Development of new feedstock formulation based on high density polyethylene for MIM of M2 high speed steels

Abstract

A new feedstock formulation for metal injection moulding (MIM) of M2 high speed steels has been developed. The binder is a multicomponent system based on high density polyethylene (HDPE) and paraffin wax (PW). The compatibility between binder constituents has been studied by dynamomechanical thermal analysis (DMTA) showing a partial miscibility between both components. Viscosity measurements of the different binder mixtures at different shear rates showed that the optimum formulation for MIM was 50 vol.-% HDPE. With this optimised binder, several mixtures were prepared with different powder loadings of M2 grade high speed steel. Torque measurements of the mixtures indicated that the maximum amount of metal to be used was 70 vol.-%. The wide distribution of the metal powder was homogeneously distributed into the polymer matrix. The polymeric part was driven off by thermal debinding using a thermal cycle designed on the basis of a thermogravimetric study of the binder. Finally the vacuum sintering of the parts allow high quality parts to be obtained. PM/1152At the time the work was carried out the authors

Production of alumina parts by powder injection molding with a binder system based on high density polyethylene

“…13 High density polyethylene (HDPE) is a polymer commonly used for plastic and powder injection molding. In particular we have used binder based on HDPE and paraffin wax as a second component for the manufacturing of M2 high speed steels 14 and bronze parts. 15 The main advantages we have found using this binder system were good homogeneity of blends, suitable rheological features allowing easy moldability, and finally, and due to the different melting temperature of both binder component ensure that when one component has melted, the remaining component act as backbone retaining the shape of the parts.…”

Powder injection moulding: processing of small parts of complex shape

“…Conventional binder systems using PE as base can be easily debounded with a double cycle of solvent debinding (i.e., using heptane) and thermal debinding (Herranz et al, 2005). By using systems based on waxes, the debinding operation can be shortened.…”

Powder Injection Moulding of Tool Materials and Materials Containing One-Dimensional Nanostructural Elements

“…In powder injection moulding, an injected preform is produced, which should then undergo debinding and sintering to achieve high functional properties [16,18,27,30,31]. Classical injection moulding in moulders is the same as the moulding of thermoplastic polymers (Figure 1).…”

“…The formability of metallic and ceramic powders and their mixtures enables to fabricate metal tools with relatively high ductility, ceramic tools with high hardness or metal matrix composites (MMC) and ceramic matrix composites (CMC) combining high properties distinct for metals and ceramics [22][23][24][25]. The forming of metallic or ceramic powders in a matrix of polymer binders, especially injection moulding or extrusion, has been applied for producing tool materials, including high-speed steels, carbide-steels and sintered carbides, characterised by their structure similar to commercial sintered tool materials [26][27][28][29]. It is not possible to achieve such high bending strength as for high-speed steels fabricated by hot isostatic pressing or for sintered carbides pressed [30].…”