Plastic Injection Molding

Product Description

What is Plastic Injection Molding?

Plastic injection molding is a high-volume production solution for plastic parts, which melts plastic and injects them to cavity with high pressure, and the parts will be finished when it get cooled and solidified. In the past, most of our customers are hesitated to choose the plastic injection molding when start the project. Some of them are on the prototyping stage, some of them finalized the prototype and ready to start the production. But they are not sure if the machining solution is suit for their products or sales capacity. They will worry about the cosmetic surface or the tooling cost. It’s easy to compare the price of plastic injection molding with other machining solution, when the design is finished. You could just send the drawings to suppliers, then you will get many prices. But it might be too late when you knew the price. As suppliers might tell you that the design is not suit for plastic injection, or the design need be adjusted, otherwise the cost will be very high. In this way, the past work and money on designing or prototyping might be wasted. In this article, we will teach you how to forecast the cost of plastic injection molding before designing.

Horizontal Plastic Injector

Processing Craft

Generally, Injection molding service will be applied for the finalized prototype or the end-use production in high-volume. The thermoplastic is most commonly used in plastic injection molding.

Plastic injection molding could be divided into 6 major stages. Clamping Stage---- Injection Stage---- Dwelling Stage---- Cooling Stage---- Opening Stage ---- Ejection Stage. This is a complete and consistent process, which also determine the quality of the product.

Process of Plastic Injection Molding

Above process will be replayed again and again, and many same products will be produced massively. The prototyping of thermoset plastic and rubber consisted the same process, but the temperature of material barrel is lower than the thermoplastic, and the injection pressure is high. At the same time, the mold will be heating. When the injection is finished, it need be solidified or vulcanized, and get ejected when the product is hot.

Injection Molding Plastic

When it comes to injection molding plastics, there are a few options available in the industry:

Advantages and disadvantages:

What's the Advantage of Plastic Injection Molding?

1. Short Production Time

The injection time is as few as 2 seconds to 5 seconds. The injection molding cycle can be less than one minute.

The output is significant.

2. Low material waste

Compare with CNC machining, the plastic injection molding is much more efficient. Few plastic material will be wasted.

3. Suit complex parts

The complex parts can be made with an plastic injection molding. The intricate structure or features can be applied on the products during the manufacturing process. Such as the logo, design.

4. Consistent quality

The plastic injection molding could produce thousands of products in one days, and their quality are highly consistent.

5. Low unit cost.

As long as the the production of plastic injection molding is lasting, the unit cost of per product will be lower and lower. In most occasions, suppliers will divide the tooling cost to the unit price of product. Then they will get competitive price.

Automatic Plastic  Inject Workshop

What's the Limitation of Plastic Injection Molding?

1. It's a challenge to Designing

The design details of the plastic parts will determine the tooling costs. The size, unnecessary features, undercuts and cosmetic finishes will increase the cost. If you want to change the design when the tooling is finished, the cost would be considerable.

2. Prototype need be finalized

The prototype of the product need be finalized before plastic injection molding. The prototype could be made by CNC, vacuum casting or 3D printing. Some suppliers will also make a prototype for the mold.

3. High-cost on Tooling

The tooling cost is huge, range from $1,000 - $200,000. There are many effects which has impact on the tooling cost. Such as the unreasonable structure or special structure, the strict tolerance of dimensions, the strict standard of mold base, the short lead time of tooling and the surface finish of products etc.

4. Testing

Some minor changes are permitted during testing phase. But the precision and difficulty of mold will affect the tooling cost. The more precise the mold is, the more labour cost and material cost need be invested in. The adjustment need be proceed according to the performance of tooling.

5. Long lead times

Usually, the lead time of tooling will take 1-2 months. If some problems are found during testing, the time will take longer. If the mold need made out in a short time, the cost will be increased as well.

Last but not the least, there is a list to help us understanding the cost.

We assume the tooling is used for the a very tiny and simple products.

The tooling cost is $2000,  the quantity is 5,000 pieces, and the supplier quoted $1 per unit. The total price should be $7,000. And the average price you spend on every products is $1.4.

Application area

The plastic injection molding is widely used in mobile phones, laptop computers, various plastic shells, communications, micro-motors, computers, electrical appliances, electronics, toys, clocks and watches, lighting, locomotives and other industries.