Wear performance of commercial polyoxymethylene copolymer and homopolymer injection moulded gears

Polymer gears are an effective solution to lightweighting, which are highly demanded in the automotive industry. Acetal is one of the most widely used polymer gear materials. In this study, two commercial grades of acetal, homopolymer (POM-H) based and copolymer (POM-C) based, were injection moulded into gears with their wear performance compared. Noticeable differences were discovered in failure mechanism, and thermal and mechanical characteristics, which led to a difference in performance prediction. The service life of over two million cycles was expected under a torque up to 10 N m, with POM-H gears having 35% better service life than POM-C. The differences in the properties of POM-H and POM-C should be considered in future industrial applications such as the replacement for metal gears

A new in-mould decoration process using real wood veneer

The results are reported of trials conducted on the back injection moulding of various real wood veneers onto PP and ABS for automotive interiors and the effect of the process on the wood veneer. Polymer/wood veneer severe boil adhesion integrity and component shrinkage are assessed and the interface between the wood veneer and back injection moulded thermoplastic is analysed by scanning electron microscopy. 12 refs

Analysis of back injecting real wood veneers using engineering polymers in an injection moulding process

An investigation was carried out to establish whether engineering polymers could be back injection moulded onto real wood veneers for the manufacture of vehicle trim and to assess the basic adhesion and dimensional performance of the moulded components. Engineering polymers evaluated were a talc-filled PP, an ABS/polyamide blend, a glass fibre-filled ABS/polyamide blend, an unfilled polyamide-6,6 and a polycarbonate/PBTP blend. The components were tested using the the DIN 53255 adhesion delamination test and the relationship between component distortion and shrinkage at both post injection moulding and post cooling studied. The glass fibre-filled ABS/polyamide blend exhibited the lowest measured shrinkage value and produced the flattest samples. 13 refs

Gas-assisted compression moulding of recycled GMT : effect of gas injection parameters

Gas assisted compression moulding (or GasComp) is a novel process based on the injection of nitrogen gas during a conventional compression moulding cycle, a technique originally introduced in the injection moulding industry. The gas is injected into the molten material at a preset gas inlet point, hollowing out the part and thus assisting the compressive force of the press in generating material flow. This paper presents gas injection parameter studies on polypropylene based recycled glass mat-reinforced thermoplastic (GMT). The parameters investigated are gas ramp rate, gas injection delay time, and peak pressure. The size of cavity was found to be inversely proportional to gas injection delay time. Rheological instabilities at the polymer–gas interface were observed; a phenomenon previously noted during the development of gas assisted injection moulding

In mould painting using thermoset powder coating and thermoplastic substrate in closed tool injection moulding

In mould decoration (IMD) is attractive because a fully, or partially, decorated component is produced directly from the moulding process, with reduced emissions at lower process costs when compared to traditional techniques. A new IMD process has been developed to produce a painted component direct from the injection moulding tool. This incorporates the pressure spraying of thermoset powders through a valve into a closed mould. The residual heat of the tool initially softens the thermoset. The high temperature of thermoplastic polymer injected in a standard injection moulding subsequently cures the thermoset. The resultant product combines both thermoplastic and thermoset in a single injection moulding cycle. This paper presents frames from high speed video capture of powder mould filling and the results of INSPIRE ( in mould spray painting, impact reduced on the environment) initial injection moulding using thermoset polyester and acrylonitrile butadiene styrene (ABS). The parameters that affect material distribution are examined and discussed. Similarities to the coinjection moulding process are noted