.1. Chemical Vapor Deposition (CVD) of Diamond 
In 1982, Matsumoto et al. made a breakthrough in CVD diamond technology. They used hot filaments 
(at 2000 °C) to directly activate hydrogen and hydrocarbon which were passed through the hot filament. 
The diamond film was then deposited onto a non-diamond substrate located 10 mm away from the 
filament. Graphite was etched simultaneously by atomic hydrogen during deposition which rendered 
the cycling of deposition and etching unnecessary and therefore led to a higher growth rate (1 µm/h). 
The growth of a polycrystalline diamond film starts from distinct nucleation sites. As individual randomly 
oriented nuclei grow larger. With increasing film thickness, more and more grains are overgrown and 
buried by adjacent grains. Only those crystals with the direction of fastest growth perpendicular to the 
surface will survive. The growth process follows a cyclic reaction: 
1) Activation of the gas mixture; 
2) Transport of the active gas mixture to the substrate; 
3) sp2 and sp3 simultaneous deposition; 
4) Dissolution of the deposited sp2 carbon in the gas phase (etching) or its conversion to sp3. 
 
 
Reactions taking place inside the CVD chamber during diamond growth 
 
Various activating methods for diamond CVD such as hot-filament CVD (HFCVD), DC-plasma, RF-plasma, 
microwave plasma, electron cyclotron resonance-microwave plasma CVD, and their modifications were 
developed. 
The HFCVD method is relatively cheap and easy to operate and produces reasonable quality 
polycrystalline diamond films at a rate of 1 to 10 μm.h−1,depending upon the exact deposition 
conditions. Despite suffering from a number of disadvantages, namely its sensitivity to oxidizing or 
corrosive gases, which limits the variety of gas mixtures that can be employed and the difficulty to avoid 
contamination of the diamond film with filament material, it is a suitable method for the mechanical 
application being tested in this work. Hot-filament CVD uses a vacuum chamber continuously evacuated 
using a rotary pump, while process gases are metered, at carefully controlled rates, through mass flow 
controllers. Throttle valves maintain the pressure in the chamber. The substrate to be coated is placed 
on a holder, a few millimeters beneath the filament, which is electrically heated to temperatures in 
excess of 2000 °C. At this temperature, as H2 passes over the hot filament, atomic hydrogen is produced. 
 
 
Schematic of a HFCVD system used to deposit the diamond films 
 
Typical Diamond Deposition Conditions 
Parameter Value 
H2 flow (sccm) 150 
CH4 flow (sccm) 3 
Filament temperature (C) 2000 
Substrate temperature (C) 700 
Filament-substrate distance 
(mm) 
8 
Deposition pressure (Torr) 30 
Base pressure (Torr) 
2 x 10-
2 
 
 
 
SEM images of diamond deposition onto AISI P20 modified steel with chromium nitride interlayer 
 
Diamond films deposited on surfaces of non-diamond materials is termed as heteroepitaxial growth. 
Such thin films and surface coatings can be deposited onto a variety of materials, which can be classified 
into the following three groups: 
- strong carbide-forming materials, including Si, Ti, Cr, W and SiC; 
- strong carbon-dissolving materials, including Fe, Co and Ni; 
- small or non-carbon affinity materials, such as Cu and Au. 
The synthesis of diamond on carbide-forming materials usually leads to the production of adherent 
diamond coatings. Silicon is a widely used material for depositing diamond films using CVD processes. 
This is because silicon has a sufficiently high melting point (1683 K), it forms a localized carbide layer and 
it has a comparatively low thermal expansion coefficient. 
On the other hand, diamond grown directly on strong carbon-dissolving materials, such as steel, or on 
non-carbon affinity materials, such as copper, yields poor adhesion. Steel is a carbon-dissolving material, 
especially at diamond CVD conditions (1.3 wt.% C at 900°C). Therefore, during diamond CVD, the carbon 
swiftly diffuses into the steel substrate, forming a soot composed of graphite, Fe3C and other carbides, 
thus leaving behind relatively little carbon precursor at the steel surface, to initiate the formation of 
carbon–carbon sp3 bonds, typically found in the diamond lattice. This normally results in poor diamond 
nucleation densities, film growth and diamond adhesion to the steel substrates. 
Nevertheless, this is not the only problem that hinders the successful deposition of diamond coatings on 
steel using vapor-assisted deposition processes. Iron (Fe) is known to have a high vapor pressure (2.53 × 
10−8 mbar), so it expectedly diffuses out from the bulk steel material towards the substrate surface 
during the growth process. Iron is known to catalyze the growth of sp2 carbon bonds found in graphite 
and also in carbon nanotubes. Furthermore, the difference in the thermal expansion coefficients of 
diamond and steel is sufficiently large, which results in the incorporation of residual stresses in the 
deposited diamond films and influences the adhesion in a negative way (weakens the adhesion strength 
at the diamond/steel interface). 
 
