What is an EDM Block?

An EDM block is a specially prepared block of conductive material such as steel that serves as the workpiece for the EDM process. EDM stands for Electrical Discharge Machining.

• "Electrical Discharge Machining" Block - Material removal through spark erosion

An EDM block, also referred to as an Eroding Block, typically doesn’t pertain directly to the field of steel production or steel processing but more so to the realm of spark erosion (electro-erosive machining). This method removes material through electrical discharges. 

• EDM block annealed - Material removed through electrical discharges and then hardened.
• EDM block hardened - Material is already hardened and can be removed.

To save work time and to avoid problems during the demanding heat treatment, already hardened erosion blocks are often used in practice.

In metalworking, EDM is frequently employed to work on complex or hard-to-reach areas of very hard materials, which would be challenging to access with conventional mechanical methods.


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An EDM block or EDM square block is typically used in the manufacturing industry, such as in tool and mold making. In particular, tool steel is a frequently used material for EDM blocks.

Some specific applications include:

• Manufacturing of high-performance cutting tools
• Production of complex shapes
• Reference or "sacrificial piece"

EDM block for the production of high-performance cutting tools

EDM blocks are used to manufacture cutting tools such as cutting dies, cutting plates, and press dies.

EDM Block for the Production of Complex Shapes

EDM blocks are used for the fabrication of molds and tools since the EDM process can work with materials that are already hardened without softening them. As EDM is capable of handling challenging profiles and tight tolerances, an EDM block is often utilized to produce molds, dies, and cavities that are difficult to produce with traditional machining techniques.

EDM block as a reference piece or "sacrificial piece"

The EDM block can also be used as a reference or "sacrificial piece" on which the erosion process is tested or calibrated before it is applied to the actual workpiece.


The production of an EDM block (electro-discharge machining block) depends on the desired composition and specific applications, but in general, the manufacturing process follows these steps:

1. Material selection
2. Preparation of the raw material
3. Heat treatment
4. Cutting
5. Surface treatment
6. Quality control

Material Selection

For the production of an EDM block, a suitable material is chosen. In most cases, steel is used, particularly tool steels, but other conductive materials can also be utilized depending on the application.

Preparation of the Raw Material

The chosen material is shaped into a suitable form, e.g., through casting, rolling, or forging, depending on the specific requirements of the end product.

Heat Treatment

To achieve the desired mechanical properties, the block can undergo heat treatment. This can include hardening, tempering, or other processes to optimize the hardness, toughness, or other properties of the steel.


The block is cut to the desired size and shape, either by sawing, shearing, or other methods.

Surface Treatment

Depending on the application, it may be necessary to process the block's surface, e.g., through grinding, polishing, or other procedures, to achieve a suitable surface roughness or purity.

Quality Control

Before the EDM block is ready for use, it undergoes a quality control check to ensure it meets the specified requirements. This can include a review of the composition, mechanical properties, and dimensions.