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HM Series Carbide Corner Radius End Mill

Engineered for high-precision radius profiling and contour finishing of hardened steels 55-68 HRC. 45° helix geometry with Balzers DR coating delivers superior wear resistance and seamless radius transitions on dies and hardened components.

Solid Carbide 4 Flutes 45° Helix Balzers DR Coated 55-68 HRC Radius Profiling
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HM Series Carbide Corner Radius End Mill
HM Series Carbide Corner Radius End Mill
Corner radius cutting edge detail
Balzers DR coating microscopic view

Procurement & Commercial Terms

MOQ1 pc (sample/stock) | 50 pcs (OEM/bulk)
Lead Time3–5 days (standard stock) | 10–15 days (custom/OEM)
InventoryR0.2–R2.0 in stock. R2.5–R3.0 available on short notice.
Custom OptionsExtended cutting length (HM-4RL), slim shanks, alternative coatings, laser marking, private packaging
PackagingIndividual vacuum blister + anti-rust paper | Rigid export cartons (50/100 pcs)
ShippingDHL/FedEx/UPS for samples | Air/Sea freight for bulk. Incoterms: EXW, FOB, CIF, DDP

HM-4R Dimensions (Standard & Long)

HM-4R Dimensions

ModelD (mm)R (mm)d (mm)H (mm)L (mm)TypeStock
HM-4R-1.0-0.2-3-4-501.00.24350Standard●
HM-4R-1.5-0.2-4.5-4-501.50.244.550Standard●
HM-4R-1.5-0.3-4.5-4-501.50.344.550Standard●
HM-4R-2.0-0.2-6-4-502.00.24650Standard●
HM-4R-2.0-0.3-6-4-502.00.34650Standard●
HM-4R-2.5-0.2-7.5-4-502.50.247.550Standard●
HM-4R-2.5-0.5-7.5-4-502.50.547.550Standard●
HM-4R-3.0-0.2-9-4-503.00.24950Standard●
HM-4R-3.0-0.5-9-4-503.00.54950Standard●
HM-4R-3.0-0.5-9-3-503.00.53950Standard●
HM-4R-3.0-0.5-12-3-753.00.531275Long○
HM-4R-3.0-0.5-15-3-1003.00.5315100Long○
ModelD (mm)R (mm)d (mm)H (mm)L (mm)TypeStock
HM-4R-4.0-0.2-10-4-504.00.241050Standard●
HM-4R-4.0-0.3-10-4-504.00.341050Standard●
HM-4R-4.0-0.5-10-4-504.00.541050Standard●
HM-4R-4.0-0.5-14-4-754.00.541475Long○
HM-4R-4.0-0.5-15-4-1004.00.5415100Long○
HM-4R-5.0-0.5-13-5-505.00.551350Standard●
HM-4R-5.0-0.5-13-5-755.00.551375Long○
HM-4R-5.0-0.5-18-5-1005.00.5518100Long○
HM-4R-5.0-1.0-13-6-505.01.061350Standard●
HM-4R-6.0-0.2-20-6-756.00.262075Long○
HM-4R-6.0-0.2-25-6-1006.00.2625100Long○
HM-4R-6.0-0.5-16-6-506.00.561650Standard●
HM-4R-6.0-0.5-20-6-756.00.562075Long○
HM-4R-6.0-0.5-25-6-1006.00.5625100Long○
HM-4R-6.0-1.0-16-6-506.01.061650Standard●
HM-4R-6.0-1.0-20-6-756.01.062075Long○
HM-4R-6.0-1.5-20-6-756.01.562075Long○
ModelD (mm)R (mm)d (mm)H (mm)L (mm)TypeStock
HM-4R-8.0-0.2-20-8-608.00.282060Standard●
HM-4R-8.0-0.2-25-8-758.00.282575Long○
HM-4R-8.0-0.2-30-8-1008.00.2830100Long○
HM-4R-8.0-0.5-20-8-608.00.582060Standard●
HM-4R-8.0-0.5-25-8-758.00.582575Long○
HM-4R-8.0-0.5-30-8-1008.00.5830100Long○
HM-4R-8.0-0.5-45-8-1508.00.5845150Long○
HM-4R-8.0-1.0-20-8-608.01.082060Standard●
