Screw-Sert
PSM Screw-Sert inserts are self-tapping metallic inserts designed to form their own threads in thermoplastic or thermoset materials, enabling a durable steel thread in plastics that otherwise may be too weak to hold repeated screw cycles. They are especially useful in applications where high pull-out loads, jack-out resistance, or weak core strength plastics are involved.
Advantages
- Easy press-in insertion
- Ideal where jack-out loading is unavoidable
- Can carry high loads in weak plastics
Key Features
Self-tapping: no pre-tapped hole is needed; the insert cuts or broaches its own thread as it’s driven in
High pull-out resistance: designed to resist being pulled from the plastic under load
Excellent torque-out strength: capable of withstanding twisting or loosening forces
High reusability: steel thread enables multiple screw cycles without degrading performance
Accommodates weak plastics: suitable for substrates with limited core strength
Flanged and stud versions available to suit different assembly geometries
Selection of Inserts
ISO Metric
Unified
Other materials and lengths possible on quotation.
Specifying an Insert & Stud
Boss Design Specification
Hole Preparation
Hole diameter will vary with the type of plastic material used – hard plastics will require larger holes than softer plastics etc. For this reason, the data table shows the hole size ranges recommended for thermoplastics and thermosetting plastics. Exact hole size is best determined by pre-production trials – please consult the P.S.M Technology Centre. It is recommended that moulded holes are used. A 60° countersink at the top of the hole is strongly recommended in order to avoid the risk of chipping to the surrounding surface. The depth of the countersink should be equal to the external thread pitch of the insert. Tapers on moulded holes should be 1° inclusive.
Type of Loading
Direct torque loads should be avoided with this type of insert.
Installation
The insert is installed using traditional tapping principles. Installation can be carried out using a hand tool (for low volumes), a tapping head attachment for a pillar drill, a standard tapping machine or fully automatic installation equipment.
Wall Thickness
This must be evaluated by pre-production tests in conjunction with the P.S.M Technology Centre – contact your local sales office for advice.
Performance Data
The complexity of materials and variations in service conditions make it impossible to detail fastener performance for specific applications. The charts below give a general guide and show the relative performance of the inserts in the range.
