Custom Plastic Washers vs. Metal: Making the Right Material Choice

Custom plastic washers solve engineering problems that no metal can address in applications requiring electrical insulation, chemical resistance to aggressive solvents, or extreme weight reduction at competitive cost when specified correctly. After manufacturing custom plastic washers for over a century alongside our full metal washer lineup, we understand exactly when plastic outperforms metal and when metal remains the only viable option. The decision between custom plastic washers and metal washers is not about cost cutting or compromise but about matching material properties to application requirements.

Custom plastic washers are the engineered solution of choice in electronics, pharmaceutical equipment, food processing, and chemical processing for reasons that have nothing to do with cost and everything to do with functional requirements that metals cannot satisfy. Understanding those requirements enables confident specification of plastic or metal depending on whether the application demands properties that only one material category can deliver. The wrong material choice in either direction creates failures that are expensive to correct after assemblies reach the field.

Custom Plastic Washer Materials We Manufacture

We produce plastic washers in four primary polymer families plus specialty materials for extreme applications:

•     PTFE (Teflon) Custom Washers: Custom PTFE washers offer the broadest chemical resistance of any polymer, withstanding virtually all acids, bases, and solvents at continuous service temperatures to 500°F, with excellent electrical insulation and the lowest friction coefficient of any solid material at 0.04
•     Nylon Custom Washers: Lightweight, tough, and self-lubricating with good resistance to oils and fuels, nylon washers serve mechanical assemblies, automotive applications, and consumer products where light loads and non-metallic construction are required for electrical isolation or weight reduction
•     Delrin (Acetal) Custom Washers: Exceptional dimensional stability and stiffness combined with low moisture absorption make Delrin washers ideal for precision applications requiring tight tolerances and consistent dimensions over time in humid environments
•     Nylatron (Nylon with MoS₂) Custom Washers: Molybdenum disulfide filled nylon provides superior wear resistance and reduced friction compared to standard nylon, serving bearing surfaces, pivot points, and sliding contact applications where metal-to-metal contact would require continuous lubrication

These four materials represent the most commonly specified custom plastic washer polymers in our manufacturing experience across industries. Each was engineered to solve specific problems that unfilled standard plastics cannot handle reliably. Mylar, Kapton, PEEK, and other specialty polymers are also available for extreme temperature or demanding electrical applications where standard engineering plastics fall short.

Where Custom Plastic Washers Outperform Metal

Electrical insulation is the most compelling advantage of custom plastic washers over any metal alternative in electronic assemblies and power distribution equipment. No metal washer regardless of alloy, coating, or surface treatment provides reliable dielectric insulation at voltages above a few volts where leakage current becomes measurable. Custom PTFE washers and nylon washers create complete electrical isolation that prevents ground loops, stray currents, and galvanic corrosion between dissimilar metal fasteners and substrates that would otherwise corrode at the interface.

Chemical resistance as the second decisive advantage cannot be overstated in severity. Custom PTFE washers resist virtually every industrial chemical including concentrated sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide, chlorinated solvents, and oxidizing agents that destroy even highly alloyed metals like Hastelloy within hours of exposure. In chemical processing plants, pharmaceutical manufacturing facilities, and semiconductor fabrication clean rooms, custom PTFE washers are often the only material option that survives the operating environment without replacement on an annual or even monthly basis.

Weight advantage delivers 50 to 85 percent mass reduction compared to equivalent metal washers across the range from heavy PTFE at 0.078 pounds per cubic inch to lightweight nylon at 0.042 pounds per cubic inch. In portable electronics where battery weight dominates system mass, medical devices where patient comfort matters, and aerospace applications where every gram affects fuel consumption, custom plastic washers deliver weight savings that aluminum and titanium cannot approach.

Where Metal Washers Outperform Custom Plastic Washers

High structural loads immediately eliminate plastic as a viable material option when bearing stresses exceed approximately 10,000 to 15,000 PSI depending on specific polymer selection. Metal washers handle bearing stresses from 30,000 PSI in soft aluminum through 130,000 PSI in hardened steel, making steel or stainless steel washers mandatory for structural fastening applications where plastic would crush, flow, or fracture under clamping loads that metal handles routinely.

Elevated temperature exposure above 200°F for standard plastics or 400°F for high-performance polymers requires metal washers to maintain dimensional stability and mechanical properties. Stainless steel washers maintain full strength to 800°F and beyond, while most custom plastic washers soften, creep, and lose load-carrying capacity well below these temperatures. Only PTFE at 500°F continuous rating and PEEK at 500°F approach metal temperature capability, and both cost substantially more than commodity plastics.

