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Injection moldsare an indispensable and important tool in the plastic processing industry. Through precise design and efficient work processes, they can produce plastic products of various shapes and sizes. The LS team will introduce the workingprinciple of the plastic injection moldand its workflow in detail.

What Are Plastic Injection Molds?

Aplastic injection mold is a metal mold specially designed for use in theinjection molding process. Through precise modeling and structural design, it can inject molten plastic into the mold cavity under the pressure of the injection molding machine, and form plastic products of the required shape and size after cooling and solidification. Injection molds usually consist of a movable mold and a fixed mold. They have the characteristics of high precision, high strength and durability. They are an indispensable and important tool in the plastic processing industry.

How Does plastic injection molds work？

The workingprocess of plastic injection moldis a delicate and efficient process, which mainly includes the following steps:

Process	Description
Plastic pellet feeding	Firstly, the plastic pellets are fed into the screw barrel of the injection molding machine through the feeding system.
Heating and melting	The screw sends the plastic particles to the heating area, where the heating band heats the plastic to a molten state.
Pressure and injection	The screw pushes the molten plastic forward by rotation, so that the plastic enters the nozzle of the injection mold.
Mold filling and cooling	The molten plastic enters the mold cavity in the injection mold, fills the entire mold cavity and contacts the inner wall of the mold. At the same time, the cooling system in the mold absorbs heat from the mold, so that the plastic cools and solidifies quickly.
Demoulding and discharge	When the plastic is fully cured, the mold will separate and push out the molded parts. Then, the screw of the injection molding machine rotates and the injection process takes place again.
Cycle Repeat	The working process of the whole injection mold is cyclic and repeated to continuously produce plastic parts.

What are the methods of making plastic injection molds?

There are two main methods of constructing molds:computer numerical control (CNC) machiningand electrical discharge machining (EDM).

1.CNC machining

CNC machining for making moldsis typically an automated process that utilizes machining and cutting equipment to shape the mold to specified dimensions following computer-programmed instructions. CNC systems convert in-depth design files into programmable instructions that the CNC machine reads and executes. Product design engineers create precise virtual product designs using computer-aided design (CAD) software that specifies every construction detail.
Once theCAD designis complete, mold engineers can use computer-aided manufacturing (CAM) software to convert the CAD into instructions that the CNC hardware can understand. The generated commands are then uploaded into the CNC machine and the metal is precisely cut using the appropriate cutting tools to meet the exact specifications of the product design.

2.Electrical Discharge Machining(EDM)

Like laser cutting, EDM does not require or use mechanical force to cut metal. Instead, it utilizes electrodes, usually made of graphite, that are mounted on the EDM machine and placed over a mold submerged in a dielectric fluid.
The electrode is then lowered onto the mold and a controlled power source is used to break and disperse the metal in the area opposite the electrode without touching the mold. Although typically slower, the EDM process can produce shapes not possible with traditional CNC machining.

What are the types of plastic injection molds?

Plastic injection molds can be classified in a variety of ways, each of which affects various aspects of the production process. These categories and their importance are detailed below:

1. Single Parting Surface Injection Mold

When the mold opens, the movable and fixed molds separate, allowing for the removal of the plastic part. This mold is a single parting surface mold, also known as a two-plate mold. It’s the simplest and most basic form in injection molding, adaptable as a single cavity or multi-cavity mold, making it the most widely used type.

2. Double Parting Surface Injection Mold

The double parting surface injection mold features two parting surfaces. Compared to the single parting surface mold, this type adds a movable middle plate (also known as an active gate plate with gates, runners, and other necessary components) to the fixed mold section, hence also called a three-plate mold (movable mold plate, middle plate, fixed mold plate). We often use it for single or multi-cavity molds with point gate feeding. During mold opening, the middle plate separates a fixed distance from the fixed mold plate on guide pillars. This separation allows for the removal of the runner system.

3.Multilayer Injection Mold

Utilize multi-layer chambers to double production without increasing floor space. They are ideal for high-volume production but require precise alignment and complex design.

