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What are the principal parts of mould ?

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From medical equipment to toys, the possibilities created by plastic products are virtually endless. Despite numerous variables in materials and machinery involved in its production, the basic structure of a successful mold remains consistent for any injection process.

The principal parts of a mold can be divided by function

Plastic injection molds feature an intricate network of components that enable their production.

From the precise pouring system and temperature adjustment to forming parts, exhaust systems, guiding elements and ejection mechanisms-each component is vitally important for maintaining accuracy during processing.

Of course out all these pieces it’s perhaps the most complex – as well as ever-changing ones– which encounter direct contact with plastic materials: namely, the pouring system and injection molding parts.

They demand absolute finesse in terms of material handling processes; from finishing touches down to every single precision factor involved!

1. Pouring system

The journey of molten plastic to the cavity begins far before it reaches its destination. A carefully constructed path must be in place, leading from the nozzle and encompassing components such as a main flow channel, cold material environment, runner system and gateways.

2. Forming parts system

The intricate combination of components that are part of injection molds determine the shape and design for a product.

Central to this is the distinction between cores (punch molds) which form inner surfaces, and cavities (die), responsible for raising external shapes.

Depending on technological complexities or manufacturing needs, different layers may be assembled into one whole piece with inserts employed in areas difficult to craft.

3. Temperature adjustment system

To ensure optimal injection molding conditions and maintain an accurate temperature for thermoplastic injection molds, a comprehensive adjustment system is necessary.

This can be achieved through the implementation of water-cooled channels within the injection molds to effectively remove heat or by installing electric heating elements.

Ultimately, this tailored approach guarantees that maximum accuracy and quality are maintained in every manufacturing process.

4. Exhaust system

During the injection molding process, an air system is utilized to facilitate the exhaust of pressure generated from liquefied plastic and any existing cavity-air.

Without a proper outlet for these elements, product surfaces can be marred by gas marks or burns while also compromising its quality through pockmarks and weaker connections.

Thus it’s imperative that this outlet remains properly functioning throughout production cycles in order to improve accuracy and efficiency when producing products with high standards of excellence.

A vent hole must be set in order to prevent high temperatures generated by compression from burning the product.

This opening should typically have a shallow groove with depths between 0.03-0.2mm and widths of 1.5-6mm on one side of the die – ensuring molten material is not released at an unsafe distance and resulting in potential harm to those operating nearby during production runs.

Additionally, gaps between ejector pins can also be used as another form of release for any accumulated air during injections into molds or dies.

5. Guide system

To ensure that the two halves of an injection mold align accurately when closed, guide parts are installed in each half. These consist typically of 4 sets of posts and sleeves which may be augmented by matching inner/outer tapers on the molds themselves to assist with centering accuracy.

6. Ejection system

The injection molding process requires a combination of components to create the finished product, including thimbles, front and rear plates, guide rods and return springs.

After cooling in the injection molds occurs and parts are separated from one another due to an ejector pin’s push action provided by an injection machine operator-new plastic products can be released for further cycle transformation or use.

The principal parts of a mold can be divided by structure

The plastic mold is a complex structure made up of several essential components, such as the injection mold base, core, and auxiliary parts. Supporting systems are also in place to ensure an optimal setup for production.

1. Mold base

Ready-to-order plastic injection molds offer a quick and efficient solution to reducing design times. These standard mold bases provide the essential foundation in constructing quality, custom plastics – making them an invaluable tool for those looking for reliable performance with minimal wait time.

2. Mold core

For complex injection molds, the core is essential to determine a plastic product’s shape and overall structure. Substantial processing time is dedicated to designing and crafting this integral component for optimal construction precision.

On the other hand, some simpler molds can form products directly on templates due to their lack of cores; such technologies may be outdated but still exist in certain parts of today’s industry.

3. Auxiliary parts

Plastic molds can be customized to a variety of shapes and size with the help of various auxiliary components, such as positioning locating rings, sprue bushings, thimbles and grab pins.

Many parts are pre-manufactured for added convenience while others require tailored designs created specially in accordance with your needs. What’s more, is that you may often receive these supplies making up part or all of the mold bases when purchased together!

4. Auxiliary system

Plastic injection molds are equipped with a quartet of important auxiliary systems – pouring, ejection, cooling and exhaust. For materials requiring higher temperatures for heating purposes an additional system can be included.

5. Auxiliary settings

The plastic mold features several additional characteristics, such as ring holes and KO holes (for inserting pins), to round out its construction.


Plastic injection molding machines utilize a two-part system called the moving and stationary molds. The dynamic mold is installed on the machine’s movable template, while the static mold is mounted to its fixed counterpart – thus forming a gating system with an enclosed cavity.

After plastic material has been injected into this space, both halves of the mould are separated in order to allow for plastic product extraction.

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