How to Choose Plastic for Molding
Injection molding is the process by which a plastic resin is injected into a pre-made mold. The resin fills the mold before cooling and hardening into the product's shape. Injection molding is used to make bottle caps, vehicle dashboards, wire spools and other household items such as sink plugs and containers. There are many different plastics to choose from when molding your design, so ensure that the plastic is suitable and appropriate for your product.
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Instructions
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Choose the right plastic by considering the stability and strength of your product. Glass-filled nylon, for example, is an extremely strong plastic that would be suitable for sturdier structures or products. Polypropylene, on the other hand, is a weak plastic blend, but it can sustain a fair amount of wear and tear. Choose a plastic by comparing each material in its strength, durability, impact resistance and temperature strength.
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Ensure that you stick to your product's budget and choose a plastic that best suits your price range. Plastics such as polystyrene, LCP (Liquid Crystal Polymer) and nylon are affordable, but are only suited for certain mold designs. Nylon, for example, absorbs water and may warp whereas ABS (Acrylonitrile Butadiene Styrene), which is a very affordable mold plastic, will create sink marks in thicker areas. Make a decision that best suits your design and price range, so pick ABS for thinner-structured products but splash out on an expensive mold resin if your budget allows you to.
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Consider the flow-capabilities of the plastic before choosing one for your product. Strong plastic resins, such as glass-filled nylon, are great for products that need to be stable and sturdy; however, they are also slow-flowing in the mold and can create voids or knit lines in thin or skinny sections. Similarly, lubricant plastics, such as Delrin, are easy-flowing but might struggle to stay strong in the thicker sections of the mold. That said, ensure that the plastic is suitable for the strength of your product, but will also fill the entire mold with efficiency and ease.
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Enquire with a molding company about which plastic is best suited to your design. Most experienced plastic providers or molding companies should be able to tell you about the strengths and weaknesses of each material. Be sure to ask about the dimensions of your design, the cost of the product and the intended outcome.
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Tips & Warnings
Some companies offer the opportunity to mold a test product. This is a good idea if you are unsure which plastic you use or if you are stuck between two different material types. A single test product also saves the cost and hassle of molding hundreds of useless units.
References
- Photo Credit tableau de bord image by richard villalon from Fotolia.com
