---
title: "Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws"
description: "Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws (ISO 898-1 property class 12.9): requires plating or black-oxide protection."
url: https://engineeringhardware.com/guide/material/grade-12-9-steel-peek-engineering-plastic-micro-countersunk-screws/
source: Engineering Hardware & Fasteners
---

# Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws

Screws · Trade series (PEEK micro screws)

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

Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws are supplied to ISO 898-1 property class 12.9. Corrosion behaviour is requires plating or black-oxide protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the highest common strength class, for high-load machine assembly.

- **Grade:** ISO 898-1 property class 12.9
- **Corrosion resistance:** Requires plating or black-oxide protection
- **Magnetic response:** Magnetic
- **Service temperature:** commonly limited to approx. +300 °C; confirm against the coating and the load

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

![Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws reference image](https://engineeringhardware.com/wp-content/uploads/2026/09/PEEK-RENY-Plastic-Micro-Countersunk-Screws.webp)

Material page for peek engineering plastic micro countersunk screws in Property Class 12.9 Steel (ISO 898-1 property class 12.9). 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 requires plating or black-oxide protection and the service range is commonly limited to approx. +300 °C; confirm against the coating and the load.

## Why Choose Property Class 12.9 Steel for PEEK Engineering Plastic Micro Countersunk Screws

The highest common strength class, for high-load machine assembly. For peek engineering plastic micro countersunk screws, this matters when requires plating or black-oxide protection is the primary requirement.

## Mechanical & Physical Properties

| Grade designation | ISO 898-1 property class 12.9 |
| --- | --- |
| Magnetic response | Magnetic |
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
| Corrosion characteristic | Requires plating or black-oxide protection |

## Corrosion Behavior in Service

Carbon and alloy steel peek engineering plastic micro countersunk screws require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.

## Comparable Grades

For PEEK Engineering Plastic Micro Countersunk Screws, class 8.8 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.

## Sizes of PEEK Engineering Plastic Micro Countersunk Screws Available in Property Class 12.9 Steel

| Thread size | Example length (mm) | Head diameter (mm) | Drive | Example tensile break load (N) | Example torsional break torque (Nu00b7m) |
| --- | --- | --- | --- | --- | --- |
| M1.2 | 2.5 | 2.3 | cross recess No. 0 | 58 | 0.03 |
| M1.4 |  | 2.3 | cross recess No. 0 |  |  |
| M1.6 |  | 2.3 | cross recess No. 0 |  |  |

Dimensions are independent of the material: the table above lists the sizes supplied, and on this page every one of them is quoted in Property Class 12.9 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 screw in a grade that is not listed?

Grade 12 9 Steel is one of the grades the catalog describes. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or warm forging.

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

[Custom screw manufacturing](https://engineeringhardware.com/custom/screws/)[Send a drawing](https://engineeringhardware.com/custom/screws/#rfq)

## Technical Drawing

Dimensioned line drawing of M1.2 PEEK Engineering Plastic Micro Countersunk Screws to Trade series (PEEK micro screws). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.

- **Example length (mm):** 2.5
- **Head diameter (mm):** 2.3
- **Drive:** cross recess No. 0
- **Material:** PEEK engineering plastic
- **Example tensile break load (N):** 58
- **Example torsional break torque (Nu00b7m):** 0.03

## Dimensions & Specifications (Trade series (PEEK micro screws))

| Thread size | Example length (mm) | Head diameter (mm) | Drive | Material | Example tensile break load (N) | Example torsional break torque (Nu00b7m) |
| --- | --- | --- | --- | --- | --- | --- |
| M1.2 | 2.5 | 2.3 | cross recess No. 0 | PEEK engineering plastic | 58 | 0.03 |
| M1.4 |  | 2.3 | cross recess No. 0 | PEEK engineering plastic |  |  |
| M1.6 |  | 2.3 | cross recess No. 0 | PEEK engineering plastic |  |  |

Product catalog

## Related Plastic Micro Screws products

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**US$0.12**MOQ 1 piece

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[View all Countersunk & Flat-Head Machine Screws →](https://engineeringhardware.com/fastener-products/screws/countersunk-flat-head-machine-screws/) [Full product catalog](https://engineeringhardware.com/products/)

## Applications & Industries

PEEK Engineering Plastic Micro Countersunk Screws are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from M1.2 to M1.6.

### Industries that specify PEEK Engineering Plastic Micro Countersunk Screws

- **Prototype assemblies:** Countersunk plastic screws avoid a metal head near the component.
- **Insulated electronics:** Engineering-plastic screws provide a nonconductive threaded joint in a compact package.
- **Vacuum and analytical equipment:** Low-outgassing plastic is used around sensitive instruments.
- **Chemical equipment:** PEEK resists service environments where ordinary metal hardware may be unsuitable.
- **Automotive & transport:** Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload.
- **Steel fabrication:** Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.

### Typical applications

- using the 90-degree head seat and No. 0 recess
- providing electrical insulation with a miniature countersunk screw
- checking the documented break loads instead of borrowing metal-screw torque
- matching the plastic screw to the parent thread without over-driving it
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload

### 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.
- **High load:** Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- **Torque and preload:** The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.

### Where to use something else

- Do not substitute metal-fastener torque for the plastic break-torque example; over-driving can fracture the screw.
- Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.

[Full application guide: where PEEK Engineering Plastic Micro Countersunk Screws are used, how to specify them, and the cases they are wrong for](https://engineeringhardware.com/applications/peek-engineering-plastic-micro-countersunk-screws/)

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

### Are Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws magnetic?

Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws are magnetic.

### What corrosion resistance do Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws offer?

Property Class 12.9 Steel PEEK Engineering Plastic Micro Countersunk Screws provide requires plating or black-oxide protection with a service range of commonly limited to approx. +300 °C; confirm against the coating and the load.

### When should I move from ISO 898-1 property class 12.9 to class 8.8 for PEEK Engineering Plastic Micro Countersunk Screws?

Step up to class 8.8 when the joint preload approaches the proof load of the current class. The higher class adds preload at the same diameter, often saving size and weight.

### Is Property Class 12.9 Steel prone to hydrogen embrittlement?

Class 10.9 and above can be susceptible to hydrogen embrittlement when electroplated. Specify post-plating baking, or use mechanical-zinc / zinc-flake finishes which avoid the cathodic plating step.

### 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 PEEK Engineering Plastic Micro Countersunk Screws page](https://engineeringhardware.com/fastener/peek-engineering-plastic-micro-countersunk-screws/)

### More PEEK Engineering Plastic Micro Countersunk Screws Guides