Why are Injection Molds So Expensive?

Foreword: Introduction to Injection Molds

Injection molds are also called plastic injection molds, Injection mold generally refers to injection molding, also known as injection molding. It is a molding method that combines injection and molding. Injection molds are made by stirring completely molten plastic material through a screw at a certain temperature, and then injecting it into the mold cavity with high pressure.

After cooling and solidification, it is formed. It has fast production speed, high efficiency, automatic operation, many designs, colors, and shapes. Injection molds are widely used in the manufacturing industry due to their wide range of dimensions and specifications. However, why injection molds are so expensive, this article will discuss the following aspects.

Plastic injection molding costs include the material and manufacturing costs of the mold, labor costs, equipment costs and other auxiliary costs. Among them, the most important ones are the material and manufacturing costs of the mold.Next, let us understand the cost ofunderstanding injection molding cost

What Are the Requirements for InjectionMolds Made of Different Materials?

Injection mold steel is currently the most commonly used material in injection mold processing. Due to its high hardness, strength and good cutting performance, it is very suitable for processing injection molds. However, different materials have different specific requirements for injection molds. The specific analysis is as follows:

It is related to the characteristics of plastic materials. For example, PVC plastic will produce corrosive acidic gases during production. If ordinary steel is used, the mold will easily rust, so corrosion-resistant steel should be selected, such as 2083, S136H, etc.

Related to product requirements, there are some very demanding transparent products, such as optical lenses and spectacle lenses, which require steel with very good polishing properties, such as S136. If you choose the wrong steel, you will find that when the mold is polished into a mirror later, Obvious material lines cannot be eliminated through polishing, and the products made by such molds will not meet the requirements.

It is related to the life of the mold. Even the same grade of steel will have different prices. Of course, the quality of the higher-priced material will be better. If the mold life does not need to be very long, you can choose relatively cheap steel.As a result, low cost injection molding are achieved.

What are the Puction CostsDuring the Injection Mold Processing and Manufacturing Process?

Mold production cost refers to the total cost paid by the enterprise to produce and sell molds. Mold production costs include raw material costs, external component costs, equipment depreciation, operating expenses, etc. They are divided into production costs and non-production costs in nature.

The mold production costs we talk about refer to the production costs that are directly related to the mold production entire process. Taking plastic molds as an example, let’s briefly introduce the cost of developing a set of molds:

Cost of Cost of injection molding machines: Injection molding machine is also known as injection molding machine or injection machine. It is the main molding equipment for making thermoplastic or thermosetting plastics into various shapes of plastic products using plastic molds.

Small injection molding machine (less than 50 tons): the price range is between 100,000 and 300,000 yuan, medium-sized injection molding machine ( 50 tons-500 tons): the price range is between 300,000-1 million yuan, large injection molding machine (500 tons and above): the price range is between 1 million-5 million yuan.: Injection molding machine is also known as injection molding machine or injection machine. It is the main molding equipment for making thermoplastic or thermosetting plastics into various shapes of plastic products using plastic molds. Small injection molding machine (less than 50 tons): the price range is between 100,000 and 300,000 yuan, medium-sized injection molding machine ( 50 tons-500 tons): the price range is between 300,000-1 million yuan, large injection molding machine (500 tons and above): the price range is between 1 million-5 million yuan.

The cost of the mold base. The mold base is usually made of S45C or S50C. Commonly used mold bases are standard products. However, if the size of the mold base exceeds the standard product, it needs to be made additionally. The cost is generally 2-3 of the standard mold base. times.

The material cost of the front mold core and the rear mold core depends on the different injection molding material characteristics and mold life. Commonly used plastic mold steels include: 718, 718H, S136, 8407, NAK80, P20, 2083, etc.

The cost of mold processing equipment, such as: lathe processing cost, milling machine processing cost, grinder processing cost, CNC machine tool processing cost, EDM electric discharge machining cost, wire cutting processing cost, mold set cost, machining The fee is generally calculated by the hour. Mold processing equipment is developing toward high efficiency, high precision, high automation, and multi-function, which increases the cost of molds accordingly.

Mold Precision And Production Cycle

Why Is Mold Design Accuracy Necessary toEnsure Product Quality?

Mold accuracy includes the part accuracy obtained during processing and the quality awareness to ensure product accuracy during production. Mold accuracy includes four aspects: dimensional accuracy, shape accuracy, position accuracy, and surface accuracy.

