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3 Material Considerations for Stamped Parts

For many stamping projects, engineers are increasingly moving away from metal materials in favor of non-metallic options like fibres, laminates, and thermoplastics.

Exploring material options outside of metals can lead to enhanced performance and cost savings when creating stamped parts for particular applications.

Vulcanized Fibre

A laminated plastic composed of cellulose, vulcanized fibre offers great electrical and mechanical properties. Lighter than aluminum, vulcanized fibre is stiffer than many thermoplastics and more resilient than leather. It’s almost 100 percent free of artificial binders, resins, or glues.

Offering resistance against impact, abrasion, organic solvent, petroleum derivative, and oil penetration, the material is light yet extremely strong. When used in a thinner format, vulcanized fibre offers flexibility with high tear and tensile strength, while thicker vulcanized fibre can be molded into distinct shapes using pressure and steam.

Vulcanized fibre is ideal for stamped parts used in the following applications:

• Automotive parts
• Electrical insulation
• Trunk fibre
• Bone fibre
• Wood laminating

Laminates

An unclad material made of varying resin systems, some laminates utilize woven glass weave while others incorporate non-woven or none at all. Each type of laminate offers distinct electrical, chemical, and mechanical properties and is differentiated by the National Electrical Manufacturers Association (NEMA) into four grades: mechanical, electrical, machinable, and general purpose. Certain laminate grades are fire retardant.

Laminates are often employed for the creation of stamped parts for use in the petroleum, aerospace, electronics, and automotive industries.

Thermoplastics

Thermoplastics can be composed of various materials, including nylon 6, 6/6, acetal copolymer, polyethylene copolymer and homopolymer, and MDS. The use of thermoplastics allows for the creation of stamped parts in differing thicknesses with a high degree of accuracy as well as a uniform appearance. Thermoplastic stamped parts offer resistance from corrosion, wear, friction, and temperature.

Thermoplastics are often used for stamped parts in consumer products or across the aeronautics and aerospace industries.

The Importance of Material Selection

Skilled design engineers must consider factors such as heat, lubricant absorption, vibration dampening, and other performance impacts when selecting materials.

As examples, commodity thermoplastics perform poorly in electric motor applications as they are likely to melt on the armatures, and thermosets often crack or break when used in the wrong conditions. This doesn’t indicate ineffectiveness of plastics or mean that they are a risky material choice, but instead highlights the importance of material selection performance requirements to design engineers when developing parts and components.

Depending on your application, choosing the right non-metallic materials for your stamped parts offers significantly enhanced component performance. Download our eBook, Material Selection Guide, for a more in-depth look at the various materials available and the benefits of each in specific use cases.

Delrin® Washers: What Are They, and How Can They Be Used?

Delrin^® is a unique formulation of Polyoxymethylene (POM) developed by DuPont™. This thermoplastic is a high-performance acetal homopolymer resin with numerous desirable physical, mechanical, and chemical properties.

It is especially renowned for its durability, stiffness, and dimensional stability. Delrin^® components can operate in a wide temperature range, displaying exceptional toughness in temperatures as low as -50^oC and as high as 90^oC.

These attributes make Delrin^® perfect for high impact and heavily loaded applications such as gears, bearings, pumps parts, and vehicle components. Washers, in particular, are subject to a range of demanding applications, making Delrin^® the ideal material for washer construction.

Delrin^® Washers

Washers are thin, flat rings primarily used to distribute the load caused by the tightening or joining of two surfaces. They are also commonly used as seals, spacers, wear pads, and locking devices. Regardless of the application, washers must resist significant axial compression, friction, torque, and abrasion to function effectively.

Delrin^® washers offer a number of benefits compared to other polymeric materials, some of which include:

• High strength properties – When tightened, washers can experience significant axial compressive loading. Delrin^® has a compressive strength of 5200psi (approximately 1000psi more than standard reinforced concrete), thus ensuring the washer maintains its structural integrity when torqued.
• Excellent dimensional stability – Delrin^® washers are highly effective at preventing leaks as they maintain their shape and overall dimensions even when exposed to sudden changes in temperature and humidity.
• Chemical resistance – Exposure to certain chemicals can cause some polymeric materials to break down or deteriorate. Delrin^® washers are particularly resistant to hydrocarbon-based compounds, making them ideal for applications in the oil and gas industry.
• Low moisture absorption – Delrin^® is highly resistant to moisture absorption, thus allowing these washers to operate in wet or humid environments without any adverse effects to its physical and mechanical properties.
• Superior resistance to abrasion and wear – Tightening procedures can be highly abrasive as the washers are squeezed and rubbed against mating surfaces. Delrin^® washers exhibit exceptional resistance to abrasion, especially in applications with frequent tightening and loosening.
• Low coefficient of friction – The low friction coefficient of Delrin^® washers prevents the buildup of excessive friction while tightening, thus allowing for greater tightening torques and higher bolt axial load.

Industries That Use Delrin^®

Available in several specially formulated compositions and grades for a diverse range of applications, Delrin’s^® composition and desirable properties make this thermoplastic an essential component in a number of sectors, including:

• Aerospace and military
• Automotive
• Consumer and kitchen appliances
• Electronic and electrical insulation
• Fasteners
• Furniture
• Materials and equipment
• Power tools
• Plumbing

Delrin^® Washers from New Process Fibre

At New Process Fibre Co., we offer a broad range of Delrin^® washers in a variety of sizes, blends, and grades to meet the requirements of almost any industrial application. Reach out to our support team to find out if Delrin^® washers are the right choice for your next project.

