Injection Moulding Tool Parts: A Comprehensive Guide

Injection Moulding Tool Parts: A Comprehensive Guide

This blog post will provide you with a comprehensive guide to injection mold parts, including their functions, types, and applications. Injection molding is a widely used manufacturing process that produces complex, high-quality plastic parts efficiently and accurately. However, for best results, it is crucial to understand the various components of an injection mold and how they work together.

First, let’s understand the basic components of an injection mold. Injection molds usually consist of the following main parts: mold base, mold cavity, mold core and mold guide system. These components work together to ensure that the plastic material is formed into the desired shape and size during the injection process.

The mold base is the foundation of the entire mold, which provides stable support and positioning. The mold cavity is a cavity that holds the plastic material and is shaped and sized to match the final product. The mold core is used to form the internal structure of the product. It can be fixed or movable and can be adjusted according to the needs of the product design. The mold guide system is responsible for controlling the opening and closing movement of the mold to ensure precise positioning and closing of the mold during the injection process.

Types of injection molds can be classified according to different design requirements and usage scenarios. Common injection mold types include single-cavity molds, multi-cavity molds, hot runner molds, and two-color molds. Single-cavity molds are suitable for producing products of a single color and shape, while multi-cavity molds can produce multiple identical or different products at the same time. Hot runner molds maintain plastic materials in a molten state by heating, thereby improving production efficiency and product quality. The two-color mold can realize two-color or multi-color injection molding of products, adding more design possibilities to the product.

Injection molds are widely used in various industries and fields. For example, auto parts in the automobile manufacturing industry, casings and connectors in electronic products, syringes and instruments in medical equipment, etc. can all be realized by injection molding. In addition, injection molds can also be used in the packaging industry, household products, toy manufacturing and other fields, providing efficient and precise solutions for product production and manufacturing.

In short, injection molds are one of the indispensable and important tools in modern manufacturing. By understanding the composition, type and application of injection molds, we can better understand the advantages and potential of this process, thereby achieving better effects and results in actual production. Whether for manufacturers or designers, mastering the knowledge of injection molds is the key to improving product quality and production efficiency.


Injection moulding is a process that involves melting plastic material in a barrel and injecting it into a mould cavity under high pressure. The mould cavity is shaped like the desired part and can have complex features and details. The plastic material cools and solidifies in the mould cavity, forming the final part. The mould then opens and ejects the part using ejector pins.

Injection moulding is suitable for mass production of plastic parts with high precision, consistency, and quality. It can also produce parts with intricate shapes and geometries that are difficult or impossible to achieve with other methods. Injection moulding can use a variety of plastic materials, such as thermoplastics, thermosets, elastomers, and biodegradable plastics.

However, injection moulding also requires a significant upfront investment in designing and manufacturing the injection mould. The injection mould is a custom-made tool that consists of several components that work together to create the part. The injection mould must be designed according to the specifications of the part, such as its size, shape, material, function, and quality requirements. The injection mould must also be able to withstand high temperatures, pressures, and wear and tear during the injection moulding process.

Therefore, it is important to understand the components of an injection mould and how they affect the performance and quality of the injection moulding process. In this blog post, we will discuss the main components of an injection mould, their functions, types, and applications.

Components of an Injection Mould

An injection mould consists of two main parts: the mould core and the mould cavity. The space that these two parts create when the mould is closed is called the part cavity (the void that receives the molten plastic). The mould core and cavity are usually made of steel or aluminium alloys that have high strength and durability.

However, there are also other components that are essential for the injection moulding process. These components include:


The hopper is the component where the plastic material is poured before the injection moulding process can begin. The hopper usually contains a dryer unit to keep moisture away from the plastic material. Moisture can affect the quality and properties of the plastic material and cause defects in the final part.


The barrel is the component that receives the plastic material from the hopper and transports it to the nozzle. The barrel has a cylindrical shape and contains a screw that rotates and pushes the plastic material forward. The barrel also has heaters that melt the plastic material as it moves along.


The screw is a component that is located inside the barrel and has a helical shape. The screw has three main functions: feeding, melting, and injecting. The screw feeds the plastic material from the hopper to the barrel by rotating and creating a pressure gradient. The screw melts the plastic material by generating frictional heat as it rotates and by transferring heat from the heaters in the barrel. The screw injects the molten plastic material into the mould cavity by applying a high force at its tip.


The heaters are components that are attached to the barrel and provide heat to melt the plastic material. The heaters can be electric or gas-powered and have temperature sensors and controllers to regulate the heat. The heaters must maintain a uniform and optimal temperature throughout the barrel to ensure a consistent and homogeneous melt flow.


The nozzle is the component that connects the barrel and the mould and delivers the molten plastic material into the mould cavity. The nozzle has a tapered shape and a small opening at its tip to control the flow and direction of the melt. The nozzle also has a shut-off valve that prevents the melt from leaking or drooling when the mould is closed.

Ejector Pins

The ejector pins are components that are attached to the mould core and help to eject the part from the mould cavity after it has cooled and solidified. The ejector pins are activated by a hydraulic or mechanical system that pushes them forward and backward. The ejector pins must be positioned and timed correctly to avoid damaging or deforming the part.

Split Mould

The split mould is a component that consists of two or more parts that can separate and rejoin during the injection moulding process. The split mould allows for the creation of parts with undercuts, holes, or complex shapes that cannot be ejected from a single-piece mould. The split mould also enables the use of multiple cavities, materials, or colours in a single injection moulding cycle.

