Injection Molding - The Basics

Injection Molding

Why Injection Molding?

Injection molding is the most popular method for manufacturing plastic parts on the planet, so it’s not surprising that the global market for the process was valued at almost 260 million U.S. dollars, with projections for continued growth in the foreseeable future. The technology is used in a wide variety of industries, including aerospace, medical equipment, and automotive, where advanced techniques such as over-molding and insert molding are used to create even the most complex parts with impeccable precision. And when you consider just the wide range of injection molding benefits, understanding why millions of companies in some of the most demanding industries in the world are using it for bringing their part designs to life. But why is injection molding machine manufacturing so effective? And how does it work? To find out, let’s dig into the subject and answer all of the important questions, including what it is, the process behind it, its main advantages, and how to choose the right service provider.

What is Injection Molding?

Injection molding is the process of using plastic to manufacture a wide range of parts and items. Even though the process was invented as early as the 19th century, it still remains one of the best ways to produce complex parts while keeping expenses under control. The injection molding machine uses custom-made molds to fill them out according to specifications, creating identical copies that can be customized in a variety of ways. What’s more, injection molding is a very versatile process, allowing for a wide range of different materials and finishes, which makes it a popular option in countless industries with completely different goals and requirements. Because of this flexibility, the injection molding machine manufacturing is even used for some of the most demanding manufacturing projects in the world, producing parts in aerospace, medical fields, and the automotive industry. Whether you’re looking to produce a small number of parts for testing or need a reliable method for producing large quantities of parts in a hurry, injection molding can be an ideal choice, especially when working with plastics. What’s more, the unique process when manufacturing part with an injection molding machine also means that you can produce complex parts with intricate designs, which is not something that can be said about all manufacturing options out there. The ability to manufacture large quantities of parts at an affordable cost also makes it ideally suited for the production of various commodities. In fact, it’s likely that quite a few of the household items that you have could have been produced using injection molding.

How Does Injection Molding Work?

Even though the injection molding process is complicated, it can actually be broken down into a few essential steps that help understand how it works and why it’s so effective. The injection molding machine is made up of three main components, which are the feed hopper, the screw, and the heated barrel. This machine works by taking plastic powder or granules and manipulating it to shape it into a part according to the requirements and dimensions. When the feed hopper receives the plastic granules, it then uses frictional action of the screw to create heat. Once the plastic reaches the correct temperature, it is then injected into the mold cavity, where it eventually cools and takes the shape according to the mold design. If necessary, advanced injection molding techniques such as repeated injection can be used to create parts out of multiple materials. It’s also possible to use insert molding to add plastic parts over existing parts made out of other materials. The basic principles behind the injection molding process may seem simple, but in reality, it is a very complicated process that requires the right equipment and the right expertise. However, when it is executed correctly, injection molding can consistently produce excellent results even for the most challenging manufacturing projects.

Pros & Cons of Injection Molding

Even though injection molding is one of the most effective manufacturing techniques that has many advantages, there are things that need to be considered before deciding whether it’s the right approach for you. Just as with any manufacturing approach, there are advantages and disadvantages that can apply to different situations, and only by understanding them can you make an informed decision. With that in mind, let’s go over some of the most significant pros and cons that injection molding can offer. 
Pros
 First, let’s go over the pros of choosing to manufacture with an injection molding machine. 
Impeccable Precision
 Because of the way that material is injected to and then shaped by the mold, the number of imperfections can be reduced to a minimum. That means that with every run, you can produce a part that is identical to the one preceding it, over and over again. As you can imagine, this type of precision is important in almost all industries, and especially in those that can’t compromise on quality, which is why injection molding is popular in highly demanding fields like aerospace and automotive. 
 Complex Details 
 As mentioned before, injection molding enables companies to produce even the most complicated mold designs, executing even the smallest of details with ease. You can add multiple details to your mold design and rest assured that each of them will be made a reality by the mold. 
Durability
 Unlike most other production methods, injection molding provides advanced possibilities in terms of the durability and reliability of the plastic parts that are produced. For instance, you can add fillers in the injection molds that are created, which can help reduce the density of the plastic material and make each part stronger.
 Automation 
One of the primary reasons why injection molding produces consistent results is that a lot of the actual manufacturing process can be automated. That means that you can not only reduce the chances of human error to a minimum, but also have the machine produce parts at a consistent rate and a high fulfillment rate.
Cost Efficiency 
For the most part, injection molding is one of the most cost-effective solutions for producing parts that you can find. Even though the bottom line of your project will depend on the materials that you use and the complexity of the designs, when comparing it with other manufacturing methods, you will usually find that injection molding will deliver more for the budget that you can allocate.
Wide Range of Materials
 If there’s one thing that injection molding really excels at, it’s the ability to customize the materials and finishes according to almost any type of requirements. You can choose plastic, thermoplastic rubber, chemical resistant plastics, biodegradable, and many others, so just be sure to figure out what you need from the part, and you’ll have plenty of options. You can also select almost any color imaginable and can also choose from a wide variety of finishes, either for aesthetic or functional purposes. 
Eco-Friendly
Finally, in a world where being conscious of the environment is more important than ever, injection molding can be useful because it produces almost no waste. Every bit of material that isn’t used in the mold can be repurposed and used in future projects.
Cons
 Now that we’ve looked at why injection molding is so effective, let’s look at some of its shortcomings to provide you a more well-rounded picture.
 High Initial Cost
As we mentioned earlier, injection molding can be very cost-effective, especially for bigger production runs, since the cost of one part is relatively low. However, before you can actually manufacture, you will need to design and create the mold itself, and that can take many hours and a lot of manpower to execute correctly. Still, even though this process can be complex, once it’s done, you can use the mold to produce thousands of parts quickly.
Takes Longer to Get Started 
Because of the fact that the mold needs to be designed and created, it’s understandable that this process will take time, and can sometimes take months to complete, depending on how complex your project is. But even though the project of mold development can take time, once it’s done, the process becomes extremely fast and reliable. And if you know what you’re looking for and have prior experience, you can cut down on the time significantly. 
 Size Limitations 
Although an injection molding machine can produce fairly large parts of up to around 60 cubic inches, if you need something bigger, you might have to choose another manufacturing method such as plastic fabrication. Still, in most cases, it’s likely that your part will fall well within the parameters, so you should be fine.

Applications of Injection Molding

When producing parts, precision and cost-effectiveness are two of the most important considerations that most companies are looking for. That’s why it’s not surprising that a process such as injection molding has become so popular and has been used both for smaller runs, as well as large-scale production of parts with tight tolerances. We already talked about some of the high-tech industries that benefit from this manufacturing technology, but let’s look at a few more of the common applications that are very common, to see what types of items you could produce. 

  • Food & Beverage
  • Construction Parts
  • Medicine
  • Toys
  • Appliance
  • Agriculture
  • Automotive
  • Furniture
  • Industrial
  • Lighting
  • Marine
  • and many more!

Because of injection molding, medical companies are able to produce vital tools and parts cheaper, which helps make healthcare more accessible to people all over the world. Many of the integral medical devices such as heart pumps, various monitors, as well as a range of medical instruments all depend on the precision of injection molding, which makes the technology irreplaceable in the field.