All you need to know on plastic injection moulding 

Plastic is a booming industry and is used by various industries. From automotive to home appliances and medical devices for components in a variety of plastics to protect, enhance, and build a range of products.

Reliable and high-quality performance makes plastic components one of the most commonly produced materials. Moreover, we expect the compound annual growth rate (CAGR) for injection-molded plastics to increase by 4.6% by 2028.

However, the ability to produce plastic components in higher numbers must be controlled to maintain the quality of final parts. Furthermore, this article will explain how to manufacture a control process to produce the best quality plastic component. 

What is plastic injection moulding?

Injection molding is a manufacturing process using a specialized hydraulic or electric machine. We follow the steps of melting, injecting, and setting plastic into the shape of a metal mold that fits into the machine.

Manufacturers widely use the plastic injection model in the manufacturing process for various reasons:

• Flexibility: manufacturers can choose the plastic injection moulding design and type of thermoplastic that is used for each component. This means the injection moulding process can produce various components, including parts that are complex and require detailing. 
• Efficiency: once the process is set up and tested, injection moulding machines can meet a high variety of compounds. The electric injection moulding machines also make the process energy efficient. 
• Consistency: if the parameters are controlled, the injection molding process can produce many plastic parts of consistent quality.
• Cost-effectiveness: once the model has been built, which is the most expensive element, after it has been built the cost of production is low. If created in high volume for mass production. 
• Quality: when looking for manufacturers for strong, tensile, or highly detailed components. The injection molding process is repeated at high quality. 

These reasons explain why many industries choose plastic injection moulding for their products.

How does plastic injection moulding work?

The plastic injection molding cycle involves checking various parameters to ensure the overall quality of the produced component. Here are some parameters you need to know:

Step 1: Selecting the right thermoplastic and mold

Before starting the process, we must identify the right thermoplastic and select or create the appropriate plastic injection molds. The final products are formed based on these choices, as certain thermoplastics and molds may not be suitable for specific molding designs.

Each mold consists of two parts: the mold cavity and the core. The mold cavity is the fixed part where we inject the plastic, while the core is the moving part that fits into the cavity to shape the component’s final form.

Due to high level of design and quality materials involved in developing the mold, it is an expensive process. Therefore, we recommend testing the material beforehand to ensure that the final component possesses the right properties.

Step 2: Feeding and melting thermoplastic

Plastic injection molding can utilize either hydraulics or electricity. Essentra has replaced its hydraulic machines with electric-powered machines, demonstrating cost and energy savings.

Injection molding machines typically include a feed or hopper at the machine, a long cylindrical heated barrel, and a large injection screw positioned at a gate where the chosen mold tool attaches.

We must maintain the right temperature to ensure efficient injection of the plastic and accurate formation of the final plastic part in the injection molding process.

Step 3: Injecting plastic into the molds

Once the melted plastic reaches the end of the barrel, the gate closes and the screws move back. This draws a set amount of plastic and builds up the pressure in the reciprocating screw ready for injection. At the same time, we close the mold halves together and hold them under pressure, known as clamp pressure.

We must balance injection pressure and clamp pressure to ensure the part forms correctly without any plastic escaping during injection. Once we reach the right pressure in the tool and the screw gate moves forward, we inject the molten plastic into the mold.

Step 4: Holding and cooling time

At Texas Technology, we use a range of plastic injection molding tools that we hold under pressure for a set period, known as the holding time. This time can vary from milliseconds to minutes, depending on the type of thermoplastic and the complexity of the part. We take the necessary time to ensure that the plastic packs out the tool and forms correctly.

After the holding phase, the screws retract to release the pressure, allowing the part to cool in the mold and the plastic to solidify. During the cooling time, which can range from a few seconds to several minutes, we ensure that the component sets correctly before we inject and finish it on the production line.

Step 5: Ejection and finish 

After holding and cooling time has passed, forming ejector pins or plates ejects the part from the tool. These drop in the compartment or conveyor belt at the bottom of the machine. Moreover, in some cases, we may need to perform processes like polishing, dying, or removing spurs before the components are ready to be packed and distributed by manufacturers.

Conclusion 

Here at Texas Technology, plastic injection molding is a key process where optimizing plastic injection molding does include replacing old hydraulic machines with electric machinery. We invest in material innovation, having all the required technology required to create and test new materials, enabling us to offer sustainable product ranges globally for customers.