Clamping Unit

The clamping unit is the component that holds the mould core and cavity together and applies a force to keep them closed during the injection moulding process. The clamping unit can be hydraulic, mechanical, or electric and must provide enough clamping force to withstand the injection pressure and prevent the melt from escaping or flashing. The clamping unit also controls the opening and closing of the mould and the movement of the ejector pins.

Types of Injection Moulds

Injection moulding is a process of producing plastic parts by injecting molten material into a mould cavity. There are different types of injection moulds that can be used for this purpose, depending on the design and requirements of the product. Here are some common types of injection moulds:

  • Two-Plate Mould: This is the simplest and most widely used type of injection mould. It consists of two halves, a fixed half and a moving half, that are separated by a parting line. The molten material is injected into the cavity through a sprue and fills the cavity. The mould is then opened and the part is ejected along with the sprue and runners.
  • Three-Plate Mould: This is a more complex type of injection mould that consists of three plates, a fixed plate, a floating plate and a moving plate. The floating plate separates the runner system from the part cavity. The molten material is injected into the runner system through a sprue and then flows into the part cavity through one or more gates. The mould is then opened in two stages: first, the floating plate moves away from the fixed plate to separate the runner system from the part; second, the moving plate moves away from the floating plate to eject the part.
  • Hot Runner Mould: This is a type of injection mould that uses a heated manifold to keep the molten material in a liquid state within the runner system. The molten material is injected into the manifold through a sprue and then flows into the part cavity through one or more nozzles. The mould is then opened and the part is ejected without any sprue or runners. This type of mould reduces material waste and cycle time, but requires more maintenance and energy.
  • Cold Runner Mould: This is a type of injection mould that uses an unheated runner system to deliver the molten material to the part cavity. The molten material is injected into the runner system through a sprue and then flows into the part cavity through one or more gates. The mould is then opened and the part is ejected along with the sprue and runners. This type of mould is simpler and cheaper than a hot runner mould, but produces more material waste and requires longer cycle time.

Applications of Injection Moulding

Injection moulding is a widely used manufacturing process that can produce parts from various materials, such as metals, plastics, and rubber. Injection moulding involves melting the material and injecting it into a mould cavity, where it cools and solidifies into the desired shape. Injection moulding has many applications in different industries, such as:

  • Automotive: Injection moulding is used to make various components of cars, such as bumpers, dashboards, door handles, and lighting fixtures. Injection moulding can produce complex and durable parts with high precision and quality.
  • Medical: Injection moulding is used to make medical devices and equipment, such as syringes, catheters, implants, and surgical instruments. Injection moulding can ensure sterility and biocompatibility of the parts.
  • Consumer Products: Injection moulding is used to make everyday items, such as toys, bottles, containers, and household appliances. Injection moulding can create attractive and functional products with low cost and high volume.
  • Packaging: Injection moulding is used to make packaging materials, such as caps, closures, trays, and boxes. Injection moulding can provide protection and convenience for the products inside.

Injection molding is a widely used manufacturing process with a broad range of applications across various industries. Its versatility, efficiency, and ability to produce complex parts with high precision make it a preferred method for creating a wide array of products. One of the primary applications of injection molding is in the production of plastic components for consumer goods. From everyday items like plastic bottles, containers, and household appliances to more intricate products like electronic device housings and consumer electronics, injection molding plays a significant role in shaping the modern consumer landscape.

In the automotive industry, injection molding is extensively utilized for manufacturing various interior and exterior components. Dashboard panels, door trims, bumpers, and grilles are commonly produced through injection molding due to its ability to meet high-quality standards, offer design flexibility, and meet the stringent requirements of the automotive sector. Additionally, injection molding is instrumental in producing small yet crucial parts such as switches, connectors, and clips used in automotive electrical systems.

The medical sector also heavily relies on injection molding for the production of medical devices and equipment. Injection molding is capable of manufacturing precise and consistent medical components like syringes, IV connectors, inhalers, and surgical instruments. The use of injection molding ensures the sterile and reliable production of medical devices that adhere to strict regulatory standards.

Injection molding finds application in the electronics industry, where it is used to produce casings, housings, and enclosures for various electronic devices. From smartphones and laptops to routers and gaming consoles, injection molding allows for the creation of aesthetically pleasing and functional electronic components that protect delicate electronics while offering user-friendly designs.

Industrial applications of injection molding include producing components for machinery, equipment, and tools. Gears, bearings, fasteners, and control panels are just a few examples of the industrial parts made through injection molding. The process enables manufacturers to create durable and precise components that can withstand the rigorous demands of industrial settings.

In the packaging industry, injection molding is utilized to create a wide range of packaging solutions. Caps, closures, containers, and trays used in the food and beverage, pharmaceutical, and cosmetic sectors are all manufactured using injection molding. The process enables the production of lightweight, yet sturdy and reliable packaging solutions that maintain the integrity of the packaged products.

The versatility of injection molding extends to the construction sector, where it is employed to manufacture various construction components. Plastic pipes, fittings, junction boxes, cable trays, and other construction materials are produced using injection molding due to their durability, corrosion resistance, and ease of installation.

In conclusion, the applications of injection molding are vast and diverse, making it an essential process in many industries. Whether for producing consumer goods, automotive components, medical devices, electronics, industrial parts, or packaging solutions, injection molding offers a reliable and efficient method for creating high-quality and complex products. Its ability to achieve precise and repeatable results while accommodating various materials and design requirements makes it a staple manufacturing process in the modern world.