Injection molding can be performed by several types of machines with varying techniques. Machine selection is an important part of planning your injection molded project, helping determine the types of materials and molding techniques available to you.

What Is Injection Molding?

The injection molding process creates parts and products by pushing a melted material such as plastic resin or polymer, into a mold so that it makes a specific shape when cooled. Injection molding machines must heat the raw material, maintain adequate pressure in the mold while forcing the raw material in, cool the molded part and eject it once cooled.

Types of Injection Molding Machines

Injection molding machines have two primary parts, the injection unit and the clamping unit, but the ways each part can work differ among types of machines. 

Power Source

• Hydraulic - Most common among injection molding machines, they are run by a hydraulic pump and a fixed speed electrical motor.
• Electrical - Functions are digitally controlled and powered by an electrical servo motor.
• Hybrid - Also known as servo-hydraulic machines, they feature hydraulic power and on-demand electric motors.

Comparing Features of Injection Molding Machines

Specific products and material choices will influence your machine choice, but some more general features to evaluate include:


Quality
Product design will determine the tolerance required in producing your project, so your injection molding machine should be able to repeatedly mold products within those tolerances. Hybrid and electric machines offer the greatest precision while hydraulic machines tend to be the least precise. Electric machines generally provide the most repeatability.

Clamping Power
Hybrid machines offer the greatest clamping force, but purely hydraulic machines are also well suited to producing larger sized products.

Speed
The rate of part production may play a role in machine selection. Electric injection molding machines tend to offer the fastest production.

Material Options
Material choices may limit your choice of machines. Hydraulic machines generally require higher molding temperatures, so not all resins will be suitable for use with them. 

Mold Size & Design
Ensure the injection molding machine has adequate size to accommodate the desired mold. Hybrid and electric machines offer the most flexible design options.

Hydraulic Accumulator
An accumulator helps provide consistency and stability in the injection process which is particularly needed for thin-walled projects.

Screw Type
General purpose screws may be suitable for the majority of plastics, though they may slow production and decrease quality with some materials. Other materials may require specialized screws for specific injection pressures.

Special Uses
Fluid leaks with hydraulic systems can render those machines useless for clean room part production.

Not sure about choosing the appropriate machine for your project? We have the machines, the expertise, and decades of experience, so contact us today to see how we can help.