• The first one is rotational molding. Plastic chairs are created in several ways and which all of them involve metal molds that are carved into desired shape. Among the most popular form of furniture molding is the rotational molding wherein large metal mold is injected with plastic polymer powder. This will be heated to melting point. The mold is turned mechanically three-dimensionally to distribute the polymers very evenly to the inside part of the mold. After a number of minutes of spinning, the mold will then be cooled off and the rotation comes to an end. Then the mold is opened and the new entirely hollow chair is being removed.
• The second method of manufacturing plastic chairs is injection molding. In this process, like the first one, a metal mold is employed. However, the result is not hollow, but rather solid plastic. This type of mold does not spin but the polymers are heated at a preset temperature and rate. Then they are poured into the mold and then cooled. Manufacturers must use a specific amount of precision with this type of molding process since the plastic is slowly poured that might cause them to dry soon. When poured too quickly, the end result will not be uniform. But when properly done, the result would be a plastic chair that is seamless molded all in a single piece.
• Injection molding can also be performed using gas which is blown at high velocity inside a mold that pushes the molten plastic out of specific parts of the mold. This would create channels in the form of plastic making the chair much lighter in weight while maintaining the same strength. The other aspects of injection molding stay the same. However, the end result is a chair which has hollow parts and other solid parts.
The plastics that were used in the process of making chair are usually composing of different types of plastics that are all mixed together in the heating part of the molding process, making the chair much stronger.