How to Choose A Plastic Injection Molding Service Manufacturer?

custom plastic parts, plastic injection molding service

Plastic injection molding is a widely used manufacturing process that creates custom plastic parts. This article aims to provide a comprehensive guide to plastic injection molding service, including an overview of the injection molding process, tips for choosing the right manufacturer, and information on custom injection molding.
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This article will provide you with more knowledge about plastic injection molding service and help you better understand its advantages and applications. When you gain a deeper understanding of the plastic injection molding service, including manufacturing processes such as injection mold design and building, injection and cooling, and part ejection and surface finishes on plastic parts, it will help you perfect your plastic product development efforts and realize high-volume injection molding production of plastic products .

What is Plastic Injection Molding?

Plastic injection molding is a manufacturing process in which molten plastic material is injected under high pressure into a mold cavity and cooled to form a solid part. The process is commonly used to produce high-volume and complex plastic parts for a variety of industries including automotive, electronics, medical and consumer goods.

The process begins with the preparation of the plastic material, which is fed into a heated vat and melted into a liquid state. The molten plastic is then injected under high pressure through a nozzle into the mold cavity to form the shape of the mold. Molds are usually made of steel or aluminum and are designed to produce the desired shape of the final product. Usually steel molds can be used to produce hundreds of thousands to millions of plastic parts, while aluminum molds are often used for small batch injection molding, usually dozens or hundreds of pieces. This is mainly due to the difference in the characteristics of the molds made of steel and aluminum.

Once the molten plastic fills the mold cavity, it is cooled and solidifies to form the final product. The part is then removed from the mold via ejector pins or other similar mechanisms after the mold is opened. The process can be repeated to produce large numbers of identical parts with high precision and accuracy.

Overall, plastic injection molding is an efficient and versatile manufacturing process that can produce complex and high-quality plastic parts at relatively low cost.

Advantages of Plastic Injection Molding Service

Efficient production: Injection molding can quickly produce large quantities of high-quality plastic products.
High degree of design freedom: Injection molding can produce plastic products of almost any shape and size, and complex geometries and internal structures can be realized during the manufacturing process.
Good repeatability: Due to the precise manufacturing of the mold, the products of each injection molding process are almost identical.
Strong plasticity: Injection molding can use various types of plastics, including polyethylene (PE), polypropylene (PP), polyurethane (PU), polycarbonate (PC) and polystyrene (PS), etc.
Material savings: Injection molding minimizes scrap and leftovers.

Steps of the Plastic Injection Molding Service

Injection molding is a common plastic processing technology that mainly includes the following four steps:

Injection mold design and manufacture

In the injection molding process, it is first necessary to design and manufacture the injection mold. Injection molds usually consist of two parts: an upper mold and a lower mold. There is a certain gap between the upper mold and the lower mold, which is called the mold cavity. During injection molding, plastic is heated and melted and injected into a mold cavity to form the desired part shape.
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Injection, cooling and part ejection

Once the injection mold is prepared, the injection and cooling process can be performed. First, plastic pellets are fed into the heating cylinder of the injection molding machine, where they are melted at high temperatures. The injection molding machine then forces the molten plastic through the injection cylinder into the cavity. In the mold cavity, the plastic cools until it becomes solid. After the cooling is completed, the upper mold and the lower mold are opened separately, and the part is taken out of the mold cavity. This process is called part ejection.
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Post-treatment of plastic products

During the injection molding process, some injection molding defects such as burrs, marks and dents may appear on the surface of the part. In order to remove these defects and improve the surface finish of the part, post-processing is required. Common post-processing methods include grinding, polishing, painting and sandblasting. Through these post-processing methods, the surface of plastic products can be made smooth and beautiful, and their quality and value can be improved.

Surface treatment of plastic products

In order to achieve different color, texture and function requirements, special surface treatment is carried out on the product surface, such as electroplating, spraying, heat transfer printing, water transfer printing, UV coating, etc.
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Applications of Plastic Injection Molding Service

Auto Parts: Plastic injection molding can be used to manufacture interior and exterior parts of automobiles, such as body, dashboard, door panels, seats, etc.
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Home appliances: Plastic injection molding can be used to manufacture various parts of home appliances, such as washing machine tubs, TV casings, vacuum cleaner casings, etc.
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Medical devices: Plastic injection molding can be used to manufacture various medical devices and medical consumables, such as syringes, infusion sets, blood separators, etc.

