Injection molds play a crucial role in modern industry, serving as key tools in the production of plastic products. The quality and design of plastic moulds directly impact the final product’s quality and cost-effectiveness.
In the following content, we will delve deeper into the process of injection mould manufacturing, unveiling the mysteries within.
Structural Components Of Injection Moulds
Plastic moulds are generally composed of the following parts according to their structure.
1. Mould Base
Typically ordered directly from standard mould base manufacturers, significantly saving the time needed to design the mould, hence it’s referred to as the standard mould base for plastic moulds.
It constitutes the most basic framework of the plastic mould.
2. Core
The core part is the heart of the plastic mould, being the most crucial component within the mould.
The shaping part of the plastic product is located inside the core, with most of the processing time spent on the core.
3. Auxiliary Parts
Common auxiliary parts in plastic moulds include locating rings, sprue bushings, ejector pins, lifter pins, support pillars, ejector guide pins and bushings, trash pins, etc.
Some of these are standard parts that can be ordered together with the mould base, while others need to be designed separately.
4. Auxiliary Systems
The auxiliary systems of a plastic mould include the gating system, the ejection system, the cooling system, and the venting system.
5. Auxiliary Settings
Auxiliary settings of plastic moulds include lifting hole, KO hole (ejector pin hole), etc.
6. Mechanisms for Dealing with Dead Corners
When a plastic product has dead corners, the mould will have one or more structures to deal with these dead corners, such as sliders, angled lifters, hydraulic cylinders, etc.
In Chinese injection moulding, this mechanism for dealing with dead corners is referred to as the “core pulling mechanism”.
How To Manufacture An Injection Mould?
Manufacturing an injection mould is a complex process that involves several key steps, from design to the final product. Here’s a simplified overview of how to manufacture an injection mould:
Design and Planning: Based on product requirements and specifications, designers use Computer-Aided Design (CAD) software to create a 3D model of the mould.
Material Selection and Preparation: Choose the appropriate materials for the mould design, typically high-strength and wear-resistant metal materials, such as tool steel.
Then, the material is processed and prepared using machinery like milling machines and lathes.
Manufacturing: Use Computer Numerical Control (CNC) machines to cut the mould base and cavities from metal blocks.
For complex details and strict tolerances that cannot be achieved through CNC machining, Electrical Discharge Machining (EDM) is used. This involves using electrical sparks to shape hard metals.
Heat Treatment and Surface Finishing: To improve the hardness and wear resistance of the mould, it may undergo heat treatments such as quenching and tempering.
Additionally, surface treatments like electroplating and polishing can be applied to the mould to enhance surface quality and corrosion resistance.
Assembly and Calibration: Assemble the manufactured mould components and perform necessary calibrations and precision checks.
This ensures that the mould can accurately replicate the shape and dimensions of the product.
Types of Injection Moulds
Different types of products require customised injection moulds to meet diverse product needs.
The most common types of injection moulds are two-plate moulds, three-plate moulds, and hot runner moulds.
Two-Plate Mould
Two-plate mould, also known as single parting surface moulds, are the simplest and most basic type of mould.
They can be designed as single cavity moulds or multi-cavity moulds and are the most widely used type of mould.
Three-Plate Mould
Three-plate mould, also known as double parting surface moulds, differ from single parting surface moulds in that they include an additional, partially movable stripper plate in the fixed mould part.
In this design, the runner is ejected between the first and second plates, allowing the part and the runner to be separated between the second and third plates.
Double parting surface moulds have a complex structure, high manufacturing cost, and the components are difficult to process. They are generally not suitable for forming large products.
Hot Runner Mould
Hot runner moulds are similar to traditional cold runner moulds, except that they inject plastic directly into the cavity through nozzles.
With hot runner moulds, there is no runner in the mould during forming, thus there is no waste.
Compared to cold runner moulds, hot runner moulds have a higher manufacturing cost, but if the moulded parts are very small, especially when the parts are smaller than the runners, hot runner moulds may be a more economical choice.
Innovations and Advances in Mold Manufacturing
The injection mould industry in China is seizing the opportunity to drive innovation and development with 3D printing technology, aiming to advance the foundation of the mould industry and modernise the industrial chain, pushing the mould industry from merely large to strong.
In injection mould China, 3D printing technology is used to create complex mould parts with intricate details, which are difficult, time-consuming, or even impossible to achieve through traditional machining methods.
This technology enables rapid prototyping, allowing manufacturers to quickly test and modify mould designs before committing to expensive tooling.
It significantly reduces the time and cost associated with mould development, enhancing the flexibility and innovation capability of mould manufacturers.
In addition to the aforementioned innovations, high-speed milling, recognised as the third generation of mould making technology, can complete more complex mould machining tasks in shorter times.
High-speed milling not only boasts high processing speeds and good precision in terms of surface quality, but compared to traditional cutting processes, it also features low temperature rise (the workpiece temperature increases by only 3°C), resulting in minimal thermal deformation.
Therefore, it is particularly suitable for machining temperature-sensitive materials, such as magnesium alloys.
Conclusion
Injection mould manufacturing plays a pivotal role in product development, enabling the mass production of complex and precise components.
As technology evolves, future trends in mould manufacturing are likely to focus on further advancements in 3D printing, high-speed milling, and the integration of AI and IoT for smarter, more efficient production processes.
These innovations promise to enhance the speed, accuracy, and cost-effectiveness of mould manufacturing, thereby supporting the rapid development of new products and technologies.
