What Is Injection Molding?

Injection molding is a manufacturing technique for a wide range of products. This method is excellent for creating parts with complex geometric characteristics and quickly producing large volumes.  

Are you interested in learning more? Explore everything you need to know about this technique with this injection molding guide. We break down the essentials of this process, including how molding machines work and whether or not it is the right method for your application. 

What Is Plastic Injection Molding?

Plastic injection molding refers to a manufacturing process for producing plastic parts and products with a special-purpose machine. The molding equipment uses heat to liquefy plastics, then injects them into a set mold. Common examples of products you can create with this method include:

Benefits of Injection Molding

Plastic bottles
Lids 
Caps
Toys
Electronic housings
Trash receptacles
Medication trays
Toilet seats
Flower pots

The plastic injection molding process can have many advantages, including the following:

Precision: One of the most significant benefits of injection molding is its ability to achieve extremely high levels of accuracy and precision during manufacturing. This method is especially useful for projects with intricate or complicated design features.
Enhanced strength: Plastic fillers reinforce parts and enhance their strength for more durable and supported products.
Quick cycles: Manufacturers can use multi-cavity molds to produce multiple parts at once with short cycle times. 
Supports mass production: Injection molding can support mass production because the machine can mold many parts simultaneously with quick cycles. 
Sustainability: This process is more sustainable than other methods because it produces less wasted material, which also means wasting less money. 
Versatility: Injection molding manufacturing can work with a wide variety of plastics and resins, including LCP and Nylon.
Low cost per part: Compared to other techniques like 3D printing, you can enjoy lower costs per part after the initial investment in your injection mold manufacturing. 

How Does Injection Molding Work?

The injection molding process is relatively quick and involves four main stages:

1. Clamping

A clamping unit holds both halves of the mold closed before attaching it to the heavy injection molding machine. The machine then injects the material into the mold while it’s clamped together. 

This stage is vital because the clamping force is necessary to withstand the pressure from the melted materials inside and ensure none of it spills out. 

2. Injection

Heat and pressure inside the molding machine melt plastic pellets, liquefying them so the machine can effectively inject them into the mold. Injection time depends on a few factors, including:

Injection pressure
Power
Shot volume

The machine’s hydraulic system controls the rate of injection and the pressure it reaches.

3. Cooling

After injection, the cooling process begins. The plastic inside the mold will start to harden and take the shape of the surrounding form. In some instances, the plastic may shrink slightly during this stage.

The mold should stay shut until the plastic is entirely cool.

4. Ejection

The final stage in the injection molding process is ejection. The machine features a specialized system to push out the plastic once it cools. Parts sometimes stick to the mold, so the machine has to force them out.

Once the newly formed part is ejected, the machine can close the mold and start the process again. 

When Is Injection Molding Used?

Manufacturers typically opt for injection molding to maintain efficiency when producing large quantities of the same products or parts. This method is often useful for applications in the following industries:

Construction: Builders utilize small plastic parts like window locks and door handles in the construction industry.
Medicine: Medical devices and instruments must be highly precise, making injection molding a perfect production method for these items.
Food: The food and beverage industries must comply with strict regulations. Injection molding can work with BPA-free plastics to create uniform items, such as lids and containers. 

Types of Injection Molding

Explore the following types of injection molding techniques and their defining characteristics: 

Thermoplastic Injection Molding

Thermoplastic injection molding is one of the most popular types of injection molding. The machine injects heated plastic resin into the mold. As it cools, the resin takes on the mold’s form and is complete. 

Liquid Silicone Rubber Molding

Liquid silicone rubber molding, also known as liquid injection molding, is a thermoset process that involves mixing and curing two compounds using heat inside the mold. This type of injection molding is ideal for forming complicated shapes. 

Overmolding

Another type of injection molding is a multi-step process called overmolding, also known as two-shot molding. During this manufacturing process, two or more components are molded on top of each other.

Insert Molding

Insert molding is a form of injection molding used to bond plastic and nonplastic materials. The method works by placing a nonplastic insert into the mold and injecting the plastic to encapsulate it. Once the plastic sets, the materials establish a highly durable bond.

Gas-Assisted Injection Molding 

Gas-assisted injection molding involves injecting inert gas into heated plastic to fill out the mold and establish hollow parts. Manufacturers use this process for making products such as:

Equipment covers 
Doors
Handles 
Cabinets

Is Injection Molding Right for My Project?

Consider the following factors to determine if injection molding is suitable for your project:

Costs: While the cost per part is low for injection molding production, you must also factor in the cost of the machinery and the specific mold you’ll use for your parts. 
Quantities: To determine whether or not injection molding is a cost-effective method to produce your products, you’ll need to determine how many parts you plan to manufacture. 
Design: You should also consider the mold’s design. The simpler it is, the easier the process will be and the lower the chances of defects occurring during production. 

If you need a manufacturing process that supports consistency and quality control, injection molding might be a perfect choice. This technique also makes it simple to scale your production volumes as needed. 

Request a Quote From New Concept Technology

If you are interested in injection molding for your upcoming project, turn to the experts at New Concepts Technology for assistance. We have a state-of-the-art facility and offer a wide range of manufacturing services, including automation and assembly. 

Our team has experience working with Fortune 500 companies to fulfill all their injection molding needs. Our systematic molding techniques support high-density precision and our expertise in a broad range of resins allows us to meet many industry-specific formulations.

Are you interested in learning more? Contact New Concept Technology for a reel-to-reel injection molding quote today!