Injection molding is one of the most preferred methods of producing plastic parts because it is extremely versatile. It has many advantages over other methods of manufacturing therefore the preferred option for thin walled plastic parts. Almost any plastic component or part can be done accurately and efficiently with injection molding – ranging from parts for automobiles, kitchen utensils, medical devices, electronics and other items. Short run injection molding or rapid /low volume injection molding uses convectional machines and molding processes to manufacture the simple plastic parts. The process is fast and cheap and the molds produced are of high-grade aluminum or low grade steels. This particular manufacturing process is fairly simple and focuses on simple parts which are easy to produce. Typically, small plastic pellets are fed into the hopper where they are crushed and heated to thick plastic slag. The hot molten slag is poured into a piston that injects the liquid into a metal die under high pressure. The finished part takes the shape of the die wherein it cools and the finished part is ejected.
This method of production has a number of benefits. First, it is a perfect way of bridging the time gap between full production and prototype. A short run production process gives the engineers a good working model to produce a full-blown design of the production tools. This method of injection molding gets your products available in the market within the shortest time possible. Surprisingly, because of the highly developed automation process, the cost of production is quite reasonable but there is a premium to pay for the quick turnaround although it is much less than expected. Lastly, little post-production work is required during this process since these parts have a finished look upon ejection.
Of course, with the manufacturing benefits mentioned, there are a number of limitations to injection molding process. The cost of machinery involved in the process is quite expensive and the size of the machine is to be considered too. Part size is a limitation to be considered as well. For example, the injection molding equipment only takes jobs that fit within set parameters especially if the product is one complete piece. Likewise, different materials and designs could limit the thickness of the walls of the product. Parts that have a large undercut cannot be cast with this method. The initial cost of creating the molds is high because the tools should be accurately machined from steel or aluminum to withstand the long production runs and heat. Injection molding for production of few parts is eliminated for cost-effective methods because it is cost prohibitive. Therefore, to lower the cost of production and amortize the molding cost, many parts must be produced.
To wind up, short run injection molding is a niche market segment that serves a highly specialized market and is regarded highly in the niche. The ability to release ready injection molded part to market in a matter of a few days is valuable to the right company. In addition, the ability of the company to bridge the gaps between high production and prototype is an important tool for the custom injection molders.