What is Precision Injection Molding? 5 Things to Know

What is precision injection molding?

Creates precise plastic components

Materials should have a low shrinkage capacity

Rely on the precision injection mold

A slow and steady process

Uses polymer optics

Many molding processes are known to mass produce products that are used in daily life. However, various industries have parts and pieces that are too complex to be made with ordinary plastic injection moldings. A process called precision injection molding is used for such processes.

But, what is precision injection molding? It is a highly technical process that makes use of precise molds. It is not used to develop whole products, instead, it develops more complex plastic parts.

It differs from convection modeling in many ways, from the materials used to the mold created to the machine used in creating the product. This article tackles all you need to know about this technical process. By the end, you can assess if this is the molding process that you need for your next project.

Creates precise plastic components

Compared to plastic injection molding, this method produces precise plastic parts. It does not mass produce whole parts. These products that are made in the process replace high-precision metal parts from different industrial appliances.

The plastic components produced in precision injection molding require a tight tolerance. That means that the requirements for the product have precise and accurate procedures. When not followed, it can break inside the mold.

Products that are produced in precise injection molding are also comprised of complex geometric parts. These items have specific shapes that are needed for certain items in automotive, pharmaceutical, information technology, and medical fields.

Materials should have a low shrinkage capacity

Precise injection molding can cause plastics to shrink during the manufacturing process. That’s why its materials are different from other injection molding materials.

When materials have a high shrinkage capacity, they melt as they undergo the precise injection molding process. It ruins the product in the end.

The materials used for this molding process need to have a low shrinkage capacity. The shrinkage required is around +/-0.01” or +/-0.02”. However, many materials can’t reach this range.

An example of this would be ABS, a thermoplastic polymer. This kind of plastic can retain its elasticity while going through high temperatures. However, its shrinkage of +/-0.06 is still not appropriate for precision molding. Glass and other resin can be added to reach the desired shrinkage. These help the material absorb the excess heat while keeping the plastic stable.

Rely on the precision injection mold

The precision made during this molding process is achieved through its mold. It needs to suit the design engineering requirements.

To craft the mold, it needs to undergo accurate study, design, and testing. Many elements need to be taken into account for the mold. Here are some of the elements that need attention:

The mold cavity size – its position and the number of cavities it has

The precision of the parting surface

The materials used for the mold (this can be made from steel alloys or cast irons)

The bottom plate’s thickness

The runner size

Precision injection models are made with tolerances between +/-0.02” and +/-0.01” or less. All elements mentioned are considered when considering the dimensions tolerance.

A slow and steady process

A high-precision model is required when creating plastic parts that have tight tolerances. Each part made in a precise injection model needs to be identical. This process can only be applied to plastic parts that are placed and connected with other parts in a fixed form.

Because of the precise products, the manufacturer should not rely on rapid tools for this method. Precise injection modeling is a slow and steady process that makes a high-precision tool.

Uses polymer optics

Polymer optics are used in precise injection molding. This is when CNC machining is used to mold the plastics into precise and calculated shapes. The machines have high pressure that helps improve the quality and precision of the plastic parts. They also manage to repeatedly create an accurate product.

The entire process is automated and conducted through computers through an automatic handling system. It allows the producer to customize the process for the product needed to be molded.

This reduces the cost of labor while increasing production efficiency thanks to its automated process.

Key Takeaway

Now that you’ve answered what precision injection molding is, you can check if you can apply it to some of your products. As stated above, it can also develop a wide variety of complex products.