When machining mechanical parts, if the workpiece is too high, it should be roughed in layers using cutters of different lengths. After roughing with a large cutter, the excess material should be removed with a small cutter. Flat-end cutters should be used for machining flat surfaces, and ball end mills should be used sparingly to reduce machining time. If there is an angle, and it is an integer, an angled cutter should be used.
At the same time, tolerances should be set reasonably to balance machining accuracy with computer calculation time. Perform more machining operations to reduce idle time. For high-hardness raw materials, choose climb milling; for low-hardness raw materials, choose conventional milling. Roughing is done with climb milling, and finishing is done with conventional milling. Tool materials with good toughness and low hardness are suitable for roughing, while tool materials with poor toughness and high hardness are suitable for finishing.
In CNC machine tool machining plants, the clamping method for workpieces must be rationally selected, choosing appropriate positioning datums and clamping schemes. When selecting precision datums, the principles of "datum unification" and "datum coincidence" should generally be followed. In addition to these principles, it's also necessary to consider completing the machining of all surfaces in a single positioning and clamping operation. Therefore, a positioning method that facilitates the machining of all surfaces should be selected.
When clamping a workpiece, the machining of all its surfaces should be completed in one operation. When determining the workpiece's placement on the worktable, the impact of machining at each station, tool length, and tool rigidity on machining quality should be considered. Fixtures used in CNC machining should, as far as possible, be assembled from common components and be adjustable to shorten the production preparation cycle.
When arranging the machining sequence, basic principles must be followed in machine tool plants, including "surfaces before holes" and "roughing before finishing." Machining should be done by concentrating tools in a single operation to avoid repeatedly using the same tool, reducing tool changes and time.
For hole systems requiring high coaxiality, the entire hole system should be machined after a single positioning before machining holes at other coordinate positions. This eliminates errors caused by repeated positioning and improves the coaxiality of the hole system. Once the tool point and tool change point are selected and determined, they should not be changed.
