Understanding Plastic Development and Blow Molding

In today’s world there are many materials that are used for creating or containing things, but one of the most common is plastic. Modern plastic comes from a variety of organic polymers such as polyvinyl chloride, nylon and polyethylene. The product gets its name from the flexibility or malleability of the material. It has become so common in modern society that people tend to forget the items it is made from. Common consumer items include plastic garbage bags and household containers for kitchens, baths or clothing. Other common uses for plastic are in the food storage industry, automotive industry and as electronics housing. Some of these products require a specific method of plastic molding known as blow molding.

Plastic is formed by one of three basic techniques, extrusion, injection molding and blow molding. Extrusion forces the molten plastic through a die and stretches the final result into the product required. Injection molding forces the resin into a mold which is the reverse of the final product. Blow molding is similar to injection molding except the end result will have a hole. Some of the most common items produced using this method are milk, soda or water containers. The technology for blow molding has been around since the late nineteen thirties, but it didn’t become widely accepted until many years later.

Blow molding has three differing methods, extrusion, injection and injection stretch. Each begin by melting the stock plastic, usually supplied as a pellet, into a preform for injection stretch molding or a parison for the other two methods. The parison has a hole in one end that is used to inject compressed gas. Once the parison is ready it will be clamped on a mold and injected with air. The injected air stretches the plastic into the mold that gives the final product its unique shape. From this point the plastic is allowed to cool. Cooling the plastic hardens the product which can then be removed from the mold. The entire process is very quick because the plastic is usually thin. While the process of blow molding is fairly simple it still requires some knowledge. A little education can teach you a lot about blow molding basics.