bedra FAQ - Frequently asked questions

Answers to frequently asked questions in the field of spark erosion (EDM)

Are you looking for quick answers to the most important questions about spark erosion (EDM)? Then you are in the right place. On this page you will find a list of the most frequent questions and answers sorted by category.

General questions

How do I select the right wire type for a defined customer inquiry or sampling?

Try the wire button on our website. It is very helpful and you can get to it by clicking here. The wire button will ask a series of questions, depending on your project needs, and recommend the most suitable wire solutions. You may also contact our EDM application team for further inquiries.

Wire button

What are the advantages of coated wire?

Coated bedra wire electrodes achieve a higher processing speed in spark erosion compared to conventional bare wires. This increases the efficiency and profitability of your EDM processes. Coated wires also increase your process reliability, such as the risk of wire cracks in case of poor flushing conditions or when machining high workpieces is reduced. In addition, our coated EDM wires achieve an excellent surface quality and edge zone integrity of the workpiece. Quality, economy and productivity therefore go hand in hand when using coated EDM wires. One example: Compared to conventional brass wire, the use of gapstar® ONE can increase the machining speed by up to 60 percent. If wire consumption and the machine hourly rate are taken into account, production costs are reduced by more than 37 percent.

More information

Will spark erosion damage my workpiece?

Spark erosion is a thermal material removal process in which very small amounts of material are locally melted and removed as a result of clocked spark discharges. In the early years of EDM, generator and control technologies were not mature. Often, a very pronounced edge zone with thermal damage such as cracks, microstructural transformations, and residual stresses could appear in the manufacturing process. The so-called "white edge layer", which is created by the very rapid resolidification of molten material, has gained special significance in spark erosion. Due to the extremely fine-grained or even amorphous structure, this zone appears white in micrographs. Many users still associate spark erosion with unavoidable severe damage to the component edge zone.

In modern wire EDM, however, the energy pulses are so short and so controlled that the heat can only penetrate the workpiece to a very small extent. In particular, the use of re-cutting with successively reduced discharge energy means that the thermal influence can now be limited to less than 1 µm. This is an order of magnitude in which the thermal influence of machining processes, such as grinding or hard milling, also lies. Modern wire EDM is safe, effective, and well suited to create custom, high-finish, specialty parts for use in a variety of medical, aerospace, and industrial applications.

Wire erosion can also lead to discoloration of the surface due to oxidation and deposition of residues. However, these can be easily removed with standard cleaning agents.

Which materials can be eroded?

Erodability requires a certain minimum electrical conductivity of the material. Metals and metallic alloys are therefore easily erodible. Common metals used in EDM are steels, aluminium alloys, titanium alloys, nickel alloys, copper and non-ferrous metals.  Sintered materials consisting of hard phase(s) and binder phase(s) can also be eroded. Even if the hard phase is an electrical insulator, the electrical conductivity of the binder phase can make it possible to erode. Classical examples of sintered materials in spark erosion are hard metals and PCD (polycrystalline diamond) and increasingly also special ceramic materials. Graphites can also be processed by spark erosion. Problems can occur if workpieces are provided with a non-conductive coating or have strong oxide layers, or if the material has larger non-conductive phases or impurities, such as non-metallic inclusions. Mechanical properties such as strength and toughness, on the other hand, have no influence on the erodibility.

Which materials cannot be eroded?

Electrically non-conductive materials and semiconductors cannot be eroded. These include, for example:

  • Wood
  • Plastics
  • Glass
  • Ceramic materials
  • Silicon

Can the wire be reused?

 The wire cannot be reused immediately, as it wears out during the EDM process. However, it can be recycled. Our sustainability principle bedra360 is ideally suited for this purpose.

What is the maximum height of my workpiece?

The maximum height of the workpiece is generally determined by the size of the wire EDM system, i.e. by the maximum travel of the Z-axis. For standard machines, the maximum cutting height is usually at least 250 mm. Depending on the size, the cutting height can be up to 1000 mm. However, even greater heights could be achieved by special machine modifications. From heights of 100-150 mm, the use of a wire diameter of 0.30 mm or larger is advisable to ensure efficient machining.

Can bedra wire electrodes be used on all eroding machines? What do I have to consider?

Most bedra products can be used universally on all common wire EDM machines. However, there are wires which are specially developed for certain machine types of the manufacturers. Therefore these wires are not necessarily suitable for use on other machines. Our wire buton will guide you to the best suited bedra wire electrode based on the machine type and other application criteria. Our EDM application team is at your disposal for further inquiries.

Wire button

What makes the patented bedra spool so special?

The patented and innovative 12-cornered shape prevents it from rolling away. Thus, bedra erosion wires can be stored lying down properly while work safety is improved.

Wire application

Up to what surface roughness can topas® plus G be used?

topas® plus G can be used to produce the highest surface qualities.

Can carbide also be machined with topas® plus G?

