1. Product overview

Molding materials used for automobile bodies and other components have increasingly adopted high-strength materials to reduce weight for the purpose of improving fuel economy. Along with this, press dies are required to be made of materials with high strength and wear resistance, and the die materials themselves are becoming harder and harder. In particular, tool life is shortened due to quick tool wear in cutting of hardened steels exceeding 55HRC. In addition, depending on the product shape, sudden tool chipping often occurs due to unstable cutting with high intermittent.
We developed “ENGU0603ER-C” insert for cutting hardened steels, that is insert for cutting of work material hardness up to 62HRC to solve these issues. This insert has been added high feed radius end mill TD4N type of the indexable tool lineup. (Fig.1)

Figure 1　High feed radius end mill TD4N type

2. Product Details

This product improves the tool life and cutting stability in cutting of hardened steels by optimization of cutting edge shape and improving the tool runout accuracy when the insert is mounted on the cutter body.

① Suitable cutting edge shape for hardened steels
We studied the cutting edge honing R and negative rake angle suitable for cutting of hardened steels in this product. As a result, it realizes a cutting edge shape with an excellent balance between wear and chipping resistance. These have improved tool life while reducing variability in machining geometries with strong intermittency.

② Improvement of tool runout accuracy
It is important the tool runout accuracy for the longer tool life in machining of hardened steels. Therefore, this product has improved tool runout accuracy by grinding the side surface of the insert. This makes the risk of sudden tool chipping is reduced.
Figure 2 shows a comparison of tool life with conventional tools. When these inserts are mounted on a φ32 diameter with 5 flutes tool, the tool runout accuracy is reduced to about 1/3 of the conventional product. The tool life in STAVAX (52HRC) cutting is 1.7 times longer, 120 minutes compared to 70 minutes for the conventional product.

Figure 2　Tool life comparison of tool runout accuracy

③ Example of machining on press die

Figure 3 shows an example of press die trim punch machining using this tool. The work material is SKD11 (60HRC) with the guide pin holes. It has intermittent shape, and is machined direct milling from a block material. Conventional tools for machining hardened steels chipped after 40 minutes and reached the tool life. On the other hand, this product was still usable after 60 minutes of machining with small damage. By the tool life improvement of more than 1.5 times, it was possible to reduce the number of tool changes and tools used. As a result, productivity was improved.

Figure 3　Example of Cutting on press die

3. Sales performance

The total number of shipments of this product by the first half of 2024 is over 40,000 units. There has recently been increase in orders from overseas. We can expect this product to make a further contribution to hardened steels machining in the future.

4. Summary

For some time now, solid end mills are the mainstream for cutting high-hardness steel. This product not only improves productivity, but also contributes to reducing environmental impact by reducing the amount of cemented carbide base material used by switching from solid end mills to indexable tools. We will contribute to society by developing cutting tools that can solve users’ machining problems.

MOLDINO Tool Engineering, Ltd.
13-2, Shinizumi, Narita-shi, Chiba-ken, 286-0825, JAPAN