Schematic of the critical processes taking place in and on the steel substrate during diamond synthesis from the vapor phase 
 
A possible solution to overcome the problems addressed above is to use an interlayer or an interlayer 
system, consisting of several intermediate sandwiched layers that block both inward carbon and 
outward Fe vapor diffusions. An ideal interlayer material should detain the following characteristics: 
- refractory material that can tolerate the high CVD temperature used for diamond synthesis 
(usually 700 – 900 °C); 
- good chemical compatibility with carbon (carbide former); 
- good adhesion to the substrate material; 
- thermally stable – structurally and geometrically – when submitted to typical temperatures of 
the CVD process; 
- accommodate thermal-induced stresses developed during the growth and ramp down 
processes, due to thermal expansion coefficient mismatch; 
- promote an effective barrier for carbon diffusion in Fe and outward diffusion of Fe vapor; 
- good control of film thickness and surface morphology; 
- should be competitively priced. 
Good adhesion requires both substrate/interlayer mutual diffusion and interlayer/carbon affinity 
(carbide formation). Hence, in order to obtain a strong coupling between the substrate and the 
interlayer, Fe must diffuse adequately into the interlayer material. Iron is known to have low diffusion in 
W, Ta and Cr; medium diffusion in Cu, Ag and Au and high diffusion in Ti. Among these materials, Cu, Au 
and Ag do not form carbides, therefore, those are not best suited for diamond deposition. However, 
carbon has a high diffusion in Ti, medium in Cr and Ta and weak in W. The literature has highlighted 
several successful attempts where chromium nitride (CrN) interlayers were used. 
 
 
Cross-section SEM images and EDS maps of diamond deposition onto AISI 304 steel with chromium nitride interlayer 
 
8.1.2. Physical Vapor Deposition 
Physical vapor deposition processes are atomistic deposition processes in which material is vaporized 
from a solid or liquid source in the form of atoms or molecules and transported in the form of a vapor 
through a vacuum or low pressure gaseous (or plasma) environment to the substrate, where it 
condenses. Typically, PVD processes are used to deposit films with thicknesses in the range of a few 
nanometers to thousands of nanometers; however, they can also be used to form multilayer coatings, 
graded composition deposits, very thick deposits, and freestanding structures. The substrates can range 
in size from very small to very large, for example the 10' X 12' glass panels used for architectural glass. 
The substrates can range in shape from flat to complex geometries such as watchbands and tool bits. 
Typical PVD deposition rates are (1—10 nanometers) per second. Physical vapor deposition processes 
can be used to deposit films of elements and alloys as well as compounds using reactive deposition 
processes. In reactive deposition processes, compounds are formed by the reaction of the depositing 
material with the ambient gas environment such as nitrogen (e.g. titanium nitride, TiN) or with a co-
depositing material (e.g. titanium carbide, TiC). Quasi-reactive deposition is the deposition of films of a 
compound material from a compound source where loss of the more volatile species or less reactive 
species during the transport and condensation process is compensated for by having a partial pressure 
of reactive gas in the deposition environment; for example, the quasi-reactive sputter deposition of ITO 
(indium—tin oxide) from an ITO sputtering target using a partial pressure of oxygen in the plasma. 
The main categories of PVD processing are vacuum deposition (evaporation), sputter deposition, arc 
vapor deposition, and ion plating. 
 
