Preform Mold Design Case Analysis

The preform is a product of injection molding and is an intermediate. The preform is blown into the final product. For example: beverage bottles, drinking water bottles, shampoo bottles, etc.

This case shows the design idea of the mold for the preform. This mold design idea is different from other PET preform moulds. Preform moulds are all multi-cavity structures. This mold has 2 cavities. Mold size: 530*320*470mm.

This mold adopts a needle valve type hot runner system. According to the characteristics of the preform mold. Valve needle type hot nozzle, has good color changing performance. Suitable for most plastics, good flow properties. The gate traces are extremely fine.

The preform mould cavity adopts spiral insert type cooling water channel. A single piece of insert is fixed in the cavity. This method has a better cooling contact area and is easy to process. A separate cooling water channel is set up for each cavity. The core adopts well-type cooling water channel. Each core is set up individually.

The thread part of the preform is an external thread. Slider mechanisms can be used. However, this set of preform mould does not use a combination of angle pin and sliders. Instead, two levers are used to drive the slider to open and close.As shown below:

The lever separates the slider in two steps. The first small slope, the product is separated from the threaded insert. Eliminates stress between the preform and the threaded insert. The second section of the large slope completely separates the slider, and the product falls automatically.
The pulling force at the end of the lever interacts with the pushing force of the push block to clamp the slider. Prevent the slider from moving again. During the mold clamping process, the tapered column on the lower fixed plate can reset the slider. The movement of the slider does not exceed the tip of the tapered post.

The ejection action of the preform mold is performed by the push plate. The push block is pulled by 4 pull drawbar on the fixed die. And control the opening and closing sequence of the preform mold. The drawbar has two no-load strokes. and in the opposite direction. This shortens the length of the drawbar.

As shown in the video. What’s interesting about this set of preform mould is the ejector and threaded slider parts.

This preform mold design is not perfect. Just his unique and interesting ideas so here it is. If you have similar design needs, it can be used as a reference.