Polyurethane has long been recognised as a material used to make comfortable, high-performance shoes, with exceptional cushioning, resistance and durability. In the last few years, the injection of polyurethane directly onto the upper has become increasingly popular in the sports and leisure footwear industries.
The success is also linked to the introduction on the market of new technologies such as the “PLUS2” (a STEMMA patent ) double-ring moulding system for soles with three densities/materials injected directly onto the upper, which has allowed manufacturers to expand and enrich their product range.
Supplied as an optional on new STEMMA machines, the system allows producing footwear with rubber or TPU soles and midsoles with two different densities of polyurethane, without loss of productivity compared to a normal injection cycle on the upper.
The main advantages are certainly the possibility of creating areas of graduated density to improve the comfort and performance of the shoe, as well as the ability to overmould the upper with polyurethane, thus reducing the risk of imperfections.doppio-anello2