Since the mold is divided into two parts: the upper mold and the lower mold during operation, the mutual position accuracy between the upper and lower molds is the most important among the four types of accuracy.

Mold accuracy serves the accuracy of products. High-precision products must be guaranteed by higher-precision molds. Mold accuracy must generally be 2 or more levels higher than the accuracy of the parts. This can improve the stability and reliability of the production line and ensure the quality of the product.

How to Improve Mold Accuracy?

Mainly considered from two perspectives: mold design and mold processing. In addition, some defects of the product itself will also affect the accuracy of the mold.

Mold designConduct mold flow analysis in the early stage of the product to find the best product entry point to achieve glue entry balance. The clamping force is within the range of the injection molding machine and the product deformation is minimal.

Product parting: if it can be flat, no curved surface will be designed; if it can be penetrated, no insertion will be done. Product positioning: three-level precision positioning: inner mold tiger mouth positioning, mold base guide pillar positioning, and edge locking position

Product cooling: The distance between the water transport and the product should be as equal as possible. If the cooling is uneven, the product will be greatly deformed.

Mold avoidance: After reserving a certain sealing surface, avoid other surfaces, and avoid both the front and rear molds. This can not only improve the processing accuracy, but also avoid the mold.

In addition, to improve processing efficiency, the fractal surface of the mold base is supported by a balance block to offset part of the PL surface locking surface and prevent the fractal surface of the inner mold from collapsing too quickly.

The support in the ejector plate is made of ball guide bushing or bronze with graphite. The depth of the cavity bottom of the B plate is as thick as possible to avoid deformation of the injection molding template. Adding a support head will not have much effect. Each part drawing indicates the processing tolerance.

Mold processing，The mold core is processed with a high-precision machine, with an accuracy of 0.02μ. It is best to form the mold core in one go to avoid repeated removal of the machine. There will be errors in the calibration every time.

Use slow wire cutting for the mold core line. Core inserts can be processed with a grinder without a computer, especially for round inserts. The flying mold cannot be processed with a grinder. It can be directly loaded into the flying mold machine. The accuracy of the mold base is controlled within 0.02mm.

Normal molds are more 0.05mm. The electrical grade of mold steel materials needs to be fully inspected with three dimensions. Better computer gongs can be directly inspected on the machine. Electric grade processing uses red copper instead of graphite. Graphite sparks quickly, but it is easy to cause damage, especially for thin steel parts.

What impact does the production cycle of injection molds have on costs?

The so-called injection mold production cycle refers to the time from the date of accepting the mold order until the mold is delivered to the client after passing the mold trial and appraisal.

Obviously, the length of the production cycle is one of the comprehensive indicators to measure the production capacity and technical level of an enterprise. The production cycle of simple injection molds is 35 days, the production cycle of general injection molds is 50 days, and the production cycle of complex injection molds is 60 days.

Generally speaking, the shorter the production cycle, the better. However, this is not shortened just because you want. The length of the growth cycle is related to many factors, including the design capabilities of technical personnel, the degree of specialization of the mold company, and the technical means of mold production.

The degree of modernization, the management level of the enterprise, and the standardization of mold technology. Each of these factors will have an impact on the production cycle of the injection mold, which will have a huge impact on the cost. Correspondingly, the longer the production cycle, the lower the cost. It may be higher.

Mold Testing And Expertise

How WillStringent Testing Protocols Increase Costs?

If the design of the injection mold is not reviewed well, the injection structure has unreasonable points, which makes the injection mold need to be improved many times after the mold trial. Not only will the cost of the injection mold exceed the budget, but after many improvements, the effect will be worse.

Strict testing protocols cause injection molds to be scrapped and reworked, failing to control costs and delaying delivery. There are also cases where the injection mold design is very good, but the processing of large-scale injection molding is not in place, which increases the number of tests without any reason and directly increases the cost of large-scale injection molding.

When testing the mold, the molding process and the model of the injection molding machine were not selected. It’s clear that the mass injection molding process is great, but the injection molded product is not ideal. There is no reason to increase the number of tests, which directly increases the cost of large-scale injection molding.

Firstly, more and more sophisticated testing instruments need to be purchased and regular maintenance of the instruments is required. Secondly, more employees are required to analyze and test the data, which will significantly increase training and labor costs.