PVD Processing Techniques: (a) Vacuum Evaporation, (b) and (c) Sputter Deposition in a Plasma 
Environment, (d) Sputter Deposition in a Vacuum, (e) Ion Plating in a Plasma Environment with a Thermal 
Evaporation Source, (f) Ion Plating with a Sputtering Source, (g) Ion Plating with an Arc Vaporization 
Source,and (h) Ion Beam-Assisted Deposition (IBAD) with a Thermal Evaporation Source and Ion 
Bombardment from an Ion Gun 
Vacuum Deposition (Vacuum Evaporation) 
Vacuum deposition, which is sometimes called vacuum evaporation, is a PVD process in which material 
from a thermal vaporization source reaches the substrate with little or no collision with gas molecules in 
the space between the source and substrate. The trajectory of the vaporized material is "line of sight." 
The vacuum environment also provides the ability to reduce gaseous contamination in the deposition 
system to a low level. Typically, vacuum deposition takes place in the gas pressure range of 10-5 Torr to 
10-9 Torr, depending on the level of gaseous contamination that can be tolerated in the deposition 
system. The thermal vaporization rate can be very high compared to other vaporization methods. The 
material vaporized from the source has a composition which is in proportion to the relative vapor 
pressures of the material in the molten source material. Thermal evaporation is generally done using 
thermally heated sources such as tungsten wire coils or by high energy electron beam (e-beam) heating 
of the source material itself. Generally, the substrates are mounted at an appreciable distance away 
from the evaporation source to reduce radiant heating of the substrate by the vaporization source. 
Vacuum deposition is used to form optical interference coatings, mirror coatings, decorative coatings, 
permeation barrier films on flexible packaging materials, electrically conducting films, wear resistant 
coatings, and corrosion protective coatings. 
 
Sputter Deposition 
Sputter deposition is the deposition of particles vaporized from a surface ("target") by the physical 
sputtering process. Physical sputtering is a non-thermal vaporization process where surface atoms are 
physically ejected from a solid surface by momentum transfer from an atomic-sized energetic 
bombarding particle, which is usually a gaseous ion, accelerated from a plasma. Generally, the source-
to-substrate distance is short compared to vacuum deposition. Sputter deposition can be performed by 
energetic ion bombardment of a solid surface (sputtering target) in a vacuum using an ion gun or Iow 
pressure plasma (<5 m Torr) where the sputtered particles suffer few or no gas phase collisions in the 
space between the target and the substrate. 
Sputtering can also be done in a higher plasma pressure (5—30 mTorr) where energetic particles 
sputtered or reflected from the sputtering target are "thermalized" by gas phase collisions before they 
reach the substrate surface. The plasma used in sputtering can be confined near the sputtering surface 
or may fill the region between the source and the substrate. The sputtering source can be an element, 
alloy, mixture, or a compound and the material is vaporized with the bulk composition of the target. The 
sputtering target provides a long-lived vaporization source that can be mounted so as to vaporize in any 
direction. 
Compound materials such as TiN and zirconium nitride (ZrN) are commonly "reactively sputter 
deposited" by using a reactive gas in the plasma. The presence of the plasma "activates" the reactive gas 
("plasma activation"), making it more chemically reactive. Sputter deposition is widely used to deposit 
thin film metallization on semiconductor material, coatings on architectural glass, and reflective coatings 
on compact discs (CDs), and for magnetic films, dry film lubricants, hard coatings (tools, engine parts), 
and decorative coatings. 
 
 
 
 
Arc Vapor Deposition 
Arc vapor deposition uses a high current, low voltage arc to vaporize a cathodic electrode (cathodic arc) 
or anodic electrode (anodic arc) and deposit the vaporized material on a substrate. The vaporized 
material is highly ionized and usually the substrate is biased so as to accelerate the ions ("film ions") to 
the substrate surface. Arc vapor deposition is used to deposit hard and decorative coatings. The ions 
("film ions") that are formed in arc vaporization are useful in the ion plating process. 
 
lon Plating 
Ion plating, which is sometimes called ion-assisted deposition (IAD) or ion vapor deposition (IVD), utilizes 
concurrent or periodic bombardment of the depositing film by atomic-sized energetic particles to 
modify and control the properties of the depositing film. In ion plating the energy, flux, and mass of the 
bombarding species along with the ratio of bombarding particles to depositing particles are important 
processing variables. The depositing material may be vaporized either by evaporation, sputtering, arc 
erosion, or by decomposition of a chemical vapor precursor. 
The energetic particles used for bombardment are usually ions of an inert or reactive gas, or, in some 
cases, ions of the condensing film material ("film ions"). Ion plating may be done in a plasma 
environment where ions for bombardment are extracted from the plasma or it may be done in a 
vacuum environment where ions for bombardment are formed in a separate "ion gun." The latter ion 
plating configuration is often called ion beam-assisted deposition (IBAD). By using a reactive gas in the 
plasma, films of compound materials can be deposited. Ion plating can provide dense coatings at 
relatively high gas pressures where gas scattering can enhance surface coverage. 
Ion plating is used to deposit hard coatings of compound materials, adherent metal coatings, optical 
coatings with high densities, and conformal coatings on complex surfaces. 
 
