Injection-Molded Plastic Allows More Creativity than Ever Before

Posted by Al Timm on Feb 25, 2014 11:57:00 AM
Al Timm

blank.pngDesign teams are always trying to come up with something better—better shapes and designs, better performance, better materials, and lower costs.  They are constantly seeking something that will give them an edge over the competition.

Cost, of course, is a huge factor. After all, there is only so much you can do to reduce costs when you use the same set of materials, designs, and processes. A one-percent gain here, a one-percent reduction there. Lean is good, but it can only go so far.

Being creative is also harder when you are limited by material choices—especially metal.

What if changing from metal components to plastic ones could save you up to 50 percent in operational costs without compromising function or quality—and evenimprove design choices and options?

Right, you say. “You can’t replace metal with plastic—how about that snow shovel I bought last year? Plastic breaks.”  Well, it’s time to change that mindset.

If you aren’t familiar with the incredible functionality that engineered plastics provide, here are some key points to consider when comparing to metal:

  • Comparable tensile strength

  • Up to 50 percent lighter weight

  • Highly repeatable process (less scrap)

  • Lower manufacturing costs

  • Greater design flexibility

  • Increased market stability for material cost

  • Lower packaging and shipping costs

  • Up to six timeslonger tool life

In general, converting from metal to plastic saves a company anywhere from 25 to 50 percent in production costs.

This is achieved several ways. Multiple metal parts can be replaced by one injection-molded part made of tough engineered plastic, eliminating the need for fasteners and assembly. Colors can be added to the plastic melt, eliminating secondary operations for painting or laser marking. Plastic also has a nominal impact on part cost compared to sheet metal.

As great as these advantages are, metal-to-plastic conversion is still relatively unknown outside the automotive industry, which has zeroed in on plastic components for reducing weight, improving strength, and resisting corrosion. Twenty years ago, thermostat housings and cooling system components were essentially all cast and machined. Today, most of them are injection-molded, polyphenylene sulfide (PPS) components. Plastic components are also used in power train, cooling, transmission, steering, fuel, braking, safety, and electrical systems—as well as interior and exterior decorative parts.

What was considered impossible 10 years ago for plastic is becoming commonplace today, across a range of industries. Plastic is replacing metal in consumer products, manufacturing and automation equipment, dental and surgical tools, pumping equipment, pneumatics, tractor roofs, pet-cage trays,  housings (water meters, lawnmowers, power equipment), fuel tanks, heat sinks, water pipes, carts, medical devices, LED lighting systems, packing materials, food processing systems, folding tables, utility pole cross bars, EMS equipment, fasteners, and conveyor belt components.

Even wood in wooden pencils is being replaced with thermoplastic because it is more durable, and can be produced at lower cost, than wood.  

If you haven’t worked with plastic, this might all sound hard to believe. But it’s true—plastic parts can be just as tough as metal parts, and meet the same tight tolerances, with fewer secondary operations. With appropriate part design, plastic parts can be designed to perform just as well as the metal parts that are being converted to plastic. In fact, plastics create more design options because they can be engineered to have specific physical and chemical characteristics that are better than metal. There are plenty to choose from—more than 25,000 engineered materials are available for manufacturing applications. High-performance blends and hybrids can also be custom-designed to meet very specific mechanical, thermal, chemical, electrical, and environmental performance requirements—at lower cost.

Not being limited to metal (or a few standard plastics), opens up a much wider range of design options for engineering and design teams. They can think in more creative ways about complex geometry, performance in harsh environments, shielding considerations, weight and structural limits, thermal management, and product differentiation—both for performance and how the product looks on the shelf. It is much easier to create complex shapes and parts (often of smaller size) using injection molding. Plastic allows for thinner-walled parts with uniform wall dimensions due to high injection pressure capabilities, replacing the more costly (and heavier) thicker-walled features of die-cast metal parts. The costly assembly of metal parts can often be replaced by a single injection molded part. This can eliminate the need for welded joints between metal parts, which also eliminates risks for leakage.

As material suppliers continue to develop high-strength thermoplastics that are increasingly impact-resistant, corrosion-resistant, and heat-resistant, more companies are converting from metal components to plastic. If you’d like to know if your project (current or new) can benefit from metal-to-plastic conversion, Contact Us and we’ll be happy to review it with you.