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Insert moulding and over moulding are two advanced manufacturing techniques that are used to enhance the functionality and aesthetics of plastic components, by fusing two different polymers (Plastics), fusing metal components with plastic products, or overlaying one plastic component with another plastic layer for different material/colour. industries like automobile, electrical, surgical, medical, consumer goods, household, and many smaller industries use these techniques to obtain certain advantages in manufacturing, costing, production and durability.
In this small blog we will explore more on both these techniques and see why insert moulding and over moulding are the future of producing high-quality goods.
What is Insert Moulding?
Insert moulding is a manufacturing process that involves placing a pre-formed component, known as an insert, into a mould cavity. The mould is then filled with molten plastic, which encapsulates the insert as it cools and solidifies. This process creates a single, integrated part that combines the properties of both the insert and the plastic material.
For example, as shown in the above-shown image, a screwdriver, where the metal insert in the shape of a shaft is placed inside a mould and the red plastic handle is moulded over the metal shaft insert, making the plastic part fuse with the metal insert and increasing the adhesion of the metal part to a plastic handle, improving the rigidity of screwdriver.
Process of Insert Moulding
Preparation of Inserts: Inserts can be made from various materials such as metal, ceramic, or other plastics. They are designed to fit precisely into the mould (within tolerances of 0.01 to 0.1mm).
Mould Design: The mould is designed to accommodate the insert and allow for the injection of molten plastic around it.
Loading Inserts: The inserts are loaded into the mould before the injection process begins.
Mould close: The mould closes and clamps down the insert in its place making sure it does not move, also clamping pressure is applied to the mould so that it does not open up during the injection process.
Injection Moulding: Molten plastic is injected into the mould, filling the cavity and surrounding the insert.
Cooling and Ejection: The mould is cooled, allowing the plastic to solidify, after which the finished part is ejected from the mould.
What is Over Moulding?
Overmoulding is a subset of insert moulding, the process of overmoulding is similar to insert moulding, in this a layer of plastic is applied over an existing substrate or component, the only major difference being in overmoulding the substrate or base layer is only partially covered leaving certain parts exposed. this process is often utilized where one type of plastic is to be applied on another type of plastic, to enhance functionality or increase aesthetic appeal, some examples are grips, floor wipers, soft insulation, toothbrushes, and many more.
Unlike insert moulding this requires higher precision and a better understanding of materials and the moulding process. One small example is let's say your substrate(base) material melts at 250°c, then your over-moulding material has to melt at a lower temperature than the base material, otherwise, the base material will melt during the overmoulding process, many more factors are needed to be considered.
Process of Over Moulding
Preparation of Base Component: The base component can be made from various materials and is prepared for the over-moulding process.
Mould Design: The mould is designed to accommodate the base component and the additional layer of plastic.
Loading Base Component: The base component is placed into the mould.
Mould Close: The close with the base component inside the cavity, and seals the area where the overmoulding is not supposed to happen.
Injection of Over Mould: Molten plastic is injected into the mould, covering the base component.
Cooling and Ejection: The mould cools, solidifying the over-moulded layer, and the finished part is ejected.
Applications of Insert Moulding and Over Moulding
Both insert moulding and over moulding have a wide range of applications across various industries:
Automotive: Used for producing components like electrical connectors and dashboard parts.
Electronics: Commonly used in producing housings for electronic devices, improving durability and aesthetics.
Consumer Goods: Found in items like toothbrushes, kitchen utensils, and tools, where enhanced grip and comfort are needed.
Medical Devices: Employed in creating components that require biocompatibility and precise tolerances.
Household: Many items used in our house use either one technology to achieve higher durability and better aesthetics.
Kitchenware: In the kitchen, many components use insert moulding and without insert moulding, it would be impossible to achieve durability in those components.
Advantages of Insert Moulding and Over Moulding
Both processes offer several advantages:
Enhanced Strength: The combination of materials can create stronger components that withstand greater stress.
Improved Aesthetics: The ability to use different colours and textures can enhance the visual appeal of products.
Reduced Assembly Time: By integrating multiple components into one part, manufacturers can reduce assembly time and costs.
Increased Functionality: The processes allow for incorporating features like grips, seals, and electrical contacts.
Wear resistance: In the areas with high friction or contact, the metal inserts can be used, and friction reduction material can be overmoulded to reduce the friction increasing wear resistance.
Insulation: There are many plastics used for better thermal, electrical and vibration insulation, just over-mould the part with ideal insulating plastic and you can have high-quality insulation on your parts.
Cost reduction: Insertmoulding and Overmoulding both are processes that can reduce the production cost as well as material cost, some full metal parts can now be inserted moulded, reducing material cost and insert moulding also reduces production assembly steps increasing your production efficiency and reducing production costs.
Considerations for Insert Moulding and Over Moulding
While inserting moulding and over-moulding offer numerous benefits, there are several considerations to keep in mind:
Material Compatibility: It is crucial to ensure that the materials used for the insert or base component and the moulding plastic are compatible to prevent issues such as delamination.
Design Complexity: The complexity of the design can impact the ease of manufacturing and the cost of producing moulds.
Cost Considerations: Initial setup costs can be high, especially for custom moulds, but can be offset by the benefits of reduced assembly time and improved product performance.
Moulding complexity: If there are too many inserts, too many moulding steps, or too complex mould then the moulding process becomes too complex and might not become feasible, while designing the mould, the moulding efficiency and complexity are also to be kept in mind.
Processing: Once the mould is manufactured and set on the machine, it is up to the operator how well can he set up the machine to optimize the process, and produce the best quality components.
Conclusion
Insert moulding and over moulding are innovative processes that play a crucial role in modern manufacturing. By understanding these techniques, their applications, and their advantages, manufacturers can leverage them to create high-quality, functional, and aesthetically pleasing products. As technology advances, the potential for these moulding processes will continue to expand, leading to even more innovative applications in the future.
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