Introduction

Surface finish and diameter tolerance directly impact downstream tool manufacturing. Sintered unground carbide rods have sinter skin, while precision ground carbide round bars have controlled surface roughness and tight OD tolerance. Rleey provides both sintered blanks and OD ground carbide rods with strict inspection standards for toolmakers producing drills, end mills and wear parts.

Unground vs Ground Carbide Rod Surfaces

• Unground sintered blank: Original sinter skin, larger dimensional variation, low cost, requires full OD grinding by customer
• Single-pass ground rod: Skin removed, moderate Ra value, standard tolerance for general tool blanks
• Fine polished ground rod: Ultra-smooth surface, tight tolerance, for micro tools and precision wear pins

Surface Roughness Ra for Carbide Round Bars

Surface roughness (Ra) describes the smoothness of carbide rod outer surface. Sinter unground blanks have Ra around 1.6~3.2μm. Standard ground carbide rods typically achieve Ra 0.4~0.8μm. Fine polished rods can reach Ra ≤0.2μm. Lower Ra reduces grinding workload and avoids surface micro cracks after machining.

Diameter Grinding Tolerance Reference

Quality Inspection & Measurement Methods

We use micrometers, laser diameter gauges and roughness testers for inspection. Full batch sampling is performed to check outer diameter, straightness, surface roughness, end face quality and surface defects. Visual inspection under magnifier checks for grinding burns, scratches, chipping and microcracks. Inspection reports can be supplied with shipments upon request.

Common Surface Defects & Rejection Criteria

• Grinding burn: discoloration and surface thermal cracks caused by excessive grinding heat
• Deep longitudinal scratches on OD surface
• Edge chipping on rod cut ends
• Surface porosity or pitting from sintering defects

FAQ