Every plastic part of an injection molding plant requires a special manufacturing process, and different products can vary greatly. Injection molding is used to make solid parts, while blow molding is used to make plastic products with hollow areas, such as bottles and containers.

Injection stretch blow molding combines injection molding and blow molding processes. The plastic is first molded into a Pet Bottle Preform to form a threaded bottleneck. Once the preform cools, it is fed into a stretch blow molding machine. The preform is then reheated using an infrared heater and the preform is blown into the plastic bottle with forced compressed air.

Injection molding and blow molding are two core processes in plastics manufacturing. Products produced through these processes are widely used in the automotive, food service packaging, electronics, medical devices, irrigation, dental, firearms, energy and environmental industries.

To help you better understand the different manufacturing methods available in the project, we outline the main injection and blow molding methods used by plastics manufacturers.
Injection molding process

Injection molding is used to make larger quantities of plastic products ranging in size from large parts to small parts requiring micro-precision.

There are many types of manufacturing methods that are classified into injection molding, such as thermoplastic injection molding, overmolding, insert molding, cold runner molding, and hot runner molding.

Thermoplastic injection molding
Thermoplastic injection molding uses a thermoplastic polymer, which means it becomes liquid when heated. Unlike thermosets that are cooled to a permanent solid, the thermoplastics can be combined into a liquid after cooling to a solid.

Overmolding
Overmolding, or two injection molding, is the process of covering an injection mold on another material, such as metal, to improve product performance or durability. A rubber-like compound, called a thermoplastic elastomer (TPE), is a commonly used overmold material. An example of a TPE overmolding application is a handle on a toothbrush. Overmolding can also be used to seal products and parts made from several injection molds.

Insert molding
As with overmolding, insert molding is an injection molding process that combines two or more components into one finished product. Insert injection molding inserts the component into the injection cavity and the plastic material fills around the insert. The insert can increase the strength of the product and does not require additional parts to reduce the weight of the product.

Cold runner injection molding
The cold runner mold uses a gate to fill the flow path for injecting plastic resin into the mold cavity. In two plate molds, the runner system and parts are connected and the discharge system can be used to separate the pair from the mold. Cold runners can reduce waste by recycling and regrinding materials, but this can also increase overall cycle time. The cold runner system can be used with a variety of polymers and can be easily changed in color.

Hot runner mold
The hot runner mold uses a manifold to heat the molten plastic resin and then inject the material into the mold cavity through the gate. The two main types of hot runner molds are external heating and internal heating. Externally heated molds can be used with polymers that are less sensitive to thermal changes, while internally heated hot runner molds allow for better control of material flow.

Because hot runner molding does not require the use of flow channels, potential waste is reduced and the recycling, regrinding and processing of the original plastic does not affect the overall cycle time.
Blow molding process

In the blow molding process, the raw material plastic is formed into a hollow tube, and one end of the opening is called a parison. The parison is pressed into a cooled metal mold and compressed air is forced into the parison. When the molded plastic cools and hardens, the metal mold opens and discharges the product.

Jilian Plastic Mould is a manufacturer of pre-formed parts with very professional experience in this area. We can be said to be the leader in this industry. We provide customers with products ranging from 5-Gallon Pet Preform to caps, handles, etc. As long as you need it, I believe we can satisfy you!