Insertion and withdrawal testing involves applying and measuring the compressive force to an object to push it into a recepticle, then measuring the tension force to pull it out. This may be done for a single cycle or over multiple cycles. If performed over multiple cycles it is common to compare the compressive and tensile forces for the initial cycle and then at specific intervals.
Electrical couplings, snap-fit connectors and locking spade terminals are all tested for insertion forces (assembly) and for withdrawal (extraction or disassembly).
Consistent insertion force is vital for security of electrical connection and rapid assembly line throughput. Extraction resistance must balance the ease of intended disconnection with connector integrity under its intended conditions of use. Other applications include industrial fixings and fasteners, stoppers, lids and push-fit closures.
Correct alignment of the mating parts is essential for accurate and repeatable testing, which should be conducted at a constant test speed of push-pull by using a motorised test system.