Injection Moulding

We are located in Shenzhen China, supplying professional mould making & injection moulding services for international companies for more than 10 years, capable of designing the mould & products based on your companies' requirements and making cost-effective injection moulding for your plastic parts. Hundreds of existing customers from America & Europe are happy with our services and willing to recommend their friend companies to make mould in our factory, also doing reference per our request for new customers.
Whether the selected injection mould factory regards you as an important customer, that is, whether they value you, this is very important. In fact, looking for a supplier is like looking for an object, but also paying attention to the door-to-door. If your own company's financial strength is not strong and the order amount is not big, blindly choose large-scale mould factory cooperation, sometimes the money spent on them, but they don't take you seriously, at present many large injection mould factories are not responsible for the small orders, because you can't reach their requirements in terms of order amount, it will give you the feeling of taking a hot face to touch people's cold butt, this metaphor may not be appropriate, but it is also more relevant and realistic.
Injection mould

In this case, most people will choose small and medium-sized injection mould factories. After all, the price of injection moulds and plastic products is more acceptable. But soon you will find that worrying things are coming again. Can the injection mould be completed on time? Can the quality of injection moulds be good? What is the mass production of the injection mould? What is the life of the injection mould?
We all know that although product will make hand board for verification before development and it will not start the mould project until the product is ok. But after mould test, it is still inevitable to be modified. Whether injection mould manufacturers should charge the fee of mould modification? How should the product developer avoid mould modification and reduce the cost of mould modification? There is a difference between modifying the mould and repairing the mould. The mould repair is caused by the reasons of injection moulding factory itself, and the mould needs to be repaired. The modification of mould is caused by the reason of customer factors, the product design need to be changed etc.
Molded parts flash Injection mould parting line, sliding surface, release pin, pad and so on, constitute a variety of slot gap between the moulds. The inflow material will cause flash. The flash looks like wedge-shaped blocks. It is gradually trend to be bigger.

The general principle to eliminate plastic parts flashes is to fix the injection mould. If the flash is caused by improper configuration, we should reduce cylinder and mould temperature, and reduce injection speed, in order to reduce material flow ability. However, it should be noted that cause a residual stress in the plastic parts.

It should be noted that add too much pressure on the injection mould will produce flashes. Foreign matters between the parting surfaces will cause damage to the mould and produce flash.Injection mould material commonly used materials such as S50C or pre-hardening HRC30 special steel, in this way, the parting surface is difficult to produce flash.
There are many different ways to calculate the an injection mould price, but, they have one thing in common, that is taking efforts to make technical and economic indicators organically combine in order to produce mutual benefits. It will make the injection mould to have competitive prices from the valuation to offer, to contract and to the settlement price.

Empirical Calculation Method
Mould price=material cost + design + process and profit + VAT + tryout cost + packing and shipping cost. Usually in the ratio:
  • Material cost: materials and standard parts accounted for 15%-30% of the total cost of the injection mould;
  • Process and profit: 30%-50%;
  • Design fees: 10%-15% of the total cost;
  • Tryout cost: medium-sized mould can be controlled within 3% while small precision moulds controlled within 5%;
  • Packing and shipping cost: according to the actual or calculated at 3% of the total;
  • VAT: 17%.
When you are moulding a part, the mould temperature and melt temperature may be same irrespective of climate. So the environment at injection moulding is uniform (assuming that the material is predried if it has moisture). If moisture is present, the weld strength would be low and at the same time you will notice surface defects. The molecular chain would break and the material strength would be low; as good as low molecular weight material. The stresses developed due to climate change can cause problems. Thus, you have to analyze the problem whether it is in individual part or in an assembly.

I used to assist periodically in a moulding shop in Nigeria, with >90% RH at >40°C (104°F) and had not been made aware of this problem. That is not to say, of course, that it wasn't there.
In the next decade, the development trends of Chinese mould industry are: mould products develop toward large-scale, sophisticated, complex, economy, rapid direction; continuously improve the technological content of the mould, mould manufacturing cycles continue to shorten; mould production towards information technology, not drawing, fine quality, automated direction; mould manufacturing companies toward technology integration, well-equipped, product branding, management, information technology, international business direction. Chinese mould industry market
Injection Mould ClampFor big PP parts with undercuts, how do you evaluate the additional clamping force needed to keep the wedges (slides) closed and avoid flash? I want to develop a method to predict Injection Mould Clamping force for big PP parts with a lot of undercuts (8 big wedges in the mould). At the moment, I am using moldflow to predict tonnage but I am always missing 25% in comparison to the real life! I know that this is due to the side pressure on the wedges which makes them moving backward and the part is flashing. Do you have any idea of how to predict the right clamping force? Or what mould design change (bolster plates thickness, wear plate angle,...) could reduce the clamping force?
In comparison to the shear stresses in the flowing polymer melt, the gravity force is very small. (You can do a simple order of magnitude comparison to confirm this). However, I have seen cases in Gas Injection Moulding where the melt sagged around the gas core during the gas pressure holding phase. This is reasonable. If all melt in the cavity is pressurized to approximately the same pressure, then the shear stress are zero (or near zero) and so the gravity force is the only significant directional force acting on the melt. (To put it another way, the buoyancy of the gas core causes it to rise up through the polymer melt. Of course it won't displace the frozen skin layer).

I once had a Chinese injection moulder argue with me about this on a project where the weld lines where located in a bad location for the part's mechanical performance. He added gates (From one to four) and rotated the tool in the press. When the weld lines moved on the part he naturally said "See! Gravity does make a difference!"

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