Introduction
Micromachining are processes, such as micromilling and microdrilling, that enable the production of extremely small components with high precision. These techniques use CNC (Computer Numerical Control) machines capable of performing complex operations on very small surfaces. With micromachining, it is possible to create parts that meet the stringent requirements of industries such as military, medical and aerospace.
What is micromilling and microdrilling?
Micromilling is the process of removing material using micromills, which are much smaller than standard milling cutters. It allows the precise shaping and finishing of the surface of microscopically sized parts, which is crucial in the production of high-precision components. Typical micromilling machines can achieve tolerances of a few micrometers, which is essential in applications requiring high accuracy.
Microdrilling involves creating holes using microdrills with very small diameters, often less than 0.1 mm. This process is essential for applications requiring extreme precision, such as producing holes in microelectronic circuits or medical implants.
Both of these processes are part of the broader category of micromachining, which includes all cutting and shaping operations of materials on a microscopic scale. Micromachining makes it possible to achieve unprecedented precision and surface finish quality.
What cutting tools are used in micromachining? – examples
Carbides
Carbides are composite materials that are characterized by exceptional hardness and wear resistance. They are made from a combination of tungsten carbide (WC) and metallic cobalt (Co), which gives them excellent mechanical properties and durability. The hardness of carbides is usually around 1500-2000 HV (Vickers), which allows them to effectively machine even very hard materials. Carbides are also characterized by high compressive strength, reaching up to 5,000 MPa, and low thermal conductivity, which allows the cutting edge to remain sharp even at high temperatures.
Use in the manufacture of micro milling and micro drilling tools
Carbides are widely used in the production of micro mills and micro drill bits because of their strength and ability to maintain a sharp cutting edge. They make it possible to precisely produce micro holes and micro channels in hard materials such as stainless steel and titanium alloys. Carbides are also corrosion-resistant, which is important in machining materials with aggressive chemical properties.
Synthetic Diamonds (PCD – Polycrystalline Diamond)
Synthetic diamonds, also known as PCD (Polycrystalline Diamond), are materials consisting of many small diamond crystals bonded into one. They are characterized by extreme hardness of about 8,000 HV (Vickers) and high wear resistance. PCD also has a high thermal conductivity of about 1,000 W/mK, which allows it to efficiently dissipate heat generated during machining. As a result, PCD tools retain their cutting properties for a longer period of time.
Application in micromachining
Thanks to their abrasion resistance, PCD tools provide a longer service life and the ability to maintain a high-quality surface finish. The use of PCD in micromachining enables previously unattainable precision. Tools made from PCD are particularly effective at machining composite materials and ceramics, making them indispensable in many advanced technological applications. PCD is also resistant to the chemical effects of many materials, allowing them to be used in a wide range of working environments.
CNC machines in micromachining – what is important?
Multi-axis machines (5-axis CNC)
5-axis CNC machines allow tool movement in five different axes simultaneously. In addition to the standard three linear axes (X, Y, Z), they have two additional rotary axes that allow for complex spatial machining. This makes it possible to perform precise operations on complex surfaces without having to repeatedly reposition the workpiece. Thus eliminating ”human” error.
Machines with high rigidity and vibration dampening
Importance of minimizing vibration
Vibrations can lead to deterioration of surface quality, shortened tool life and reduced machining precision. They are an undesirable effect that can result from inadequate machine rigidity, improper workpiece clamping or suboptimal cutting parameters. Machines with high structural rigidity and effective vibration dampening ensure stability in the machining process, which translates into higher quality and repeatable results.
Examples of high rigidity machines
Examples of machines with high rigidity and vibration dampening capabilities include advanced machining centers from manufacturers such as Makino, Okuma and Mori Seiki. These machines are designed for maximum stability and precision machining, using materials and structures with high mass and rigidity. In addition, they are equipped with advanced vibration dampening systems that actively monitor and compensate for vibrations during the cutting process.
For example, Makino T-Series machining centers, known for their precision and stability, offer Vibration Control System (VCS) vibration dampening systems that automatically adjust machining parameters in real time to ensure optimal working conditions.
What are digital twins and what impact do they have on CNC micromachining accuracy?
Digital twins are virtual models of physical machines and manufacturing processes. Thanks to advanced digital technologies such as IoT (Internet of Things), artificial intelligence (AI) and data analytics, digital twins enable simulation, monitoring and analysis of real processes in real time. These virtual representations can accurately replicate the behavior of real systems, allowing them to predict how they will react to different operating conditions.
Digital twins use data collected from sensors mounted on real machines, which are then processed and analyzed to create an accurate virtual model. This makes it possible to monitor the condition of machines, detect anomalies and predict potential failures before they occur. Digital twins can also be used to optimize production processes by simulating different operating scenarios and selecting the most efficient one.
Coolants and lubrication in micromachining
Minimal Quantity Lubrication (MQL)
Minimal Quantity Lubrication (MQL) is a lubrication technique that applies minimal amounts of coolant directly to the tool and cutting area. Unlike traditional cooling methods, which require large amounts of liquid, MQL uses only a few milliliters per hour. Lubrication is by means of an oil mist, which effectively reduces friction and temperature while minimizing coolant consumption.
Environmental and economic benefits of MQL
MQL technology offers numerous environmental and economic benefits. Reduced coolant consumption translates into a smaller environmental footprint, reducing waste and consumption of natural resources. In addition, lower coolant consumption means lower operating and maintenance costs, which benefits businesses. In addition, MQL improves working conditions by reducing the risks associated with coolant leaks and contamination. The use of MQL eliminates the need to dispose of large quantities of coolants.
Summary
CNC micromachining technologies enable the realization of complex, high-precision components that are used in the aerospace, medical and military sectors. The tools discussed, such as carbides and synthetic diamonds (PCD), and the advantages of 5-axis CNC machines are revolutionizing today’s mechanical component manufacturing market.