 
 
 
8.2. Photochemical machining 
Photochemical machining is a chemical milling process used to fabricate components using a photoresist 
and etchants to corrosively machine away selected areas. It is mainly considered for sheet metal, but 
nonmetal machining can be done, with the selection of appropriate etchants. This process emerged in 
the 1960s as an offshoot of the printed circuit board industry. Photo etching can produce highly complex 
parts with very fine detail accurately and economically. 
This process can offer economical alternatives to stamping, punching, laser or water jet cutting, or wire 
electrical discharge machining (EDM) for thin gauge precision parts. The tooling is inexpensive and 
quickly produced. This makes the process useful for prototyping and allows for easy changes in mass 
production. It maintains dimensional tolerances and does not create burrs or sharp edges. It can make a 
part in hours after receiving the drawing. 
 
8.2.1. Wet etching and photolithography 
Etching is used in microfabrication to chemically remove layers from the surface of a wafer during 
manufacturing. Etching is a critically important process module, and to arrive to a final part, it undergoes 
many etching steps before it is complete. For many etch steps, part of the substrate is protected from 
the etchant by a "masking" material which resists etching. In some cases, the masking material is a 
photoresist which has been patterned using photolithography. Other situations require a more durable 
mask, such as silicon nitride. 
Photolithography is a process used to pattern parts of a thin film or the bulk of a substrate. It uses light 
to transfer a geometric pattern from a photomask to a light-sensitive chemical "photoresist" on the 
substrate. 
 
The etch can be a plasma or, most often, a liquid liquid-phase ("wet") etchants. In wet etching the wafer 
can be immersed in a bath of etchant. Buffered hydrofluoric acid (BHF) is used commonly to etch silicon 
dioxide over a silicon substrate. 
It must noted that different etching solutions can have different etching rate in different crystalline 
directions,therefore it permits the formation of distinct geometric structures. 
 
 
8.2.2. LIGA Process 
The LIGA-process is used to manufacture micro structures by deep X-ray lithography. LIGA is the german 
acronym for lithography, electroplating and molding. 
The LIGA-process provides high aspect ratio micro structures in polymers like e.g. PMMA (better known 
as acrylic glass). Via electroplating these structures can be replicated in metals like gold, nickel, magnetic 
nickel-iron alloys or copper. Even replications in ceramics are possible. 
The main characteristics of LIGA-structures are: 
● large layout freedom in the mask geometry 
● high aspect ratios of up to >100 achievable 
● parallel side walls with flank angle very close to 90° (deviation: about 1 µm for 1 mm high 
structures) 
● smooth side walls (Ra in the 10 nm range) suitable e.g. for optical micro mirrors 
● lateral precision in the few micrometre range over distances of several centimetres 
● structural details on side walls in the 30 nm range possible 
● different side wall angles via double exposure possible 
The LIGA-process includes these principal steps (as illustrated in the figure bellow): 
1. Apply resist, X-ray exposure through mask 
2. Remove exposed portions of resist 
3. Electrodeposition to fill openings in resist 
4. strip resist for (a) mold or (b) metal part 
 
 
 
8.3. Micromachining 
8.3.1. Ultra-High Precision tooling 
Ultra-high-precision machining indicates machining techniques within 0.1 micrometer of absolute 
machining precision, and with Ra of 0.01 micrometer as the surface coarseness, as well as the ratio 
between the machining allowance and machined dimension being 10- 6. It is a comprehensive set of 
techniques, requiring the consideration of high-precision machine tools and equipment, precision 
instruments and meters, control apparatus, optimal quality workpiece and materials, cutting tools, as 
well as techniques and environmental cleanliness. 
 
 
 
8.3.2. Laser Micromachining 
Laser micromachining is the generic term for a process used to make tiny features in parts - measured 
in micrometers or millimeters. Pulsed lasers effectively complete this work by depositing very small, 
finite amounts of energy into a material, resulting in extremely precise and reproducible material 
removal. Suitable deposition of energy enables the laser to ablate, cut, drill, machine or scribe a 
material. Two common micromachining processes are laser drilling and laser micro milling. 
It presents an high degree of flexibility, contact- and wear-less machining, the possibility of high 
automation as well as easy integration allows using this tool in a wide field of macro machining 
processes for many materials including silicon, ceramics, metal and polymer. 
 
