---
title: "A2 (304) Stainless Steel Heat-Set Threaded Inserts for Plastic"
description: "A2 (304) Stainless Steel Heat-Set Threaded Inserts for Plastic (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70): good general corrosion resistance."
url: https://engineeringhardware.com/guide/material/a2-stainless-steel-heat-set-threaded-inserts/
source: Engineering Hardware & Fasteners
---

# A2 (304) Stainless Steel Heat-Set Threaded Inserts for Plastic

Threaded Inserts · Trade series (heat-set insert)

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

A2 Stainless Steel Heat-Set Threaded Inserts for Plastic are supplied to ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70. Corrosion behaviour is good general corrosion resistance, 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 the most common stainless group for indoor and general outdoor fasteners.

- **Grade:** ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70
- **Corrosion resistance:** Good general corrosion resistance
- **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.

![A2 (304) Stainless Steel Heat-Set Threaded Inserts for Plastic reference image](https://engineeringhardware.com/wp-content/uploads/2026/09/Heat-Set-Inserts.webp)

Material page for heat-set threaded inserts for plastic in A2 Stainless Steel (ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70). The sizes below are the ones we supply; there is no published dimensional standard for this article, so the table rather than a standard number is what to quote. Corrosion behaviour is good general corrosion resistance and the service range is approx. -200 °C to +400 °C, subject to the property class and the joint.

## Why Choose A2 Stainless Steel for Heat-Set Threaded Inserts for Plastic

The most common stainless group for indoor and general outdoor fasteners. For heat-set threaded inserts for plastic, this matters when good general corrosion resistance is the primary requirement.

## Mechanical & Physical Properties

| Grade designation | ISO 3506 group A2 (304 / 1.4301), commonly supplied A2-70 |
| --- | --- |
| Magnetic response | Largely non-magnetic |
| Service temperature | approx. -200 °C to +400 °C, subject to the property class and the joint |
| Corrosion characteristic | Good general corrosion resistance |

## Corrosion Behavior in Service

A2 (304) gives excellent atmospheric and most-water corrosion resistance and is the most common stainless for Heat-Set Threaded Inserts for Plastic in indoor and general outdoor service. In chloride-bearing environments (marine air, road salt, swimming pools) consider stepping up to A4 (316).

## Comparable Grades

For Heat-Set Threaded Inserts for Plastic, the alternative stainless grade is A4 (316). Choose A2 (304) for general use and A4 (316) wherever chlorides are present; the molybdenum in A4 is the whole difference. Remember that stainless is the corrosion answer, not the strength answer — for load, look at class 8.8 or 10.9 instead.

## Using Stainless Fasteners in Aluminum

The galvanic couple here runs the wrong way: aluminum is the less noble metal, so it corrodes and the fastener does not. What governs the rate is the ratio of areas — a large anode and a small cathode is a tolerable combination, the reverse concentrates the attack into thin material around the hole. An isolating washer plus sealant breaks the circuit; where that is impractical, match the fastener to the substrate.

## Sizes of Heat-Set Threaded Inserts for Plastic Available in A2 Stainless Steel

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

Dimensions are independent of the material: the table above lists the sizes supplied, and on this page every one of them is quoted in A2 Stainless Steel. The catalogue's default material column has been omitted here so it cannot be read as contradicting that.

Custom manufacturing · Made to drawing

## Need this threaded insert in a grade that is not listed?

A2 Stainless Steel is one of the grades the catalog describes. Thread size, body length, knurl or key form and installation method are all variable against the parent material. Made by tapping or knurling.

Minimum order from 2,000 pieces; samples within 7 days of drawing approval.

[Custom threaded insert manufacturing](https://engineeringhardware.com/custom/inserts/)[Send a drawing](https://engineeringhardware.com/custom/inserts/#rfq)

## Technical Drawing

Dimensioned line drawing of M2 Heat-Set Threaded Inserts for Plastic to Trade series (heat-set insert). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Outer diameter (mm):** 3.2
- **Length L (mm):** 3.0
- **Hole in parent (mm):** 3.0
- **Recommended boss OD (mm):** 6.4
- **Knurl bands:** 2
- **Material:** Brass CuZn39Pb3
- **Installation:** Heated tip, 200-250 u00b0C

## 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 |

Product catalog

## Related Heat-Set & Molded-In Inserts products

[![Itb Itc Knurled Threaded Insert Nuts Brass Stainless Steel Injection Molding Fastener](https://img.engineeringhardware.com/Itb-Itc-Knurled-Threaded-Insert-Nuts-Brass-Stainless-Steel-Injection-Molding-Fastener.webp)](https://engineeringhardware.com/product/itb-itc-knurled-threaded-insert-nuts-brass-stainless-steel-injection-molding-fastener/)

Heat-Set, Knurled & Molded-In Inserts

### [Itb Itc Knurled Threaded Insert Nuts Brass Stainless Steel Injection Molding Fastener](https://engineeringhardware.com/product/itb-itc-knurled-threaded-insert-nuts-brass-stainless-steel-injection-molding-fastener/)

Round Head · DIN

**US$0.012 – 2.40**MOQ 1,000 pieces

[![Sonic-Lok Insert for Plastic Heat-Set Threaded Inserts](https://img.engineeringhardware.com/Sonic-Lok-Insert-for-Plastic-Heat-Set-Threaded-Inserts.webp)](https://engineeringhardware.com/product/sonic-lok-insert-for-plastic-heat-set-threaded-inserts/)

Heat-Set, Knurled & Molded-In Inserts

### [Sonic-Lok Insert for Plastic Heat-Set Threaded Inserts](https://engineeringhardware.com/product/sonic-lok-insert-for-plastic-heat-set-threaded-inserts/)

