In the plastic injection moulding process, when adopt multiple gates or there is holes and inserts in the cavity, and the thickness of injection moulded parts changes greatly, the plastic melt will flow to more than two directions in the injection mould, when the two strands plastic melt meets, it will form a weld line in injection moulded part.

According to the different production methods, the weld line can be divided into hot-melt lines and cold-melt lines. From the apparent point of view, the weld line has a curved shape, but also approximate to a straight line. From the product thickness section view, the weld line is on the outer surface, there is also a depth in the surface layer is a V-shaped groove marks, and even some through the entire wall thickness section.

Outdoor products exposed to strong light, the light fastness (sun-proof) grade requirement of the colorant used is an important indicator, if the light fastness grade is poor, the injection moulded plastic parts will quickly fade in the use. Organic pigments undergo molecular structure changes and small amounts of decomposition at a certain temperature. Especially for PP, PA and PET injection moulded parts, the processing temperature is above 280°C. When choosing the colorant, it is necessary to pay attention to the heat resistance of pigment. Acid and alkali resistance: The fading of colored injection moulded plastic parts is related to the chemical resistance (acid and alkali resistance, revivification of resistance to oxidation) of colorants.

Some plastic parts are quickly swollen or bubbling on the back of the metal insert or in particularly thick areas after demoulding. This is caused by the expansion of the released gas under the effect of internal pressure when the plastic is not completely cooled and hardened. There are the following solutions:

1. Effective cooling, reduce injection mould temperature, extend injection mould opening time, reduce material drying and injection mould processing temperature.
2. Reduce injection mould filling rate, reduce cycle time, and reduce flow resistance.
3. Improve holding pressure and time.
4. Improve the condition that the walls of the products are too thick or vary in thickness.

With the development of society, and with the enhancement of design and injection mould manufacturing, and the realization of new technology of injection mould, injection mould quality has received more and more attention. Injection mould quality is improved with the improvement of injection mould technology.

The driving and driving forces (pressing force, clamping force of injection mould, drop weight of the material, extrusion force, etc.) of the injection mould processing movement are provided by the power transmission mechanism of forming machine tool and equipment.
The driving of injection mould processing, such as aluminum alloy profiles, plastic profiles, sheets, or films, generally use extrusion moulding process. The mould is fixed on the head of machine, the material passes through the mould in the form of extrusion, and relative movements act on the mould to produce a various of moulded parts. For example, the plastic profile do spiraling movement relies on the screw of the continuous extrusion machine. The plastic is extruded into the mould and passed through the profile of the mould, and the shaping material is cooled and shaped. Extruded profiles are pulled forward by the traction mechanism for continuous forming machining.

Although the use of hot runners in plastic injection moulds is relatively small, everyone should not be unfamiliar, giving the impression that moulds are expensive. Why is there such a hot runner technology? What are the advantages of hot runner technology? What is the role of plastic injection mould manufacturing process? What is the problem with the general process?

Mould is the foundation of industrial manufacturing. It is precisely because of the existence of the mould that the product can be reproduced in large quantities. The injection mould has become an increasingly widely used part of the mould field. Injection moulding companies need to be related to a variety of precision equipment in the process of producing the injection mould. Finally, a set of injection mould can be produced out. And then what production equipment does the injection moulding manufacturer have? 

After long-term development, the Chinese injection mould industry is currently in a rising period. In such a stage, what kind of development methods that injection mould companies in China should adopt, which have became a problem that Chinese injection mould companies should thinking actively. Currently there are many companies engaged in plastic injection mould production in China, but the scale is relatively small, basically a small workshop model, there is no scientific and technological content.


Chinese die and machine tool industry is still "large but not strong" Although Chinese injection mould industry is well-known as a global "manufacturer" with a huge annual import and export volume, due to the limitation of factors such as technical, talents, Chinese injection mould all are relatively concentrated in the low-end and medium-end markets. Therefore, the high-end injection mould markets has great attraction to Chinese plastic injection mould manufacturers. If Chinese plastic injection mould industry want to gain long-term development, it is essential to promote the construction of Chinese injection mould industry association.

The proportion of some high-level injection mould has reached to about 40%. The characters of these injection mould is complexity, precision, large scale, and long life. The self-processing technology and the flexibility of injection mould, the integration technology, the structural design system of injection mould, the large-scale progressive die, the advanced injection mould manufacturing technology and the research and development of the 3D design technology, the stamping process design system, the reverse engineering and the body mould digital manufacturing system, etc., that all of them are inseparable from the vigorous development and promotion of digitization and information technology.

In injection moulding products development, the injection mould cost will account for a large amount of money. The premise of choosing an injection moulding companies is that customer firstly need to know their own product requirements.
For large-scale moulds, we not only have requirements for equipment,
but also have requirements for site, driving and technology. Therefore, the customer must conduct a field visit to the mould factory to inspect their equipment and site. Medium-sized moulds can be made in ordinary mould factories, including: well-equipped, enough space, more than 2 tons of cranes, and even large mould factories can also make medium-sized moulds. Small moulds can be made in virtually all level mould factory. Of course, if there is precision requirements, it should be determined by reference to the various objective and subjective factors that have been written previously.
Choosing an excellent injection moulding company that suits yourself is very important in product development. For example, the reasonable price of the mould and the timeliness of the service, that is, the cycle time of the mould and the efficiency of modifying the mould, will directly affect the entire product process and market share. At the same time, the excellent injection moulding company will also provide a series of product development technical support, such as spray screen printing, etc. This is also very important.
           
           

The mould releasing difficulty often encountered in the process of injection moulding, it has a very large influence on the quality of injection moulding products. It may cause the scratch or pattern of the product surface, even can lead to product warp and even rupture damage. Therefore, it is necessary to solve the problem of mould releasing, which affects the quality of the final injection moulding product. The solution is considered in the following aspects:

The warping and deformation problem of plastic injection mould products should be solved mainly from injection mould design. For the overflow problem, the emphasis should be on the improvement of the mould. In terms of moulding conditions, we can start with the reduction of liquidity.

Injection mould is a tool to produce plastic products and also to make plastic products have complete structure and precision size, which is mainly used in industrial circle. Gating system of injection mould is also called the runner system. It is a group of feeding channel which lead the plastic melt to the cavity from injection machine nozzle. It usually consist of main runner, sub-runner, gate and cold slag cavity. It is directly related to the quality of plastic products and production efficiency.
A set of high quality mould, not only need to have good processing equipment and skilled mould manufacturing workers, another important factor is to have a good mould design, especially for complex mould, mould design quality accounts for more than 80% of the mould quality. A good mould design is: On the premise of meeting customer requirements, to make processing cost low, machining difficulty small and processing time short. To make it, not only need to meet the requirements of the guests, but also know about the injection moulding machine, the structure of mould, processing craft and the processing capacity of the injection mould factory itself.