Introductory Chapter: Current Trends in Micromachining Technology

1. Introduction

Originating in the mid-1900s, micromachining became a cutting-edge method that is changing the way we think about small-scale component fabrication. Micromachining usually refers to a precise micrometer scale subtractive manufacturing processes that are essential for producing highly precise micro components, which are needed in the electronics, medical, aerospace and other growing industries. Fabrication capabilities are constantly being improved by the meticulous design of tools and processes that can handle dimensions and tolerances that traditional machining cannot handle. The industry’s constant search for increasingly accurate and finer techniques is reflected in the progression from basic mechanical micromachining to more complex methods.

Through its special abilities and applications, micromachining sets itself apart from traditional machining. To meet the needs of a wide range of industries, micromachining can be used on a wider range of materials, such as polymers, metals and composites. Far beyond what is possible with conventional machining, micromachining produces features and tolerances on a micrometer scale. In these processes, much smaller and more precise micro tools are used, which frequently call for specific handling and setup. Precision that micromachining can provide is crucial for industries that require high levels of accuracy, such as semiconductor manufacturing and medical device fabrication.

This chapter provides a brief summary of the materials and techniques currently used in micromachining, as well as an overview of the main applications, challenges, and advancements in micromachining technology. It also provides a brief analysis of the current micromachining market.

2. Micromachining techniques and materials

The field’s precision and versatility are greatly enhanced by the multitude of techniques [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13] that are currently employed in micromachining, each well-suited to particular material and application. These techniques can be grouped into five major categories:

1. Mechanical micromachining [1, 2, 3, 4, 5, 6]– a method used in precision engineering to create small, detailed features on workpieces. It is crucial for high-precision industries like electronics and medicine because it allows realization of miniature parts with outstanding precision and surface qualities.

2. Thermal micromachining [7, 8]– a highly precise method for processing materials that are challenging to machine. Intense and focused energy source is used to modify or remove materials and create intricate details.

3. Chemical and electrochemical micromachining [9]– methods where chemical and electrochemical reactions are used for precise material removal and adequate surface finish.

4. Hybrid micromachining [10, 11]– a synergy of different machining techniques formed to improve the overall micromachining process.

5. Innovative techniques [12, 13]– techniques designed to meet specific requirements.

Each of these micromachining categories includes several key techniques presented in Table 1.

Category: Mechanical micromachining
Technique	Description	Application
Micro milling	CNC machines are being used for precise sculpting of complex shapes and geometries.	Micro molds, channels, and other intricate components.
Micro turning	Production of high surface quality and dimensionally accurate miniature cylindrical parts. Often combined with micro milling technique.	Small-scale components for medical, aerospace, and precision engineering applications.
Micro drilling	Creates precise microscale holes often using laser and ultrasonic technologies for advanced drilling.	Components for microfluidics, micro vias in PCBs.
Micro grinding	Creates components with exceptionally fine surface finishes using fine abrasive particles. Often used with other micromachining techniques.	Optical and other precision components.
Micro-USM*	Creates glass, hard metal or ceramic components using ultrasonic vibrations and abrasive slurry.	Semiconductor and MEMS components.
Category: Thermal micromachining
Micro-EDM*	Shaping hard metals using electrical sparks.	Micro molds, dies, precision components with high aspect ratios.
Micro-LBM*	Technique that uses focused laser beams to form high aspect ratio microscale features.	Metal, plastic, ceramic components, PCB production.
Micro-EBM*	Technique that uses electron beams for precise material removal	Complex components for aerospace and medical applications.
Category: Chemical and electrochemical micromachining
Chemical micromachining	Non-contact technique that uses controlled chemical reactions for etching micro-scale features.	Micro-scale glass, metal, silicon components.
Electrochemical micromachining	For high-precision micromachining free of the thermal stress anodic dissolution in an electrolytic solution is used in this technique.	Hard metal and alloy micro-components for medical, aerospace and automotive applications.
Category: Hybrid micromachining
Combined Hybrid Micromachining	Technique that combines different micro machining processes, often mechanical and thermal processes.	Precision engineering components.
Assisted Hybrid Micro Machining	Technique that combines primary micro machining and an auxiliary process that temporarily modifies material properties for easier material removal.	Aerospace and medical components.
Category: Innovative techniques
Micro-AJM*	Technique that uses high-velocity abrasive particles for material erosion	Glass and ceramic components.
Micro-FIB*	Technique that uses ion beams for accurate material deposition or milling.	Semiconductor manufacturing, MEMS fabrication.

Table 1.

Micromachining techniques.

*

Abbreviations: Micro-USM—Micro Ultrasonic Machining, Micro-EDM—Micro Electrical Discharge Machining, Micro-LBM—Micro Laser Beam Machining, Micro-EBM—Micro Electron Beam Machining, Micro-AJM—Micro Abrasive Jet Machining, Micro-FIB—Micro Focused Ion Beam Machining.