Round Head · DIN, GB, JIS, GOST, BSW

**US$0.06**MOQ 500 pieces

[![Made in China Series 63 and Series 65 Aluminum Molded-in Inserts for Automotive Industry](https://img.engineeringhardware.com/Made-in-China-Series-63-and-Series-65-Aluminum-Molded-in-Inserts-for-Automotive-Industry.webp)](https://engineeringhardware.com/product/made-in-china-series-63-and-series-65-aluminum-molded-in-inserts-for-automotive/)

Heat-Set, Knurled & Molded-In Inserts

### [Made in China Series 63 and Series 65 Aluminum Molded-in Inserts for Automotive Industry](https://engineeringhardware.com/product/made-in-china-series-63-and-series-65-aluminum-molded-in-inserts-for-automotive/)

DIN, ANSI, GB, JIS, GOST, BSW · Carbon Steel

**US$0.12 – 1.20**MOQ 1,000 pieces

[![St5*0.8 Threaded Metal Heat Set Screw Inserts for 3D Printing](https://img.engineeringhardware.com/St5-0-8-Threaded-Metal-Heat-Set-Screw-Inserts-for-3D-Printing.webp)](https://engineeringhardware.com/product/st5-0-8-threaded-metal-heat-set-screw-inserts-for-3d-printing/)

Heat-Set, Knurled & Molded-In Inserts

### [St5*0.8 Threaded Metal Heat Set Screw Inserts for 3D Printing](https://engineeringhardware.com/product/st5-0-8-threaded-metal-heat-set-screw-inserts-for-3d-printing/)

Common · Stainless Steel

**US$0.06 – 0.12**MOQ 1 piece

[![Automotive Chassis Double Ring Knurled Insert Nut High Precision](https://img.engineeringhardware.com/Automotive-Chassis-Double-Ring-Knurled-Insert-Nut-High-Precision.webp)](https://engineeringhardware.com/product/automotive-chassis-double-ring-knurled-insert-nut-high-precision/)

Heat-Set, Knurled & Molded-In Inserts

### [Automotive Chassis Double Ring Knurled Insert Nut High Precision](https://engineeringhardware.com/product/automotive-chassis-double-ring-knurled-insert-nut-high-precision/)

Auto Fasteners · DIN, GB, ISO, ANSI/ASTM, BS, Bsw, JIS etc.

**US$0.096 – 0.12**MOQ 20,000 pieces

[![CNC Part Custom M5 M6 M8 Golden Brass Copper Plastic Use Injection Flange Head Bushing Knurled Insert Nut](https://img.engineeringhardware.com/CNC-Part-Custom-M5-M6-M8-Golden-Brass-Copper-Plastic-Use-Injection-Flange-Head-Bushing-Knurled-Insert-Nut.webp)](https://engineeringhardware.com/product/cnc-part-custom-m5-m6-m8-golden-brass-copper-plastic-use-injection-flange-head/)

Heat-Set, Knurled & Molded-In Inserts

### [CNC Part Custom M5 M6 M8 Golden Brass Copper Plastic Use Injection Flange Head Bushing Knurled Insert Nut](https://engineeringhardware.com/product/cnc-part-custom-m5-m6-m8-golden-brass-copper-plastic-use-injection-flange-head/)

Insert Nut · DIN, GB, Per Customers' Desire

**US$0.072 – 0.14**MOQ 20,000 pieces

[View all Heat-Set, Knurled & Molded-In Inserts →](https://engineeringhardware.com/fastener-products/threaded-inserts-clinch-fasteners/heat-set-knurled-molded-in-inserts/) [Full product catalog](https://engineeringhardware.com/products/)

## Applications & Industries

The sectors that buy Heat-Set Threaded Inserts for Plastic, and the duty each one buys them for. Stocked from M2 to M6.

### Industries that specify Heat-Set Threaded Inserts for Plastic

- **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.
- **Additive manufacturing:** Threads in printed parts, where layer adhesion will not hold a screw.
- **Plastics & moulded parts:** Durable metal threads in housings that would strip if screwed into directly.
- **Aluminium & castings:** Reinforced threads in soft alloy, and repair of stripped holes.

### Typical applications

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

### 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.

[Full application guide: where Heat-Set Threaded Inserts for Plastic are used, how to specify them, and the cases they are wrong for](https://engineeringhardware.com/applications/heat-set-threaded-inserts/)

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](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 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](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 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

### Can A2 Stainless Steel replace plated alloy steel structurally?

Only at the standard strength classes — A2-70 / A4-80 are roughly equivalent to class 7 steel; A4-100 reaches class 8.8. For class 10.9 or 12.9 strength, plated alloy steel is required.

### Are A2 Stainless Steel Heat-Set Threaded Inserts for Plastic magnetic?

A2 Stainless Steel Heat-Set Threaded Inserts for Plastic are largely non-magnetic.

### What corrosion resistance do A2 Stainless Steel Heat-Set Threaded Inserts for Plastic offer?

A2 Stainless Steel Heat-Set Threaded Inserts for Plastic provide good general corrosion resistance with a service range of approx. -200 °C to +400 °C, subject to the property class and the joint.

### Should I choose A2 Stainless Steel or A4 (316) for Heat-Set Threaded Inserts for Plastic?

For Heat-Set Threaded Inserts for Plastic, A2 Stainless Steel suits general indoor and outdoor use; A4 (316) is preferred for marine, coastal and chemical environments. Choose by corrosion exposure first.

### 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.

## Related Pages

[View the full Heat-Set Threaded Inserts for Plastic page](https://engineeringhardware.com/fastener/heat-set-threaded-inserts/)

### More Heat-Set Threaded Inserts for Plastic Guides