- Interlocking mushroom-shaped stems snap together to form a strong, fast and easy attachment
- Die-cut base incorporates counter-sunk hole for attachment using screws or rivets
- Strong holding power reduces the rattling and vibration of components
- Resistant to high temperatures and solvents
- Does not require any special tools or processing equipment for installation
- Audibly snaps together for a secure, dependable and repeatable attachment
- Mates with other stem densities to achieve a variety of engagement and disengagement forces
3M™ Dual Lock™ Reclosable Fastener SJ3251, Die-Cut Piece Part is a round, die cut reclosable fastener with a rigid polypropylene backing and a counter sunk hole for screws or rivets. It has a stem density of 250 stems per square inch. The mushroom-shaped stems interlock to supply very high tensile strength and replace mechanical fasteners in many applications.
Interlocking mushroom-shaped polyolefin stems
Convenient for Automotive Trim
Ideal for attaching automotive trim components, 3M™ Dual Lock™ Reclosable Fastener SJ3251 is a round, die-cut piece part that provides a high-strength closure that is easy to assemble and just as easy to open and reclose in high cycle applications. Moreover, the pieces audibly snap together with a satisfying click to form a secure, dependable and repeatable attachment.
Dual Lock fasteners are constructed with polyolefin stems and hold tight regardless of high heat, cold, moisture or humidity. These fasteners are also an excellent attachment solution when vibration is an issue — not only do the fasteners hold tight, but actually reduce vibration and rattling.
How It Works
This die-cut fastener is designed to be screwed or riveted to a base where attachment is desired. It is supplied with a counter sunk hole for easy attachment using pan-head screws, pop-in rivets, or an ultrasonically stacked post. The head of the screw or rivet must be recessed below the bottom of the mushroom stems to allow proper engagement of the mushroom heads.
The fastener has a rigid polypropylene backing that holds firm to the base through many openings and closings. The die-cut piece can be snapped to a second Dual Lock fastener attached to another part — forming a secure, dependable and repeatable attachment.
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 is easy with no special tools required. This means that these fasteners can be used to attach components before they enter the final assembly plant, helping to reduce the number of parts and the length of assembly time.
250 stems/inch2 (39 stems/cm2)
Combinations of stem densities and the engaged area provide adjustable and proportional engagement and disengagement force to meet application requirements. Dual Lock fasteners are offered in three different densities (stems per square inch): 170, 250, and 400. The Dual Lock fastener SJ3251 has 250 stems per square inch (25mm), offering the tightest hold, and can be mated to Type 170, 250 or 400.
3M™ Dual Lock™ Reclosable Fasteners can replace conventional mechanical fasteners in a wide range of assembly and attachment applications where reclosability or serviceability 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. Other application examples include attaching accessories and equipment, window and door trim panels, and vibration and sound damping control.
3M Science Delivers Closures You Can Count On
3M™ Dual Lock™ Reclosable Fasteners 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 high moisture levels and wide temperature ranges. For applications that require a round, die-cut piece and multiple closures, look no further than the long-lasting durability of the 3M™ Dual Lock™ Reclosable Fastener SJ3251 Ultimate Pop-In Piece Part. It is yet another outstanding example of how 3M technologies advance operations in the automotive industry, providing both ease of use and superior results.
Learn more about 3M™ Dual Lock™ Reclosable Fasteners
(PDF, 2.95 Mb)