Introduction
CNC machining feed is the speed at which part stock is advanced into the cutting tool. It is measured in inches per minute (IPM), millimeters per minute (MMPM), or in the case of lathes, in revolutions per minute (RPM). When designing a CNC machining strategy and selecting a feed rate, factors such as the geometry, stock material, and tool path all need to be taken into consideration.
Geometry
The geometry of a part is the key factor that determines an appropriate feed rate. Features such as sharp internal or external geometries require slower feed rates than more gradual shapes. In the case of a milling operation, the feed rate should be set slowly enough that the cutting tool can accurately trace the shape being machined. If the cutting tool is moved too quickly, it will not travel the desired path and the part surface finish and accuracy will be compromised.
Stock Material
The material of the part being machined also plays a role in determining an appropriate feed rate. Harder materials require lower feed rates, as the cutting tool must be moved more gradually to avoid chip seizing. On the other hand, soft materials can often tolerate higher speeds, assuming that the cutting tool is appropriate for the application.
Tool Path
The tool path of a CNC machining strategy must also be taken into consideration when setting a feed rate. If a job requires a large amount of material removal, the cutter must be moved quickly enough to efficiently remove the material. On the other hand, if a job requires delicate machining or surface finishing, the speed may need to be reduced to avoid material damage.
Conclusion
When setting a feed rate on a CNC machining center, many factors must be taken into consideration. The geometry of the part, stock material, and the tool path are all important factors that can help determine an appropriate feed rate. By understanding these variables and determining an appropriate feed rate, machine operators can ensure that parts are machined accurately with a acceptable surface finish.
