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Design Course
Designing of Plastic Products for Injection Moulding
Manufacturing Methods and Technologies
by
Snap Fits
Snap fits are most economical and rapid methods of assembly for high volume production. Snap-fits may be a detachable or a non-detachable joint. All snap-fit designs consist of two basic parts. First one is a flexible member which is acting like a cantilever which bends and returns to its original position during snapping action. The second member holds the cantilever having sufficient space to accommodate the flexing of cantilever. Snap-fits can be broadly categorized as cantilever snap-arms and annular snap joint. The shape of the undercut determines whether the joint can be separated or not. Snap-fits with angled undercut can be disassembled easily. Snap-fit provide both secure as well as easy assembly of the parts. They facilitate easy and quick detachment of electrical components for repair.
Design considerations
- The flexure during snapping should not exceed the allowable strain limit of material.
- The flexing member of the snap-fit joint should return to a relaxed position after assembly.
- Avoid sharp corners in high stress areas, such as at the base of cantilever arm.
