1 Stop Wasting Tools on Mold Steel! CNC Steel Milling Machine Tips for Longer Tool Life
Factories often face "tools breaking in 1 hour" or "frequent tool changes delaying schedules" when machining mold steel (50-60HRC, e.g., H13, Cr12MoV) with CNC steel milling machines. Tool costs can even take 30% of the total costs for 10 parts. This issue isn’t due to "hard steel"—it’s about wrong tool choices and poor wear control. This article focuses on "tool selection wear control for mold steel" to double tool life.
2 Why Wrong Tools Ruin Your CNC Steel Milling Machine Results
As a typical high-hardness steel, mold steel needs tools with high hardness, wear resistance, and impact resistance. 90% of tool wear comes from "mismatched tool materials":
• Using regular carbide tools for H13 mold steel (tool edge hardness 60-65HRC < steel hardness) causes edge chipping; life < 1 hour.
• Using high-speed steel tools for Cr12MoV (poor heat resistance) leads to softening at 300-400℃ milling temperature.
• Using one tool for different mold steels (e.g., H13 tool for harder D2 steel) cuts tool life by 50%.
3 Tool Selection Table for Mold Steel (CNC Steel Milling Machine-Specific)
| Mold Steel Grade | Hardness (HRC) | Recommended Tool Material | Tool Advantages | CNC Steel Milling Params (Ref) | Avg Tool Life |
| H13 | 50-55 | Ultra-fine grain CBN tools | Hardness≥ 80HRC, high impact resistance | Speed 1800-2000 rpm/min, Feed 25-35mm/min | 50-60 parts |
| Cr12MoV | 55-60 | Coated CBN tools (TIN coating) | Wear-resistant, heat-resistant | Speed 1500-1800 rpm/min, Feed 20-30mm/min | 40-50 parts |
| P20 | 30-35 | Carbide tools (WC-Co) | Cost-effective for low-hardness steel | Speed 2000-2200 rpm/min, Feed 35-45mm/min | 80-100 parts |
4 Tips to Control Tool Wear (CNC Steel Milling Machine)
4.1 Optimize cutting params
For H13, keep feed at 25-35mm/min (not 50mm/min, which raises load by 40% and shortens life). Single cut depth ≤1mm.
4.2 Enhance cooling
Use an oil mist cooling system (30% more efficient than water cooling) to target the cutting point. (Internal link: mold steel product page)
4.3 Pre-run new tools
Break in new CBN tools on low-hardness P20 mold steel (3-5 parts) to avoid edge chipping on hard steel.