4. Hot Runner Injection Mold

A hot runner mold uses an insulating heating method to keep the plastic between the injection molding machine’s nozzle and the mold cavity in a molten state, eliminating the need for a runner system in the mold. This type includes insulated runner molds and hot runner molds.

5.Cold Runner Injection Mold

Uses unheated channels to guide molten plastic into the mold cavity. This type of mold costs less but requires more post-processing to remove the runners from the final product.

6.Single Cavity Injection Mold

A single-cavity injection mold refers to a mold that has only one cavity inside the mold and can only produce one product per injection. Single-cavity molds are suitable for producing small quantities of products, such as samples, small batch production, etc. At the same time, it is also widely used in fields that require high precision and high gloss, such as electronic product casings, auto parts, home appliances, medical equipment, etc.

7.Multi-Cavity Injection Mold

Multi-cavity injection molds, also known as multi-hole molds, refer to injection molds that combine multiple cavities (i.e. injection holes in the mold). Multi-cavity molds are suitable for producing large quantities of products, such as daily necessities, toys, etc. At the same time, it is also widely used in automobiles, electronics, electrical appliances, medical equipment and other fields, and can meet the needs of different industries for injection molded products.

8.Series Injection Mold

Series injection molds refer to molds used to produce a series of similar or related products. These molds usually have similar structure and design, but the shape and size of the cavity may vary to accommodate the production needs of different products. Serial injection molds are widely used in industries that need to produce a series of similar or related products, such as automobiles, electronics, home appliances, etc.

What are the advantages and disadvantages of plastic injection molds?

Injection mold processing has significant advantages in the production of plastic products, but there are also some shortcomings. In practical applications, factors such as product characteristics, production scale, technical capabilities, and environmental protection need to be comprehensively considered to select the most suitable production process.

Advantage

1. High production efficiency
Injection molds are produced by injection molding machines, which can produce a large number of products in a short time. At the same time, because the injection molding machine can be automated and does not require too much manpower input, the production efficiency is greatly improved and the production efficiency is higher.

2. High precision of the product
Injection mold manufacturing requires high precision, and the product precision of injection mold manufacturing is also higher. Accuracy directly determines the accuracy of the product, and the manufacturing accuracy of the injection mold can reach the micron level, which can produce high-quality products

3. Stable product performance

In the process of injection mold manufacturing, the performance of the product can be controlled by changing the parameters of the injection molding machine, the temperature of the mold and other factors, so as to create a product with stable performance. The products made by injection molds usually have excellent resistance, toughness, corrosion resistance and other characteristics.

4. Wide range of application
Injection mold manufacturing is suitable for businesses of all sizes, from small parts to large industrial equipment. Therefore, injection mold manufacturing has a very wide range of applications and is a very flexible production method.

Disadvantages

1. High manufacturing cost
Injection mold manufacturing requires a lot of manpower and material investment, and the manufacturing cycle is long, so the manufacturing cost is relatively high. The manufacturing cost of injection molds also includes the costs of mold design, manufacturing and commissioning, which are also part of the manufacturing costs.

2. Applicable products are limited
Injection molds are suitable for the production of plastic, rubber and other plastic materials, for special materials or complex shape products, the production of injection molds is difficult, and the manufacturing cost is also high.

3. It is difficult to maintain the mold
Injection molds require high positioning accuracy, and if the mold is damaged or damaged, it is difficult to repair and needs to be replaced or remanufactured. It is difficult to maintain the mold, which also increases the production cost and time cost.

4. The investment is risky
Injection mold manufacturing requires a large amount of upfront investment, including machinery and equipment, manpower and material resources and other aspects of investment for small and medium-sized enterprises, such investment risks are greater, and it is necessary to grasp the market demand and production scale to ensure production efficiency.

What are the challenges faced by plastic injection molds?

