A tray of pogo pin springs can leave the coiling machine as separate parts and arrive at assembly as a clump. Usually, the springs have not formed a true knot. One coil has slipped into the gap between another spring's coils; movement during washing, feeding or transport then pulls more springs into the group.
For a pogo pin manufacturer, the cost is more than the time spent separating them. Tangled springs can stop an automatic feeder, slow assembly and become bent during removal. A spring that looks usable after being pulled free may no longer deliver the specified force.
Why does it happen?
Open coil gaps allow springs to nest. When the space between turns is large enough, the end of one spring can enter another. A protruding or tilted end coil makes that more likely. Very small springs are particularly troublesome because a slight end defect is large relative to the spring itself.
Long, flexible springs move into one another. Free length, diameter and wire size affect how a loose spring behaves in a batch. A slender spring can bend during handling, bringing its end coils into contact with neighboring parts.
Bulk processes give the springs repeated chances to catch. Springs may tumble together in a cleaning basket, collect at the bottom of a feeder or shift inside a partly filled transport box. A large batch under vigorous movement can develop tangles even when its springs are dimensionally consistent.
Dimensional variation makes the problem less predictable. Changes in coil diameter, pitch, free length or end shape may leave some pieces much easier to hook than others. Burrs and distorted ends can add another catching point. If tangling begins after a change in production conditions, compare those measurements with an earlier acceptable batch.
What problems can tangled springs cause?
The first visible symptom is usually lost assembly time: feeders stop, operators separate parts, and a batch has to be handled again. There is also a quality risk. Pulling intertwined springs apart can stretch an end coil, change free length or bend the spring body.
Inside a finished pogo pin, that damage may appear as low or inconsistent contact force, rough plunger movement or incomplete return. Separating a clump is therefore not the same as restoring the springs to specification. Parts that were stretched or distorted need inspection, and visibly damaged parts should be rejected.
Find the step where tangling begins
Inspect small samples after coiling, heat treatment, cleaning, feeding and packing. Record how many springs are tangled at each point. If they leave cleaning individually but reach the assembly feeder in clumps, changing the coiling dimensions may be unnecessary. If the first clumps appear immediately after coiling, concentrate on pitch, end formation and dimensional consistency.
A short trial with smaller batches can be revealing. Run the same springs through a reduced cleaning load or a different feeder setting and compare the result. This establishes whether handling is driving the problem before changing the spring drawing.
Changes that can help
Review the end coils. A consistent, closed end can reduce the opportunity for one spring to catch another. Check that the end geometry still seats correctly inside the pogo pin. An end change that solves bulk tangling but tilts the spring in the barrel is no improvement.
Control the geometry that matters. Inspect coil outside diameter, free length, pitch, squareness and any protruding wire ends. If a change to pitch is proposed, calculate and test its effect on spring rate, available travel, solid height and fatigue life. Simply closing every gap can leave too little compression space.
Reduce movement in bulk handling. Smaller cleaning loads, shallower layers and handling containers suited to the spring size can limit nesting. Feeder settings should separate and orient the springs without repeatedly driving them into a dense pile.
Choose packaging for the journey to assembly. Bulk bags may be economical, but they allow springs to move against one another during transport. Trays, divided containers or other controlled packaging may be justified when the cost of tangling and inspection exceeds the packaging cost.
These measures should be evaluated together. A spring with clean, consistent ends may still tangle if it spends a long time tumbling in an overloaded basket.
When the spring sticks inside a pogo pin
A pogo pin that does not return freely is often described as having a "tangled spring." Once the spring is inside the barrel, the failure is more likely to be buckling, rubbing, coil distortion or assembly interference than entanglement with another spring.
Check the spring outside diameter against the barrel's internal diameter, including their tolerances. Inspect the barrel for burrs or debris, and confirm that the spring seats squarely against the plunger and base. At full intended compression, it must have enough room to operate without being forced beyond its design limit. The working force and return action should then be measured on the assembled pin, not inferred from the loose spring alone.
For a custom pogo pin, we can review a customer drawing as a complete spring-and-barrel assembly, including available travel, force at the working height, internal clearance and the process used to handle the springs before installation. That makes it possible to address both assembly tangling and finished-pin performance without sacrificing one to improve the other.
FAQ
Will reducing spring pitch stop tangling?
It may reduce opportunities for another spring to enter the coil gaps, but it also changes the spring's behavior. Rate, working travel and solid height must be checked before changing the drawing.
Can tangled springs be separated and used?
Only if they still meet the dimensional and force requirements. Springs with stretched ends, bends or altered free length should not be returned to assembly on appearance alone.
Why do springs tangle only after cleaning?
Bulk movement in a cleaning basket may bring previously separate springs together. Compare the batch size, basket depth and cleaning motion with conditions that did not produce tangling.
Is a sticking pogo pin always caused by a tangled spring?
No. Check for spring buckling, poor clearance, a tilted spring seat, barrel burrs and foreign material. Testing the loose spring and the assembled pogo pin separately helps locate the fault.
