An Investigation of Surface Engineering Techniques to Minimize Wear of Thermoplastic Injection Mold Tooling

Wear and corrosion are significant industrial issues resulting in high financial losses. With continuously increasing demands placed on thermoplastic injection molded products with regards to increased mechanical properties, leading to the incorporation of highly abrasive fillers and corrosive additives, and narrow dimensional tolerances, the surface engineering techniques to increase wear and corrosion resistance and improve the lifespan of mold tooling are of paramount concern. Proper surface engineering of expensive injection molds which can cost over 300,000 U.S.D. to fabricate is a technically challenging issue due to limitations imposed by the injection mold, coating deposition processes, the wide array of coating architectures, and coating suppliers available. This study investigates three commercially supplied surface treatments for injection molding, electrodeposited chromium, and PVD TiAlN, and PVD/PACVD DLC containing an interfacial layer of chromium nitride. Testing methodologies for evaluation of the tribological performance of these surface treatments in the plastics processing environment have been developed and employed. Analysis of the pristine coatings is conducted to investigate porosity, surface roughness, inherent defects, frictional properties against nylon and polybutylene terephthalate, and elemental composition. Pin-on-plate wear testing is used to evaluate coating-metal sliding contact. Also, a novel test apparatus has been developed and fabricated to emulate the tribology of flowing polymer compounds 2 against mold tooling during the injection process. The dominant wear mechanisms of the chrome coating in exposure to the flowing polymer compound are micro-milling from the abrasive fillers in the compound and corrosive pitting, while the DLC coating exhibits localized delamination from the substrate material. TiAlN shows superior resistance to both corrosion and abrasion in addition to excellent adhesion to the substrate material. Results indicate that TiAlN is a promising candidate for replacement of electroplated chrome which has long been an industry standard.

Líbí se ti tento článek? Přidej ho na Top Články

This entry was posted on Úterý, Únor 28th, 2012 at 8:46 and is filed under plastic injection mould maker. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

Comments are closed.