G70 Finishing Cycle in CNC Programming Explained
G70 finishing cycle in CNC programming is used to perform a final, smooth cut on a previously rough-machined surface. It follows a roughing cycle to clean up the part by removing a small amount of material for a precise finish.How It Works
The G70 finishing cycle works by following the path created by a roughing cycle, such as G71, to make a final pass that smooths the surface. Imagine sanding a wooden table after cutting it roughly; the sanding is like the finishing cycle that removes small imperfections.
In CNC terms, after the rough cuts remove most of the material, the G70 cycle uses the stored roughing path to guide the tool for a precise, gentle cut. This ensures the final shape matches the design exactly with a clean surface.
Example
This example shows a simple CNC program using G70 to finish a turned part after roughing with G71.
N10 G71 U2.0 R0.5 N20 G71 P100 Q200 U0.2 W0.1 F0.15 N100 G70 P100 Q200 N110 M30
When to Use
Use G70 finishing cycle after roughing cycles when you want a smooth, accurate surface on turned parts. It is ideal for parts that need tight tolerances and good surface quality, such as shafts, bushings, or any precision cylindrical components.
In real life, think of it as the final polish on a product before it goes to assembly or shipping, ensuring it meets quality standards.
Key Points
- G70 is a finishing cycle that follows roughing cycles.
- It uses the roughing path to guide the tool for a smooth final cut.
- Commonly used in turning operations on CNC lathes.
- Improves surface finish and dimensional accuracy.
- Must be programmed with matching block numbers to roughing cycle.
Key Takeaways
G70 is used to finish and smooth surfaces after roughing in CNC turning.G70 with a roughing cycle like G71 using matching block ranges.