Common Finishing Problems
- Burrs
- Scallop marks
- Chatter Marks
Factors That Influence Part Finish
- Specific material and hardness
- Cutting tool speeds & feeds
- Tool design and deployment
- Tool projection and deflection
- Tool-to-workpiece orientation
- Rigidity of workholding
- Coolant and lubricity
- Final-pass depth of cut
Finishing Problem Solutions
- Tools with high helix angles and flute counts work best for finishing operations. Softer materials show great results with higher helices, while harder materials can benefit greatly from increased flute counts.
- Increase your RPM and lower your IPT (Figure 2).
- Ensure that tool runout is extremely minimal.
- Use precision tool holders that are in good condition, are undamaged, and run true.
- Opt for a climb milling machining method.
- Use tooling with Variable Pitch geometry to help reduce chatter.
- A proper radial depth of cut (RDOC) should be used. For finishing operations, the RDOC should be between 2 and 5 percent of the tool’s Cutter Diameter.
- For long reach walls, use reduced neck tooling which help to minimize deflection (Figure 3).
- Extreme contact finishing (3x cutter diameter), may require a 50% feed rate reduction.
Common Surface Finish Nomenclature
Ra = Roughness average
Rq = RMS (Root Mean Square) = Ra x 1.1
Rz = Ra x 3.1
What is IPT?
Hi Juan! IPT = Inches Per Tooth. Chip load per tooth is the appropriate amount of material that one cutting edge of the tool should remove in a single revolution. This is measured in IPT.
I’m going have to disagree with you — Increase your RPM and lower your IPT (Figure 2). ??? did a machinist write this – i think not – he would know better
Why don’t you make some high flute count alu finishers? This would really speed up alu finishing passes. I could really use a 1/4”, .75loc, 6 or so flute alu finisher.
Hello Pete,
Thank you for your suggestion, we will pass this along to our New Product Development team so they can look into this further.