Types of ultra-precision machining
Intensive research
Optical sanding is the process of grinding the surface roughness of a workpiece to a level that allows it to be polished. Glass lenses are processed using abrasives such as aluminum oxide, SIC, and cast iron or aluminum abrasive discs. For precision grinding, a cast iron platen with correct shape accuracy is commonly used. The workpiece and the platen are supplied with abrasives and lubricants, and the relative motion of the two transfer the shape of the platen to the workpiece.
They can be categorized into flat surface grinding, spherical surface grinding, and round hole grinding If a scratch is formed during the fine grinding operation, it may be caused by environmental contamination, foreign matter mixed with the abrasive, or uneven grinding pressure.
Precision molds and other small workpieces, such as engraved mold electrical discharge machining, non-simple plane or spherical surface, can not be high-efficiency precision grinding, surface roughness is coarse to the point that it is impossible to free die material pressure ulcer, so grinding stone grinding, grinding stones are divided into the WA (aluminum oxide) system, the SIC system, the latter is particularly hard, the force is easy to cause scars easily, to prevent the grinding stone caused by the grinding scars to be from the beginning of the soft grinding stone, and do not use a large grinding stone, and then sufficiently replenish the grinding oil, and reduce the stroke of the grinding stone to move.
polished
Polishing is the final process of grinding, and the amount of processing is very small, and there is no need to set the disk. The base material of the polishing tool is made of wood rods such as white pine, American pine, tung, willow and so on as the abrasive tool, WS can also use plastic rods such as acrylic, Nylon, PBT and so on, and the polishing of steel is carried out with diamond paste in principle. The main reason for the workpiece to be out of square in polishing operation is that there are scars on the workpiece, which may be caused by micro-cracks occurring in the processing, collision, material defects, and excessive grinding force, in short, the abraded parts should be handled with care to avoid injury.
During or at the end of the grinding process, the following three items are measured or evaluated.
- outlook
- surface accuracy
- Dimensional accuracy
Most of the dimensional accuracy is evaluated qualitatively by visual method and microscope, and there are subjective qualitative evaluation based on experience, strict quantitative evaluation by measuring machine, and also by gauge, etc. to decide whether it is qualified or not by embedded touch, etc. The inspection of the grinding surface is also divided into general method and optical method.
Grinding the general mold to the optical surface will increase the cost of grinding, even if the shape of the mold is slightly incorrect, it is often smooth enough, if the flow channel does not affect the flow of resin or demolding, leaving abrasion marks is not a big problem, in addition, if the optical products are ground according to the feeling of the expensive workpieces will become waste, we must understand the hardness of the workpiece material, the amount of grinding to stay, the shape of the precision requirements, in order to efficiently achieve a reasonable specification.
Ultra Precision Machines
Ultra-precision machining machine can be divided into two types, one is aspheric surface creation machine, which can create the workpiece into the required shape and has the grinding function; the other is ultra-precision machining machine, which achieves the final surface accuracy by grinding and cutting process.
Aspherical Forming Machine
Asphere creation machine suitable for the production of telescopes in the beginning of the control mode of imitation cutting, the middle of the control mode of punching belt, the latest computer control, suitable for large-scale workpieces and the shape of a single, symmetrical rotary axis, extremely high precision, but the processing speed is extremely slow, the device is expensive, for the purpose of special-purpose machines can not be moved, and is not suitable for the processing of small workpieces.
Ultra-precision Machining Machines
Ultra-precision machining machine control for computer control, can process aluminum, stainless steel, gold and silver, various crystals, plastics and other materials, the workpiece holding method is mostly for the vacuum clamping method, the environment needs to be constant temperature, constant humidity, constant pressure, dust-free, the cutting tool is the use of diamond mono-crystalline lathe tool, grinding diamonds, CBN sintered grinding wheels, or coated grinding wheels. However, due to the processing speed is not fast, and the workpiece material is limited, the price of the device is high, and the setup site is limited, it is inevitable to have processing marks.
