Cable and connector overmoulding
The point where a cable enters a connector or device is where most cables fail. An overmoulded silicone body seals that point, spreads the bending…
See the serviceProject record · Marine equipment · Cable overmould
A marine equipment maker's sealed connector overmould.
Salt water was finding its way along the cable jacket and into the connector. We replaced a potted joint and heat-shrink with a single silicone overmould designed to grip the jacket.
The brief
A connector that lived in salt water.
A UK maker of marine monitoring equipment had a connector on a sensor cable that sat permanently in seawater. Field returns showed corrosion inside the connector body.
The existing design used a potted joint covered with heat-shrink tubing, done by hand. Water was wicking along the cable jacket under the heat-shrink and reaching the pins.
They asked us whether an overmould could seal the joint more reliably and reduce the hand work.
The problem
The seal was on the heat-shrink, not the jacket.
Heat-shrink sealed well to itself but not reliably to the cable jacket, especially after temperature cycling. The potting compound sealed the pins but left a path along the jacket.
The fix was to bond and grip the jacket directly, over a long enough length to stop wicking, and to seal the connector body in the same moulding.
We proposed a silicone overmould with a primed jacket, a series of moulded grip rings and a tapered strain relief.
What we changed
We moved the seal to where water was getting in.
A modest design change with a big effect on reliability.
Jacket preparation
The cable jacket was cleaned and primed over the sealing length.
Grip rings
Moulded internal rings compress onto the jacket to block water paths.
Integrated strain relief
A tapered boot spreads bending load away from the joint.
Low-temperature cure
Grade and cure chosen to protect the connector and cable.
Sacrificial trials
Early samples were cut open and pressure tested.
Batch checks
Continuity and sample pressure checks on every batch.
The commercial shape
One moulding replaced two manual steps.
The overmould tool was a modest investment. Removing the potting and heat-shrink steps reduced assembly labour, and the field return rate for water ingress fell away.
The customer's own team now fits connectors to cable and sends assemblies to us for overmoulding in regular batches.
“The overmould made the connector the most reliable part of the system instead of the weakest.”
Services used
How this programme was actually delivered.
Hardware encapsulation
Wrapping a sensor, board or cable joint in silicone protects it from water, dust, vibration and hands. Done badly, it cracks solder joints or cooks…
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