Thechallenges of plastic injection moldsmainly include the following aspects:

• Contradiction between supply and demand:the demand for mold market is strong, but the production volume of most enterprises is difficult to keep up with the pace of rapid development, and the situation of short supply continues. The domestic market satisfaction rate of domestic injection molds is insufficient, especially the satisfaction rate of large-scale precision molds is even lower.
• Unbalanced industrial development:There is a gap between the molds produced by domestic enterprises and the international advanced level in terms of accuracy, production cycle, service life and other indicators. Although the production technology of some enterprises has reached a high level, on the whole, the overall level of industrial development is still low.
• The overall technical level is backward:compared with the international advanced level, the overall technical level of domestic mold manufacturing enterprises needs to be improved. Enterprises have poor organizational and coordination capabilities, and it is difficult to integrate or mobilize social resources to promote technological innovation.
• Lack of innovation ability:most enterprises have the problems of low proportion of technical personnel, low innovation ability, low investment in scientific research and development, and backward management system. The innovation points of mold design, such as product innovation, material innovation, structural innovation, process innovation, etc., need to be further strengthened.
• Environmental and sustainability pressures: With the global emphasis on environmental protection and sustainable development, mold makers need to adopt more environmentally friendly materials and production processes. Reduce waste and pollution emissions in the production process, and promote the green transformation of the mold industry.

What are the innovations in plastic injection molds?

Theinnovation of plastic injection moldsis a key force to promote the development of the plastic products industry. The following is a detailed analysis of the plastic injection mold innovations:

• Technological innovation:Introduce new molding technologies such as hot runner technology, CAD/CAM/CAE technology, and gas-assisted injection molding.
  Improve the efficiency and accuracy of mold design, optimize the injection molding process, and reduce material waste and production costs.
• Material innovation:The use of high-performance materials, such as high-strength, high-wear-resistant, and high-corrosion-resistant materials, improves the service life and performance of the mold. Environmentally friendly materials, such as biodegradable plastics, are used to reduce environmental pollution.
• Structural innovation:develop multi-cavity molds to improve production efficiency. Optimize the mold structure, such as the use of sliders, inclined tops and other mechanisms to achieve complex shape molding.
• Process innovation:apply precision machining technology, such as laser processing, ultrasonic processing, etc., to improve the manufacturing accuracy and surface quality of molds. Introduce automated production equipment and technology to realize the automation and intelligence of mold manufacturing.
• Management innovation:Introduce lean production concept, optimize production process, reduce waste, and improve production efficiency. Adopt digital management methods, such as ERP, MES and other systems, to realize the digital and intelligent management of the mold production process.

How to choose a plastic injection mold manufacturer?

▲Professional Competency Assessment

Understand the professional ability and experience of service providers in the field of injection molding, including the product types, materials, processes and other they are good at. Investigate the r & d and development capabilities and technological innovation capabilities of service providers, which can be achieved by reviewing their technology patents, r & d results and cases.

▲Production Capacity Investigation

Understand the production scale, equipment configuration, and line automation to ensure they can meet your production needs. Ask the service provider about production cycles and delivery times to ensure they can deliver on time.

▲Quality Control System

Understand the quality management system and certification of service providers, such as ISO 9001, to ensure that they have perfect quality assurance capabilities. Ask the service provider about the quality testing methods and standards, as well as their defective product processing procedures, to ensure that the product quality meets your requirements.

▲Service And Support

Understand the pre-sales and after-sales service support of service providers, including technical support, training, maintenance, etc. Investigate the response speed and problem-solving ability of the service provider to ensure timely and effective support in the cooperation process.

▲Cost And Price

Ask service providers for quotes and cost structure to see if their prices are reasonable. When comparing prices, do not just pursue the lowest price, but to consider the comprehensive cost performance, including product quality, delivery time, service support, etc.

▲Sustainability

Understand the environmental policies and sustainability practices and ensure that their production process complies with environmental regulations.
Investigate the measures and results of service providers in resource conservation, energy utilization and waste treatment.

▲Word Of Mouth And Credibility

To understand the service provider’s reputation and reputation in the industry, we can obtain relevant information by consulting customer reviews, industry reports, media reports, etc. If possible, you can visit the service provider’s production site and management situation, so that you can have a more intuitive understanding of their strength and level.

LS: Your plastic injection molds manufacturing partner

At LS, whether you need prototype parts manufacturing or mass production, we have the corresponding capabilities and experience to meet your needs. We are committed to providing reliable, quality parts to assist you with success in the competitive automotive market.

Rapid quotation:Just upload the CAD file, you can quickly understand the manufacturing cost and keep abreast of the order status.

