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HSS Roughing End Mills for Steel

Engineered for heavy stock removal in steel machining. Available in Standard HSS or premium HSS-Co (M35/M42) substrates. Features a specialized scalloped edge design combined with AlTiN Nano-Coating to maximize material removal rates while protecting your CNC spindle from overload.

HSS / HSS-Co (M35/M42) 4 Flutes AlTiN Coated Scalloped Edge Heavy Duty Steel Milling
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HSS Roughing End Mills for Steel
HSS Roughing End Mills for Steel

Procurement & Commercial Terms

MOQ1 pc (sample/stock) | 50 pcs (OEM/bulk)
Lead TimeSame day dispatch (standard stock) | 7–10 days (custom/OEM)
InventoryD6mm–D25mm full range in stock. Both standard and extra-long lengths available.
Material & CoatingSubstrate: HSS or HSS-Co (M35 / M42) | Coating: AlTiN (Nano Black)
PackagingIndividual plastic tubes + anti-rust paper | Rigid export cartons (50/100 pcs)
ShippingDHL/FedEx/UPS for samples | Air/Sea freight for bulk. Incoterms: EXW, FOB, CIF, DDP

HSS & HSS-Co 4-Flute Roughing End Mill Specifications

Product Configuration:      Material: Standard HSS or HSS-Co (M35/M42) |      Coating: AlTiN |      Edge: Scalloped (Roughing)
ModelD (mm)H (mm)d (mm)L (mm)Stock
HSR-4F-6-19-6-60619660● In Stock
HSR-4F-8-25-8-66825866● In Stock
HSR-4F-10-25-10-7510251075● In Stock
HSR-4F-12-35-12-8512351285● In Stock
HSR-4F-14-35-12-8514351285● In Stock
HSR-4F-16-42-16-9516421695● In Stock
HSR-4F-18-42-16-9518421695● In Stock
HSR-4F-20-50-20-110205020110● In Stock
HSR-4F-22-50-20-110225020110● In Stock
HSR-4F-25-60-20-125256020125● In Stock
ModelD (mm)H (mm)d (mm)L (mm)Stock
HSR-4F-6-25-6-68625668● In Stock
HSR-4F-8-38-8-83838883● In Stock
HSR-4F-10-45-10-9510451095● In Stock
HSR-4F-12-53-12-110125312110● In Stock
HSR-4F-14-53-12-110145312110● In Stock
HSR-4F-16-63-16-123166316123● In Stock
HSR-4F-18-63-16-123186316123● In Stock
HSR-4F-20-75-20-141207520141● In Stock
HSR-4F-22-75-20-141227520141● In Stock
HSR-4F-25-100-20-1602510020160● In Stock

● All sizes in stock | Diameter tolerance: h6. Custom sizes available upon request.

Application Note: Scalloped (roughing) edges leave a slightly textured surface finish. They are strictly designed for heavy stock removal. For final fine finishing passes requiring smooth surface roughness (Ra), we recommend switching to our standard 4-flute flat end mills from the Steel Series.

Why Choose Our Steel Roughing End Mills?

Scalloped Edge Design

The wavy cutting edge breaks long, continuous steel chips into small "C" or "6" shapes. This prevents chip clogging, reduces cutting resistance, and protects the machine spindle from overload.

AlTiN Nano-Coating

Provides exceptional heat resistance (up to 800°C). During aggressive roughing, the coating forms a protective aluminum oxide layer, preventing premature flank wear and edge deformation.

HSS-Co Durability

M35 (5% Co) or M42 (8% Co) substrates offer superior red hardness compared to standard HSS. Essential for maintaining edge integrity when roughing abrasive alloy steels or stainless steels.

High Core Rigidity

The 4-flute geometry provides a thicker core than 3-flute alternatives. This maximizes torsional stiffness, minimizing tool deflection and chatter during heavy side-milling or slotting operations.

CAM Setup & Cutting Parameters Guidance

Recommended Cutting Data (HSS-Co + AlTiN)
Workpiece MaterialCutting Speed (Vc)Feed per Tooth (fz)Radial Engagement (ae)
Carbon Steel (< 30 HRC)50 - 80 m/min0.05 - 0.12 mm/tooth40% - 60% of D
Alloy Steel (4140, 4340)40 - 70 m/min0.04 - 0.10 mm/tooth30% - 50% of D
Mold Steel (P20, 718)35 - 60 m/min0.03 - 0.08 mm/tooth30% - 50% of D
Stainless Steel (304, 316)30 - 50 m/min0.03 - 0.07 mm/tooth20% - 40% of D

*For standard uncoated HSS, reduce Cutting Speed (Vc) by approximately 20-30%.

Best Practices for Roughing Steel
  • ⚠️ Use Climb Milling - Reduces cutting forces and prevents work hardening on the machined surface.
  • ⚠️ Maximize Rigidity - Keep tool overhang as short as possible. Use the shortest length of cut (H) that clears the part.
  • ⚠️ Chip Evacuation - Even though chips are broken, ensure they are cleared from the cut zone to prevent re-cutting.
  • ⚠️ Avoid Dwell Marks - Maintain a constant feed rate. Pausing the tool in the cut will cause rapid localized wear.
  • ⚠️ Coolant Strategy - Use flood coolant for steel to manage heat and flush chips. For AlTiN coated tools, MQL (Minimum Quantity Lubrication) is also highly effective.

Factory Production & Quality Control

HSS-Co roughing end mill grinding and quality inspection

Manufacturing Process & QA Steps

  • 🔹 Raw Material: Premium HSS and HSS-Co (M35/M42) steel blanks sourced from certified mills.
  • 🔹 Grinding: 5-axis CNC tool grinders ensure precise scalloped flute geometry and h6 diameter tolerance.
  • 🔹 Heat Treatment: Vacuum heat treatment with triple tempering to achieve optimal hardness (64-66 HRC) and toughness.
  • 🔹 Coating: AlTiN nano-coating applied via advanced PVD process for uniform thickness and adhesion.
  • 🔹 Inspection: 100% visual inspection under microscope. Batch sampling for coating thickness, hardness, and cutting tests.

Frequently Asked Questions

A 4-flute roughing end mill features a scalloped (wavy) cutting edge that breaks chips into small pieces, significantly reducing cutting resistance and vibration. The 4-flute design provides a larger core diameter than 3-flute tools, offering superior rigidity for heavy stock removal in steel without overloading the CNC spindle.

AlTiN (Aluminum Titanium Nitride) coating provides exceptional heat resistance up to 800°C. During aggressive roughing of steel, the coating forms a protective aluminum oxide layer that prevents premature flank wear and edge deformation, allowing for higher cutting speeds or dry/near-dry machining.

Upgrade to HSS-Co (M35/M42) when roughing abrasive alloy steels (like 4140), stainless steels, or cast iron. The 5-8% cobalt content drastically improves red hardness, preventing the scalloped edges from softening and wearing prematurely under the high cutting temperatures generated during heavy steel milling.

Request Quote for HSS Roughing End Mills for Steel

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

ISO 9001 Certified Factory
Export Packaging Standard
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