Additive manufacturing technology has a very wide range of application prospects in various fields, but the disadvantage is that its roughness is very high, and the roughness of 10-50 microns cannot meet the requirements of high-end equipment for the surface quality of components. Its practical application is still very limited. For additively manufactured products, it is imperative to carry out reasonable surface finishing treatment if it is to embark on a practical road.
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What is the standard of mirror-level processing, and what levels are there?
When it comes to the mirror level, customers often ask us if we can help them process it to the mirror level. We need to further ask him which level his mirror level should be. What is the approximate roughness range? Customers often don't know anymore. Regarding the mirror surface, no matter what kind of molding or processing method, some knife marks or undulations will be left on the surface of the workpiece. This is the so-called surface roughness, which was also called surface finish in the past. For general lathes, there are more than 3.2 microns, and 1.6 microns is already a high level for the lathe.
Of course, this 1.6 has nothing to do with the mirror polishing we are talking about. When the roughness reaches the level of 0.8 microns, the image of the object can be reflected more clearly. We think that the effect of mirror processing is initially obtained. Therefore, the mirror surface is considered to be 0.8 microns, and 0.8 microns is basically impossible to get out of the car, and it is usually necessary to use a grinder.
Relatively clear mirror processing level, the roughness is about 0.3~0.4 microns, when the roughness is reduced to 0.1 microns, it has entered the high-quality mirror processing stage, such as 0.1, it is a dark glossy mirror, 0.05 is usually called For the bright and glossy mirror effect, 0.025 achieves the mirror-like glossy effect, and 0.012 and 0.006 are basically relatively high-standard mirror standards, which are also difficult to achieve.
How do different surface treatments affect the properties of the material?
It mainly depends on the surface of the material, the type of force received, and the integrity of the surface of the material after processing. For example, the forces such as machining and abrasive flow are mechanical friction forces. There will inevitably be some micro-cracks and residual hard forces on the surface of the processed product, which will have a certain impact on the quality and service life of the workpiece. . For example, if the product has work hardening with residual stress, its hardness may increase.
The other type is chemical and electrochemical corrosion, which may have some corrosion traces, which will affect the strength of the product, and may also have some oxide films. For example, stainless steel will form a rich junction film during electrochemical polishing. , This film can have a certain impact on the corrosion resistance of the product. Plasma polishing technology, because it mainly relies on the continuous bombardment of various parts of the surface of the product by the high-energy particles closely covered on the surface of the workpiece, so the surface of the product made by it is basically free of damage, and there is no residual impurity and residual stress. the phenomenon, so the strength change of its processed products will not be obvious. However, the hardness may be slightly reduced. This uniform blow treatment method will relieve the effect of work hardening to a certain extent and may have a certain impact on the hardness.
The high-precision polishing case for runners
Perhaps the most famous runner is the mold. Many friends have come to consult before. For the mold, its internal requirements must be mirror-level. The starting level should be about 0.06, and the high level maybe 0.01. It is a very high mirror level.
Polishing methods such as electrolytic polishing and fluid polishing may not be suitable for molds because it is difficult to precisely control the geometric accuracy of parts. Methods such as chemical and ultrasonic and magnetic fluid polishing may not have the surface quality required for the roughness grade. Therefore, at present, the field of mold is still dominated by mechanical polishing. The general polishing process is to use coarse oilstone to roughen the cavity surface of the mold. The purpose of rough grinding is to remove the processed knife marks, and then use For the next grade of whetstone, polish off the processing marks of the coarse whetstone of the previous grade. After these processing marks are removed step by step, then use fine sandpaper to polish its surface, and finally use polishing paste, abrasive paste, etc., to further finish the cavity surface, so as to To achieve the processing effect as bright as a mirror.
Of course, there are also some parts of the mold, which can be brightened by ultrasonic polishing. This kind of processing efficiency is relatively high. Some people in the industry are using it, but the penetration rate is still not high, mainly by mechanical labor.