 
 
 
8.4. Molding 
8.4.1. Soft Lithography 
The term soft lithography refers to the fabrication of patterned copies using a polydimethylsiloxane 
(PDMS) stamp. Elastomeric stamps and molds provide a great opportunity to eliminate some of the 
disadvantages of photolithograpy. In the case of “soft lithography” there is no need for complex 
laboratory facilities and high‐energy radiation. Therefore, this process is simple, inexpensive, and 
accessible. 
 
 
 
Microcontact printing. Standard photolithographic techniques are used to create a mold. Photoresist is 
spun onto a silicon wafer, after which a chrome mask is placed over the photoresist and the exposed 
areas of photoresist irradiated with UV light. After developing the exposed photoresist, the mold is 
created. PDMS is poured over the mold and allowed to cure at 90°C for 1 hour. The PDMS stamp is 
coated with biologically active molecules, such as laminin, and used to stamp a cellular growth surface. 
 
 
(A) SEM of a PDMS stamp. Patterns are 7 μm high and 5 μm wide. (B) Fluorescence image of plastic 
surface that has been stamped with 50 μg/mL mouse laminin. Fluorescein has been added to the ink for 
visualization of the laminin micropattern. (C) Hoffman modulation contrast (HMC) image of a 
microelectrode array used for electrical stimulation. (D) Fluorescence image of microelectrode array 
surface that has been stamped with 200 μg/mL mouse laminin and Texas red. Scale bars: (A) 500 μm; (B, 
D) 200 μm; (C) 1 mm. 
 
 
8.4.2. Micro Injection Molding 
Several molding processes such as hot embossing, microinjection molding (µIM), reaction injection 
molding, injection compression molding and thermoforming are used for making thermoplastics 
microparts. Special applications that use these different processes have recently emerged, such as 2K 
injection molding, over-molding or micro-assembly injection molding. Other processing techniques for 
making high precision product such as extrusion, roll-to-roll and thermoforming could be cited. 
The hot embossing and the µIM seem to be the most industrially viable processes used for molding 
microparts. The hot embossing process uses a pre-heated mold in which a microstructured tool (mold 
insert), situated in an evacuated chamber, is brought into contact with the semi-finished thermoplastic 
polymer. After melting the polymer, the whole tool and part are cooled down and the part is demolded. 
 
Schematic drawing of the hot embossing process. 
A major inconvenience for this process is that long cycle times until 30 min are needed for heating both 
the mold and the material. Some tool improvements exist in order to reduce cycle times. The hot 
embossing process uses low flow velocities, low pressures, as well as slow cooling rate, leading to weak 
internal stresses in the material. The residual layer created during the process makes the demolding 
easier. Accordingly, the hot embossing process suits for replicating complex or high aspect ratio 
microstructures (>2), sometimes used for optical devices. 
The second industrially viable process, the µIM, involves melting the polymer into a plasticization unit, 
and injecting it into a microstructured mold insert. The material is then cooled and the part demolded. 
 
