Benefits of Metal-to-Plastic Conversions
For decades, metal was the material of choice for healthcare OEMs because conventional plastics could not deliver metal’s combination of high modulus, strong chemical resistance and compatibility with stringent sterilization methods. Today, high-performance specialty polymers are changing that reality—not only by offering metal-like performance, but also by enabling the fabrication of more complex and integrated parts.
OEMs are becoming more knowledgeable about plastics either through hiring design engineers familiar with plastics or relying on polymer suppliers for assistance with material selection, design validation and processing advice. As more OEMs realize the benefits of converting from metal to plastic and invest more heavily in the right people and the right partners to bring more plastic medical devices to market, manufacturers that are slow to follow suit will see their competitive advantage get increasingly smaller—or worse, find themselves even further behind their competitors.
Select high-performance polymers can offer the same level of strength as some metals at ambient temperature, along with added advantages. They deliver cost benefits, enhanced aesthetics, and ergonomic improvements such as a range of grip options. We’ll explore these benefits in more detail, and hopefully shed light on why OEMs are doing more with plastics—and why you should too.
Cost Savings
OEMs facing the pressures of shrinking margins and increasing competition may be able to cut costs by converting from metal to plastic. Replacing metal with high-performance polymers can in many cases lower the overall part cost over the life of the product. Plastic processing methods, such as injection molding, have the potential to lower overall manufacturing costs through tooling amortization and lower labor costs. Plastic molding also allows design engineers to consolidate parts, thereby eliminating the expense of multiple components, assembly steps and losses in yield at each operation. Functional integration reduces the number of overall parts and simplifies supply and logistical constraints, decreases cycle time, while requiring fewer tools and facilitating quality inspection.
Let’s Do the Math
How much can you save by converting from metal to plastic? Depends on a lot of different factors, including what kind of device(s) you make. For the sake of an example, let’s say you manufacture a single-prong metal hip retractor. Assuming 200 stock keeping units (SKUs), the annual cost of production is about $3.9 million USD. Even if we account for a one-time tooling and mold investment of $2 million USD, you would recover the costs associated with converting to plastic in eight months. After amortization, your company would save $3 million per year per 200 SKUs for the remainder of the program’s life. These calculations (see table below) are based on actual numbers in a real case study performed by Syensqo to demonstrate the cost-saving potential of converting from metal to plastic.
Example of cost savings due to converting from metal to plastic
Weight Reduction and Improved Ergonomics
One of the biggest roadblocks to replacing metal parts with plastic used to be the fact that plastic simply couldn’t compete with the strength, toughness and durability of metal. Today, plastic parts can actually be made as strong as metal thanks to high-performance polymers and proper structural design. The ability to “mold in” structural strength with features like ribs, bosses and gussets means design engineers can reduce part weight (and processing cost) without sacrificing strength.
Replacing metal surgical instruments with plastic counterparts can reduce their weight by as much as 80 percent. Lightweighting can provide numerous downstream benefits for OEMs. For example, lighter instruments can increase end-user satisfaction by reducing practitioner fatigue, which could help cement your products in hospitals and operating rooms by having more surgeons and physicians ask for them specifically.
From the total cost perspective, lightweighting can also increase profit margins by lowering associated logistics costs. A few ounces may not seem like much on the surface for any one device, but at the scale most OEMs are dealing with, those few ounces can add up to a significant amount across thousands of SKUs.
Specific tensile strength, strength to density ratio
Design Freedom
At first glance, weight reduction and total cost savings may be the most striking advantages of converting from metal to plastic, but in comparison to metal there is also far greater design freedom. Injection molding, for example, provides nearly limitless design options and can produce thin parts and complex shapes not possible with metals. Plastics also allow OEMs to incorporate long, thin geometries that would be difficult (or prohibitively expensive) to produce otherwise. By replacing metal, polymers let all your ideas take shape.
With the ability to add new shapes and features that would otherwise be impossible to produce with metal, OEMs are able to differentiate plastic devices from their all-metal counterparts. Plastics also provide OEMs the ability to prototype, test, measure and iterate different concepts that have virtually the same look and feel as the finished device, enabling design engineers to gather better feedback from actual users that could impact the final design.
What About the Environmental Impact?
Are you concerned about the environmental impact of converting from reusable metal to single-use plastic instruments or devices? You’re not alone, but according to the results of an 18-month study, industry perceptions about the negative environmental impact of single-use instrumentation are not entirely accurate.
Syensqo Specialty Polymers, in conjunction with Medacta International and Swiss Climate, performed a complete cradle-to-grave life cycle analysis (LCA) of two types of surgical instrument systems: a “single-use” concept based entirely on plastic instruments and a traditional “reusable” system comprised entirely of metal components. The LCA measured the environmental impact of both systems, considering their raw materials, production, use and disposal, as well as post-use management, reuse and recovery.
Overall, the life cycle analysis demonstrated that the carbon footprint of the single-use plastic instrumentation is neutral when compared to the average CO2 equivalent annual emission of a hospital using conventional re-usable metal instrumentation. Swiss Climate, an independent sustainability consultant, also noted that the single-use plastic system eliminates the need for repeated washing and sterilization, which can save up to 115 gallons (435 liters) of water for each surgical knee procedure.
Infection and Disease Prevention
According to the World Health Organization, 7% of hospitalized patients in developed countries and 10% of patients in developing countries will acquire at least one healthcare-associated infection (HAI). The Centers for Disease Control (CDC) estimates that the overall annual direct medical costs of HAIs to U.S. hospitals ranges from $28 to $45 billion.
High-performance plastics enable OEMs to produce single-use instruments which can significantly reduce HAIs. Healthcare organizations are increasingly favoring disposable medical devices because they help maintain a better standard of hygiene and prevent the reuse of instruments and equipment. OEMs who make the switch from metal to plastic may be able to capitalize on the growing demand for single-use devices and can present a stronger value proposition to hospitals and GPOs that are focused on reducing HAIs.
The Journey from Metal to Plastic: A Syensqo Case Study
Specifying plastics for medical devices can be a major challenge for those who have been used to working with and designing with metals. To help OEMs make this transition, Syensqo conducted an in-depth case study and a comprehensive overview of the process used to convert a reusable steel hip retractor to both a single-use and reusable plastic hip retractor.
This case study shows how simple design modifications make it possible to replace a metal device needing very high strength and stiffness with a high-performance polymer, which provides the added benefits of lighter weight and improved ergonomics. The seven steps for metal-to-plastic conversion documented in this overview include:
- Classification of polymers
- Material selection
- Improving strength and stiffness
- Design iteration
- Prototyping
- Manufacturing
- Validation
This metal-to-plastic conversion case study is available as a pre-recorded webinar presented by Jeff Hrivnak, Syensqo Specialty Polymers global healthcare business manager. This is the same presentation that was delivered center stage at MD&M West 2019, the world’s largest medtech trade show.
Thinking About Converting Metal Parts to Plastic?
Syensqo can help. In addition to the industry’s broadest selection of high-performance specialty polymers, we provide guidance and support at each step along the way for OEMs that are new to plastics. And with over 30 years of experience as a leading materials supplier to the healthcare industry, we know what OEMs expect (and need) from their partners.
