When turning copper screws, the first step is to ensure that the copper content of the workpiece is at least 99.5% or above, while the hardness of pure copper in the annealed state is generally 35-45HB. To ensure the processing quality of copper screws, the following precautions should be taken during processing:
1. During the machining process, chips may stick to the cutting edge, affecting the machining quality of copper screw workpieces and affecting the service life of the tool.
2. The surface of copper screws is prone to water like waveforms, which should be noted.
3. Pure copper has a high coefficient of expansion. During cutting, deformation occurs under the influence of high temperatures, making it difficult to grasp the size and accuracy of copper screw processing.
4. If copper parts contain easily cutting elements such as sulfur, it will affect the machinability of the copper parts. The toughness and plasticity of the copper parts are relatively large, and the deformation generated during cutting is also significant. So the cutting tool should be sharp, so that the cutting will be smoother, the temperature generated during cutting will be lower, and the deformation of the copper sheet will also be smaller.
If lead is added to copper parts, the machinability is greatly improved and the cutting speed is also improved. There are many types of bronze with poor anisotropic properties, but in the case of lead bronze, the cutting ability is greatly improved.
In the processing of copper parts, the faster the cutting speed, the smaller the cutting force, and thus the deformation of the copper parts during the processing will be relatively small. The surface quality of copper alloy is very good, so there is no need for further precision machining in the later stage. The faster the cutting speed, the better the surface quality of the copper screw.