Plastic injection mold making/Mold manufacturing

Injection mold making is a huge investment, so it is crucial to choose a reliable supplier who can guarantee high quality molds. The success of the plastic parts depends on the quality and precision of its mold. First, the production of a reliable and durable injection tooling can take a long time, depending on the complex of the mold. On the other hand, a scientific and strict process planning from the mold design to the manufacturing up to the final mass production of plastic molded parts has to be carried out. Because any deviation in the process leads to quality damage, which will lead to enormous time and cost waste.

structure of injection mold

What is an excellent injection molding tool

A precision manufactured injection mold is durable and also is worth for your investing. The following factors prove to be a good mold:

• Perfect product design and mold design

• Structures and cavity made of high-quality steels

• Made with advanced equipment and automation

• Control of total costs and process optimization

How does Lushi company make a injection mold?

Lushi team offers the best quality of mold steel, taking into account the state of use of the injection mold, paying particular attention to the material properties, NEVER use the inferior material. To achieve the highest productivity in the production process, the largest number of cavities is provided for each mold. In fact, efficiency and cost reduction are always focused by Lushi. Our employees, who are excellently trained in machining, design and programming, can optimally optimize the complex process and minimize errors and waste.

Structure and function of the plastic injection mold

Although the structure of the plastic injection mold is dependent on the type and function of the plastic part, the mold structure is very similar. In principle, every injection mold consists of the following systems: gate system, cooling system, mold core as well as cavity, demolding and venting. In some cases the hot runner system will be used for better surface quality.

Forms of injection mold: two-platen mold, three-platen mold and stack mold.

forms of plastic injection tool

Gating system: differs from cold runner and hot runner.

Cold runner: positioned to the area between the nozzle and tool cavities. The molten plastic is kept in channels by the injection pressure and its own heat. The solidified mass is a part of the injection mold, which must be eliminated in the post-processing.

Hot Runner: The mold with hot runner system is another type of injection mold that will increase the whole mold costs. Nevertheless, the hot runner has some advantages than cold runner as shown below:

1. Saving of raw materials and reduction of mold making costs.
2. Shortening cycle time and improving productive efficiency.
3. Uniform surface quality to improve the external appearance.
Gating system in the injection mold

Mold plates: consists of core and cavities, also called A-, B-Plate. In the mold plates, the injection molded part is formed by injecting the molten granules and then cooling in the region of core and cavities. Mold plates are the most important parts of an injection molding tool, so it is important to use high quality steel for it.

Cooling system: After injection, the plastic must be immediately cooled to form the part. To regulate the temperature of the mold is a controllable cooling system required. A common method of cooling is to introduce a cooling water channel in the mold, by circulating the water in the cooling system can dissipate the heat out of the mold. For mass production, the temperature control has a positive effect on the molding process, the shorter the cooling time, the more efficient the production cycle.

Demolding system: In the ejection side are the ejector elements that are responsible for demolding. After cooling, the mold parts remaining in the core are separated from the mold under the pressure of ejectors. The difficulty of demolding differs depending on the type of injection molded part. It is necessary and effective to establish a proper ejection system in the injection mold before the production process. There are generally the following variants of the demolition:

Injection molded part without undercut: simply strip and demolded.

Injection molded part with undercut: the sliding unit is inserted and thereby removed from the mold.

Injection molded part with internal or external thread: is stripped by forced ejection with cores or rotating cores.

Mold steel of the injection molding tool

P20 steel is one of the most common materials by mold making. Not only it’s hard enough with the pre-cured state of Rc 30-32, but also easy to machining. When the mold cavity dimension exceeds 306.6 * 306.6 * 306.6mm, P20 steel is highly recommended because the larger size requires more time and money for the heat treatment.

For injection molding with short tool life, P20 steel is very useful. General is P20 steel for the mold base while the cavity and core from H13 steel in an injection mold. For injection molds with a long life of up to 1 million, it is recommended to use mold steels to produce the parts with glass fiber reinforced polymer, such as BS BD3 or BD6 with hardness of 56-60 HRc, because they have outstanding toughness, ductility and high hardness .

In order to reduce the corrosion of a mold under a high humidity condition, it is necessary to select the stainless or nickel-plated steels. It makes sense to nickel-mold steels when the mold needs to be stored for a long period of time. Chemical nickel plating offers excellent corrosion resistance and better mechanical properties (such as toughness, hardness, wear resistance or adhesive wear) compared to stainless steel.

Lushi: Custom plastic injection mold making company










From inquiry to mass production, our engineer is always in touch with you. Especially in the project preparation phase, all the details should be discussed. Only after your final confirmation, then we will start to arrange production.


Our professional project management means high efficiency and can be delivered in a short time. Project progress tracking, with the notification of the customer, the whole progress of the project and some problems encountered in the process will be timely solved.


Rapid Prototyping or 3D Druck describes the production of a model to visualization, explore solutions, or test preliminary results. Rapid prototyping at various points in the development process accelerates product development and ensures the safety of large-scale production.


We have some experienced molding designers who complete the structural design work with the help of modern software (CAD / CAE / UG / ProE). We use software for motion simulation, component analysis and filling simulation to ensure subsequent process reliability. The more precise the design is worked from the beginning, the less reworking is required. This has a positive effect on the budget and time costs as well as the manufacturing difficulty.


Our machinery is equipped with modern machining centers in a clean factory of approx. We offer individual solutions for a complex plastic injection molding tool in various industrial sectors. We have a complete quality management system with ISO certification and promise our customers the injection mold with the highest quality level.


After the production of plastic mold we will measure it and then try out the sample. We offer injection molding machines with different clamping forces from 50 to 1000 tons. The sample will be measured and output a test report that will be sent directly to our customers.


Whether it's train, air or sea - a product-oriented packaging program, we handle all the formalities. With the help of our logistics partners, we ensure that sample parts and molds are delivered to you safely and on time.


In terms of after-sales service, LUSHI gives you all-round protection, such as mold repair and maintenance, which will be assisted by our partners around the world to make the mass production of the products smoother.

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