Composites vs. Metals: More Parts Producers are Replacing Metals with Thermoset Composites

The market for thermoset molding compounds is expected to grow in the coming years, driven by higher demands from industries such as aerospace, automotive and power distribution. An increasing number of companies are switching their traditional metal parts to parts made from mineral-filled, glass fiber reinforced composites. These innovative composites have high durability, low shrink, dimensional stability, strength, light weight, UV stability and color choices, making them excellent replacement for steel, aluminum and other metals in select applications.

Lighter weight

In grams per cubic centimeter, many engineered structural composites, on average, weight nearly 400% less than steel and 150% less than aluminum without sacrificing performance. Lighter weight parts can make a product easier to move or use for workers and consumers. An electrical line technician would rather hoist and install a 20-lb. composite part rather than a 300-lb steel part. Aerospace and automotive manufacturers are seeking ways to reduce the weight of their products by using lighter parts wherever possible in the application. For electrical vehicles, lightweighting is especially important.

Lower cost

In general, the cost per pound of thermoset composites can be 1/3 to ½ less than metals such as aluminum and steel. Prices can fluctuate for metals and composites, so it’s best to check with a thermoset composite supplier to compare actual per-pound costs. Also, lighter parts reduce freight costs for shipping. These lower prices can give some companies a price advantage in highly competitive markets.

Integrated inserts

Inserts can be integrated into the thermoset process, so the threads are automatically built into the part. Adding threads to metal parts requires extra finishing steps, such as drilling and tapping, which increases labor costs and slows down throughput.

Corrosion resistance

In applications with exposure to chemicals, moisture, or other corrosives, thermoset composites are better at resisting degradation over time compared to steels and aluminums. A pump housing exposed to pool chemicals and an oil rig railing in the ocean are better suited for thermoset composites than metal, which are prone to rust. 

Thermal stability

For applications that include high heat exposure, thermoset composite parts may not be as robust long term when compared to steel or aluminum. A typical composite can handle temperatures up to 425∞ F without warping, expanding, or degrading. Comparatively, cast iron can remain stable up to 700∞ F, and aluminum alloy can be stable up to 520∞ F.   However, the coefficient of thermal expansion of metal opens the door for composite parts to be implemented in an engine application.

Dieletric properties

Thermoset composite parts do not conduct electricity like metals do, so parts used in electrical, electronic, and power transmission applications are ideal for these composites with dielectric strength varying 350 to 450 volts per unit thickness, depending on the formulation. The over molding of an electrical components is a good application for thermoset composites. 

Color options

Thermoset composites are offered in a variety of colors, so manufacturers can mold products without having to apply a coating or paint that may need to be touched up later. Metal parts require secondary operations to add color. Also, these composites are slow to fade or discolor over time as UV stabilizers can be added to the formulation. This is especially useful for parts that are exposed to elements in outdoor applications.  

More environmentally sustainable

Parts made from thermoset composites may last longer than metal parts, which reduces waste in landfills. Plus, thermoset composites take less energy to manufacture and ship than metals, and the thermoset molding process take less energy to produce parts than metal fabrications. This lower energy use adds up to a lower carbon overall footprint, helping companies address their sustainability goals. Environmental impact is especially important for aerospace and automotive companies that have aggressive sustainability initiatives.

Choosing between thermoset Composites and metals

Each part has a unique set of performance requirements, so it’s best to contact a professional supplier to evaluate whether composites or metals are the better option. There are several composite options available to meet specific application needs. Contact Ci-Dell Plastics for a design review and recommendations on a material selection.