Special processing refers to techniques that are not part of traditional processing technology. Unlike traditional processing methods, which use tools and abrasives to remove excess material through mechanical energy, special processing involves the direct use of electrical, thermal, acoustic, light, chemical, and electrochemical energy, sometimes in combination with mechanical energy, to process the workpiece.
Special processing is a relatively recent development and is an important addition to traditional processing methods. It is still undergoing ongoing research and development.
Two of the most widely used special processing techniques are EDM (electrical discharge machining) and electrolytic processing, which are primarily based on electric energy. These techniques are collectively known as electric machining.
The EDM process was invented in the 1940s and revolutionized the way hard workpieces could be machined using soft tools without the need for mechanical force.
In the 1950s, electron beam processing, plasma arc processing, and laser processing were introduced. These methods do not rely on forming tools but instead process the workpiece using a highly concentrated energy beam.
Special processing is increasingly being used to manufacture molds, measuring tools, blades, instrumentation, aircraft, spacecraft, and microelectronic components due to its great potential and applicability for high hardness materials and complex shapes, as well as its ability to produce precise and fine special parts.
The main direction of development for special processing is:
- Improve machining accuracy and surface quality
- Increase productivity and automation
- Develop composite processing using several methods in combination
- Develop nano-scale ultra-precision machining, etc.
1. Independence from Mechanical Properties of Workpiece
Some special processing methods, such as laser processing, EDM, plasma arc processing, and electrochemical processing, rely on thermal energy, chemical energy, and electrochemical energy, among others. These methods are not influenced by the mechanical properties of the workpiece, such as its hardness, allowing for processing of a wide range of metal and non-metallic materials with various properties, including hardness, brittleness, heat sensitivity, corrosion resistance, high melting point, and high strength.
2. Non-Contact Processing
Not all special processing methods require a tool, and even when tools are used, they do not come into direct contact with the workpiece. As a result, the workpiece is not subjected to large forces, and the tool hardness can be lower than that of the workpiece, enabling processing of components with low rigidity and elasticity.
3. Micro Processing
Some special processing methods, such as ultrasonic, electrochemical, water jet, and abrasive flow, allow for fine machining allowances, enabling not only the processing of small holes or slots but also the production of high-precision, low-roughness machined surfaces.
4. Minimal Mechanical and Thermal Strain During Processing
Special processing results in low surface roughness and minimal thermal stress, residual stress, and cold work hardening, leading to good dimensional stability.
5. Combined Use of Multiple Types of Energy
Special processing can involve the combination of two or more different energy sources, resulting in a new composite processing method with a noticeable improvement in effectiveness and ease of use.
6. Positive Impact on Processing Technology and Product Design
Special processing simplifies processing technology and enables changes in the design of new products and the structure and processability of parts.