Micromachining techniques can handle fine micron scale features with extreme precision. Depending on the technique and material used, as well as on the component complexity, general tolerances are typically in the ± (0.001–0.005) mm range. Tolerances for high precision can be as low as ±0.0001 mm. Typical method-specific tolerances are presented in Figure 1. Micromachining tolerances [14] depend on multiple factors: material properties, tooling quality and precision, workpiece stability, machining environment, etc.

Figure 1.

Method-specific tolerances.

The precision and quality of the micromachined component are affected by how different materials react to micromachining techniques. Commonly used materials are metals (stainless steel, copper, titanium, etc.), ceramics (alumina, silicon carbide, etc.), polymers (ABS, Polycarbonate, etc.) and composites (Carbon Fiber Reinforced Plastics, etc.) [15, 16, 17, 18, 19]. Stainless steel, favored for its strength, durability and corrosion resistance, is one of the most popular materials used in micromachining [15]. Stainless steel is commonly used in medical applications for realization of various medical devices, implants and surgical instruments. Although highly-priced and difficult to machine, titanium is a valuable asset for micromachining [16]. It is light, heat and corrosion-resistant, biocompatible and inert and has a high strength-to-weight ratio. For these reasons, titanium can be used in a variety of applications ranging from medical to aerospace. Another metal suitable for precision machining, highly regarded for its natural corrosion resistance, thermal and electrical conductivity, durability and versatility, is copper. It is commonly used in electronics and cooling systems. Cost-efficient, nonconductive, nonmetal materials for micromachining are polymers [17]. Because of their inertness and adaptable properties, micromachined parts based on polymer materials are used in various industries ranging from medical to automotive. Micromachined alumina and silicon carbide parts are used in various industrial applications because of their thermal and chemical stability, dielectric strength, hardness, dimensional stability, ability to withstand harsh environments, etc. [18]. Micromachined ceramics allow fine feature formation without occurrence of heat-affected zones or microcracks while maintaining high cut quality. Carbon fiber-reinforced plastic (CFRP) materials are being recognized for their lightweight properties and high strength-to-weight ratio [19]. Micromachined CFRP parts are used in advanced engineering applications like electronics, aeronautics, automobiles, etc. Lately, micromachined glass has become of interest in the medical, aerospace, or microelectronic industries because micromachined glass parts can be manufactured with great accuracy while staying strong, are reusable and can be easily cleaned [19].

3. Primary micromachining applications

Contemporary micromachining techniques offer high precision and ability to work with diverse materials. They drive innovation and efficiency in a broad range of industries. Some of primary micromachining applications are in electronics, optics, telecommunications, medicine, MEMS, aerospace and automotive industries etc. (Figure 2). Micromachining is fundamental in microelectromechanical system (MEMS) manufacturing. MEMS microscale devices, actuators and sensors are being used in medical, electronics and automotive industries. In electronics, micromachining is essential in realization of miniature electronic devices such as microprocessors and microcontrollers. Electronic devices often require sub-micron range tolerances. Micromachined components for communication devices, such as micro-scale antennas and fiber-optic connectors, are essential in the field of telecommunications. Optical devices require precise geometries and excellent surface finishes. Performances of small-scale mirrors, lenses and other optical devices depend on high-precision micromachining techniques. Medical applications demand precise, complex, safe and effective micromachined implants and tools for surgical, diagnostic and other medical purposes. They require great precision, with tight tolerances, lower than ±0.002 mm. The aerospace industry requires miniature high-precision aerospace components of outstanding reliability and performance, e.g. fuel injectors, sensors, control mechanisms, etc. The automotive industry uses micromachining for creating small components for electric vehicles automotive sensors, fuel injection nozzles, etc. It can be concluded that micromachining’s capacity to deal with diverse materials and produce intricate micro-scale geometries makes it a leader in the development and prototyping of new devices in a number of industries, including nanotechnology and new material creation.

Figure 2.

Primary micromachining applications.

4. Micromachining advantages and challenges

Micromachining, as a key method in advanced manufacturing, has several advantages:

• It is highly precise with tight tolerances down to the sub-micrometer range.

• Micromachining is able to process diverse materials, ranging from ceramics and metals to glass, polymers and composites.

• An outstanding feature is the capability to produce micro-scale complex components.

• Micromachining techniques can deal with diverse industrial demands.

• Micromachining reduces material waste and enhances cost-effectiveness and environmental sustainability.

However, micromachining also comes with a number of challenges:

• Micromachining requires specialized equipment and highly skilled staff resulting in high initial costs.

• Micromachining techniques are complex.

• Facilities have special requirements (e.g. ability to house large micromachining equipment, controlled environment, etc.).

