CoilSert Screw-Locking Inch UNC Coarse #5-40 × 2-1/2D
CoilSert screw-locking wire thread insert, inch UNC coarse 5 (.125)-40, length 2-1/2D, precision-wound from 304 stainless steel diamond-section wire; the coil expands elastically to anchor itself after installation—no staking required. Provides continuous self-locking torque and resists vibration loosening. Volume pricing is negotiable.
| Part No. | 3585-05CN312 |
|---|---|
| Features | Self-locking, anti-loosening |
| Thread Size | 5 (.125)-40 |
| Thread System | Inch UNC coarse |
| Length | 2-1/2D |
| Material | 304 stainless steel |
| Finish | Plain (cadmium / silver / dry-film lubricant optional) |
Overview
A screw-locking CoilSert differs from the free-running version by a polygonal locking coil at one end, which presses on the flanks of the mating screw and creates a controlled friction torque. The insert still installs like a standard coil, but the screw needs deliberate torque to run through the locking zone. This provides vibration resistance without threadlocker fluid, which matters where adhesives are prohibited or where parts are serviced repeatedly. This listing: thread 5 (.125)-40, thread system Inch UNC coarse, length 2-1/2D, material 304 stainless steel, finish Plain (cadmium.
Advantages
No adhesive is required, so the joint can be disassembled and reassembled in the field without cleaning cured threadlocker from the hole. This is the usual reason the locking variant is chosen over a free-running insert plus Loctite.
The locking zone sits at the top of the insert, so engagement begins as soon as the screw enters, giving immediate resistance rather than locking only at final torque.
The same diamond-section wire form carries the load, so tensile and torque performance match the free-running insert of the same size.
The locking coil produces a defined prevailing torque rather than a random interference fit, so the locking force stays within a predictable band across assembly cycles instead of dropping after the first tightening.
Applications
Inch-thread joints subject to vibration, equipment that is field-serviceable and must be re-opened without adhesive, instrumentation mounts, and any assembly where threadlocker contamination would damage nearby components.
Prevailing torque is a specified value, not a side effect: state the required band when ordering, because too much locking torque causes screw fatigue and too little defeats the purpose. Do not lubricate the locking coil.
Product information is supplied by Toprecision. Custom parts can be produced to drawing — contact us for samples or a quotation.
Specifications across this series
220 parts in this series
Values are taken from each part’s own attribute set. Changing length, material or finish changes pull-out strength and installation torque, so compare the row that matches your drawing.
Selection and test data: engagement length, standards, salt-spray hours
FAQ
What are the key dimensions of this part?
Part No. 3585-05CN312, Features Self-locking, anti-loosening, Thread Size 5 (.125)-40, Thread System Inch UNC coarse.
What material and finish is it supplied in?
304 stainless steel; Plain (cadmium / silver / dry-film lubricant optional).
What should I verify before ordering or installing it?
Prevailing torque is a specified value, not a side effect: state the required band when ordering, because too much locking torque causes screw fatigue and too little defeats the purpose. Do not lubricate the locking coil.