Schematic drawing of the injection molding process. 
The main difficulty for making such parts is that the aspect ratio, defined as thickness/lateral dimension, 
is generally higher than 1. Thus, the thickness of parts is not negligible with regard to the other 
dimensions, as in the conventional IM process. 
Specific conditions should be chosen for a good replication of parts. Different studies have shown that 
the main process parameters are: 
i. the mold temperature; 
ii. the injection speed; 
iii. the injection pressure; 
iv. the holding time; 
v. the holding pressure. 
The independent system for melting the polymer allows a limitation of the cycle times. The polymer 
flows through small sized runners and gates using high speed and high pressure, which can favor its 
degradation. The fabrication of high aspect ratio micro features can be achieved by using a mold 
temperature close to the softening temperature of polymer, with structure sizes in the nanometer 
range. 
This technology does not consist of a scaling down of the classical IM process, but needs radical changes 
in methods and practices. Different technological issues for each process component: 
i. mold construction technology 
ii. application engineering 
iii. raw material variation 
iv. precision technology 
v. nano-rheology 
vi. process measurement 
vii. product properties 
viii. modeling of the molding process. 
Structure heterogeneities were frequently observed within the thickness of classical injected parts. 
These microstructure variations are related to different cooling conditions during processing,and could 
involve dramatic effects for replicated microparts. The contact of the flow of semi-crystalline polymer 
with the cold cavity wall is responsible for the formation of a skin and thus for variations within the 
crystalline structure in the thickness of samples. Consequently, microstructures replication is affected by 
the processing conditions, and can result in some defects in replicated parts. The viscosity of polymer 
melts is shear rate and temperature dependent. The rapid cooling of the polymer is accentuated in the 
case of µIM because of a high contact surface of polymer with the mold wall. This results in a great 
increase in the polymer's viscosity, which can favor the development of defects in microparts. Such an 
effect should be minimized by increasing the melt temperature or using a higher mold temperature than 
those recommended by the manufacturers. A system defined as 'Variotherm' varies the mold 
temperature during the injection cycle. This system is highly recommended to minimize the increase of 
cycle time in microinjection process due to the high temperatures needed to fill the microfeatures. The 
advantages of using a variotherm system are numerous. Indeed, this prevents the material degradation 
by decreasing the different injection conditions. The cooling of material is better controlled and internal 
residual stresses are lower. Concerning final products, weld line presences and short shots are avoided. 
However, this process leads to an increase in the cycle time, compared to a fixed mold temperature, as 
used in conventional process. The high temperature range variation, from several tens of degrees to 
hundreds, can also reduce the mold lifetime. Materials with a high thermal conductivity should be 
preferred for the realization of the mold. 
 
Bibliography 
A Review on Micro-manufacturing, Micro-forming and their Key Issues 
https://doi.org/10.1016/j.proeng.2013.02.086 
Handbook of Physical Vapor Deposition (PVD) Processing 
https://books.google.pt/books?id=aGUxoVTYjA8C 
Laser Micromachinig 
https://dx.doi.org/10.1007/978-3-642-17782-8_2 
Soft lithography for micro- and nanoscale patterning 
https://www.nature.com/articles/nprot.2009.234 
Microinjection molding of thermoplastic polymers: a review 
http://iopscience.iop.org/0960-1317/17/6/R02/ 
Injection Moulding of Parts with Microstructured Surfaces for Medical Applications 
http://dx.doi.org/10.1002/masy.200451332 
Commercial Micro Manufacturing 
http://www.cmmmagazine.com/ 
9. Nanotechnology processing technologies 
Nanotechnology is helping to considerably improve, even revolutionize, many technology and industry 
sectors that depend on materials at the nanoscale to achieve specific properties and, consequently, 
greatly extend the well-used toolkits of materials science. Using nanotechnology, materials can 
effectively be prepared to be stronger, lighter, more durable, more reactive, better electrical 
conductors, among many other properties. 
Nanotechnology can be defined as working at the atomic, molecular and supermolecular level, in the 
length scale of approximately 1-100 nm range, to understand, analyse, create and use materials, devices 
and systems with fundamentally new properties and functions due to their small structure. This is 
because in the 10-20 nm range, the physical, chemical and biological characteristics of matter can be 
significantly changed, which lead to the unique properties of nanomaterials and, consequently, 
improved product functionality. Historically, the term nanomaterial is applied to products derived from 
nanotechnology. Its definition has been proposed by several organizations including the International 
Organization for Standardization (ISO), Organisation for Economic Co-operation and Development 
(OECD), by means of the Comité Européen de Normalisation, EU Scientific Committee on Consumer 
Products (SCCP), EU Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) and 
the European Commission (EC). 
In this scope, other nano-related terms should also be defined, as is the case of nanoparticle and 
nanomaterial. Nanoparticle is defined as a particle that has at least one of its three dimensions in the 
order of 100 nm (maximum limit or less) and may be referred as nano-object. Nanoparticles with sizes 
below 20 nm are those for which the physical properties may vary more drastically in comparison with 
the conventional size materials. Another common notion is nanostructured nanoparticles, consisting of 
particles with structural features smaller than 100 nm, which may influence their physical, chemical 
and/or biological properties. Nanomaterial is a material with any external dimension in the nanoscale or 
having internal structure or surface structure at the nanoscale (ISO/TS 80004-1, 2010), which could 
exhibit novel characteristics compared to the same material without nanoscale features. It may refer to 
a material with just one dimension at a nanometer scale (as in the case of nanolayers, thin films or 
surface coatings), two dimensions at the nanoscale (such as nanofibers, nanowires, nanotubes or 
biopolymers) and three dimensions at the nanoscale (such as nanoparticles, dendrimers or quantum 
dots). The hierarchical relationship between many of the mentioned terms is presented in the bellow 
figure. There are other core terms and definitions to particles in the field of nanotechnologies. The 
bellow table shows a summary of the general terms used in the field. 
 