• Tool maintenance and calibration are mandatory.

While micromachining entails a number of inherent challenges, these can be effectively managed with the appropriate approaches. It is important to ensure that available micromachining equipment can process materials and achieve tolerances needed for selected applications. The components’ size and complexity must be taken into consideration when machining them. Machinery must be able to handle a range of microtools and work with CAD/CAM software to streamline processes. Feed rates and speed need to be carefully controlled to guarantee precision and reduce tool wear. Microtools are prone to rapid wear because of their small size and precision. This can be lessened by using premium materials and fine-tuning the machining parameters. Speed and efficiency in high-volume production environments must be carefully evaluated. It is important to choose energy-efficient equipment compatible with long-term growth strategies.

5. Micromachining market

Recent trends in product miniaturization in the electronics and semiconductor industries, where micromachining is essential for producing tiny parts, are driving the market. The micromachining market is expanding due to factors like faster data rates, greater compatibility with various wireless technologies, and longer battery lives of products, which is pushing IC manufacturers to rethink traditional production techniques. As a result, more electrochemical and laser machining processes are being used to produce micro components and provide precision machining. The application of Artificial Intelligence and the integration of the Internet of Things, Augmented Reality, Virtual Reality and 5G industries are also expected to benefit the market [20, 21]. Also, due to its widespread use in automotive industry, micromachining is becoming more and more in demand. It is used in fuel injection devices and electrical parts found in electrical vehicles.

Micromachining market share can be segmented on the basis of type, process, axis, end-use and regions [22, 23, 24]:

• By type, micromachining market can be divided into three segments: traditional, nontraditional and hybrid micromachining. The nontraditional micromachining encompasses laser, electrochemical (ECM), electro discharge (EDM) and laser micromachining. The nontraditional segment is being propelled by the precision, efficiency and wide applicability of the dominant laser micromachining. Ultrafast lasers are being developed especially for micromachining purposes stimulating the micromachining market expansion. The traditional segment owns its rapid growth to fast and adaptable material removal micro-milling process.

• By process, micromachining market can also be divided into two main segments: the dominant subtractive and additive micromachining. The subtractive segment owns its leading position in the cost and time-effective mass production, the ability to process various materials and produce large-scale components. The additive micromachining is also rapidly growing. Known as 3D printing for micromachining, additive micromachining is being used for versatile applications in MEMS sensors and industries such as medical, semiconductor, electronics, etc.

• By axes, micromachining market can be divided into three main segments: 3-axes, 4-axes and 5-axes micromachining (Figure 3). Until recently micromachining industry was led by 3-axes micromachining especially in advanced optics market. Nowadays, 5-axis micromachining replaces the casting process in realization of ultra-complex solid components mostly used in aerospace, automobile, medical and military equipment.

• By end-use, the micromachining market is oriented towards numerous industries: semiconductors, electronics, telecommunications, energetics, medical, automotive, military, aerospace, polymers, etc. (Figure 4). Electronic assemblies, sensors and optical MEMS components are driving the growth of military and aerospace industry.

• By region, micromachining market is being dominated by the Asia Pacific Region and North America (Figure 5). These regions hold the highest market share primarily because of the micromachined components (sensors, actuators, electrical assemblies, navigation controls, etc.) used in the automotive sector.

Figure 3.

Micromachining market share by axis.

Figure 4.

Micromachining market share by end-use.

Figure 5.

Micromachining market share by region.

6. Conclusion

Although it is recognized as a milestone in manufacturing technology, providing excellent flexibility and high precision, micromachining technology still needs to be improved upon and developed. However, in comparison to other modern techniques, micromachining offers advantages like low production costs, small batch sizes, and the ability to manufacture precise 3D surfaces in a variety of materials. The ability of micromachining technology to reliably fabricate much smaller features at very tight tolerances is one of its main advantages. Even though lithography-based manufacturing can produce finer component features, micromachining still has many advantages over it in terms of produced geometry complexity, material choices and accuracy. Furthermore, the technology shows promise in terms of its ability to close the gap between the macro and nano/microdomains.

Another major asset of micromachining technology is the way micromachining intersects with environmental sustainability [25]. Precise machining reduces the material waste. Novel equipment designs are focused on reduced energy consumption. Eco-friendly practices are being introduced in manufacturing processes as well as a tendency towards the recyclability of micro components and waste materials.

As technology advances and its impact extends across various industries, micromachining will continuously work on reshaping the future of manufacturing by driving innovation and efficiency and redefining what is achievable in miniaturization and precision engineering.

Acknowledgments

The authors are grateful to the Ministry of Science, Technological Development and Innovations of the Republic of Serbia (Contract No. 451-03-66/2024-2103/ 200017) for the financial support.

Conflict of interest

The authors declare no conflict of interest.