Foaming, or urethane foam molding, is the process of casting polyurethane foam. The material is mixed and placed in a closed mold to set up and expand during the polyurethane reaction.
The yellow EVA ball and red PU ball were made with foaming technology. The parting line of these foam stress balls was inevitable via injection molding but can be removed.
Solution
Step 1: A foamy solution was mixed along with the appropriate colorant or other materials, as needed.
Step 2: The injection molding machine was heated to a proper temperature, and the solution was inserted into the mold.