The Benefits of 420 Chrome Stainless Steel Coiled Spring Pins

In applications requiring a combination of high strength, superior fatigue life, and corrosion resistance, 420 martensitic chrome stainless steel offers a host of technical benefits and provides an overall robust cost-effective solution.

Solid Pins

Solid Pins are straight, cylindrical, relatively inflexible press-fit pins. Available with or without a head, they are commonly used to locate components in a fixed position, to maintain alignment, or to act as axles, pivots or hinges.

SPIROL’s standard Solid Pins include Straight Pins, Knurled Pins, and Barbed Pins in diameters ranging from 2mm / .078” (5/64”) up to 6mm / .250” (1/4”). Standard materials include low carbon steel and nickel stainless steel.

straight pins
Straight Pins
Offered with or without a head, Straight Pins are distinguished by their uniformity. The chamfered ends are more consistent than tumbled edges—making installation with automatic assembly equipment more reliable. Straight Pins are retained by compressing the host, not the pin. They are suitable for use in plastics for press-fit applications limited to those cases where the host material can withstand compression in the order of 0.05mm – 0.08mm (.002” – .003”). These pins are often used to replace ground dowels in applications that do not require the tight tolerances of a ground dowel.

SPIROL offers two different types of Straight Pins: The Series DP100 Straight Pin and the Series FH100 Headed Pin.

knurled pins
Knurled Pins
Offered with or without a head, Knurled Pins are available with either straight or helical knurls. Unlike a Straight Pin where retention is provided by the uniform interference between the pin and hole, knurled pins are designed to cut into the host. The displacement of the host material into the valleys of the knurls yields more frictional contact area between the pin and hold this resulting in higher retention. With Helical Knurled Pins, a 30º knurl causes the pin to rotate as it enters the hole creating even more surface contact with the host. This results in higher frictional forces, greater engagement and improved resistance to back out.

Straight knurls have lower insertion forces than helical knurls, offer resistance to turning within the assembly, but provide limited retention when axially loaded. Therefore, straight knurls are often recommended when the pin is used to transmit torque such as when used as an axle to rotate a wheel. Helical knurls provide both resistance to torque and push out when axially loaded.

SPIROL Standard Knurled Pins include: The Series KP200 Straight Knurled Pin, Series KP300 Helical Knurled Pin, the headed Series HP200 Headed Straight Knurled Pin and the Series HP300 Headed Helical Knurled Pin.

barbed pin
Barbed Pins
SPIROL's Barbed Pins were created specifically for use in flexible plastics where optimum resistance to axial force is desired. The raised barbs are angled backwards, opposite the direction of insertion. After installation, the plastic will backfill into the area around the barbs resulting in maximum retention. Barbs are recommended for use in flexible plastics where optimum resistance to axial force is desired. After installation, the plastic will backfill into the area around the barbs resulting in maximum retention. Barbed Pins are ideal for applications requiring high pull-out (tensile) strength, and to prevent disassembly (i.e. tamperproof). Barbs are not appropriate for brittle plastics or those containing high percentages of fillers. As barbs are a radial feature, they do not resist rotation of two components relative to one another. For this requirement, a straight or helical knurl should be used. All Barbed Pins are provided with a generous pilot to facilitate alignment with the hole and ease installation.

SPIROL's BP100 Press-N-Lok™ Pin has opposing barbs on each end of the pin and is designed to permanently retain two plastic components to each other such as two halves of a plastic enclosure. Press-N-Lok™ Pins are installed in two stages: First, press the pins into one half of the plastic housing. Next, align the other half of the housing with the exposed pins and press into place. SPIROL's Press-N-Lok™ Pins are manufactured from lightweight, lead free aluminum as a standard, and available to order in austenitic stainless steel. BP100 Press-N-Lok™ Pins are available in diameters ranging from Ø2mm to Ø 4mm.

SPIROL's HP400 Headed Barbed Pin has a series of barbs extending down the entire length of the pin. Headed Barbed Pins are a great replacement for self-tapping screws in plastic assemblies as Barbed Pins are installed into standard molded (or drilled) holes, they install much faster than screws, and they eliminate issues associated with cross-threaded or skewing during installation. Unlike screws that resist back-out (or loosening) by being tightened to a preset torque, Barbed Pins are retained by the plastic backfilling over the aggressively-designed barbs. The head provides a positive stop and is also used to retain a thin component to a thicker component within an assembly. SPIROL's FH400 Headed Barbed Pins are available in metric diameters ranging from Ø2mm to Ø6mm and inch diameters ranging from Ø.078" (5/64) to Ø.250" (1/4) in low carbon steel and austenitic stainless steel.
pin installation

Installation Technology for Pins

In addition to a comprehensive line of engineered components used for joining and assembly, SPIROL also offers a full range of Pin Installation Equipment designed to facilitate cost-effective and high quality assembly of your products. Our installation solutions range from manual machines to fully automated work cells with statistical process control and error-proofing options. We are the only company of our kind that offers the total integrated solution.

Additional Information

Read The Difference Between Cold Headed and Machined Solid Pins and other White Papers on Press Fit Solid Pins.

Review our Application Stories for how SPIROL Engineers and Products have helped provide quality and cost saving solutions for fastening and joining problems.

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