OKI EDM wire

1. What is a wire for EDM machine?

There is a machining method that uses a high voltage electrical discharge phenomenon for cutting metal. Two types of tools utilize this method, the wire EDM machine and the die-sinking EDM machine. The term wire for EDM machine refers to the wire that is used to generate the electrical discharge in the wire EDM machine.

2. How the wire for EDM machine is used

Wire EDM generates an electrical discharge between the work piece (metal) and the wire for EDM machine, as the wire is continuously fed. This melts and cuts the metal in a way similar to a fret saw.
The diameter of the wire is determined according to the shape and thickness of the metal to be machined. A wire of 0.1 to 0.3mm in diameter is typically used. The metal to be machined is melted and cut by the discharge, but the wire is partially consumed at the same time, as a discharge trace is formed. (The trace is created when the wire surface melts and splatters.)
The partially consumed wire has insufficient strength to withstand any significant tension. Therefore, new wire must be continuously supplied. The wire is sold on a bobbin, so that it can be continuously supplied during EDM.

• * : The wire for EDM machine is a consumable item that is discarded after one use.

3. Types of wires for EDM machine

There are two main types of wire used for the main wire for EDM machine, brass wire and coated wire.

(1) General-purpose brass wire

Brass is an alloy of copper and zinc and has excellent discharge characteristics.
These discharge characteristics improve as the zinc content of the brass increases. However, it becomes difficult to form high zinc-content brass into a thin wire, because the malleability of the brass is reduced.
Brass with 35% to 40% zinc content is widely used, considering the balance between product performance and machining characteristics.

OKI product line-up

Model No.	Wire diameter	Quality	Paraffin	Alloy No.	Tensile strength	Elongation
OB-P	0.1 to 0.3mm	Hard material	Yes	JIS H 3260 C2700W	> 980 N/mm2	< 3 %
OB-PZ	0.1 to 0.3mm	Hard material	Yes	JIS H 3260 C2800W	> 980 N/mm2	< 3 %
OB-7S	0.07mm	Hard material	Yes	Brass alloy	> 950 N/mm2	< 2 %
OB-PN	0.07 to 0.3mm	Hard material	No	JIS H 3260 C2700W	> 980 N/mm2	< 3 %
OB-PZN	0.1 to 0.3mm	Hard material	No	JIS H 3260 C2800W	> 980 N/mm2	< 3 %
OB-B	0.1 to 0.3mm	Soft material	Yes	JIS H 3260 C2700W	> 442 N/mm2	< 20 %

(2) Coated wire

A number of the characteristics of the single-layer structure have limitations. The coated wire has functionality that overcomes these limitations.
Currently, the main types of coated wire on the market are zinc-coated wire and diffusion-annealed wire.

OKI product line-up

Model No.	Wire diameter	Type	Paraffin	Tensile strength	Elongation
OS-Z	0.1 to 0.3mm	Zinc-coated	Yes	> 883 N/mm2	< 3 %
OS-SN	0.2 to 0.3mm	Diffusion-annealed	No	> 883 N/mm2	< 3 %
OS-GN	0.2 to 0.3mm	Diffusion-annealed	No	> 700 N/mm2	< 20 %

4. OKI’s commitment to wire for EDM machine

Since OKI began selling wire for EDM machine in 1976, the product has been well received by the market. OKI’s customers can be found across Asia, North America, and Europe, as well as in Japan. For the future, OKI will continue to broaden the manufacturing know-how it has cultivated for over 30 years, so that OKI’s products become a favorite the world over. Moreover, OKI will further improve wire products to meet their customers’ needs, and bring new products to the market.

OB-P wire/OB-B wire

This wire is the basic type in the series. It is available in two types, hard (P type) and soft (B type). This wire exhibits maximum EDM performance in a general-purpose, standard grade, or other wire EDM machine.

OS-Z wire

This zinc-coated wire consists of brass wire electroplated with high purity zinc. The high plating accuracy realizes faster machining speed and also provides a better surface finish on the work piece.

OB-PZN wire

This wire is not coated with paraffin. It is ideal mainly for a wire EDM machine which has an AWF mechanism manufactured by Fanuc.
This wire provides the work material with a fine finish and also realizes superior automatic threading ability.

OB-PN wire

This wire is not coated with paraffin. It is ideal mainly for a wire EDM machine used in combination with an AT unit made by Mitsubishi Electric. This wire provides the work material with a fine finish and also realizes superior automatic threading ability.

OB-7S wire

This type has the smallest wire diameter in the series. It uses a brass type special alloy, realizing a reduction of cost compared to expensive tungsten wire. It exhibits maximum EDM performance in a wire EDM machine intended exclusively for using fine wire for precision machining of molds for lead frames, and so on.

OS-UZ wire

Compared with conventional wires, OS-UZ achieves 30% higher cutting speed while rough cut, also improves the smoothness of surface and positioning accuracy. 
Special coating on the wire prevents rusting and much improves its shelf-life.
A newly developed manufacturing technology enables the wire to reduce metal powder drastically compared with the conventional wires.