Iwako Japan uses injection molding to make the parts of the Japanese erasers. Many components of things we use everyday are made by this process. The keys on your computer, many toys and even car dashboards are made by this method.
Right of center in the photograph is a stainless steel hopper with a big paper bag in it. The rubbery material that the Japanese erasers are made of feeds into the injection molding machine from the hopper. The Japanese eraser material is heated so it becomes viscous. This thick hot goop is fed into a mold and after a rapid cooling, is dumped into the box at the left hand side of the machine.
The Japanese eraser parts are then assembled by hand, packaged and sent to Iwako USA.