Quick molding:LS has extensive experience in prototype manufacturing, ensuring that your components are completed with high quality in the later stages of the design and manufacturing process.

ISO attestation:LS is aISO 9001 certifiedmanufacturing company, which means that we employ internationally recognized best practices to develop your products and ensure that they meet the standards, regardless of the complexity of the design.

Customized on demand:Our auto parts manufacturing process is fully customizable according to your specifications, sizes, materials and surface requirements to ensure meeting your unique needs.

Express delivery:We are committed to providing, fast manufacturing and delivery to meet your production needs while providing you with greater flexibility to quickly respond quickly to market changes. Longsheng is a partner of your auto parts needs.

FAQs

1.How does injection molding work step by step?

Injection molding is a continuous and delicate process. The specific steps are: ① Raw material preparation: Add dry plastic materials (granular or powdery) into the hopper of the injection machine. ②Plastification: The plastic is heated and melted in the barrel of the injection machine and kept in a flowing state. ③Injection: Under the thrust of the screw or plunger, the molten plastic is injected into the closed mold at a certain speed and pressure. ④ Cooling and shaping: The molten plastic injected into the mold is cooled and solidified in the mold to form the required shape of the plastic part. ⑤ Demolding: When the plastic part cools to a certain temperature, the mold is opened, and the ejection mechanism pushes the plastic part out of the mold.⑥ Post-processing: After demoulding, the plastic parts may need to undergo a series of post-processing operations, such as annealing, humidity control, etc., to eliminate internal stress, stabilize dimensions, improve performance, etc. Injection molding is a complex and delicate process that requires precise control of parameters and conditions in each step to ensure the quality and performance of the final product.

2.What is the process of plastic molding?

The plastic molding process is a process of processing raw materials such as plastics or synthetic resins into plastic products. It mainly consists of ingredients, molding, machining, joining, modification, assembly and other steps. The plastic molding process involves many of the above steps and links. Each link requires strict control of process parameters and operating conditions to ensure the quality and performance of the final product.

3.What is the working principle of injection molding?

The entire injection molding process is based on the property that plastic can melt into liquid after being heated to a certain temperature. The molten liquid is injected into a closed mold cavity using high pressure, and the desired plastic product is obtained after cooling and shaping.

4.What is the process of PVC injection molding?

The process of PVC injection molding is similar to the general injection molding process, but it also has some specific requirements: First, material preparation: use PVC particles as raw materials to ensure that the particles are dry and clean to avoid affecting product quality. Second, mold preheating: Before injection, the mold needs to be preheated to ensure that the molten PVC can quickly and evenly fill the mold cavity. Third, injection filling: Inject molten PVC into the mold cavity, paying attention to controlling the injection pressure and speed to avoid problems such as bubbles and shrinkage. Fourth, pressure holding and cooling: After the injection is completed, continue to maintain a certain injection pressure for pressure holding, and at the same time cool the mold to gradually solidify the PVC. Finally, demoulding and post-processing: After the PVC product is completely cooled and solidified, perform the demoulding operation. The demoulded products may require post-processing operations such as trimming and deburring to meet product quality requirements.

Summary

Injection molds are important tools in the plastic processing industry. Through precise design and efficient work processes, they can produce a variety of high-quality plastic products. During the injection molding process, it is necessary to pay attention to multiple points such as mold design, injection molding machine selection, injection molding process and subsequent processing to ensure processing quality and efficiency. Through continuous technological innovation and improvement, injection molds will be applied and developed in more fields.

Disclaimer

The content on this page is for reference only.LSdoes not make any express or implied representation or warranty as to the accuracy, completeness or validity of the information. No performance parameters, geometric tolerances, specific design features, material quality and type or workmanship should be inferred as to what a third party supplier or manufacturer will deliver through the Longsheng Network. It is the responsibility of the buyerseeking a quote for partsto determine the specific requirements for those parts.Pleasecontact usfor moreinformation.

LS Team

This article was written by multiple LS contributors. LS is a leading resource in the manufacturing sector, withCNC machining,sheet metal fabrication,3D printing,injection molding,metal stamping, and more.