large injection molded parts

large injection molded parts

How to manufacturer large plastic parts


Large plastic parts are used often in our daily life: such as water tanks, beer or fruit crates, displays, large trash cans or waste bins and, yes, even nowadays transportaion pallets are made of molded plastic. Plastics are usually made with the help of injection molds or dies and these require a substantial investments if you are an inventor or Small medium company. New designed parts requires custom made molding in china

In this article we discuss which mold technology suits the best for your large molded part.

There are basically 3 main technologies to make these large parts in mass or serial manufacturing. In this article we donnot discuss plastic parts that are large and made in a very low quantity which are usually made by hand. Think of parts made by by fiber glass layer. Such as large sailing boats…

  1. By injection molding.

This is a process used for large series of your product. It uses a positive die and negative mold that are can open and close. If closed , under pressure, plastic will be sprue-ed into the mold. Disadvantage is the mold cost, upfront costs are pretty high.

Think of plastsi restaurant chairs or dust bins. large encasings for electronical parts. Triple-c has experience injection molding large parts in China.

  1. Manufacturing by rotational molding :

In plastic rotational molding, one half of a hollow mold is filled with plastic powder, usually polyethylene (PE). After filling, the mold is closed and starts to rotate around both a horizontal and vertical axes. The rotating  mold is then placed in an oven where the powder liquifies at a temperature of 240-325 ° C, Due to the rotational forces it forms a uniform layer against the mold wall. At the end of the heating cycle the mold is brought to a cooling chamber. Here the mold is cooled with the aid of air, whereby the plastic becomes hard again and cures. Then rotation molding is stopped and the product can be taken out of the mold. This makes an indestructible hollow product.

  1. Made by vacuum forming or thermoforming.

Thermoforming is a  technique in which plastic plates are formed  by means of heat and a die that pushes into the direction of the plate ’a surface..

The main starting material of a thermoform is always a plastic plate.

A positive mold (as shown in the picture is used when the inside dimension of a product is leading or a product does not have to be molded to the nearest mm.) A positive mold is cheaper because less material is needed for a positive mold to mold the mold. to make.


Vacuum forming is a similar technique but the plate will be suck into a negative mold due to the vacuum that has been created. A negative mold is used when the outside size of a product is leading. …

Thermoforming is so popular because of the following advantages:

  1. Low mold costs compared to injection molding and rotational molding
  2. Fast turnaround time
  3. Changes to the mold are still possible later in the process
  4. Great freedom of shape
  5. Large choice of materials

Perfectly clear products