Yes, topas® plus G is also suitable for machining tungsten carbide.

What is the wire recommendation for conical applications?

Wires with an elongation >10% are recommended for cutting cones >7°. Our gapstar® ONE.5 is very well suited for this purpose.
For cutting cones >30°, wires with an elongation of >30% are recommended. Our gapstar® ONE.4 is very well suited for this purpose. For more detailed information please use our wire button.

Wire button

What is bedra's wire recommendation for machining carbide?

For the machining of carbides we recommend the wires cobracut® Type G and topas® plus G.

Which wires are particularly suitable for highest precision and fine surfaces?

In terms of precision, our cobracut® Type G is the measure of all things.

Which wire type is particularly suitable for series production?

Our new wire type gapstar® ONE.9 is particularly suitable for series production due to its uniquely high cutting performance.

Which wire is best suited for particularly high workpieces? ( > 100 mm )

For most machine types we recommend our new wire type gapstar® ONE.9, for a safe recommendation please use our wire button.

Wire button

Which wire is best suited for poor flushing conditions?

For most machine types we recommend our new wire type gapstar® ONE.9, for a safe recommendation please use our wire button.

Wire button

Which wire is best suited for machining nickel and titanium alloys?

For most machine types we recommend our new wire type gapstar® ONE.9, for a safe recommendation please use our wire button.

Wire button

Which wire is best suited for aluminium processing?

For most machine types we recommend our new wire type gapstar® ONE.9, for a safe recommendation please use our wire button.

Wire button

Which wire is best suited for graphite machining?

For most machine types we recommend our new wire type gapstar® ONE.9, for a safe recommendation please use our wire button.

Wire button

Which wire is best suited for contamination-free processing?

This depends on the exact requirements of the individual application. Our application team is at your disposal for concrete recommendations.

Send inquiry

Which wire is best suited for standard machining of polycrystalline diamond (PCD) and cubic boron nitride (CBN)?

This depends on the machine type and manufacturer. Our wire button will help you here.

Wire button

Which wire is best suited for micromachining with a diameter of 0.10 mm?

We recommend the microcut® CCA.

Which wire is best suited for micromachining with a diameter of less than 0.10 mm

This depends on the machine type, manufacturer and specific diameter. Our wire button will help you here

Wire button


How do I support the cause analysis at Berkenhoff in case of a complaint?

For a quick analysis of the causes and elimination of the error, it is crucial that we inspect the rejected goods. You can therefore support the complaint process by returning at least one wire coil that contains the fault as quickly as possible. An additional short description of the fault in picture or text form is also very helpful. Furthermore, you are welcome to contact our application team personally.

Send inquiry

Wire handling & wire storage

My wire is stuck. What can I do to fix it?

Expose the snagged coils and cut the bundle of coils with scissors. Grasp all ends by hand and pull the wire layers over the coil flange.

What is the best way to store bedra spools?

The spools are packed in shock, dust, and oxidation-proof material to protect the wire from shipping damage and contamination. The wire should be stored in the original packaging until ready for use. This will ensure the highest quality for your EDM applications. The storage of the EDM spools should also always be stored in a horizontal manner to prevent loosening / falling of individual turns of wire and thus disturbances during unwinding. Warranty will void in case of improper storage. You can find more information on the EDM product page.

EDM product page

What is the best way to store a used spool?

It is very important to properly secure the loose end of the wire on partially used spools. This will prevent the wire from shifting on the spool and becoming tangled. Improper handling and storage techniques can cause unwinding problems and unnecessary wire breakage. Partially used spools should be stored in their original packaging material when not in use. This will minimize contamination and shifting of the wire on the spool. You can find more information on the EDM product page.

EDM product page


What is bedra360?

bedra360 - the all-round sustainability principle enables the recovery of copper and brass wire and its return to a closed recycling loop. The return of used wire recyclables is carried out by our authorised dealer network directly at the end customer. The recyclable materials are collected in transport containers provided by bedra and then collected by us from the dealer. Afterwards, the recyclable materials are reprocessed (cleaning, melting down, casting) to produce new wire.

This offers the following advantages:

  • Reduction of the metal price dependency
  • Cost advantages due to metal quenching and tempering
  • Image and sustainability gain without additional costs

bedra360 is currently only available in Europe.

More information about bedra360

Please contact me and my team

Stefan Flügge

Stefan Flügge

Director Sales & Marketing EDM Europe
bedra Germany

Jackie Smith

Jackie Smith

Sales Manager EDM North America
bedra USA

Willy Gao

Willy Gao

Sales Director EDM Asia (without China)
bedra Hong Kong

Berkenhoff GmbH (headquarters)

  • Kinzenbach plant
  • Berkenhoffstrasse 14
  • 35452 Heuchelheim
  • Germany

Berkenhoff GmbH

  • Merkenbach plant
  • Rehmühle 1
  • 35745 Herborn
  • Germany

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