Electronics:Plastic injection molding can be used to make housings and parts for various electronic products, such as mobile phone cases, camera cases, computer keyboards, etc.
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LED lamps: Plastic injection molding plays an important role in the manufacture of lamps, it can manufacture lamp products in various shapes, sizes and colors. Such as round, square, strip and other LED lamp housings.
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Toys and sporting goods: Plastic injection molding can be used to manufacture various toys and sporting goods, such as plastic balls, bowling balls, swimming goggles, etc.
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Packaging: Plastic injection molding can be used to manufacture various packaging materials such as plastic bottles, plastic boxes, plastic bags, etc.
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Choosing a Plastic Injection Molding Manufacturer

Selecting a suitable plastic injection molding manufacturer can be a difficult but very important task as the choice of manufacturer directly affects your product quality, lead time and cost. Usually, it is necessary to comprehensively consider the production capacity, manufacturing experience, cost and delivery date of the injection molding supplier.

Production capacity

You need to ensure that the injection molding manufacturer has sufficient production capacity to meet your needs. For example, if you need large-sized products, you need to choose a manufacturer with large injection molding machines and production lines. If you need precision plastic parts, you need to choose a supplier who can make precision molds and have precision injection molding machines.

Experience and expertise

Choosing an experienced injection molding manufacturer ensures that they know how to handle various issues during production. Manufacturer expertise also affects your product quality and cost. A plastic injection manufacturing supplier with rich manufacturing experience will be able to assist you from the initial product design to evaluate the later mold manufacturing process and injection molding production. The earlier the problem is found, the better the later production. Otherwise, a large number of mold modification work will cause great cost loss and waste of time.

Quality Control

A good plastic injection molding manufacturer should have a complete quality control program to ensure that the quality of the product meets your requirements. Manufacturers should be able to provide various testing and inspection services.


Price is of course an important factor to consider when choosing a manufacturer. It is necessary to choose a plastic injection molding manufacturer with a reasonable price, and at the same time, be careful not to sacrifice quality and service with low price as the main factor. Because the price of injection molding manufacturers may vary due to factors such as their equipment, experience, and quality control. You need to choose a manufacturer that fits your budget.

Delivery time

Injection molded products will eventually go to market consumers. It is very important to choose a manufacturer who can deliver on time, because this may affect your production plan and customer satisfaction.

Customer Service: A good manufacturer should be able to provide good customer service, including quick response, problem solving and technical support. Good customer service is the key to maintain the relationship between supply and demand, especially in international trade, a professional and reliable injection molding supplier can be an excellent partner.

Therefore, choosing a suitable plastic injection molding manufacturer is a critical decision. You need to consider several factors to ensure that the manufacturer you choose can meet your needs and provide high-quality products and services.
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Sungplastic is an excellent Chinese injection molding manufacturer, located in Shenzhen and Dongguan, has more than 20 years of manufacturing experience. The core business of our company is the production of plastic injection molded parts, providing mold making services, injection molding services and rapid prototyping.

Sungplastic focuses on injection molding manufacturing and continuously invests in advanced injection molding equipment and technology to provide high-quality products and services. Our company is equipped with 10 Japanese TOSHIBA injection molding machines and 20 HAITIAN injection molding machines to meet the requirements of different customers for customized plastic products. If you are looking for injection molding service, please contact us now for an instant quote.

If you liked reading this article, we recommend the following content:

Plastic Surface Finishes Guide: Mold Pre-Treatment & Injection Molding Post-Treatment
Comprehensive Guide to 12 Injection Molding Defects and Their Solutions
Choose Aluminum Injection Molding for Rapid Low-Volume Manufacturing

About Sungplastic

About Sungplastic

Sungplastic is a plastic product manufacturer with rich experience in injection molding. According to the different product development requirements, we flexibly adjust the manufacturing process to achieve high quality, high efficiency and more economical.

We offer a variety of manufacturing services: Rapid Prototyping, Tool Making, Injection Molding, Product Design and Development, CNC Machining and Metal Stamping. You can choose from a variety of plastics, silicone rubber, or metal for your product. Regardless of mass production or small batch customization, Sungplastic has always been committed to providing assured, efficient and more economical one-stop processing services for your projects.

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