Injection Moulding and the Manufacture of Shoes
Footwear is an important sector in the UK with around £6billion of footwear sold to UK consumers and another half a billion pounds exported around the world. Whilst some premium level footwear is still produced in over 20 factories across the UK, the majority is exported for mass production in factories across the world, especially China, where the manufacturing process is underpinned with the application of heating elements.
A popular material for the production of footwear is PVC, which is increasingly used in the soles and uppers of modern shoes as a substitute for leather, not only because a leather-like appearance can be achieved at a cheaper cost, but because PVC offers fashion designers greater flexibility in creating innovative styles through its capacity to be moulded into shape with the application of heating element technologies. Modern sports shoes also make extensive use of PVC to provide shock absorbance, support and strength in demanding use environments. PVC is popular with manufacturers for a number of reasons including; it is easy to use and convert into many different forms, it is strong and durable yet light weight, it is waterproof and resistant to attack by chemicals, there is a relatively low energy demand in manufacture and longevity in service, it is cost competitive.
The manufacture of PVC shoes uses injection moulding machinery, where the raw plastic material will be fed into a hopper and pushed through barrels which are heated to a specific temperature using heating elements such as band heaters and cylinder heaters, in order to melt the plastic into a molten state ready for injection into a mould fabricated in the appropriate size, fit and style of footwear, and then cooled and finished to the desired footwear appearance which could include textures ranging from enamel gloss to delustred suede.