Article#200120: The Making of “Rubber” Shoes, Part 1: Moulds
Unlike traditional footwear which shoe uppers are being produced through pattern cutting; stitching sewn; cementing and lasting via a series of production steps manually. These rubber alike footwear uppers are entirely produced via a set of aluminum molds through industrial scale injection machines. This shoe is designed to be produced in 3 sets of moulds. One is for upper; one is for midsole and one is for outsole.
In footwear manufacture there are 2 types of most common moulding method used in producing sneaker bottom toolings, one in injection moulding, the other one is compression moulding. This rubber alike shoe is produced using both moulding methods. The entire upper and bottom midsole part are both produced in injection moulds. The bottom outsole part is produced in a compression mould.
Upper Injection Mould
The largest and the most complicated is the upper mold. I enclosed an upper injection-mold picture here to showcase the size of this mold is almost double the size of traditional midsole mold.
The inside of the upper mould is certainly a work of art which you can’t image how intricate it is from the exterior of a block of aluminum.
Midsole Injection Mould
The midsole injection mould is almost half the size of the upper injection mould.
Outsole Pressing Mould
Rubber outsole is produced in the most common waffle style pressed mould.
Tools to Make Tools
Before these moulding tools can be used to produce shoe parts, we need tools to make these moulds. Then whatever the number of mould parts (minimal 2 top and bottom) produced will be put together using hinges, screws and other mechanisms. These moulds are produced using industrial scale intricate carving machine with diamond tips controlled by a computer. These carving devices are also used to make footwear tooling mockups. Please see What is a Sneaker Tooling Mockup? And How is It Made? article.
Please see Part 2 of The Making of Rubber Shoes: Injection which I explain the magic process of actual producing of shoe parts.