Hierarchical relationship between terms 
 
 
General terms used in the field of nanotechnology 
Term Definition 
Nanoscale Size range from approximately 1 nm to 100 nm. (a) 
Nanoscience Study, discovery and understanding of matter in the nanoscale, where size- and structure-dependent 
properties and phenomena, as distinct from those associated with individual atoms or molecules or with 
bulk materials, can emerge. 
Nano-object Material with one, two or three external dimensions in the nanoscale. (b) 
Nanostructure Composition of inter-related constituent parts, in which one or more of those parts is a nanoscale region. 
(c) 
Nanostructured 
material 
Material having internal nanostructure or surface nanostructure. (d) 
Nano-aerosol Aerosol comprised of, or consisting of, nanoparticles and nanostructured particles. 
Engineered 
nanoparticle (ENP) 
Nanoparticle intentionally engineered and produced with specific properties. 
Engineered 
nanomaterial (ENM) 
Nanomaterial designed for a specific purpose or function. 
Manufactured 
nanomaterial 
Nanomaterial intentionally produced for commercial purposes to have specific properties or specific 
composition. 
Nanofluid Dilute liquid suspension of nanoparticle with at least one of their main dimensions smaller than 100 nm. 
(a) Properties that are not extrapolations from a larger size will typically, but not exclusively, be exhibited in this size range. For such 
properties the size limits are considered approximate. 
(b) Generic term for all discrete nanoscale objects. 
(c) A region is defined by a boundary representing a discontinuity in properties. 
(d) This definition does not exclude the possibility for a nano-object to have internal structure or surface structure. If external 
dimension(s) are in the nanoscale, the term nano-object is recommended. 
 
 
 
 Nanomaterial 
 
Nano-object 
(one or more external 
dimensions on the 
nanoscale) 
 
Nano particle 
(3 external 
dimensions at the 
nanoscale) 
 
Nanofiber 
(2 external 
dimensions at the 
nanoscale) 
 Nanowire (conducting nanofiber) 
 
Nanotube 
(hollow nanofiber) 
 Nanorode (rigid nanofiber) 
Nanoplate(1 external 
dimensions at the 
nanoscale) 
 
Nanostrutured 
material 
(internal structure or 
superficial at the 
nanoscale) 
9.1. Trends in Nano-based products commercial production and use 
In 2016, the Organization for Economic Cooperation and Development (OECD) identified forty key and 
emerging technologies for the future, mapped into four quadrants that represent broad technological 
areas: biotechnologies, advanced materials, digital technologies, and energy and environment. 
Nanomaterials are highlighted in the advanced material quadrant. However, their applications and 
usage are transversal to other technologies and areas. The utilization of nanoparticles/materials within 
energy and environment, digital and biotechnologies fields reinforce the relevance of understanding 
their potential and increase the mission of a responsible fabrication and product’s life-cycle to respect 
Society. Furthermore, nanomaterials are expected to have impact in research and, mostly, consequent 
commercial applications and usage in industry sectors. 
Medicine is the area with highest expectations for the usage and improvements provided by advanced 
nanomaterials. Other sectors of Society are highlighted as well, such as textile by nanofibers, including 
military safety, energy with smart polymeric nanomaterials and food packing industry. 
Graphene and related materials are evidenced as promoter of enhanced applications, processes and 
products in a large range of sectors and industries. Future trends consider a better understanding of its 
physical properties, decrease the economic cost, and increase its production. Potential areas of 
application include consumer electronics, efficient energy storage solutions, such as lightweight 
batteries for electric cars, biological and chemical sensors, replacing option of scarce elements as 
platinum in the role of catalysts in chemical processes, coatings and lightweight composite materials for 
vehicles, aircrafts and satellites, and vehicles. Graphene, due to its uniqueness of combination of nano-
scale electronic and optical properties, could be a potential possibility for the next generation of 
electronics, displays and photovoltaic panels. Its flexibility allows for considering it to address 
fundamental societal challenges in Europe, e.g., in ICT, air and land transport, building and cities, 
(renewable) energy production and in healthcare applications, amongst others. 
In the energy sector, reduction of costs and efficiency improvements are estimated in wind-power and 
in photovoltaic cells, as well as for storage, in batteries and superconductors. In the transport sector it is 
also highlighted, considering that new graphene-based composite materials will improve the fuel 
efficiency of road vehicles and aircraft, reducing their weight also. 
Focusing the trend analysis in applications, nanomaterials will improve or create smart polymers for 
smart irrigation and environmental biotechnology. There is the conviction that nanomaterials, 
particularly multilayer materials, will have a strong utilization for ICT and transport, advanced smart 
multifunctional foams with improved structural integrity, sound absorption and dielectric losses; 
Nanoporous materials in assembled products as gas storage, batteries will be capitalized and the 
exploitation of quantum phenomena in nanomaterials will allow their application in several 
nanoelectronic and nanophotonic applications. 
 