Custom Non-Metal Stamped Part Production

This past summer, we had the pleasure of sitting down with engineering.com to talk about non-metal stamped parts production. We talked about a little bit of everything, ranging from non-metal stamp considerations, to custom tooling and production volumes for stamped parts produced in house. Check out the article below, or click here for the full edition.

A part of Everything, with New Process Fibre Company, Inc.

Achilles was a great warrior of ancient Greece and the hero of Homer’s Iliad, but despite his legendary invulnerability, an arrow to the heel led to his downfall. Likewise, something as small as a washer can become the Achilles heel of any design if not considered carefully.

Stamped parts like washers – found in everything from recliners, to kitchen blenders, to cars, and much more – come in a variety of shapes, sizes and materials. With so many options, design engineers might pick the first material and form that meets their basic requirements, but this can lead to a sub-optimal design and problems down the line.

Engineers can work closely with washer manufacturers like New Process Fibre Company, Incorporated (NPF) to ensure they avoid any unexpected arrows to the heel of their design.

“A lot of engineers pick out the material, dimensions and tolerances they are looking for, but if they pick out a material and it doesn’t work, then they’re kind of stuck,” said Bill Rust, director of sales and marketing at NPF. “We’re here to help.”

Material Considerations for Stamped Parts

Engineers have plenty of good reasons to move away from metal materials and toward non-metallic ones such as thermoplastics, laminates and fibers for stamped parts.

Vulcanized fibre is a light and strong material often comprised of wood pulp, paper and rag material. With good impact and abrasion resistance, as well as high flammability ratings, vulcanized fibre can be used in automotive components or provide electrical insulation, among many applications.

Laminates are composed of various resins and are graded by the National Electrical Manufacturers Association (NEMA) for electrical, mechanical and chemical performance characteristics. They are often suitable for aerospace, automotive, electronics, industrial and petroleum applications.

Thermoplastics are composed of materials such as polyethylene copolymer and homopolymer, acetal copolymer, nylon 6, 6/6 or MDS—and the list goes on. Thermoplastics can be used for a wide range of consumer products and parts.

Good design engineers keep in mind tolerances for factors like heat, and capabilities like lubricant absorption and vibration dampening, when choosing a material.

For example, commodity thermoplastics are poor in electric motor applications, and are likely to melt on the armatures, while thermosets can crack or break in the wrong conditions, Rust said. This doesn’t mean plastics are ineffective or risky materials to use, but that design engineers need to be considerate of their performance requirements when selecting a material.

“Punching plastic is a little different than punching metal,” Rust explained. “Once you punch metal, that size isn’t going to change. Now plastic can pull moisture out of the air a little bit, and it can change the washer’s dimensions by a couple thousandths of an inch, especially if you leave the bag open overnight.”

Custom Design and Manufacturability for Stamped Parts

Just as important as the material type, the thickness and the inner and outer dimensions (ID and OD) of the part must also be determined.

“We make parts to print here,” said Rust. “We need to know tolerances, dimensions and we need to know if this is a washer that they’re trying to retain to a bolt, where it will stay fixed in place without falling off.”

To ensure the tightest fits and tolerances, engineers can send in bolts to be built around and custom-order specific shapes and dimensions.

NPF’s standard tolerances achieve plus or minus ten-thousandths of an inch to even a thousandth on some materials.

Stamped parts can also be designed to meet specific absorption, compression and alignment requirements. For design engineers who aren’t quite sure what they are looking for, NPF can supply samples for inspection and testing.

“A lot of the stuff we do here are speciality washers and so instead of having a round ID or OD, they might have tabs on them or have a hex ID,” Rust said. “We have over 8000 washer dies on the floor. If we don’t have it, we build it and we make all of our own tooling here too.”

Custom Tooling and Production Volumes for Stamped Parts Produced In-House

Design engineers resort to custom tooling and die making when washers or other stamped parts require unconventional shapes and dimensions.

NPF has an in-house tool room with CAD/CAM and wire EDM capabilities, which allows them to create their own custom tooling.

“If you wanted a part that was in a special shape, like a rectangle, I would only quote a customer for the metal that it costs to build the tool and the die set, and it would be a one-time partial tooling charge,” Rust explained.

NPF holds ownership of the tool and maintains it for the lifetime of the part, which takes the worry and cost of having to inventory, maintain or store the tool off the customer’s shoulders. This practice extends to inventory and storage for excess production volumes to achieve lower costs on the quote.

“If a customer were to place an order for 100,000 parts and only needed 25,000, we would run the whole hundred,” Rust said. “We would keep the extra here on the shelf and release them as the customer needs them.

Working Together with New Process Fibre Company

NPF stamps non-metal materials including vulcanized fibre, acetal, nylon, Teflon, nylon MDS, high- and low-density polyethylene and other speciality materials for industries including consumer goods, aerospace, military, automotive, electronics, plumbing and many more.

With a large inventory and production equipment, NPF tackles production orders of all sizes, without the need for outsourcing, Rust explained.

“We extrude all our own materials,” Rust said. “We also slit our own materials and run the parts out on the press. Making and maintaining our own tooling, we do everything under one roof.”

NPF also manufactures custom discs, end laminations, gaskets, insulators, spacers and tags, as well as washers and parts.

Design engineers in need of assistance finding the right material for their application, can find help in the NPF Material Selection Guide, which includes material characteristics and highlights, common applications, and comparisons.