When it comes time to consider a materials choice for a new parts, or a designed part needs to be replaced due to unforeseen circumstances, it may be a good time to select plastic over metal. There are many reasons that plastic can be a better solution than metal, and we’ve outlined five of the top reasons to choose plastic over metal.
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Corrosion Resistance
Plastic is naturally corrosion resistant by nature, where most metals need a secondary or tertiary operation to apply a coating via a dipping or a spray process in order to prevent corrosion over time. Some metal alloys are very corrosion resistant, and with that can also be very expensive. Plastic resin should not need the extra steps to prevent corrosion from a harsh environment.
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Lower Manufacturing Costs
Injection molding by nature does not produce many side effects, nor does it have much in the way of scrap materials. Casting will typically have large runners to flow the molten metal that need to be removed as a secondary process. Stamping and machining can use lubricants that need a secondary cleaning operation before they can be shipped to a customer. Plastic injection molding shouldn’t require much additional work beyond the molding stage, which will reduce the extra labor cost and secondary process materials. That will reduce the part cost, increase your process efficiency, and directly translate to profit.
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Regulatory Compliance
While corrosion resistance has been mentioned, one additional issue with a secondary coating may be tied to regulated materials in certain countries. Even if the metal hasn’t been treated, it could bring additional restrictions. Lead, for instance, is a restricted material in countries with a strong RoHS It may be troublesome exporting into a country that restricts lead. You could replace that lead part with an engineered resin for equal or less cost and have little to no restriction exporting into the same region or country.
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Lower Tooling Costs
Tooling costs are always a subject of conversation, and the comparison of a casting or set of forming dies to an injection mold is a good discussion. Metal casting dies can take up to 12-16 weeks to complete. Plastic injection molding dies can be created in as quickly as 6 weeks, or in half the time. If you consider time is a direct correlation of money, you could be saving money going with an injection mold just for the fact that you can be producing parts in shorter time than waiting for a casting die to be finished and trialed. Beyond the initial tool time and cost, plastic injection molds can last up to six times as long as a casting mold before it will need to be replaced. That can save additional money over the life-cycle of the product.
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Design Flexibility
Complex designs are hard to create in metal without complex molds that require a significant amount of development time. Casting is typically done using gravity to move the molten metal into all areas of a casting molds. When it comes to creating tight corners, using just gravity may impact the ability of the metal to flow and completely fill every area. Plastic injection molding has the ability to use pressure to fill the mold completely regardless of the corner conditions. Plastic molds have the option of slides to create embosses for extra part attachment also. These wouldn’t typically be feasible in a casting mold. Beyond that, you can also produce a design that weighs less in plastic and can also cost less to package and ship.
Our design team will help you verify what will be required for a given part when moving from one type of material to plastic.
If you have a potential design option or an idea to move from metal to plastic, we’d like to hear about it. When you’re ready to work with our elite team that produces world-class products, call (425) 339-0288 or email us at mattp@sealectplastics.com.