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Where can I find plastic injection molding manufacturers in China?

We provide answers to common questions about manufacturing and sourcing plastic injection molding products from China in this blog.

Vaughn Cook RockWell Window Wells
Jeff Crawshaw
November 22, 2019
“What kind of materials can be used in plastic injection molding?”

PLASTIC INJECTION MOLDING

 

What is the plastic injection molding process?

This process is similar to that of metal die casting. In this process, molten plastic is injected into a die under pressure and held until it cools. Once it becomes solid, the die is opened and the plastic casting is taken out. Plastic injection molding is an extremely versatile, precise, fast and inexpensive method of mass producing plastic products.

 

What materials can be used?

This process mainly uses both thermoplastics and thermoset plastics, each of which have their own advantages and limitations. The primary difference between the two is that thermoplastics can be melted back into liquid form or recycled while thermoset plastics cannot.

Thermoplastics

Pros: Recyclable, cost efficient (because waste during manufacturing process can be reused), increased impact resistance because of flexibility.

Cons: Lower heat and chemical resistance (they degrade faster.)

Thermoset

Pros: Higher chemical and thermal resistance and higher mechanical strength and dimensional stability.

Cons: Cannot be recycled, lower impact resistance. Also, thermoset plastics are more difficult to work with so you might find it difficult to find suppliers for them.

 

What will I need in terms of design input?

We must have 3D files in STEP or IGES formats.

 

Where in China can you find plastic injection molding factories?

Depending on what kind of plastic you want to use for your product, these suppliers can be found all around China. Different factories have different quality levels and expertise.

 

How much does tooling cost?

It can cost from a few thousand dollars for simple tooling to hundreds of thousands for more complex multi-cavity tools.

 

How long does tooling last?

It depends on the material, but most likely 200,000 pieces is not a problem.

 

What is the average lead time for tooling?

15 days to three months depending on complexity.

 

Do plastic injection molding products or their tooling need any final finishes?

It is not unusual for injected parts to need final machining. This may also include addition of inserts (that can also be inserted during casting) or threads cutting. Final surface finishes may also be needed such as powder coating or paint application. Sometimes, under some circumstances the tool itself may need a special surface texture added, which will imprint on the final injected parts.

 

What are the pros and cons of plastic injection molding?

Pros:

Consistent measurements.

Quick production rate.

Low cost per unit.

Good surface finish.

Products can often be recyclable.

Manufacturing process can be quite cheap because scrap can be recycled/reused.

 

Cons

Tooling cost.

Warpage and shrinkage.

Some thermosetting plastics or rubbers cannot be recycled.

Recycled material will not give as good performance as new material.

 

What are the known challenges of the plastic injection molding process?

Some suppliers will use recycled material without telling you. Material type used is critical if you are looking for specific physical properties or performance. Additionally, shrinkage can be problematic across larger surface areas.

 

Sourcing Allies is a team of expert China sourcing agents that has helped western customers manufacture and source products from low-cost regions since 2006.

For more on plastic injection molding visit our website or write to us at info@sourcingallies.com.


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