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.