A Manufacturer’s Guide to Understanding Injection Molding Machines

A REVIEW ON THE IMPACT THAT INJECTION MOLDING MACHINES HAVE HAD AND CONTINUE TO HAVE ON INDUSTRIAL BUSINESSES

Automobiles, airplanes, and computers are all significant innovations, but the success of these industries is due primarily to one invention, the injection molding machine. Injection molding systems are vital to the sustainability of manufacturing processes, materials, and design applications across every industry.

In fact, many of the industrial innovations and new-age technological advances of the last 150 years may have never come to fruition without the invention of the plastic injection molding machine.

Plastic is, perhaps, the most critical medium in manufacturing. It’s affordable, durable, and allows for high-quality mass production. However, plastic would not be viable without injection molding systems, and if injection molding did not exist, the world would look astonishingly different.

The History of Injection Molding Machines

Back in 1868, John Wesley Hyatt received a patent for the process of producing celluloid. Hyatt used the technique to replace ivory in billiard balls. In 1872, he became the first person to inject melted celluloid into a mold.

Along with his brother, Isaiah, they patented an injection molding machine. Their injection molding machine utilized a plunger to inject celluloid through a heated cylinder and into a mold. The brothers used the machine to create collar stays, buttons, and hair combs. Little did they know the groundwork of their invention would eventually go on to change the world forever.

The injection molding process remained essentially unchanged until 1946. The events of World War II created a need for affordable products that could easily be mass-produced — enter American Inventor James Watson Hendry. Hendry revolutionized the plastics industry by creating the screw injection molding machine, which used screws to heat, mix, and inject plastics into molds.

The versatility of Hendry’s screw injection molding machine enabled manufacturers to introduce color and pre-mix before injection — creating endless possibilities. His design has stood the test of time, as most injection molding machines still use a similar technique.

The major difference between injection molding machines of the past and modern ones today is that the machines are more refined. Plus, the implementation of computer technology provides greater precision.

Plastic injection molding machines are integral to the manufacturing of products for industries, including electronics, automotive, home appliances, medical, aerospace, and more.

The Process of Injection Molding Machines

Injection molding is one of the most common ways to produce plastic parts. The cyclic process involves injecting heated, liquefied materials into a temperature-controlled mold placed under high pressure. After the materials have cooled and solidified into the finished part, the machine opens up the mold, and the part can easily be removed.

The materials begin as grains or powder, and various types can be used, including metals, glass, elastomers, and confections. However, a machine must be configured accordingly to each material before use.

The two most common materials used today are thermoplastic and thermosetting polymers.

The main difference between the two is that thermosets permanently cure, meaning once melted into a shape, it cannot be melted again — it will just burn. On the other hand, thermoplastic can return to molten plastic and mold to a new shape.

The advantages of injection molding have not changed since World War II. It is an exceptionally economical, fast, reliable, and precise method for mass-producing integral plastic parts.

Auxiliary Equipment

Auxiliary Equipment plays a vital role in the injection molding process, helping to:

  • Properly prepare and dry raw materials
  • Deliver materials to injection molding machines without contamination
  • Assure accurate and reliable temperature control
  • Maintain process consistency
  • Properly remove finished parts
  • Efficiently manage scrap materials

Disadvantages and Advantages of Injection Molding Machines

Injection molding machines produce many parts but are typically only used when a manufacturer needs to mold thousands or even millions.

Disadvantages of Injection Molding Machines

There are many advantages to injection molding, but usually, there is a downside to any process, and injection molding is no exception. The upfront cost can be expensive, and there is trial and error in the beginning. Prototypes must be made and tested, which is a costly process.

Due to size limitations, injection molding is also not ideal for producing large single-piece parts. However, a large part can sometimes be sectioned into smaller parts and assembled into a single piece after processing.

Advantages of Injection Molding Machines

As previously mentioned, the main advantage of injection molding machines is their ability to mass-produce parts. Once the machine and the molds are paid off, the cost of manufacturing parts becomes lower, and as a company produces more parts, its profits greatly increase.

Another advantage is that material wastage is minimal with injection molding machines compared to computer numerical control (CNC) machines, which are designed to cut parts out of block-sized materials, causing excess waste.

Additionally, using a mold ensures that every part is identical, no matter how high the production volume is.

Types of Injection Molding Machines

There are three types of injection molding machines: hydraulic, electric, and hybrid. No machine is perfect for all applications, so working with a knowledgeable molder is essential. Someone with little experience can cripple a project before it even begins by making the wrong decision.

Some of the world’s top manufacturers of injection molding machines include ARBURG, ENGEL, Haitian International, Husky Injection Molding Systems, and Sumitomo Demag.

ARBURG

ARBUG has been making injection molding machines since the 1950s. Today, the company has 33 locations worldwide and specializes in hybrid injection molding machines. Additionally, service packages and turnkey systems are available.

ENGEL

ENGEL has nine locations worldwide offering hydraulic and electric injection molding machines. ENGEL also has turnkey systems and a range of specialist injection molding processes suitable for many materials.

Haitian International

Haitian International, based in China, has nine locations worldwide and sells electric and hydraulic injection molding machines.

Husky Injection Molding Systems

Husky Injection Molding Systems has 35 locations worldwide. Husky offers hydraulic, electric, and hybrid injection molding machines.

Sumitomo Demag

Sumitomo Demag’s predecessor company Ankerwerk Gebr. Goller developed the first single-screw injection molding machine in 1956. Today the Sumitomo Demag has nearly 100 locations worldwide and has hydraulic, electric, and hybrid injection molding machines.

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