Did you know that the global market size of plastic injection molding may reach $419.1 billion by 2030? Why are the demands for injection molds so high?
Injection molding is one of the most common methods for producing large volumes of plastic. Its also used in many industries, from medical devices to home appliances. However, despite its ability to create components, it needs constant control and management to create quality parts.
So learn all there is to know about injection molding in this guide. Read on for more about its types, cons, pros, and applications.
What Is Injection Molding?
Injection molds are hollow forms where molten plastic gets injected to make a particular part or product. They have a hole in the middle with the shape of the needed part.
On the other hand, injection molding is the process of forming using those molds. It’s a manufacturing process that allows large productions for parts.
The most common molding materials used are thermoplastic and thermosetting polyester. Other materials involved typically include glasses, metals, confections, and elastomers.
Types of Injection Molds
The types of injection molds that manufacturers use depend on their budget, tool design, budget, production volume, and geometry. Here are the different kinds of injection molds used to manufacture plastic components:
According to the Number of Cavities
There are only three types according to the number of cavities or parts produced every injection cycle.
The first type is the single-cavity injection mold, which can produce only one part per cycle. Using multiple single-cavity molds ensures that the production continues, even when there’s a breakdown in one mold. This provides more flexibility in controlling the production and molding process.
The next type is the multi-cavity mold, which produces more than one part every cycle. This type is often used to increase the production rate of parts. However, multi-cavity injection molds have a higher price tag and require a higher tonnage machine to run.
The last type of injection mold is the family mold. This mold can produce one or two different parts every injection cycle. With this mold, you can create the bottom and top parts of a plastic housing in a single injection cycle.
According to the Feeding System
There are two types of molds according to how the molten material goes into the injection molds. This is the hot runner mold and cold runner mold.
The hot runner injection mold has a heated physical channel that directs molten materials to an injection mold cavity. In this mold, the runners are always part of the injection mold.
Cold runner molds have an unheated physical channel. This leads the molten materials to the injection mold tool after it leaves the nozzle. The runner is often cooled and removed with the injection molded part in this mold.
According to the Mold Opening
By how the core separates with the cavity injection molds, there can only be two types: two-plate mold and three-plate mold.
The two-plate injection mold is the most commonly used type of mold. This type of mold consists of one parting plane to split the mold.
On the other hand, three-plate molds have two parting planes and three sections of mold splits. This allows the components and runners to have different parting planes. In this mold, the runner is typically ejected separately from the molded part, making automatic de-gating possible.
Pros of Injection Molds
Injection molding yields low scrap rates compared to other traditional manufacturing techniques. This includes CNC machining, plastic forming, and 3D printing.
Injection molding is also highly repeatable. All parts produced from these molds will be identical, providing consistency and reliability with high-volume production. They can also create complex parts with the most accuracy.
Another advantage to injection molds is the cost. Once you’ve paid the initial costs for the molds and design, the manufacturing costs drop. The price typically becomes lower as more parts get produced.
The flexibility of injection molds is another factor to look for when looking for molds. As of today, there are more than 25,000 engineered parts that can work with injection molding. With all the options, you’ll be able to find the best material that offers the best balance of properties.
Cons of Injection Molds
Although injection molds can produce complex parts, they can’t produce large parts as one piece. This is due to the size limitations of the tools and machines. You need to divide large parts into multiple pieces that can join together later on.
Injection molds take the longest initial lead times compared to other manufacturing machines. It can take up to seven weeks to manufacture tooling. In addition, producing and shipping parts can take two to four weeks.
Aside from the expensive start-up costs, changing the designs can also cost a lot. You’ll likely need to create a new mold from scratch, pouring a lot of money and time into the project. There are also some design restrictions that you need to consider, like no sharp edges or various wall thicknesses.
Where Is Injection Molding Used?
Injection molding is the most versatile out of all the molding techniques. Due to its wide range of applications, many industries rely on injection molding.
One industry that uses injection molding the most is the medical and pharmaceutical industries. This is because many medical products need to be non-porous and shatter-proof.
Injection molding offers the best mechanical properties, like high-temperature resistance and high tensile strength. These are all ideal features needed for the demanding nature of medical parts.
To safeguard human health and ensure safety, the beverage and food industry also needs injection molding. Injection molding helps these industries meet their nontoxic and BPA-free guidelines. It produces parts that comply with GMA-safe regulations and are FDA-certified.
Other industries that use injection molding include telecommunications, packaging, and automotive. Household products, electronics, agriculture, cosmetics, and construction also make use of molding.
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