Dimensional precision and stability over time favor metal custom washers that achieve plus or minus .0005″ thickness tolerances routinely compared to plastics that absorb moisture, creep under sustained load, and drift dimensionally by several thousandths of an inch over months of service. Applications requiring precise spacing in optical assemblies, precision instruments, or calibrated systems should specify metal washers with explicit tolerance callouts rather than accepting the dimensional variability inherent in most plastic materials.

Custom PTFE Washers: A Deeper Look

PTFE (polytetrafluoroethylene) deserves detailed coverage as our most-specified custom plastic washer material for demanding chemical and electrical applications. PTFE’s chemical resistance is essentially universal across industrial environments, with the only materials that attack PTFE being elemental fluorine, molten alkali metals, and certain fluorinating agents encountered only in specialized chemistry research. This property makes custom PTFE washers the standard solution in chemical processing plants, semiconductor fabrication facilities, and pharmaceutical manufacturing where other materials fail within weeks or months of exposure.

PTFE’s unique combination of properties that no other material matches simultaneously explains its widespread use: chemical inertness to essentially all industrial chemicals, dielectric strength of 60 kV per millimeter, continuous service temperature of 500°F, coefficient of friction of 0.04 which is the lowest of any solid material, and FDA compliance for food contact applications. These properties explain why custom PTFE washers appear in applications ranging from spacecraft propellant systems to commercial kitchen equipment. The breadth of PTFE applications reflects the breadth of problems it uniquely solves where no alternative material delivers the complete property set required.

Cost Comparison: Custom Plastic vs. Metal Washers

Custom plastic washers vary widely in cost depending on material selection and geometric complexity across the range of available polymers. Standard nylon and Delrin custom washers are among the least expensive washer options in any material, often costing less per unit than equivalent steel washers in small quantities due to lower raw material cost and easier processing. Custom PTFE washers cost more than commodity plastics due to PTFE’s higher raw material price but remain competitive with stainless steel washers at equivalent geometries and quantities.

PEEK and other high-performance engineering polymer washers command significant premiums of 10 to 30 times the cost of nylon, but these premium polymers remain justified by their combination of high temperature capability at 500°F continuous service, chemical resistance approaching PTFE, and mechanical strength exceeding all other plastics. Applications that once required metal washers with elaborate coating systems often achieve better performance with PEEK at comparable or lower total cost when coating application, inspection, and maintenance are factored into lifecycle economics.

Our no-tooling-charge approach for custom washers makes complex geometries including slotted profiles, non-circular shapes, and multi-hole patterns economically accessible for low-volume prototyping alongside high-volume production. Complex plastic washer geometries are produced through our EDM and precision blanking processes without dedicated tooling charges that would otherwise make custom shapes prohibitively expensive for prototype quantities.

Material Selection Decision Framework

Begin material selection by identifying hard requirements that eliminate one material category immediately: electrical insulation requirements above a few volts eliminate all metals, bearing stresses above 15,000 PSI eliminate all plastics, temperatures above 500°F eliminate all plastics except specialty polymers, and chemical exposure to concentrated acids or chlorinated solvents eliminates most metals. These bright-line rules resolve the majority of selection decisions without detailed analysis of secondary factors.

For applications where both plastic and metal could theoretically work based on individual property requirements, evaluate the complete operating environment including simultaneous exposure to multiple stress factors. A washer might need moderate load capacity at 300°F in a mildly corrosive environment with electrical isolation requirements, creating a specification that no single material satisfies completely.

When the application falls genuinely at the boundary between plastic-preferred and metal-preferred service conditions, request quotes for both material options and evaluate total system cost including any secondary operations, special fasteners, or assembly complexity that one material choice would require. The per-unit price difference between plastic and metal washers is often smaller than engineers assume when all factors are considered, and prototyping both options in small quantities can reveal unexpected advantages or problems with either choice.

Get Custom Plastic Washers for Your Application

At Brewster, we have made custom plastic washers including custom PTFE washers, Delrin, nylon, Nylatron, Mylar, Kapton, and PEEK for over 100 years alongside our full metal washer product line. Color-coded thickness identification is available for our plastic washer line, enabling instant visual sorting without measurement equipment during assembly operations where multiple thicknesses are used in a single product. Whether you need ultra-thin .0005″ Mylar shims for electronics or heavy-section PTFE load washers for chemical processing equipment, we manufacture to your exact specifications with complete material certifications. Schedule a free consultation with our team today for the guidance you deserve.