Threaded Inserts · Trade series (heat-set insert)

A4 (316) Stainless Steel Heat-Set Threaded Inserts for Plastic

Mechanical properties, corrosion behaviour and the full dimensional range for this grade.

A4 Stainless Steel Heat-Set Threaded Inserts for Plastic are supplied to ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80. Corrosion behaviour is superior, including marine and chloride environments, the material is largely non-magnetic, and the usable service range is approx. -200 °C to +400 °C, subject to the property class and the joint. In practice this grade is specified for marine, coastal and chemical applications.

Grade: ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80
Corrosion resistance: Superior, including marine and chloride environments
Magnetic response: Largely non-magnetic
Service temperature: approx. -200 °C to +400 °C, subject to the property class and the joint

Property values are typical for the grade. Certified mechanical test data is available on request for production orders.

Heat-Set Threaded Inserts for Plastic manufactured in A4 Stainless Steel (ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80) are dimensioned to Trade series (heat-set insert). The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.

Why Choose A4 Stainless Steel for Heat-Set Threaded Inserts for Plastic

Specified for marine, coastal and chemical applications. For heat-set threaded inserts for plastic, this matters when superior, including marine and chloride environments is the primary requirement.

Mechanical & Physical Properties

Grade designation	ISO 3506 group A4 (316 / 1.4401), commonly supplied A4-80
Magnetic response	Largely non-magnetic
Service temperature	approx. -200 °C to +400 °C, subject to the property class and the joint
Corrosion characteristic	Superior, including marine and chloride environments

Corrosion Behavior in Service

A4 (316) adds 2–3% molybdenum to the A2 (304) composition, which dramatically improves resistance to chloride-pitting corrosion. For Heat-Set Threaded Inserts for Plastic in marine, coastal, swimming-pool or food-processing environments, A4 is the default selection.

Comparable Grades

For Heat-Set Threaded Inserts for Plastic, the alternative stainless grade is A2 (304). The practical dividing line is chlorides: A2 (304) is fine until salt is involved, and A4 (316) exists for the cases where it is — coastal, marine and road-salt service. Neither reaches the strength of a plated class 8.8 or 10.9 fastener.

Using Stainless Fasteners in Aluminum

Stainless steel is more noble than aluminum, so with an electrolyte present — rain, condensation, salt spray — the aluminum becomes the anode and corrodes at the joint. Area ratio decides how bad it gets: a small stainless fastener in a large aluminum section is normally acceptable, a large stainless fastener in thin aluminum is not. Where the joint gets wet, isolate the metals with a coated or nylon washer and a sealant, or specify an aluminum or coated fastener instead.

Sizes of Heat-Set Threaded Inserts for Plastic Available in A4 Stainless Steel

Thread size	Outer diameter (mm)	Length L (mm)	Hole in parent (mm)	Recommended boss OD (mm)	Knurl bands	Material	Installation
M2	3.2	3.0	3.0	6.4	2	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M2.5	3.6	4.0	3.4	7.2	2	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M3	4.6	4.0	4.4	9.2	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M3	4.6	5.7	4.4	9.2	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M4	5.6	5.7	5.4	11.2	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M5	6.9	5.8	6.7	13.8	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M6	8.2	9.5	8.0	16.4	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C

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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Specification

Item / category Standard Size(s) Material / finish Quantity

Business Information

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Notes

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

Thread size	Outer diameter (mm)	Length L (mm)	Hole in parent (mm)	Recommended boss OD (mm)	Knurl bands	Material	Installation
M2	3.2	3.0	3.0	6.4	2	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M2.5	3.6	4.0	3.4	7.2	2	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M3	4.6	4.0	4.4	9.2	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M3	4.6	5.7	4.4	9.2	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M4	5.6	5.7	5.4	11.2	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M5	6.9	5.8	6.7	13.8	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C
M6	8.2	9.5	8.0	16.4	3	Brass CuZn39Pb3	Heated tip, 200-250 u00b0C

Applications & Industries

Where Heat-Set Threaded Inserts for Plastic are used, and what decides the specification in each case. Stocked from M2 to M6.

Industries that specify Heat-Set Threaded Inserts for Plastic

Additive manufacturing Threads in printed parts, where layer adhesion will not hold a screw.
Consumer electronics Housings assembled and re-opened for service.
Injection moulding Post-moulded threads in bosses.
Prototyping & product development Real threads in a printed prototype.
Aluminium & castings Reinforced threads in soft alloy, and repair of stripped holes.
Aerospace & motorsport Certified thread repair under vibration and inspection.

Typical applications

boss hole size is the critical dimension, not the insert length
a reusable metal thread in a plastic or printed boss
installed with a heated tip so the plastic flows into the knurl
assemblies opened and closed many times over their life
creating a reusable metal thread in a soft or thin parent
repairing a stripped hole to its original size

Service conditions to specify against

Marine and coastal: Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
Parent material first: The insert type is chosen by what it goes into — moulded plastic, printed polymer, alloy casting or timber — not by the screw that goes into it.

Need help matching Heat-Set Threaded Inserts for Plastic to your application? Send the assembly, the load and the environment with your enquiry and we will specify the size, material and finish against them.

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.

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.
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.
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.
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

What corrosion resistance do A4 Stainless Steel Heat-Set Threaded Inserts for Plastic offer?

A4 Stainless Steel Heat-Set Threaded Inserts for Plastic provide superior, including marine and chloride environments with a service range of approx. -200 °C to +400 °C, subject to the property class and the joint.

Should I choose A4 Stainless Steel or A2 (304) for Heat-Set Threaded Inserts for Plastic?

For Heat-Set Threaded Inserts for Plastic, A4 Stainless Steel suits general indoor and outdoor use; A2 (304) is preferred for marine, coastal and chemical environments. Choose by corrosion exposure first.

Can A4 Stainless Steel Heat-Set Threaded Inserts for Plastic gall during installation?

Yes — stainless on stainless is prone to thread galling under load, especially at smaller sizes. Use an anti-galling lubricant or wax thread compound, and slow the tightening rate where possible.

Is A4 Stainless Steel food-grade?

A4 (316) is the standard food-contact stainless grade in most jurisdictions, particularly where chloride exposure (brines, dairy CIP) is present.

How do I request a quotation?

Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.