The process of injection moulding is highly versatile, meaning that it can be used to create a plethora of different objects of all shapes and sizes. It was first invented in the 19th century, in 1872, and since then has become one of the staple procedures in manufacturing and production. The objects created via this procedure are used in daily life and are so ubiquitous that you most likely don’t even think about how they’re made most of the time.
The procedure is relatively straightforward, starting with heating the tools and injecting molten resin into a metal mould. From then, the tools are cooled so the material hardens into its designated shape. This allows it to be removed in order to be inspected and subjected to secondary operations.
So, if you’ve ever wondered which products in your home have been created through this process, here are a few of the most ubiquitous ones.
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Plastic bottles
Most of the items created through injection moulding are plastics. Bottles are the most common in this sector, with billions produced yearly of all shapes and sizes. Bottles are most commonly used to hold water and other beverages. The material used is polyethylene terephthalate, more commonly referred to as PET, which is both light and durable enough to protect the integrity of the contents inside. However, creating large-scale plastic bottles has also raised issues concerning sustainability and resource depletion.
Roughly 500 billion are manufactured and used annually, of which less than half are estimated to be recycled. As such, efforts pushing towards sustainability have become increasingly relevant to current society. There are several ways in which recycled bottles can be reused, the most common being textiles. Carpets and clothing commonly have added polyester, as well as containers, including those aimed to store foodstuffs. Roofing insulation, bags and seat belts are some of the other objects created using repurposed PET material. By extension, injection moulding was used in their manufacturing process as well.
Large items
Although the procedure might suggest that only small items are created in this way, the truth is that many large objects are created through the moulding process. An injection moulding company will use specific tools to make the items and ensure they abide by the correct standards. The techniques and materials used are a little more sophisticated than in the case of smaller objects, so clients typically require the expertise of a team of professionals throughout the process.
High-pressure, sequential, and structural foam moulding are typically employed for the optimal effect and presentation. The latter is often the favoured option, as it can compensate for some of the disadvantages of the high-pressure method. The main advantages of this process include higher durability and reduced risk of deformation, the possibility to create thicker walls, and more freedom in terms of the design, particularly when compared with high-pressure moulding. As such, the structural foam helps create products with much better functionality.
Generally, the electronics created this way include computers, televisions, and other household objects. Car body panels, dashboards, cup holders and bumpers are also produced using this technology. Injection moulding is also employed for items used in aerospace, the sciences, and medicine. Because it can be used to create objects of practically any application and size, many are custom-made to serve highly specific, niche purposes.
Agricultural uses
Since we’ve mentioned household uses, it’s also essential to discuss the benefit of injection moulding in the agricultural sector. The marketplace has been increasingly switching to plastics as a low-cost alternative compared to the traditionally used mental components. As a result, structural foam moulding has become increasingly popular. There are several advantages to using injection moulded items in this area, including the high resistance to impact, reduced possibility of deformation, protection against humidity and the ability of the material to withstand significant temperature shifts.
Plastics can also be reinforced with UV stabilisation additives. These compounds combat the natural deterioration and material breakdown, which occurs when a plastic object is exposed to UV light. They are highly effective for short-term exposure and function by absorbing the radiation. Typical stabilisers used include benzotriazoles and benzophenones.
Food industry
Used in packaging and storage, injection moulding can be safely utilised only when the proper materials are employed. There are many advantages to using plastics in this business sector, as the material can be moulded to fit the products perfectly. Food and beverages stay fresh for longer, which is especially valuable for products manufactured in lower volumes. Samples, advertising products, and seasonal items are commonly part of this category.
Using plastic comes with less post-production work, as the containers are often adequate for usage straight out of the machine. Even when additional operations are required, they are typically not labour-intensive. If some containers come with defects and are unfit for packaging, they can be easily remade into a new product. This ensures that there’s no additional waste.
The most common polymer resins used in this manufacturing niche include styrene, polyethylene and polypropylene. Their chief advantages are that they’re highly tolerant to heat and flexible. They can withstand wear and tear, the use of chemicals and the presence of different substances while maintaining the integrity of the product and remaining within hygiene standards.
Toys
The popularity of plastic toys can be traced back to the years following WWII. From the late 40s into the early 50s and moving onward, consumerism became more visible. The general public became more eager to spend, and many young adults saw a considerable increase in purchasing power. As such, different items suddenly became widely available, among them plastic dolls and toys.
Plastic creates objects that are highly flexible while still durable. It is highly versatile and can be moulded into many different shapes and forms. All shades and colours can be added to create a unique design, as it doesn’t corrode. Over the years, more and more toys were made using plastics, many becoming iconic. From the Barbie dolls to LEGO, continuous innovations in the field created sturdier and safer items for children to play with.
Injection moulding is a relatively straightforward process that employs many complex issues, including the safety of the materials and sustainability. It is also used to create most of the objects the average person uses daily.
