The Process of Making Foam
Foam rubber is used for many purposes. Foam is used for cushioning in furniture and automobile seats and for insulation in walls. There are two common kinds of foam know as flexible and rigid foams. Foam is made by forming gas bubbles from a plastic mixture using a blowing agent.
The most common type of foam is flexible foam. It is created as an open-cell which can be produced in either high or low density. Flexible foam is mainly used for cushioning in automobile and furniture seats, making mattresses and pillows and footwear soling.
On the other hand, rigid foam is created as a closed-cell structure in which gases cannot penetrate. Rigid foam is used in refrigerators, insulating buildings, freezers and container refrigeration.
What kind of raw materials are used?
Mainly, foam is made of the following chemicals polyisocyanates, which consists of 40%, polyol, which consists of 50%, water and other chemicals which consist of 10%. These elements belong in the group of liquid polymers. When the chemicals are mixed with water, they undergo an exothermic reaction to form polyurethane.
Liquid chemicals are ferried to the manufacturing station by either railroad tankers or truck tankers. The chemicals are then injected into a huge storage tank. The process goes on, and the chemicals are injected into relatively small mixing tanks. The substances that react with each other are kept separate.
Mixing and dispensing
A process known as open pouring/ continuous dispensing is used to produce flexible and rigid low-density foam. The process involves mixing a specific amount of each chemical in a mixing tank. These reactive elements are added onto a moving conveyor belt where foam comes up and cools to form slab stock. In the next stage, foam is cut to size.
Curing and cutting
The foam is always in a continuous motion moving towards the end of the conveyor belt. It is at this end that foam is cut to size automatically. The foam is cut into 12ft long pieces and cured at room temperature for 12 hours. Foam is automatically cut by a bandsaw into desired sizes.
Testing the quality
The end product is tested and inspected for various mechanical and physical properties. An essential feature of foam called indentation load deflection is measured to gauge the load-bearing quality and spring tension of the material.