A type of bowl for ten-pin bowling has been developed by the German company KMV, on which the outer skin is an injection-moulded layer of DuPont’s Delrin acetal resin. Several benefits are said to result from the material’s properties, namely abrasion-resistance, impact-resistance and recyclability.
Manufacture of the bowl starts with the creation of an injection-moulded framework, for which a relatively stiff thermoplastic material such as glass-reinforced Zytel nylon is used. In this framework a void-free core is built up, layer by layer, in a sequence of moulding operations. The choice of core material depends on the end-product’s required resilience and weight. The final layer to be overmoulded is the functional external skin of Delrin. The whole process takes about 25mins.
The bowls withstand a 5m fall without shards of the cover layer splitting off, as sometimes happens with bowls made of thermoset resins. Delrin’s low friction provides a further advantage in that when the bowl is launched at high speed onto the lane, the lane’s special varnish does not `burn’ into the ball’s cover layer.
DuPont Engineering Polymers Tel: 01442 218500