Content area
Full Text
PIM and MIM tools compressing abrasive metal and ceramic powders suffer from wear leading to dimensional and shape changes, burr and poor finish of the produced parts. Hardide coating can increase the tooling life, cutting production downtime costs, thus enhancing the PIM/MIM competitiveness. Hardide-T nano-structured Tungsten Carbide coating combines high hardness (70-77Rc) with excellent toughness. Unlike other hard coatings Hardide CVD gas phase deposition produces conformal coating layer on complex-shaped tools, including internal surfaces, and can be polished to a mirror finish. In ASTM-G65 abrasion-resistance testing Hardide coating outperformed WC/Co(9%) hardmetal by a factor of 4X: thus steel tooling with Hardide coating is 4-fold more abrasion-resistant than Cemented Carbide. Hardide was tested on pharmaceutical powder tabletting tools. The coated highly-polished tools showed no signs of wear after making over 36 million tablets, had no scratching striations or loss of edge sharpness, both of which were visible on the uncoated punches.
1. Introduction
Powder injection moulding (PIM) and metal injection moulding (MIM) techniques are increasingly used as cost-effective and material-saving methods to produce large quantities of highly complex parts for the automotive industry, electronics and household appliances. Moulding tooling for PIM and MIM is complex in design and expensive which is a significant factor in the economics of these production processes. During the injection stage the tooling is rapidly filled with slurry containing metal or ceramic particles which can be highly abrasive. The higher viscosity of the PIM and MIM feedstock, the use of higher injection pressure, the more abrasive nature of metal, and especially ceramic powders (such as WC), contribute to excessive wear of the tooling when compared to conventional plastics injection moulding. The tooling wear may lead to a cavity dimensional change, especially critical for micro-MIM and thin wall products, as well as degradation of its finish, increasing the risk of the moulded parts or the feedstock particles sticking to the tool surface, which can interrupt production and incur additional downtime costs. Wear of the die parting line produces burr on the manufactured PIM and MIM components. Debris from the tool wear may cause undesirable contamination of the feedstock for some ceramics used in electronics or for pharmaceutical tablets. Other parts of the PIM and MIM equipment also suffer from wear, in...