There are three main processes of precision machining, namely soft machining, hard machining, and electrical machining. So how do we choose the process? Below, Qingdao Haixinnuo Machinery Co., Ltd. will give you a detailed introduction:
1. CNC precision machining sequence
When the mold is large and deep, soft machining is used for roughing and semi-finishing before quenching, and hard machining is used for finishing after quenching; small and shallow molds can be milled at one time after quenching. If the mold walls are thin and the cavity is deep, electrical machining is used.
If the mold cavity has a large and flat bottom surface, after roughing with an integrated milling cutter, use a round nose milling cutter to clear the corners. The integrated milling cutter has a good cutting force and heat dissipation effect. The round nose milling cutter is more efficient than the flat bottom cutter in machining the parts that need to be cleaned, and it is not easy to chip.
2. Selection of NC precision machining tools
When CNC precision machining hardened molds, it is very important to choose the correct milling cutter. Generally, it is a good choice to choose a high-rigidity tool body design, a high-temperature, wear-resistant coating, and a tool made of superhard materials. In addition, the rigidity of the tool is very important. In order to increase the rigidity of the small-diameter milling cutter, the diameter of the tool holder is made much larger than the diameter of the tool to improve the machining finish and prolong the tool life; the overhang length of the tool clamping should be as short as possible. On the other hand, choose a new coating that allows the tool to withstand higher cutting temperatures.
3. Selection of CNC precision machining tool holder and tool clamping
The shank should have a dynamic balance or choose a sintered shank, and the shape of the shank should be adapted to the structure of the mold. Usually, there should be a half-degree gap between the milling cutter and the side of the workpiece. For example, if the side of the workpiece is a 3° inclined plane, the shape of the tool holder should be made 5/2 to obtain great rigidity. If the side of the workpiece is a 90° straight face, the tool holder should have a thin neck structure.
It is very important to clamp the milling cutter, which involves factors such as the tolerance of the tool holder, the fit of the tool holder and the tool holder, and the radial jump after installation. To this end, the tool holder should be manufactured to a tolerance of -0.0025mm to -0.005mm, or a shrink-fit clamp should be used to clamp the tool.
4. the selection of NC precision machining machine tools and the main points of NC programming
The use of rigid, high-precision machine tools can achieve good results. When programming a high-hardness mold, the path of the tool cutting into the mold should be a helical interpolation, and the cutting process is relatively stable. In cases where side or helical cutting cannot be used, oblique wave cutting should be used to avoid axial cutting. Programming also determines the size of the radial pass and the depth of the cut.