Why is drill bit inspection conducted before shipment?
1.Avoid rejection upon arrival
Drill bits are consumables for machining. Defects including dimension deviation, damaged cutting edge and insufficient hardness will make the items unusable. If large quantity non-conformities are found after goods arrive at destination port, buyers may reject the shipment, claim compensation, which leads to extra ocean freight, detention and storage charges.
2.Ensure stable machining performance
Drill bits with inadequate hardness wear quickly or suffer tip breakage. Poor concentricity causes offset drilling and may damage workpieces and machine tools. Sorting defective units before delivery helps maintain customers' processing efficiency and production yield.
3.Prevent mixed and wrong items
There are various types of drill bits, such as straight shank, taper shank, twist drill and carbide drill in different diameters. Factories often mix different sizes or mismatch labels with actual products. Inspection can detect wrong goods in advance.
4.Lower after-sales disputes
Inspection records serve as official evidence between buyer and supplier. It helps clarify liabilities when quality disagreements arise and reduces prolonged negotiation.
5.Prevent secondary damage during transit
The sharp cutting edges are vulnerable to collision damage without proper protection. Packaging check during inspection avoids damages caused by transportation.
Inspection Standards
1. Visual Inspection
·No chipping, notches, cracks or grinding burns on cutting edges and drill point.
·Flutes and margins shall be free of heavy collision marks and deep scratches.
·Welded drill bits shall have no porosity, slag inclusion, incomplete penetration or cracks on weld joints.
·Uniform surface treatment (oxidation, nitriding or coating); no rust, peeling or large-area coating shedding.
·Clear marking of size and material, not easy to wipe off. Marking can be exempted for drill bits below 4 mm diameter.
2. Dimensional Inspection
·Working diameter, overall length, flute length and shank diameter shall conform to tolerance shown on customer drawing and standard.
·Standard point angle for general twist drill: 118°±2°. Special angle shall follow customer's requirement.
·Dimensions within the same batch shall be stable without obvious batch deviation. Measuring tools: outside micrometer, vernier caliper, angle gauge.
3. Geometric Tolerance
Radial run-out (working section relative to shank axis):
·Standard grade drill bit: ≤0.08 mm
·Precision grade drill bit: ≤0.06 mm Test method: V-block with dial indicator during rotation.
4. Hardness Inspection
Hardness of cutting area for HSS drill bits: 62.5～66.5 HRC. Shank hardness
shall be lower than cutting area to avoid slipping during clamping.
Hardness test is destructive; customer approval shall be obtained in advance.
5. Cutting Performance Test (Optional)
Carry out drilling test on 45# steel specimen. Under normal cutting parameters, no chipping, breakage or abnormal rapid wear after drilling, and chips can be discharged smoothly.
6. Packaging & Marking
1.Inner packaging shall separate drill bits to protect cutting edges against collision during transit.
2.Anti-rust oil and desiccants shall be provided for sea shipment to prevent rust.
3.Outer cartons marked with product name, size, quantity and brand, consistent with purchase order.
4.Cartons intact, no damage or dampness.
