Ground Flat Stock

Also known as tool steel, ground flat stock is the high-quality choice for tool production. Available from Cromwell in a wide variety of sizes, we're proud to use Indexa® as our supplier of choice.

What is ground flat stock?

Much like silver steel, ground flat stock is a high carbon alloy supplied in annealed condition and is ground to precise tolerances.

Why ground flat stock?

The oil-hardening tool steel delivers extremely durable tools. Thanks to its high stability, it has wear-resistant properties and maintains a good cutting edge.

When is ground flat stock used?

Used mainly for the engineering of tools, this medium alloy is used to create punches, broaches, gauges, and tools used for precision measuring to name but a few.

Ground flat stock types

There are 3 types of ground flat stock, defined by the metal hardening type, these are named according to their series. O series describes oil-hardening metal and A series covers air-hardening alloys. All are cold working types that can be machined and shaped without the need for heating.

• BO1 - Used for cutting tools and gauges

• A2 - General purpose medium alloy, mainly used for cutting tools and gauges

• A6 - General purpose medium alloy, used for tool making and gauges

Ground flat stock jargon buster

We want to keep it simple, so we've broken down the key standard for ground flat stock to help you navigate the range a little better.

What does the standard BS 4659:1970 BO1 mean?

BS 4659:1970 BO1 specifies the technical requirements of tool steel, including the chemical and mechanical properties.

Let's break it down...

• BS - This is the abbreviation for British Standard

• 4659 - This is the assigned legislation number

• 1970 - This is the year this standard was updated

• BO1 - This is the type of metal to which the British Standard applies. In this case, it covers oil-hardening tool steel


What does precision ground mean?

Let's break it down. 'Precision' refers to the quality of the steel and the fine precision engineering process. 'Ground' describes how the bar faces are polished to precise tolerances.

How do you harden ground flat stock?

The hardening process requires the initial slow heating of the metal at a constant temperature of between 300°C and 500°C. The temperature is then raised to between 780°C and 820°C (the hardening temperature) before being quenched.