CNC metal parts processing – design and application of multi piece processing fixture.

With the progress of science and technology, the mechanical processing equipment has been continuously optimized and improved, its processing capacity and accuracy have been continuously improved, and the mechanical processing technology has also moved towards the direction of high efficiency and accuracy. The complicated process steps have been gradually optimized and reduced, the machining time of parts has been continuously shortened, and the production efficiency has been greatly improved. However, for some parts with simple processing technology, the processing time of the main process is far less than the auxiliary time such as the clamping time of the workpiece and the tool replacement time according to the traditional processing method of single piece processing, with low production efficiency and high labor intensity. 

However, the tooling with reasonable design can realize multi piece or small batch production, which not only reduces the labor intensity of workers, but also greatly shortens the auxiliary time, and improves the production efficiency while ensuring the product quality. Now let’s introduce some parts that need to be used inmetal parts  .

processed by CNC machined metal parts

Design principle of multi piece clamping tooling

The rationality of fixture design directly affects the quality, production efficiency and processing cost of the workpiece. In actual production, the design of tooling and fixture is mainly based on the processing technology scheme and the experience of operators. The number of clamping times and the frequency of tool change should be reduced as far as possible, and multiple processes should be completed at a time to save auxiliary time and improve production efficiency. When designing the fixture, the principle of reasonable structure, low cost and easy installation and disassembly shall be followed while ensuring the machining accuracy of the lathe.

Tooling design of screw

The processing technology of the screw is simple, and the metal parts processed by CNC machined metal parts are concentrated at both ends (the middle outer surface is not processed, and the anti-corrosion paint is sprayed at last). When milling the two sides of the plane with the traditional processing technology, only one piece can be clamped on the three jaw self centering chuck at a time. The clamping assistance time is long and the production efficiency is low.

However, the production of screw is large and the construction period is short, so the single piece processing may delay the construction period. 

After the special tooling is designed, 8 pieces can be clamped at a time. The tooling is positioned by counterbore. The center of every two holes is cut into a through groove with a width of 2mm to form a half opening. The tooling is made of super hard aluminum with high strength. Because the external surface roughness in the middle of the screw is not required to be high, after the workpiece is installed, the clamping force of the precision bench clamp is used to make the tooling produce a small amount of elastic deformation, and the workpiece is clamped to achieve multi piece processing. With the use of multi piece clamping tooling, four sides can be milled at a time, the tool stroke is greatly reduced, and the production efficiency is nearly 3 times higher.

Because the jaw height of the precision bench vise is limited, if the screw length is > 80mm, the workpiece cannot be fixed in the metal parts processed by cnc machined metal parts with the help of the clamping force of the precision bench vise. Therefore, the special fixture for long screw is designed according to the annual production capacity. The fixture also uses 8 positioning holes with the same diameter as the screw for positioning, and the chip discharge grooves are respectively milled below the 8 positioning holes to facilitate the cleaning of the tooling.

The tooling can clamp 8 pieces each time, and each two pieces are clamped with a special pressing plate to achieve multi piece processing. With this tool, 8 sides can be milled in the CNC metal processing process. The tool travel is short. At the same time, the time for auxiliary clamping and tool replacement is significantly shortened, and the production efficiency is significantly improved.

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