Large Part Injection Molding

A specialized field in injection molding, this service involves injecting molten materials into a mold to produce parts in large formats. It’s mainly used to make a wide range of plastic products — from plastic pallets, to car bumpers, and many more. If you’re interested in learning more about what large part injection molding is, keep on reading.

What Is Large Part Injection Molding?

Large part injection molding involves injecting molten materials into a mold to produce plastic parts. It is not that different from normal injection molding. Both manufacturing methods involve pouring resin pellets into the feed, before going into the nozzle and getting heated before going through the mold’s runners.

But injection molding of large parts requires greater tonnage because it’s needed for the clamping force of the machine. The right type of equipment is needed for large part injection molding, one that is usually made of a sheer size. Because the parts processed from these machines are extremely heavy, heavy-duty machinery is also needed to lift, transfer, and store the finished product.

Large part injection molding process
Specialized services for large part injection molding process

Why is Large Part Injection Molding a Specialized Service?

Large part injection molding requires specialized machines and tools. Namely, they are made with what we call large-tonnage injection molding machines, and these use up plenty of resources. They take up more space on the factory floor, and the utilities used to operate each one are expensive. The capital costs of just one large tonnage machine are also significantly higher than any other injection molding machine.

The injection molds that are used in these machines also need special care. They are extremely heavy and require special lifting equipment to install and remove as needed. Handling the large plastic parts these machines make also requires considerable space for staging, packaging, and storing. These considerations limit how many companies can offer large part injection molding services.

Other Considerations for Large Part Injection Molding

As we touched upon previously, large part injection molding is a highly specialized service. This is in part due to the machine requirements such a service has. In addition, there are many injection molding factors that engineers and manufacturers have to account for in each project — this is crucial in making large parts that are structurally sound, durable, and aesthetically pleasing.

Injection Pressure and Clamping

Injection pressure and clamping are other factors manufacturers like Richfields have to accommodate. How much pressure and clamping a mold needs for each large part design is influenced by other aspects of the project. This includes things like wall thickness, geometry, gating of part, the viscosity of resin, and temperature of the injection mold.

Resin Selection

Plastic resins are generally categorized into what physical, environmental, and chemical resistance properties they can fulfill. Each resin also has a differing ideal processing temperature range. Making sure that the resins stay within this range during injection molding ensures their beneficial properties will not degrade as they are processed.

They also have a differing Melt Flow Index, which is the rate at which they flow through a mold once melted. This affects which resins are ideal for thicker, larger designs, and which are not.

Injection molding facility

Benefits Of Large Part Plastic Injection Molding

Large part injection molding might require the right equipment, skills, and budget, but it has its benefits too. We can help you experience these advantages if you work with us:

High Volume Production

Injection molding of large parts is primarily done to produce large size parts in big batches, which can be done reliably and with shorter cycle times than other plastic manufacturing methods. It’s a necessity when the same part needs to be recreated thousands of times in succession. This is beneficial if you’re in an industry in need of such parts in a specific time period.

Minimal Waste

Compared to other processes, injection molding of large parts creates fewer waste plastic or scraps, so it’s more cost-efficient. Having fewer scraps means that manufacturers don’t have to waste too much plastic resin in the process. The resin used during the manufacturing process can be maximized.

Fast Cycle Time

Many businesses choose large part injection molding, because it is more efficient. The time it takes for the plastic part to be manufactured is short, so more products can be produced in a short amount of time.

Versatility In Design

Large part injection molding is used to create a variety of products — from plastic decking, to large-size electronic casing and enclosures, to plastic chairs and tables, and many large-format items and designs you can think of.

Types Of Molding For Creating Large Parts

There are a variety of molding techniques used for creating large parts:

Air Assist Molding

Gas assist molding can be incorporated into the large part injection molding process to improve quality, provide short cycle times, and also reduce weight of the resulting product. During the process of injection molding, nitrogen gas is injected into the tool through controlled high pressure. This ensures that the molten resin that fills the mold can fill the cavities. It also helps the material maintain consistent surface contact.

With this, gas assist injection molding is primarily used for plastic parts that are bigger and thinner.

Air assist molding process for large parts
Hot runner molding process for small to large parts

Hot Runner Molding

Hot runner molding can accommodate small to large parts. It uses heat to materialize plastic resins. A hot runner molding system has two heated plates that have a manifold system. The manifold sends the molten plastic to the nozzles to fill the cavities. By using hot runner molds, you can produce larger parts with faster cycle times.

Why Choose Richfields for Large Part Injection Molding?

One of the specialties of Richfields is large part injection molding manufacturing and tooling. We are capable of manufacturing large plastic items, such as automotive parts, plastic enclosures, refrigerator components, instrument panels, television parts, and more.

With our equipment ranging from 800 to 2200 tons in size, we have a full range of plastics capabilities. That, added with our years of industry expertise, allows us to make almost any large plastic part that you can think of. We can fulfill projects using all types of engineering grade resins, and successfully manufacture designs requiring close-tolerance specifications — all with superior quality and aesthetics.

Warehousing and engineering facilities in our US and China locations also gives Richfields an edge — we can provide services to those with large custom plastics needs at cost-effective prices. We are also a full-service business, and can see to the needs of your project from start to finish. This allows us to be a single source supplier for all your large plastic part needs.

Large part injection molding manufacturing and tooling

Industries That We Serve

A variety of large part molds can be used for large part injection molding. Here at Richfields, we pride ourselves on being a one-stop service provider. We can help you with both injection mold making and injection molding. We are a trusted exporter of injection molds to clients all around he world — including the US, Brazil, Europe, UK, and others.


The automotive industry is well-known for using metals in manufacturing products, but plastics have also become an important material in automobiles. Large part injection molding is beneficial for producing parts for fenders, hoods, grills, paneling, door covers, and more.


The electronics industry uses injection molding for both small and large parts for the mass production of important parts. This is because plastic is the ideal product as it can be combined with watertight seals and is UV resistant, and has numerous design capabilities.


Injection molding of large parts is a necessity for sports equipment makers all around the world. This is because molded plastic components are durable and can withstand heavy impacts with frequent use.


There are a variety of injection molded products in the household industry — from plastic furniture, toys, appliances, and many more.

Inquire About Large Part Injection Molding Here At Richfields!

If you’re interested to learn how large part injection molding can help you, don’t hesitate to leave us a message here at Richfields! With decades of experience in the industry, up-to-date facilities, and a highly-skilled team, you can rely on us when it comes to injection mold making and injection molding services. We are located in Dongguan, China, so we ensure that raw materials and special resins are always available at competitive prices.