Fuji Mould develops a super-hard alloy punching needle for high-precision machining with a diameter of only 20μm, which increases the number of punches

FUJI DIE (headquarters: Tokyo) has developed a durable hard alloy mold part – a needle with a diameter of only 20 μm. By refining the tungsten carbide (WC) raw material, the hardness is maintained at the same level as the original, and the bending strength (bending strength) is increased by nearly three times. It can ensure high precision of processing for a long time.

The raw material is a powder prepared by mixing cobalt (Co) which acts as a binder in WC. Originally, "ultra-ultrafine particles" (the company) having a WC particle size of about 0.5 μm were used, and this time it was fined to "nanoparticles" (the company) smaller than 0.5 μm (500 nm). The original "ultrafine particles" have a size of 0.8 to 1 μm. The production method is as follows. First, the raw material powder is cold-rolled into a pressed powder and processed into a desired shape. Next, the thus obtained molded body is subjected to vacuum sintering, and subjected to HIP treatment for removing voids (holes) under high temperature and high pressure to obtain a material for use in a mold part. Finally, mechanical processing such as grinding is performed to form a punch needle.

The Rockwell hardness (HRA) was 95.0, which remained at the same level as the original 95.1. The bending resistance increased from about 1.5 GPa to 4.2 GPa. Moreover, the wear resistance is also improved, and the wear amount under the ASTM standard is reduced to less than half of the original.

With this new type of punching needle, when a workpiece having a thickness of 75 μm made of stainless steel SUS430 was machined under a half punch and a punching amount of 30 μm, the number of punches was increased to 900,000 times or more. The original product was about 700,000 times.