Processes Involved In Molding Foam Rubber Closures

By Susan Baker


A foam rubber can be made from either polyurethane or natural latex material. In mattresses, latex rubber is used because of its endurance. This can also be used in cushioning seats and furniture and in insulating the roofs, walls, and some appliances.

Flexible and rigid foams are two basic types. Rigid foams are mostly used in insulating freezers, refrigerators, and buildings. It has a closed cell structure which prevents gas movement. Flexible rubbers are mostly used for cushioning pillows, furniture, and mattresses. These foam rubber closures have open cell structures which are produced in low and high densities.

Formulating the chemicals and ingredients that are to be used for production must be done properly to produce the desired final product. Each ingredient has its certain amount, reaction temperature, and molecular structure. The use of ingredients is to determine the characteristics and the purposes of the foam.

When foaming, for example, if the blowing agents have high quantity, much amount of water will be needed also to maintain the size of the bubbles and its formation rates. Foam density can be determined by the blowing quantity. The stiffness and hardness characteristics of a polyurethane can be changed also.

Formulation of polyurethane can be molded by hand, but doing it would take long when doing the mixing. This can be done faster and in a short period time but with the use of some machines. Using these machines would make the operation faster. These formulations are processed by different techniques.

Manufacturing the products Cobourg ON involves five different processes. First is preparation of the materials. Liquid chemicals are delivered by car tanks and will be transferred to large tanks. From large tanks, it will be moved to smaller tanks for them to be separated. Second is distribution and mixing. Low density foams are distributed to be used for production. Each chemical has specific amount that is mixed in other components. Chemicals are mixed in large mixing tanks and poured to a conveyor belt after production.

Third, product cutting and curing. Before it is poured into a conveyor belt, it will be sliced into smaller pieces in horizontal form, then it is stored at room temperature for 12 hours or more. And because it not yet firm, it will not be stacked. After curing, it will be sliced again according to thickness.

Fourth is the process of lamination. Rigid insulation panels form the board stocks. Insulators for appliances are injected by liquids between its inner and outer wall. Fifth is the molding of product. The distribution machine will vary the poured components and chemicals. Distribution makes the molded foams increase its hardness.

After all of the processes, outputs will be monitored, inspected, and tested for its physical and mechanical properties. Indentation is a very important property of a foam rubber because it will measure the quality of the product. Now, industries continue investigating ways on how to reduce and recycle scraps. Manufacturers are investigating for processes in producing new molded foams out of shredded materials.




About the Author: