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Date: 2023-2-21

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Injection molding is one of the technologies that is so important in our everyday life, we hardly notice it. We are constantly surrounded by objects created through this process. Almost everything made of plastic (almost everything) is made by injection molding. As a product designer, it is important to understand this process! let’s start.

What is Injection Molding?
It is a process used to manufacture a wide variety of items from small components to large components. It uses granular plastic that is gravity-fed from a hopper, forced through a screw-type ram into a heated chamber, melted, and pressed against a mold. It was then cooled and removed as a solid fraction. Rapid injection molding uses aluminum molds, which are produced quickly, while mass production typically uses steel molds.

Injection molding manufacturing makes it possible to produce parts in high volumes. That’s why it’s often used in mass production processes that require thousands or even millions of parts. In fact, the biggest downside is that the tool time and cost required to set up the molding process makes the technology unsuitable for low-volume production runs (fortunately we have 3D printing technology now).

The injection molding process cycle is divided into 4 phases and typically takes 2 seconds to 2 minutes per part

Clamping injection molding
This is the part of the mold where the two halves are securely closed by the clamping device. Hydraulic power is used to hold the clamps in place while a specific material (usually thermoplastic) is injected.

injection
At this stage, raw plastic or pellets are fed into the injection molding machine, pushed through the injection unit, melted, and injected into the mold.

cool down
Cooling allows the molten plastic to solidify and form the shape of the mold. Different parts and assemblies have specific cooling times, which depend on the maximum wall thickness of the part and the thermodynamic properties of the plastic material

catapult
The ejection system is used to push the molded part out of the clamping unit. A release agent can be sprayed on the cavity surface before injection to facilitate demoulding and prevent damage to new parts.

What are the benefits of injection molding?

low production cost
In injection molding manufacturing, the unit price is extremely low. The most important cost is the setup cost. Prices tend to drop dramatically as more parts are produced. Once the initial cost of manufacturing is paid for, the profit margins are very high. This makes financial sense in terms of business as long as there is demand to meet production.

Low scrap rate
Unlike traditional manufacturing processes, where a significant portion of the original block or sheet is cut off during production, injection molding cuts with precision, and waste plastic often comes from spilled material that leaks from the cavity. It can also come from runners, sprues, and gate locations.

repeatable and consistent
As a process used in high-volume production, injection molding is well suited to producing nearly identical parts. Every part produced will be identical to the first, which is important for consistency and reliability.

Of course, injection molding isn’t perfect. But its advantages often outweigh the disadvantages.

A major challenge in injection molding is designing the mold. The main focus is usually on the finished product, but without the molds that form the parts, no parts will be made. The design aspect of components is often overlooked, but is the most important.

As a source of experienced engineers and product designers, we can provide you with an individual or a professional team to help you develop your injection molded part from scratch. We’ll match you with pre-vetted, highly qualified design professionals. We also offer contract manufacturing services.