In recent years, markets such as Aerospace and Defense (A&D) and industrial have witnessed an innovation shift, moving away from traditional metals to high-performance and engineering plastics. This transition is driven by a myriad of advantages these materials offer, including weight reduction, corrosion resistance, improved durability, and cost-effectiveness.

The Move from Metals

In the A&D and industrial industries, metals have long played a starring role. As the traditional material of choice, metals properties, such as high strength, heat resistance, and durability, are paramount to these industries and were difficult to find in other materials. However, metals bring their own set of challenges. They are heavy, prone to corrosion, require significant energy in production, and can be costly to repair and maintain. This led to a quest to find materials that can offer the coveted properties of metals while mitigating the drawbacks. Engineering and high-performance thermoplastics fit the bill.

The Switch to Engineering and High-Performance Thermoplastics

Engineering and high-performance thermoplastics are a class of plastics that offer significant advantages over metals in many situations. They tend to be lighter, resistant to corrosion and wear, offer excellent thermal and electrical insulation, and can be tailored using a mixture of polymers or additives to offer specific properties required for the application. While conversion isn’t possible for every application, these thermoplastic characteristics make them an ideal choice for a multitude of applications in the A&D and industrial markets. Below are the top three advantages of making the switch.

  1. Weight Reduction: One of the biggest advantages is that a significant weight reduction can be gained by converting materials from metal because of the high weight-to-strength ratio of these materials. Aluminum, which is a lightweight metal, has a density (weight/volume) of more than twice that of any high-performance thermoplastic. Steel is about six times heavier than these polymers. This is significant in A&D, where reducing an aircraft’s weight is critical for enhancing fuel efficiency and reducing carbon emissions. The use of high-performance plastics in place of metal components can significantly reduce the aircraft’s weight without compromising the parts’ strength and durability.The weight reduction may be beneficial in industrial applications for making equipment lighter or safer for operators. For example, guards or covers that must be removed for maintenance may need the strength and chemical resistance of the metal, but the weight can make handling large pieces dangerous for employees. Conversion to plastic that offers the properties needed for the application will reduce the weight without compromising safety.
  1. Longer Service Life: Aviation products are exposed to some of the harshest conditions – extreme temperatures, speed, and vibrations – so the components must be built to last. High-performance and engineering plastic meet the stringent requirements for aerospace components.Similarly, in the industrial market, where machinery and equipment often operate in harsh and corrosive environments, the corrosion resistance of high-performance plastics can result in longer-lasting parts and reduced maintenance costs. In addition, the lower friction coefficient of these plastics can lead to smoother operation and reduced wear and tear.Engineering thermoplastics provide both chemical and wear resistance and can be used at temperatures between 185°F and 300°F. For use in higher temperatures, high-performance thermoplastics work effectively in temperatures exceeding 300°F extending to 500°F for applications with the most demanding performance requirements.
  1. Design Flexibility: Plastic provides greater design flexibility than metal because it can be customized to meet environmental, functionality, and structural requirements. Additives combined with the resin during manufacturing can bolster properties such as strength and durability or offer additional benefits such as UV protection and flame resistance.In addition to customizing the material properties, design flexibility is greater. Complex shapes and geometries can easily be achieved with injection molding. When working with metal, multiple components will often be welded together or require a secondary operation to complete. Welds can add a weak point to the part. When multiple metal parts can be converted into a single molded part, the process is faster as cycles are faster. Even machined metal parts can be converted to machined or injection molded plastic parts and have benefits. There are no secondary or finishing (painting or coating) steps, and the part often performs better than the metal part.

The Conversion Process

Converting metal parts to plastic involves several key steps, the first of which is material selection. This involves choosing the right plastic that can meet the specific demands of the application. Factors such as strength, temperature resistance, electrical properties, and cost all play a role in this decision. If you are only used to working with metals, the options and possibilities that plastics offer can be overwhelming. Your plastics partner should be able to help you decide what material is best for converting your product based on its needs.

Once the material has been selected, the next step is the design phase. This involves creating a design that leverages the unique properties of plastics while maintaining the functionality of the original metal part. Design for manufacturability (DFM) principles should be used to optimize the product for production and reduce costs.

At Ensinger, our next step would be to review your design and perform a mold flow analysis for injection molded parts. Other manufacturers may not do this. We do this to predict and remedy manufacturing issues before tooling is built. Once the design is set, which may be after prototyping, tooling is built for injection molded parts.

A prototype will allow you to test and validate your design before it goes into full production to ensure an effective conversion from metal to plastic. Having a prototype is a good idea when parts are expected to fit together or work together. Having tolerances off by a small amount can lead to significant issues.

Once the part is approved and validated and tooling is completed if required, injection molding or machining of the parts can begin.

Challenges and Future Outlook

Despite the many advantages, converting metal parts to engineering or high-performance plastics is not without its challenges. The initial cost of retooling and redesigning can be high; however, long-term gains can make up for it. This is why comparing the two solely by material costs does not create the full picture.

The part redesign must be done carefully. The characteristics of plastics can vary more widely with temperature and load than metal, and the manufacturing process can impact the design requirements. Designing for plastic is much different from designing for metal. Ribs and gussets may be needed to promote stability for injection molded parts. Material shrink must be considered. The rate varies by materials and can vary within the part if sections cool at a different rate, so wall thickness must be consistent, and gate placement matters. Shrink is also a concern with machined parts and should be accounted for during the design stage. These are just a few of the considerations. If you are not used to designing plastic parts, ensure you are working with an injection molder with experience with metal-to-plastic conversion.

Despite some challenges, the future outlook for using high-performance and engineering plastics in the aerospace and industrial markets is promising. As more research is done and new materials are developed, these plastics are expected to play an increasingly significant role in these sectors.

The shift towards high-performance and engineering plastics represents a significant advancement in the aerospace and industrial sectors. By capitalizing on the unique properties of these materials, companies can create more efficient, durable, and cost-effective products. Converting metal parts to plastics might be complex, but the potential benefits are vast and will pave the way for future innovations.

Convert Your Metal Part to Plastic With Ensinger

We have decades of experience solving tough application challenges for A&D and industrial industries. While converting from metal to plastic has its challenges, we are a partner that will be there guiding you every step of the way. Connect with us today and see the benefits and value you will receive by making a conversion.