The world we live in today is a global village of considerable proportions. The high demand for a large portion of standardized goods means that a substantial part of our design industry manufactures products via mass production. The popularity of this type of production is mostly based on its economies- administering out large quantities of products in a small amount of time, with less room for error and labor costs. In such a setting, industrial designers are challenged by a broad and growing field of specialized materials and manufacturing methods. Yet, when it comes to choosing manufacturing technology for the mass-production of identical plastic parts (with adequate tolerances), it seems that injection molding is the most popular method.

In this article, we’ll take a closer look at what exactly this method is, why it is so popular when it comes to mass production, and what are some of the new technologies in the world of injection molding that execute industrial design ideas in reality.

Injection Molding- Basic Facts

Injection molding is a method used in manufacturing parts or mechanical components in a process that involves an injection of material into a mold. The process entails an injection of melted polymer granules under pressure into a mold to acquire the shape of the item. Once the liquid plastic cools and solidifies, it is shaped through machining to get the form of the final (desired) product.

The most common types of injection molding are thermoplastic and thermosetting polymers, which gives the manufacturer a pervasive range of available materials with distinct physical properties to design with. The reason why these types of plastics are used is because of their high-temperature resistance. Unlike many other plastics, the thermoplastics require much temperature to convert into a liquid. They can also be colored or filled with other additives to achieve the desired level of strength, stiffness, or impact resistance. Conclusively, components produced with injection molding have excellent physical properties.

The Simplicity and Advancement of the Injection Molding Machines

An injection molding machine is composed of three main parts: the injection unit, the mold (the core part), and the clamping/ejector unit. The injection unit melts the raw plastic and guide it into the mold. Once injected into the mold through the runner system, the liquid material fills the whole cavity. As the material cools down, it re-firms and takes the shape of the mold. Finally, the mold opens, and the now hard part is driven out by the ejector pins. The mold then closes, and the process repeats.

Popular and advanced injection molding methods include:

Injection molding using gas is a process that entails injecting the plastic into a mold through the assistance of pressure from the gas (most commonly nitrogen). Importantly, pressure can be exerted from different points, making this technique popular in the plastic industry because of its effectiveness.

Injection using foam is an effective method, especially when the manufacturer wants to achieve high structural rigidity and resistance in the final product. It also leads to superior chemical resistance and thermal isolation. The process is mostly used in the manufacture of light vehicle panels.

The thin-wall method is vital in the production of thin-walled final products. Meaning it is generally used for parts that need to have less than 0.5mm diameter.

The multi-component method involves the use of more than one material with varying colors in the same mold. The result is a mold with different texture, shape, and color. This method is advantageous because it leads to parts that have superior chemical, thermal and mechanical resistance.

The Universality and Popularity of Injection Molding

In everyday life, we come across many plastic items of various sizes and designs, which are part of a large functional system. From packaging, bottle caps, toys, to items in medicine and aerospace, every plastic part can be produced with the help of the injection molding process.

The repeatability, low scrap, and simplicity of the process are probably the most critical factors behind the popularity of the injection molding in the mass-production of different plastic items. It is both a cost-effective and cost-efficient production method. It can produce many standardized plastic items with the help of a single mold, which means that the process is repeatable. Since the plastics usually heat and cool faster than metals, the process is also fast, enabling the production of an optimal number of plastic parts at a time. As an added value, the excess plastic wastes can be again melted and reused.

Another key strength of injection molding is that finished products need little to no extra finishing with this method. The surfaces of the mold can be polished to a very high degree to create mirror-like parts. Or they can be bead blasted to create textured surfaces.

Also, the process is economical- by using injection molding and assuming that you know your product well, the economies of scale can be conveniently achieved. That said, the cost of installation is less than installing a drill machine and can produce several molds in one go. Due to the fast cooling rate, the surface finishing and machining can be done quickly, allowing it to be dispatched to the market overnight. However, compared to other technologies, the start-up costs of injection molding are relatively high, mainly because custom tooling is needed. The final price is shaped depending on its complexity, material (aluminum or steel), and accuracy (prototype, pilot-run, or full-scale production mold). For this reason, if you need to test out the market with low volume parts or you want to create large quantities of parts, but buying an injection molding machine is out of option, then opting for injection molding services is the best deal for you.

The Future of Injection Molding

Plastic injection molding today is still based on the same principles. Yet, as a result of current manufacturing pressures for even lower costs, higher quality, and greater productivity, technological developments have enhanced the versatility and reliability of injection molding in a few important directions:

  • Increased use of lighter-weight (plastic) materials in the process,
  • Reclaimable, recyclable, and renewable plastics are increasingly popular due to environmental reasons and consumers awareness,
  • High tech plastic molds can now be created of metal, epoxy or carbon fiber and may increase output through quicker cooling and cycle times,
  • Robotic automation of molding machines cuts down on costs and labor needs,
  • Enhanced customization options are allowing for more tailored plastic solutions.

Final Thoughts

Injection molding is a great and the most economical technological process for getting finished products on a massive scale. The manufactured items have excellent and detailed features thanks to the fact that they are subjected to extreme and excessive-high pressure in the manufacturing process. The method also offers predictability, efficiency, and less troubleshooting. Moreover, highly sophisticated, engineered plastic materials are quickly and readily available for market distribution. Ultimately, injection molding is also useful for finalized prototypes that are used for consumer and product testing.

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