This paper describes the characteristic problems of aluminum cnc machining. If the object is limited to aluminum, cnc machining can be seen from a different point of view than steel materials. His characteristics have opened up new uses for aluminum and made it possible to apply fabricate methods with different manufacturing conditions than steel materials. There are many types of cnc machining, but here we will focus on machining. Even in aluminum, cnc machining such as machining, grinding and polishing is actually used. However, machining is the most widely used. There are excellent contributions regarding machining and polishing, so please refer to them 1), 2). The recent developments in machining technology are remarkable. For machining machines, examples are ultra-high-speed machining machines with spindle speeds of tens of thousands of revolutions and cnc machining centers that can perform various types of machining with auto tools and changers. As for tools, carbide tools are already common, and natural single crystal diamond tools are also used on an industrial scale. In addition, a large number of ultra-precision cut products that make full use of these techniques are also available. The current situation is that such technological development is closely related to the machining characteristics of aluminum, and the machining technology is becoming more sophisticated. Therefore, the author believes that machining aluminum also needs to be seen in terms of both machining technology and materials. In this article as well, he would like to consider machining aluminum from this perspective.
What Is Aluminum Alloy Machinability ?
The meaning of the machining workability of aluminum is “Is it possible to produce it economically, efficiently, and accurately?” Machinability can be explained by four factors: machining resistance, tool life, chip control, and surface finish. Therefore, in the steel department, this order is emphasized.
However, Alminium, which has different material properties, requires a different point of view. In the case of aluminum, the order of chip control, surface finish, tool life, and machining resistance is important.
The First Reason Is The Automation Of Machining Equipment.
Along with this, automation and unmanned machining processes have been promoted in order to improve productivity. However, originally, the chip control property of alminium is not very good. Therefore, it causes the problem of production interruption due to the entanglement of chips and seriously hinders productivity. So chip control becomes an important issue for him. Recently, the finishability of the machining surface has become important. One of the reasons is the increase in precision machining products. Computer discs, photoconductor drums, porigon mirrors, etc. are mass-produced as precision-cut products. Its production was in 1988, with 66 million computer discs and 20 million photosensitive drums. The reason why the market for precision machining products has grown so large is that alminium has excellent mirror workability. The background is that research and development of materials, tools, and equipment for ultra-precision machining have been actively carried out.
On The Other Hand, Tool Wear Is Minor Compared To Steel Materials.
However, it is a big problem for materials containing a large amount of Si, such as abrasion resistant metal. In precision machining, there are cases where even a few microns of wear, which has not been a problem until now, affects the condition of the machining surface. This is also different from machining steel materials. Machining resistance is also less important for aluminum. In the steel department, the machining resistance is large, so the scale of the equipment is also large, but in the case of aluminum, the machining resistance is about 1/3 of that of steel, so this is not a problem. However, recently, it has been reported that machining resistance has a subtle effect on the machining finish in precision machining 3). In the case of aluminum, deterioration of tool sharpness due to welding of the tool machining edge becomes a problem in terms of tool life. In the case of steel materials, the wear of the tool itself dominates the tool life. As described above, the way of thinking about machinability in alminium is quite different from that of steel materials.
Of course, cnc machining aluminum has not only advantages but also drawbacks. In some cases, the characteristics mentioned as points act as disadvantages. The following is a list of them.
- Long and continuous chips are often generated. Except for some alloys, aluminum has long and continuous chips. many. This is a fatal drawback in NC cnc machining. For he wouldn’t be without him, leaving a human to remove the chips. Also, entangled chips can be problematic because he scratches the cut surface.
- Easy to deform during cnc machining: Due to the soft material, it may be deformed by the pressure of the tool or by checking. If the work material is thin or long, it is easily deformed.
- Scratches on the surface: Because the material is soft, it is easy for the cut product to get scratches. When removing the product from the check, contact with a tool or machine may cause damage. Alternatively, the products may come into contact with each other and cause scratches.
- Processed altered layer is likely to be formed on the cut surface: Due to the soft material, a processed altered layer with a different structure from the inside is likely to be formed near the cut surface. Therefore, residual stress may be generated or it may interfere with the surface treatment in the subsequent process.
- Generally, a large amount of cnc machining oil is required: Since the cnc machining surface is easily peeled off without using cnc machining oil, it is a general rule to use cnc machining oil when cnc machining aluminum. In fact, it is common to use a large amount of cnc machining oil in NC aluminum machining. Therefore, it is necessary to prevent oil from scattering. Also. Aluminum has a large coefficient of thermal expansion, and its dimensions are easily changed by cnc machining heat. Therefore, cnc machining oil is required to prevent this.