Tag Archive How to make precision parts

How to make precision parts

Numerical control tool is one of the preconditions to improve machining efficiency, its selection depends on the geometry of the machined parts, material state, fixture and machine tool rigidity. The following aspects should be considered:

(1) The cutting tool is selected according to the cutting performance of the part material. For example, turning or milling high strength steel, titanium alloy and stainless steel parts, it is recommended to choose indexable carbide tools with good wear resistance.

(2) The tool is selected according to the processing stage of hardware parts. That is to say, the roughing stage is mainly to remove the allowance, and the tool with better rigidity and lower accuracy should be selected. The semi finishing and finishing stages are mainly to ensure the machining accuracy and product quality of the parts, and the tool with high durability and high accuracy should be selected. The precision of the tool used in the roughing stage is the lowest, while the precision of the tool used in the finishing stage is the highest. If the same tool is selected for rough machining and finish machining, it is suggested that the tool eliminated from finish machining should be selected for rough machining, because the wear of tool eliminated from finish machining is mostly slight edge wear, and the coating is worn and polished. Continued use will affect the machining quality of finish machining, but has less impact on rough machining.

(3) According to the characteristics of NC lathe processing area, the tool and geometric parameters are selected. If the structure of the part permits, the cutter with large diameter and small ratio of length to diameter should be selected; the end edge of the over center milling cutter for cutting thin and ultra-thin wall parts should have enough centripetal angle to reduce the cutting force of the cutter and cutting parts. When machining soft material parts such as aluminum and copper, the end mill with slightly larger rake angle should be selected, and the number of teeth should not exceed 4.

When selecting the cutting tool, the size of the cutting tool should be adapted to the surface size of the workpiece. In production, end milling cutter is often used to process the peripheral contour of plane parts; when milling plane, cemented carbide blade milling cutter should be selected; when machining boss and groove, high speed steel end milling cutter should be selected; when machining rough surface or rough hole, corn milling cutter with cemented carbide blade can be selected; Ball end milling cutter, ring milling cutter, cone milling cutter and disk milling cutter are often used to process some solid surface and variable angle profile.

In free-form surface machining, because the end cutting speed of ball end cutter is zero, in order to ensure the NC machining accuracy, the cutting line spacing is generally very small, so ball end milling cutter is suitable for surface finishing. The end milling cutter is much better than the ball end milling cutter both in the surface processing quality and processing efficiency. Therefore, on the premise of ensuring that the parts can not be cut, the end milling cutter should be selected as far as possible when rough machining and semi finish machining curved surface.

In the machining center, all the tools are pre installed in the tool library, and the corresponding tool change action is carried out through the tool selection and tool change instructions of the NC program.