Injection Molding vs. Blow Molding

Injection Molding vs. Blow Molding

Blow Molding and Injection Molding are two manufacturing methods that are used to create plastic products. These are made using thermoplastics, which typically come as plastic pellets. The pellets are fed into a heated cylinder and are mixed using large augers, which then moves the melted plastic forward with rotation. Depending on the type of product you are making, you will be looking at one of these molding types to design plastic parts.

What is Injection Molding?
Injection molding is used to manufacture parts from thermoplastic materials such as polystyrene. These plastics can be formed into different shapes once heated then pressured into a mold for a range of parts. Injection moldings typically makes solid parts like Frisbees or body panels for cars.

Injection Mold

What is Blowing Molding?
Blow molding is a manufacturing process that begins with melting down plastic and forming it into a parison. The parison is then clamped into a mold and air is blown into it. Unlike injection molding, blow molding makes hollow plastic parts like plastic bottles and containers.

Blow Molding


Main Differences

Injection Molding                                                 Blow Molding

– Typically solid plastic parts                            – Used for making hollow bottles,
or components.                                                  containers, etc.

– The part’s thickness is influenced                – The part’s thickness differs
by the mold and core.                                        from place to place.

– Making the mold takes 90% of                      – 50% of the time spent on blow
the time.                                                              molding is needed to make the mold.

– The main focus for injection                         – Since a hollow interior is required,
molding is minimizing the                               air is needed to force the plastic to
presence of air.                                                   expand.

– Once the plastic cools and the                      – The process may end in the first
process ends, the machine                               mold, but the air may also be
releases the part.                                                injected in another section of the machine.

Although both of these manufacturing processes are used to design molded plastic, it is important to determine your needs before finding a contractor. At Design-Tek we specialize in custom molding, whether it be blow molding, injection molding, etc. We produce quality work when it comes to plastic part design. Learn more about our work by visiting our website.