Before

As-coated 3/8-inch 5-flute AlCrN-coated carbide end mill prior to automated coating polishing, showing unrefined coating surface.

After

3/8-inch 5-flute AlCrN-coated carbide end mill after automated coating polishing, showing smoother coated cutting surfaces and preserved tool geometry.

Objective

Automate the polishing of AlCrN-coated 3/8” 5-flute carbide end mills to remove coating irregularities, improve surface smoothness, and enhance cutting performance and tool life—while maintaining tool geometry and edge integrity.

IndustryCutting Tool, Machine Shop Applications
Part DescriptionImpact Step Drill Bit
Fabrication Method Cutter Ground
MaterialM2 High-Speed Steel (HSS)
Process TechnologyDeburring, Dry Finishing, Edge Preparation/Honing
Equipment TypeAutomated Drag-Spindle Finisher (AutoHone™)

Solution

Bel Air developed an automated coating polishing process for M2 high-speed steel (HSS) impact step drill bits using the AutoHone™ Robotic Honing & Polishing Machine. A controlled drag-spindle finishing motion drives polishing media across the coated surfaces at precise velocity, selectively removing coating droplets and surface irregularities created during the coating process—without damaging the coating or altering tool geometry.

This automated coating polishing method delivers:

  • Removal of coating droplets and nodules for smoother coated cutting edges
  • Improved coating surface uniformity and reduced surface friction
  • Cleaner step transitions that support smoother drilling performance
  • Preservation of coating integrity without manual hand polishing
  • High repeatability compared to manual or batch finishing methods

The result: a production-ready coating polishing process that improves coated tool performance, reduces variability, and eliminates labor-intensive hand finishing.

If you are unsure what equipment and media you require to achieve your desired surface finish, then send us your part, and we will evaluate it and provide you with a metrology report.