HM-4R-8.0-1.0-25-8-758.01.082575Long○
HM-4R-8.0-1.0-30-8-1008.01.0830100Long○
HM-4R-8.0-1.0-45-8-1508.01.0845150Long○
HM-4R-8.0-1.5-20-8-608.01.582060Standard●
HM-4R-10.0-0.2-25-10-7510.00.2102575Long○
HM-4R-10.0-0.2-30-10-10010.00.21030100Long○
HM-4R-10.0-0.5-25-10-7510.00.5102575Long○
HM-4R-10.0-0.5-30-10-10010.00.51030100Long○
HM-4R-10.0-0.5-50-10-15010.00.51050150Long○
HM-4R-10.0-1.0-25-10-7510.01.0102575Long○
HM-4R-10.0-1.0-30-10-10010.01.01030100Long○
HM-4R-10.0-1.0-50-10-15010.01.01050150Long○
HM-4R-10.0-1.5-25-10-7510.01.5102575Long○
HM-4R-10.0-2.0-25-10-7510.02.0102575Long○
HM-4R-10.0-2.0-30-10-10010.02.01030100Long○
HM-4R-10.0-3.0-25-10-7510.03.0102575Long○
HM-4R-10.0-3.0-30-10-10010.03.01030100Long○
ModelD (mm)R (mm)d (mm)H (mm)L (mm)TypeStock
HM-4R-12.0-0.2-30-12-7512.00.2123075Long○
HM-4R-12.0-0.2-35-12-10012.00.21235100Long○
HM-4R-12.0-0.5-30-12-7512.00.5123075Long○
HM-4R-12.0-0.5-35-12-10012.00.51235100Long○
HM-4R-12.0-0.5-55-12-15012.00.51255150Long○
HM-4R-12.0-1.0-30-12-7512.01.0123075Long○
HM-4R-12.0-1.0-35-12-10012.01.01235100Long○
HM-4R-12.0-1.0-55-12-15012.01.01255150Long○
HM-4R-12.0-1.5-30-12-7512.01.5123075Long○
HM-4R-12.0-2.0-30-12-7512.02.0123075Long○
HM-4R-12.0-2.0-35-12-10012.02.01235100Long○
HM-4R-12.0-3.0-30-12-7512.03.0123075Long○
HM-4R-16.0-0.5-40-16-10016.00.51640100Long○
HM-4R-16.0-0.5-40-16-15016.00.51640150Long○
HM-4R-16.0-0.5-75-16-15016.00.51675150Long○
HM-4R-16.0-1.0-40-16-10016.01.01640100Long○
HM-4R-16.0-1.0-75-16-15016.01.01675150Long○
HM-4R-16.0-2.0-45-16-10016.02.01645100Long○
HM-4R-16.0-3.0-45-16-10016.03.01645100Long○
HM-4R-20.0-0.5-45-20-10020.00.52045100Long○
HM-4R-20.0-0.5-75-20-15020.00.52075150Long○
HM-4R-20.0-1.0-45-20-10020.01.02045100Long○
HM-4R-20.0-1.0-75-20-15020.01.02075150Long○
Note: Corner radius tools combine flat bottom milling with rounded corners. Ideal for radius shoulders, profile milling, and avoiding sharp 90° corners that can cause stress concentration or premature tool wear.

● In stock | ○ Make-to-order | Full range: D3.0–D16.0 with R0.2–R3.0. Tolerance: D≤12 → 0~-0.020mm | D>12 → 0~-0.030mm. R → ±0.01mm. CAD/STEP files available.

Why HM Series 45° Helix & Balzers DR for Hardened Steel?

45° Helix Optimization

Higher helix angle reduces axial cutting force during radius profiling, enabling smoother tool engagement, reduced vibration, and consistent Ra≤0.8μm surface quality on hardened materials.

Balzers DR Coating

High-performance PVD coating with exceptional thermal stability. Minimizes flank wear and prevents built-up edge when machining 55-68 HRC steels, extending tool life significantly.

55-68 HRC Capability

Specialized substrate + edge prep allows stable finishing of pre-hardened and quenched steels up to 68 HRC without micro-chipping or premature flank wear.

