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Threaded Inserts · Trade series (heat-set insert) · Application guide

What Are Heat-Set Threaded Inserts for Plastic Used For?

Typical applications, the industries that specify heat-set threaded inserts for plastic, and how to choose the right size, material and finish for the joint.

Heat-Set Threaded Inserts for Plastics are used for putting a durable metal thread into a plastic or printed part, where a screw driven straight into the plastic would strip within a few cycles. They are manufactured to Trade series (heat-set insert), and selection is driven by the thread size, the fit and tolerance the assembly requires, and the service environment.

Primary duty
Putting a durable metal thread into a plastic or printed part, where a screw driven straight into the plastic would strip within a few cycles
Governing standard
Trade series (heat-set insert)
Thread size range
M2 to M6
Category
Threaded Inserts

Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation.

What Are Heat-Set Threaded Inserts for Plastic Used For? application image

Heat-Set Threaded Inserts for Plastics (Trade series (heat-set insert)) are specified where the joint requires putting a durable metal thread into a plastic or printed part, where a screw driven straight into the plastic would strip within a few cycles. The sections below cover the typical end-uses by industry, the size and material decisions for each, assembly practice, and the applications this fastener type is not suited to. Stocked across roughly M2 to M6, they cover light-duty and instrument-scale work.

Typical Applications for Heat-Set Threaded Inserts for Plastic

The most common settings where these are specified:

  • Maintenance & repair (MRO): a stocked size for servicing existing plant where the original fastener spec must be matched.
  • Fabrication & metalwork: bench and on-site assembly of steel frames, enclosures and weldments.
  • Aluminum & cast housings: durable steel threads in soft alloy that would otherwise strip.
  • Thread repair: restoring a stripped or cross-threaded hole to its original size.
  • Plastics & composites: reinforced, reusable threads in molded parts.

How to Specify Heat-Set Threaded Inserts for Plastic for Your Application

  • Size: Match the nominal size to the mating thread or hole. This product spans M2–M6; check the full table below for the exact dimensions of each size.
  • Tap & length: Drill and tap to the specified STI size, and pick insert length (commonly 1.5×D or 2×D) for the load and parent material strength.
  • Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
  • Standard: This product is supplied to Trade series (heat-set insert). Quoting the standard on your order guarantees interchangeable dimensions between suppliers.

Installation & Assembly Practice

  • Drill and tap with the specified STI tap — a standard tap will not produce the correct thread for the insert.
  • Install to the specified depth (typically 0.25–0.5 mm below the surface) and remove the tang where the design requires it.

Common Selection Mistakes with Heat-Set Threaded Inserts for Plastic

  • Fitting an insert into strong steel that already holds a thread — added cost for no gain.
  • Skipping the tang removal, which then blocks the mating screw.

Where Heat-Set Threaded Inserts for Plastic Are Not the Right Choice

Not a fix for a hole that is already oversized beyond the STI tap range, and not needed in steel that already holds a thread well.

Technical Drawing

Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.

Sends the selected values to the quote form below.

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The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.

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Specification
Business Information

Dimensions & Specifications (Trade series (heat-set insert))

Thread sizeOuter diameter (mm)Length L (mm)Hole in parent (mm)Recommended boss OD (mm)Knurl bandsMaterialInstallation
M23.23.03.06.42Brass CuZn39Pb3Heated tip, 200-250 u00b0C
M2.53.64.03.47.22Brass CuZn39Pb3Heated tip, 200-250 u00b0C
M34.64.04.49.23Brass CuZn39Pb3Heated tip, 200-250 u00b0C
M34.65.74.49.23Brass CuZn39Pb3Heated tip, 200-250 u00b0C
M45.65.75.411.23Brass CuZn39Pb3Heated tip, 200-250 u00b0C
M56.95.86.713.83Brass CuZn39Pb3Heated tip, 200-250 u00b0C
M68.29.58.016.43Brass CuZn39Pb3Heated tip, 200-250 u00b0C
Inside the plant

Manufactured in our own plant

This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.

  1. Wire rod feeding into a cold heading machine
    01

    Cold heading

    Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.

    Head dimensions and under-head radius checked at set-up and per shift.

  2. Thread rolling machine producing bolt threads
    02

    Thread rolling

    Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.

    Go / no-go ring gauges to ISO 965 tolerance class 6g.

  3. Baskets of bolts staged for heat treatment
    03

    Heat treatment

    Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.

    Core hardness and tensile tested per lot to ISO 898-1.

  4. Zinc plated bolts in a treatment basket
    04

    Surface treatment

    Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.

    Coating thickness and neutral salt spray hours to ISO 9227.

Frequently Asked Questions

Which industries use Heat-Set Threaded Inserts for Plastic?

They are commonly specified in maintenance & repair (mro), fabrication & metalwork and aluminum & cast housings, among other sectors.

How do I choose the right size of Heat-Set Threaded Inserts for Plastic?

Match the nominal size to the mating thread or hole. This product is available from M2 to M6; the full dimension table on this page lists each size.

When should I use Heat-Set Threaded Inserts for Plastic instead of tapping directly?

Use them in soft alloys, plastics or thin sections where a cut thread would strip, or to repair a stripped hole. In strong steel that already holds a thread well, they are usually unnecessary.

What material should Heat-Set Threaded Inserts for Plastic be for outdoor use?

For damp, coastal or chemical environments specify A4 (316) stainless or a suitably coated steel. For indoor or dry use, A2 (304) stainless or zinc-plated steel is normally adequate.

Can I get a quote for Heat-Set Threaded Inserts for Plastic in the size and material I need?

Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time.