Plastic injection molding is a popular manufacturing technique for mass-producing plastic parts and products. The technique is so popular that virtually all plastic parts around us, from toys to car parts, kitchen appliances and electronic enclosures, are produced using plastic injection molding.
Regardless of the plastic parts in question, injection molding involves the following three-step process:
- Plastic granules get poured through a material feeder (also known as a hopper) into a heated barrel for melting.
- A rotating screw mixes the molten plastic while generating sufficient pressure for injection.
- The molten plastic gets injected into a steel or aluminum mold cavity tool that takes the shape of the desired final product.
It is no coincidence that injection molding is prevalent among manufacturers and regarded by many as the most efficient molding process available. Compared to other production methods, injection molding is blazingly fast, not to mention its high production output and cost-effectiveness.
Although production speeds vary by product size and complexity, the average cycle time of most products ranges between 15 and 120 seconds per piece. With such short cycles, manufacturers can produce large quantities of molds in a limited time span, possibly increasing their revenues and profit margins.
Injection molding machines produce little waste, if any, and might even be one of the leanest users of raw materials. Thanks to minimal human input, rejects due to human error are almost non-existent in injection mold manufacturing. On the rare occasions that the injection molding process produces waste, manufacturers can recycle all the material into their machines as components for future products.
In addition, the labor costs involved might be too negligible to consider, especially for products that do not need any training or joining after the molding process. Once production commences, everything runs like clockwork, with little supervision and oversight needed. Manufacturers can program modern injection molding machines with reproducible conditions and replicate them anytime with the push of a button.
With the right design and mold cavity tool, injection molding machines can produce parts of just about any size and shape imaginable. Add this to the fact that injection molding machines can use virtually all thermoplastic material and some silicones, and it becomes easy to see why manufacturers can produce products with diverse physical properties using a single process.
By mixing different additives and pellets, e.g. glass fibres and PC/ABS blends, manufacturers can adjust their input to achieve products with varying levels of flexibility, impact resistance and strength all on one machine. For instance, co-injection molding machines are designed to process multiple types of plastic in one production cycle.
Examples of Injection-Molded Products
Products manufactured using injection molding are everywhere. The most common examples include:
- Consumer Electronic Enclosures
Most consumer electronics use enclosures made via injection molding. Manufacturers prefer using ABS and PS (polystyrene) due to their superb electrical insulation and impact resistance.
Popular toys, including Lego bricks, are made using injection-molded ABS due to its impact resistance and flexibility.
Packaging is by far the most common use of injection molding. Everything from bottle caps to bottles and food containers is injection-molded using PP (polypropylene) due to its good chemical resistance.
Injection molding is a brilliant technology and perhaps as close to the holy grail of mass production as manufacturers may get. Businesses eager to take their manufacturing to newer heights should definitely consider integrating it into their production processes are.