4-Flute Rigidity & Finish

Larger core diameter minimizes tool deflection during radius shoulder milling. Four cutting edges distribute load evenly, maintaining tight tolerances and superior surface quality.

Material Compatibility & Hardness Limits

WorkpieceHardnessSuitabilityNotes
Pre-hardened / Quenched Steel55-68 HRC◎ ExcellentOptimized for mold finishing, die repair & hardened components
Tool Steel (D2, A2, H13)55-65 HRC◎ ExcellentStable for tool & die finishing operations
Bearing Steel (GCr15)58-65 HRC◎ ExcellentHigh-precision finishing of bearing races & components

◎ = Very Suitable | ○ = Limited | ✗ = Not Recommended |        HM Series is engineered specifically for hardened steels 55-68 HRC.        For materials <55 HRC, please use our PM Series.        For stainless steel & titanium alloys, please use our SM/TM Specialized Series.

CAM Setup & Hardened Steel Finishing Guidance

Recommended Finishing Parameters (55-68 HRC)

  • ✅ Radius Shoulder Finishing: ae = 0.02D–0.04D, ap = 0.3D–0.5D, Vc = 60–90 m/min

  • ✅ High Hardness (60-68 HRC): Reduce Vf by 15–20%, maintain ae ≤ 0.02D to protect cutting edge

  • ✅ Surface Finish (Ra≤0.4μm): Use ae = 0.01D–0.02D with consistent chip load

  • ✅ Use climb milling to maximize 45° helix advantage and surface quality

Machine & Setup Requirements

  • ⚠️ Use high-precision collets/chucks. Runout must be <0.003mm for hardened steel finishing

  • ⚠️ Minimize overhang. For L/D > 4, reduce feed by 20% to prevent harmonic vibration

  • ⚠️ Balzers DR performs best with air blow or minimum quantity lubrication (MQL)

  • ⚠️ Avoid full-width slotting. Use ramping or helical interpolation for pocket entry

Typical Hardened Steel Finishing Applications

🔩 Mold Repair & Finishing

Precision finishing of D2, A2, H13, and hardened inserts (55-68 HRC). Achieves Ra≤0.4μm with minimal polishing required for mold repair operations.

⚙️ Tool & Die Finishing

Finishing of punches, dies, and tooling components. 45° helix ensures dimensional stability & surface integrity on 55-65 HRC tool steels.

🎯 Bearing Steel Components

High-precision finishing of bearing races, shafts, and components. Balzers DR coating withstands abrasive wear on 58-65 HRC bearing steels.

Factory Production & Quality Control

CNC grinding and Balzers DR coating line for HM series

Manufacturing Process & QA Steps

  • 🔹 Substrate: Ultra-fine carbide (0.3μm grain) with specialized heat treatment for 55-68 HRC stability

  • 🔹 Grinding: 5-axis CNC maintains 45° helix ±0.5° & radius accuracy ±0.01mm at corner transition

  • 🔹 Coating: Balzers DR layer (2.0–3.0μm) applied under controlled conditions for maximum adhesion and thermal resistance

  • 🔹 Inspection: 100% laser diameter check, coating thickness verification, and runout <0.003mm test

  • 🔹 Traceability: Each batch includes laser-etched SKU, grinding date, coating certificate, and QC report. Available upon request.

Frequently Asked Questions

The HM series with Balzers DR coating is specifically engineered for hardened steels in the 55-68 HRC range. For materials below 55 HRC, we recommend our PM series for better cost efficiency.

Balzers DR coating provides exceptional thermal stability and wear resistance. This combination minimizes edge wear and prevents built-up edge when machining hardened steels, extending tool life by 30-50% compared to standard coatings.

No. HM series is engineered specifically for hardened steels 55-68 HRC. For stainless steel or titanium alloys, please use our SM/TM specialized series with geometry optimized for gummy and low-thermal-conductivity materials.

For 55-68 HRC steels: use ae = 0.02D–0.04D, ap = 0.3D–0.5D. Reduce feed 15-20% for hardness >60 HRC. Use climb milling, ensure runout <0.003mm, and maintain air blow cooling for consistent surface quality.

Request Quote for HM Series Carbide Corner Radius End Mill

Specify your diameter range, material, and monthly volume. We respond with pricing, stock status within 24 hours.

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