1. All 3M Products
  • 3M™ Dual Lock™ Reclosable Fastener SJ3221, Pop-In Piece Part, Stem Density 250, Black, 20 mm x 20 mm
  • 3M™ Dual Lock™ Reclosable Fastener SJ3221, Pop-In Piece Part, Stem Density 250, Black, 20 mm x 20 mm

    3M ID B40068986
    • Interlocking mushroom-shaped head design offers strong, fast and easy attachment without use of adhesives
    • Helps reduce vibration for long-term performance
    • Secures with an audible snap for closure verification
    • Resistant to high temperature and solvents, ideal for automotive applications
     More...
    Product Details
    • Interlocking mushroom-shaped head design offers strong, fast and easy attachment without use of adhesives
    • Helps reduce vibration for long-term performance
    • Secures with an audible snap for closure verification
    • Resistant to high temperature and solvents, ideal for automotive applications
    • Reduces the rattling and vibration of components
    • Does not require any special tools or processing equipment
    • Single disk base inserts into a key hole slot for attachment

    3M™ Dual Lock™ Reclosable Fastener SJ3221 is a square reclosable fastener with a single disk base for pop-in insertion into a key hole slot. It is lined with polyolefin mushroom stems of density 250, and can be paired with other stem densities for varying levels of interlocking strength. Stems provide superior strength over hook and loop closures yet easily peel apart for internal access.

    Convenient Assembly and Re-Assembly for Automotive Trim
    Ideal for attaching automotive trim components, our 3M™ Dual Lock™ Reclosable Fastener SJ3221 provides a high-strength closure that is easy to assemble and just as easy to re-open and re-assemble, even hundreds of times. Moreover, the pieces audibly snap together with a satisfying click to form a secure, dependable and repeatable attachment.

    Designed with hundreds of interlocking mushroom-shaped stems, this polypropelenepolypropylene fastener can replace conventional attachments such as screws or adhesives, which can be time-consuming to fit and assemble, may weaken the part, or are susceptible to vibration and weather extremes. A Dual Lock™ Fastener is constructed with polyolefin stems and holds tight regardless of high heat, cold, moisture or humidity. It is also an excellent attachment solution when vibration is an issue — not only does the fastener hold tight, but it actually reduces vibration and rattling.

    3M™ Dual Lock™ Reclosable Fastener SJ3221 provides a high-strength closure that is easy to assemble and just as easy to re-open and re-assemble, even hundreds of times.
    Mushroomshaped polyolefin stems that snap together
    Additional Features include:
    • Fast assembly with no drilling or additional tools required
    • Hidden attachment avoids unsightly mechanical fasteners on the show surface
    • High temperature and solvent resistance
    • Mushroom heads that allow flexibility in alignment for easy attachment of components
    • Can be used to attach components before they enter the final assembly plant, thus helping to reduce the number of parts and the length of assembly time
    • Combinations of stem densities and the engaged area provide adjustable and proportional engagement and disengagement forces
    • An audible snap confirms that the part is correctly installed with minimal insertion force required by the assembly worker
    How It Works
    This pop-in fastener is designed to be popped into a key hole slot where attachment is desired. Its polypropylene disk base grips the inside of the hole and holds tight. The fastener can then be mated to a second Dual Lock™ fastener attached to a piece of trim or other part — when the two fasteners mate, the two parts are firmly secured together.

    When two pieces of 3M™ Dual Lock™ Reclosable Fasteners are pressed together, the stems flex and the mushroom heads slide past each other. After passing the opposing mating piece, the stems snap back into their original position and the opposing mushroom heads interlock. These fasteners can provide high tensile strength but can be opened by simply cleaving or peeling open the closure.

    Alignment and re-alignment are easy and no special tools are required. This means that they can be used to attach components before they enter the final assembly plant, thus helping to reduce the number of parts and the length of assembly time.

    Stem Densities
    Combinations of stem densities and the engaged area provide adjustable and proportional engagement and disengagement force. Dual Lock™ fasteners are offered in three different densities (stems per square inch): 170, 250, and 400. Our Reclosable Fastener SJ3221 has 250 stems per square inch, and can be mated to Types 17, 250, or 400.

    Designed with hundreds of interlocking mushroom-shaped stems, this polypropylene fastener can replace conventional attachments such as screws or adhesives, which can be time-consuming to fit and assemble, may weaken the part, or are susceptible to vibration and weather extremes.
    250 stems/inch2 (39 stems/cm2)
    Applications
    Dual Lock™ Reclosable Fasteners can replace conventional mechanical fasteners in a wide range of assembly and attachment applications where reclosability is desired. Dual Lock™ fasteners are used primarily to secure rigid and semi-rigid surfaces such as trim or door panels, instrument panel bezels, headliners, and other automotive interior and exterior trim. Some examples of applications include:
    • Headliners
    • Trunk liners
    • Door panels
    • Toll transponders
    • Vehicle headliners
    • Sunroofs
    • Interior lighting
    • Window and door trim
    • Vibration and sound dampening control
    • CHMSL — Center Height Mount Stop Lamp — cover plates
    • Center console flanges
    3M Science Delivers Closures You Can Count On
    3M™ Dual Lock™ Reclosable Fastener are ideal for many applications where a high strength, reclosable fastening system is required. 3M engineers have uniquely combined physics and materials science to bring the automotive industry reliable fasteners that supply high performance even after exposure to ultraviolet radiation, high moisture levels and wide temperature ranges. For applications that require a key hole slot pop-in piece and multiple closures, look no further than the long-lasting durability of our 3M™ Dual Lock™ Reclosable Fastener SJ3221. It is yet another outstanding example of how 3M technologies advance operations in the automotive industry, providing both ease of use and superior results.

    See More about 3M™ Dual Lock™ Reclosable Fasteners (PDF, 2.9 Mb)

    Follow Us
    The brands listed above are trademarks of 3M.
    Change Location
    United States - English