DIN338 HSS Twist Drill Bits Roll Forged Black Polished

DIN338 HSS Twist Drill Bits Roll Forged Black Polished, Twist drill bit with universal standard geometry, roll forged bits For drilling on hand-guided drills and CNC machines, HSS DIN338 Drill Bits With Rolled & Polished, DIN338 HSS Straight Shank Twist Drill Bits With Roll Forged, With Fully Ground, Fully Ground Cobalt

DIN338 HSS Twist Drill Bits Roll Forged Black Polished
Feature Rolled (HSS-R) Fully Ground (HSS-G)
Flute production Hot roll-forged CNC ground from solid bar
Diameter tolerance h9 (typical) h8 (typical)
Substrate M2 (6542) M2 (6542) or M35
Production cost Baseline +30–40%
Best for Retail, MRO, hardware sets CNC, trade tool, premium
Lead time 25–35 days 30–45 days

Rolled HSS (HSS-R) drill bit manufacturer and OEM supplier for distributors, importers, and budget retail brands: M2 substrate, roll-forged production, DIN 338 / DIN 340 ranges, 1.0-13.0 mm, 118° or 135° point options, black oxide and bright finishes. Cost-effective for retail blister, hardware sets, and high-volume MRO channels.

Rolled HSS is the volume default for retail and hardware channels because the price point demands it. Fully ground earns its premium in industrial and CNC drilling where tight tolerance matters.

What Rolled HSS Production Actually Is
Rolled HSS manufacturing takes M2 round bar stock, heats it to forging temperature (~1100°C), and passes it through shaped rollers that form the twist flute geometry in a single continuous pass. The bit emerges with its flute geometry roughly correct; the shank stays straight from the original bar; the cutting tip is later ground to final point geometry.

The advantages of the rolling process:

Speed. Flute forming takes seconds versus minutes per bit for grinding.
Material yield. Rolling re-shapes the steel instead of grinding it away — minimal waste.
Grain orientation. The hot rolling aligns steel grain along the flute curvature, theoretically giving toughness benefits at the cutting edge.
Cost. Lower energy, lower labor, lower abrasive consumption per bit.
The trade-offs:

Tolerance. Hot forming holds h9 diameter; fully ground holds h8. For most uses h9 is fine.
Surface finish. Rolled flute surface is rougher than ground — sometimes polished afterward for retail appearance.
Geometry precision. Helix angle and web thickness vary slightly more between batches than fully ground.
Recommended Rolled HSS Ranges for OEM Buyers
Range Specification Channel Fit
Rolled M2 retail standard DIN 338, 1.0–13.0 mm 0.5 mm steps, 118° point, black oxide Hardware retail, DIY blister
Rolled M2 economy line DIN 338, 1.0–13.0 mm 0.5 mm steps, 118° point, bright Budget MRO, general workshop
Rolled M2 set programs 19, 25, 29, 99, 115-piece in plastic or metal case Retail multi-pack, gift sets
Rolled M2 long series DIN 340, 4.0–10.0 mm selected, M2, 118° point Electrician retail, deep-hole general
Rolled TiN coated DIN 338, 1.0–13.0 mm, 118° / 135°, TiN gold finish Retail premium upgrade SKU
Inspection on Rolled HSS
M2 substrate verification. Same as fully ground — mill certificate, heat number, chemistry breakdown. Rolled does not excuse 4341 substitution.
Edge hardness 63–66 HRC. Heat treatment is identical between rolled and fully ground; hardness target is the same.
h9 diameter tolerance. Sample 5% or minimum 30 pieces per batch with a micrometer.
Flute geometry visual. Check both flutes match in depth and width — rolled production occasionally produces asymmetric flutes.
Cutting edge integrity. Under 10× magnification confirm no rolling burrs or temper colour at the edge.
RFQ Checklist
Process: rolled (HSS-R).
Substrate: M2 (6542) — specify and require mill certificate per batch.
Standard: DIN 338 / DIN 340.
Size range and step (typically 0.5 mm for rolled).
Point: 118° conventional or 135° split point.
Surface: bright, black oxide, amber, or TiN.
Packaging: blister, tube, plastic case, metal index, or industrial bulk.
Set format if applicable.
Per-batch hardness and tolerance inspection.
Quantity per SKU and reorder cycle.
Trust Signals
ISO 9001:2015 quality certification.
20+ years HSS production in China.
M2 mill certificates per batch — rolled does not mean unverified material.
Hardness records per batch at the cutting edge.
Free engineering review before sample order.
Free sample for documented OEM buyers. Multi-color High Hardness Alloy Steel Impact Magnetic Driver Bit Set