Press-Lok
PSM Press-Lok inserts are press-in, self-locking threaded inserts designed for thermoplastic use. They combine ease of installation with reliable locking, torque performance, and pull-out resistance. Press-Lok inserts are well suited to plastic parts where tapped threads are impractical or would degrade over time.
Advantages
- Degree of self-locking action on screw
- High pull-out and torque performance
- Easy press-in insertion
- Suitable for most thermoplastics
Product Features
- They provide a degree of self-locking action, helping the screw resist loosening under vibration.
- High pull-out and torque performance when properly installed ensures thread integrity in plastic substrates.
- Easy press-in insertion—no special tooling is required beyond controlled pressing.
- Suitable across most thermoplastics, offering versatility across common plastics.
Selection of Press-Lok Inserts
ISO Metric
| PRODUCT CODE | THREAD SIZE | INSERT LENGTH A | PREFERRED OTHER LENGTH A* | INSERT Ø D | REC. HOLE SIZE -0.00 +0.10 | MIN. WALL THICKNESS | |
|---|---|---|---|---|---|---|---|
| PLK-B | M2 | 4.0 | - | - | 3.7 | 3.2 | 1.6 |
| M2.5 | 5.8 | 4.0 | - | 4.5 | 4.0 | 2.0 | |
| M3 | 5.8 | 4.0 | - | 4.5 | 4.0 | 2.0 | |
| M3.5 | 7.2 | 4.0 | - | 5.3 | 5.8 | 2.4 | |
| M4 | 8.2 | 5.8 | - | 6.2 | 5.6 | 2.8 | |
| M5 | 9.5 | 5.8 | 8.2 | 6.9 | 6.4 | 3.2 | |
| M6 | 12.7 | 7.2 | 9.5 | 8.5 | 8.0 | 4.0 | |
| M8 | 12.7 | - | - | 10.1 | 9.6 | 4.8 | |
Other lengths possible on quotation.
Unified
| PRODUCT CODE | THREAD SIZE | INSERT LENGTH A | PREFERRED OTHER LENGTH A* | INSERT Ø D | REC. HOLE SIZE -0.000 +0.004 | MIN. WALL THICKNESS | |
|---|---|---|---|---|---|---|---|
| PLK-B | 2-56 | .157 | - | - | .146 | .126 | .063 |
| 4-40 | .228 | .157 | - | .177 | .157 | .079 | |
| 6-32 | .283 | .157 | - | .209 | .189 | .094 | |
| 8-32 | .323 | .228 | - | .242 | .220 | .110 | |
| 10-24 | .374 | .228 | .322 | .272 | .252 | .126 | |
| 10-32 | .374 | .228 | .322 | .272 | .252 | .126 | |
| 1/4-20 | .500 | .283 | .374 | .335 | .315 | .157 | |
| 1/4-28 | .500 | .283 | .374 | .335 | .315 | .157 | |
| 5/16-18 | .500 | - | - | .398 | .378 | .189 | |
| 5/16-24 | .500 | - | - | .398 | .378 | .189 | |
STANDARD MATERIAL: BRASS (B)
Other materials and lengths possible on quotation.
Specifying an Insert
Boss Design Specification
Hole Preparation
Molded holes are recommended wherever possible. The taper on a molded hole should be 1° inclusive and the hole diameter recommended should apply at the point reached by the bottom of the insert. Drilled holes may be used but performance may be reduced when compared with a molded hole. The top of the hole should not be chamfered or counterbored and care must be taken to avoid bell mouthing. Hole diameter tolerance: -0.00 +0. 10mm.
Direction of Loading
The fixing screw must always be assembled from the knurled end of the component to develop the necessary expansion action.
Influence of Screw Dimensions
It is important that the fixing screw fully penetrates the insert in order to achieve full expansion, screw length should therefore be calculated to ensure that this condition is met before final clamp torque is applied.
Wall Thickness
A general guide to minimum wall thickness is given in the data table but this will vary depending upon the nature of the plastic. Where thinner walls are required these can often be accommodated, but consultation with the P.S.M Technology Centre or local sales office and pre production testing is strongly advised.
Performance Data
The complexity of materials and variations in service conditions make it impossible to detail fastener performance for specific applications. The chart below gives a general guide and show the relative performance of the inserts in the range.
Installation Best Practices
- Install by pressing the insert into the prepared hole using a controlled squeeze action, not by impact or shock loading.
- Ensure that the insert is square during press-in; any side load can distort the insert or damage surrounding plastic.
- After press-in, perform torque and pull-out testing under expected working conditions to confirm performance.
Applications & Use Cases
Press-Lok inserts are suited for any plastic part requiring a durable thread, especially when tapping isn’t practical. Typical uses include housings, enclosures, control panels, molded plastic parts, and assemblies where reusability, vibration resistance, and strong engagement are needed.
Enhance Your Assembly with Our Press-Lok Inserts
Start browsing our products or request a quote today to find the ideal fastening solution for your application.