Over the last five years, raw material prices have gone up and down. Steel has increased over 30% from this same time five years ago. Crude oil has decreased approximately 20% in that same time period. Manufacturers are looking for ways to decrease the volatility of their raw materials, while still making elite quality products. One of the ways manufacturers are avoiding the tariff hikes on the global metal industry is to transition their products from metal to plastic.
The development of engineered resins to convert metal products to plastic started in the 1950s. Over the last few decades, manufacturers have continued to search for new opportunities for plastic injection molding to become a dominant material choice for manufacturing. Many parts that were only considered for metal are now a feasible option for injection molding. Companies that have made a change in materials from metal parts to plastic have found a cost savings of 25 % – 50% through the manufacturing process.
7 Benefits of Replacing Metal with Plastic
It may seem like a logical choice to replace metal parts with plastic, but there are a few considerations to keep in mind when making the switch. Plastic injection molding has thousands of resins to choose from, and only the right combination of fillers and base resin will produce a part that can outperform metal. Here are 7 reasons your product may be a good candidate to convert from metal to plastic:
Lower Tooling Costs – The cost for developing tools is always a large portion of the overall product budget. Metal casting dies can take up to 16 weeks to complete. Plastic injection molding dies can be done as quickly as 6 weeks. If time is money in business, those extra 10 weeks can be turned into production time versus waiting time. Plastic injection molds can also last up to 6x longer than a casting mold, which can save additional investment over the life of the product.
- Lower Manufacturing Costs – Injection molding by nature does not produce many side effects, nor does it have many scrap materials that need to be discarded. Casting will typically have large runners 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. Companies can achieve cost savings of up to 50% with metal to plastic conversion by eliminating extra metal fasteners and assembly operations, reduced cycle times compared to metal forming processes, and secondary coloring operations.
- Better Corrosion Resistance – Plastic is naturally corrosion resistant by nature. Most metals will need a coating via a dipping or a spray process in order to prevent corrosion over time. Any metal alloy that is corrosion resistant also has a higher cost, which may make it a poor choice for strict budget criteria.
- Reduced Overall Weight – Plastic injection molded parts can weigh up to 6x less than an equivalent steel part, and be half the weight of an aluminum competitor. That weight reduction can also pay forward with shipping costs and material handling effort reductions. Your parts can be equal strength, but much easier to move.
- Easier Regulatory Compliance – While corrosion resistance has been mentioned, one additional issue with a secondary coating may be tied to regulated or prohibited materials in certain countries. Even if the metal hasn’t been treated, it could bring additional restrictions. Lead, for instance, is a heavily restricted material in many countries with a strong RoHS It may be unlikely or almost impossible to export a product containing Lead. You could replace that Lead component part with an engineered resin for equal or less cost, and have little to no restriction exporting into the same region or country.
- Increased Strength – Injection molded components with engineered resins can exhibit equal or increased strength compared to metal. For instance, thermoplastic composites have been proven to be as strong as steel or aluminum without the additional weight. Three categories of reinforced plastics offer the most competition to metals:
- Short Glass Fiber-Reinforced Plastic – increased strength and stiffness, with a high heat tolerance
- Long Glass Fiber-Reinforced Plastic – high-performance with additional weight reduction
- Carbon Fiber-Reinforced Plastic – additional weight reduction and perfect for large components or panels
- More Design Flexibility – Complex designs are hard to create in metal without complex molds. Complexity often adds significant cost and development time. Casting uses gravity to move molten metal into all areas of a casting mold. Gravity has a hard time filling tight corners and areas away from the runners. This can cause voids in the part as a result. Plastic injection molding uses pressure to fill the mold completely regardless of the corner conditions. Plastic injection molds have the option of slides to create embosses for extra part attachment also. These features usually aren’t feasible in a casting mold.
Industries Already Converting Metal Parts to Plastic
Many industries are already making the conversion from metal to plastic through replacement tooling and new product development. Here are some of the latest ideas coming to market:
- Aerospace: With plastic injection molded products weighing less than metal, many metal options are being replaced with engineered plastics. Small changes can add up, and that can reduce the overall weight of the airplane. Cabin interiors, insulating components, fasteners, gears, and more are slowing converting to plastics to offer more competition to metals.
- Automotive: The automotive market has seen major body panels made from engineered resins. Niche markets and low volume production are benefitting from plastic with the aftermarket able to 3D print large parts on a reasonable scale. Replacement and new products may be developed with plastic in mind to reduce cost and weight.
- Home Appliances: The home appliance market has seen more and more appliances, both large and small, converted to plastic. Individual components can be made more efficiently with plastic molding, while the exterior appliance body could be designed for plastic to reduce weight and secondary coatings. Any product can have multiple color options with the simple change of the resin coloring. A similar option for metal may not be available.
- Logistics and Supply Chain: With increased global commerce every year, packaging is being converted from disposable materials to reusable plastic. Shipments on cargo ships encounter corrosive sea water that doesn’t affect a plastic container. Individual parts and bulk packaging are also not affected, which makes the plastic packaging indefinitely reusable.
Plastics can offer characteristics to thrive in almost any environment. The key to future changes will be limited to the imagination of the creator. Plastics are used on the space shuttle and satellites that orbit the globe. They are used in large construction equipment building cities. And they are used in your home to keep you safe, secure, and comfortable. New engineered resins are always being developed with better properties for more uses and environments. With the price of petroleum near record lows, and the limited availability of renewable materials, where will plastics find a new use in the future?
The choice to convert metal to plastic is very enticing, but you may need a partner versed in the process. SEA-LECT Plastics can aid with resin selection, turn-key assembly options, and program management to see the complete development cycle through with success. Give us a call at (425) 339-0288 or email us at email@example.com. We can offer you advice on the best technology to use, the best materials to meet your product demands, and how to navigate through each development stage. At SEA-LECT Plastics, we specialize in military product applications, outdoor adventure gear, musical instruments, supporting the medical and consumer product industries. Our goal is to make your project efficient and cost-effective to manufacture, assemble, and ship no matter how complicated your concept is.
Matthias Poischbeg was born and raised in Hamburg, Germany. Matt moved to Everett, Wash., after finishing his bachelor’s degree in business in 1995 to work for Sea-Dog Corporation, a manufacturer, and distributor of marine and rigging hardware established in 1923.
In 1999, Matt took over the reins at Sea-Lect Plastics Corporation, a sister company of Sea-Dog and a manufacturer of plastic injection molded products with an in-house tool & die shop. Matthias Poischbeg is also a contributor to Grit Daily.