Quick Tips on Machining Quality (10–12)
Due to the complexity of CNC machining—involving variables such as different machine tools, materials, cutting tools, cutting methods, and parameter settings—it takes a considerable amount of time for personnel (whether in machining or programming) to reach a proficient level. The following is a summary of practical experience regarding CNC machining processes, operational steps, tool parameter selection, and process monitoring, compiled by engineers during long-term production.
10. Q: What are the principles for setting the safety height during programming?
A: The general principle is to set the safety height above the highest point of the “island” (the highest feature on the workpiece). Alternatively, setting the program origin at the highest point can also minimize the risk of tool collisions.
11. Q: Why is post-processing required after generating the toolpath?
A: Because different machine tools recognize different address codes and NC program formats, the correct post-processing format must be selected for the specific machine tool to ensure the generated program runs correctly.
12. Q: What is DNC communication?
A: (I) Program transfer methods fall into two categories: CNC and DNC. In CNC mode, the program is transferred via a medium (such as a floppy disk, tape reader, or communication cable) to the machine tool’s memory for storage, and is then retrieved from memory during machining. Since memory capacity is limited, DNC mode is used for large programs; in DNC mode, the machine tool reads the program directly from the control computer (streaming the data while machining), thereby bypassing memory capacity limitations.
(II) There are three key elements of cutting parameters: depth of cut, spindle speed, and feed rate. The general principle for selecting these parameters is: shallow cuts and fast feed rates (i.e., a small depth of cut combined with a high feed rate).
(III) Based on material, cutting tools are generally classified into: standard high-speed steel (HSS) tools, coated tools (e.g., titanium-coated), and alloy tools (e.g., tungsten carbide, boron nitride tools).