Furthermore, strict testing The protocol may increase the injection molding production cycle, thereby increasing inspection procedures and steps, and may increase manual costs. Finally, the strict testing protocol may increase the number of unqualified products, thereby increasing the product scrap rate and wasting resources, thus Increased injection molding costs.

Why Is the Cost of Injection Mold Manufacturing Process Higher?

The manufacturing process of injection molds takes a long time. In order to achieve high precision, some plastic mold manufacturers make this aspect of the mold very detailed and have dedicated personnel to follow up and strive to satisfy customers. Therefore, more time is required and the funds invested are will also increase accordingly.

There are many manufacturing processes for injection molds, the cost of purchasing standard parts is high, and the complex processes require relatively more manpower. In order to ensure quality, plastic mold manufacturers also need to go through a lot of tests when the processes are complex.

Injection molding is difficult to manufacture, and the design requirements for injection molded parts are very high. The main thing is to design the mold flow channel accurately, such as the early mold flow analysis. If the design work is not done well and in place, the subsequent trial mold proofing will not be successful. In this case, it is very difficult to modify the mold, and most of the molds need to be made from scratch.

The number of injection mold manufacturing sets depends on the sample. Sometimes a plastic part that seems to have a very simple structure requires two or even three sets of injection molds to complete.

Mold Maintenance And Lifespan

Since plastic injection molding consumes certain raw materials, equipment, and labor during the production process, the most important consumption of plastic injection is equipment. Therefore, the maintenance of plastic molds is very necessary.

Why Is the Maintenance Cost of Injection Molds High?

Compared with other molds,injection mold tooling have a more complex and precise structure, and have higher requirements for product operation and maintenance. The structural design of the plastic injection moulding, the processing quality of the parts and the assembly accuracy of the mold all affect the quality accuracy and production efficiency of the plastic parts. During the trial and production of the injection mold, some common mold failures will occur. Such as guide pillar damage, difficulty in demoulding, etc.

During normal use of plastic molds, due to normal or accidental wear and tear, as well as various abnormal phenomena that occur during the injection molding process, mold repair is required.

Injection mold maintenance is divided into two types: general maintenance and special maintenance. General maintenance is for the maintenance of mold components such as hot runners, heaters, guide pillars and ejector pins, and molding inserts. Special maintenance is for the maintenance of components such as plastic mold cores or cavities. Therefore, in summary, the maintenance cost of injection molds is relatively high.

What Are the Reasons That Affect the Life of Injection Molds?

To improve the quality of the mold, materials must be selected rationally. The corresponding heat treatment process and optimized processing technology for different materials can improve the manufacturing accuracy and service life of the mold and avoid early failure of the mold. The following aspects mainly affect the life of the injection mold;

Mold material: The material that has the greatest impact on the life of the mold is the mold material. The material properties of the mold greatly affect the service life of the mold. For example, if Cr12MoV steel is used in the production of the drawing die, it is easy to bite and nap. However, if GT35 steel is used, Made of cemented carbide, it can greatly reduce the tendency to bite and increase the service life of the mold.

Working hardness of the mold: The increase in mold hardness mainly refers to the compressive strength, wear resistance and bite resistance of the mold steel, but it will also reduce the mold toughness, hot and cold fatigue resistance and grindability.

Metallurgical quality of mold materials: The metallurgical quality of mold materials primarily affects molds with large and medium cross-sections and mold steels with high content of carbon and alloying elements.

The actual manifestations are non-metallic assimilation, carbide segregation, intermediate looseness, etc., which are harmful to Those high-carbon and high-alloy steels often easily cause quenching cracking of the mold and initial damage to the mold.

Accuracy and stiffness of the equipment: The higher the guidance accuracy of the slider movement, the higher the positioning accuracy of the front and rear molds, and the less likely it is to generate lateral loads and torques, making the molds wear evenly. The longer the mold life is. The stiffer the equipment, the smaller the elastic deformation produced during molding, the better the front and rear molds can cooperate.

Conclusion

To sum up, injection molding is a widely used molding method, but due to factors such as the material and manufacturing cost of the mold, the precision and production cycle of the mold, the testing and expertise of the mold, the maintenance and life of the mold.

Injection molding Molds are expensive, but despite this, companies should be aware of the strategic importance of investing in quality molds for long-term business benefit, and should consider long-term return on investment when evaluating injection mold costs.