9.2. Engineered nanomaterial manufacturing processes 
Several fabrication techniques and processes are applied for the production of engineered 
nanomaterials (ENM). In numerous cases, it is possible to have multiple methods to manufacture a 
specific nanomaterial. In other situations, some techniques were developed and/or improved to meet 
specific synthesis needs of nanomaterials. Manufacturing processes, related to engineered 
nanomaterials synthesis, can be classified, depending on the production method adopted, as: top-down, 
bottom-up or hybrid approaches; type of the nanomaterial; production process (physical, chemical or 
biological); growth medium (vapor, liquid, solid phases or hybrid); the nanomaterial features, such as its 
morphology or chemical composition; or even the engineered nanomaterial result, by means of the 
nano-based product type. 
Bottom-up manufacturing assumes the building of structures, atom-by-atom or molecule-by-molecule. 
Top-down manufacturing initiates with a macroscopic structure material and milling, etching or 
machining a nanostructure from it, trough material removing, by using techniques such as precision 
engineering and lithography. Top-down methods, such as electron-beam (EB), focused ion beam (FIB), X-
ray, deep UV, atomic force microscope, etc., and various lithography and etching methods can be 
applicable to fabricate nanometer size holes. 
 
 
Top-down (nanomachining) and bottom-up techniques (nanodeposition) 
 
Considering the growth medium and other related features, the major synthesis processes are 
vapor/aerosol phase, liquid phase and solid phase. Vapor/aerosol phase synthesis start with the 
evaporation of a compound material that participates in chemical reaction (precursor), to produce other 
one, in a reactor followed by a rapid cooling to generate an engineered nanomaterial. It includes 
processes as aerosol, gas condensation, arc discharge, chemical vapor deposition, physical vapor 
deposition, flame, laser ablation and vapor-liquid-solid. Vapor/aerosol phase have advantages compared 
to others, that considers less process stages, fewer by-products, better process design options, more 
pure products and capacity to build complex structures. It presents disadvantages which include 
aggregation/agglomeration of (nano)particles due to high temperatures, generation of inhomogeneous 
particle morphologies and polydisperse particle size, high reaction times (in a scale of seconds), leading 
to higher uncontrol of the process. 
Liquid phase processes may include sol-gel, solvothermal and sonochemical, among other techniques. 
The common procedure assumes mixing of the precursor material(s) with suitable solvents and 
appropriate reactants to generate a supersaturated solution and initial nucleation. It is followed by 
growth of the initial nucleus into nanoparticles (or precursors) via precipitation. The engineered 
nanomaterials are collected by means of filtration or centrifugation or as a coating on a specific 
substrate, followed by cycles of washing and drying to remove impurities and calcination of 
nanomaterials with the desired morphology. 
Better control of the chemical composition/stoichiometry and the possibility of production of 
multicomponent complex materials, morphology, and size distribution, a higher variety of engineered 
nanomaterials (ENMs) that can be generated due to wider selection of precursor materials, better 
control of aggregation or agglomeration, formation of well-dispersed material, and ease of surface 
modification and functionalization are advantages of liquid phase techniques, being the dominant 
synthesis for nanomaterials manufacturing. Disadvantages involve chemical contamination and, 
consequently, the necessity for purification, increased processes stages, longer reaction times, and the 
utilization of hazardous chemicals, their treatment and final disposition. 
Solid phase synthesis, also denominated physical methods, include milling, mechanochemical 
processing, sintering, among others. Engineered nanomaterials generated by solid phase methods have 
larger particle sizes and distribution and higher chemical inhomogeneity. 
The following presents the general methods, classified by joint production approaches