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 does spark erosion work?

Surrounded by an insulating dielectric fluid, the electrically charged wire electrode never touches the workpiece. Instead, high-energy, plasma-hot sparks over 10,000°C, vaporize the material in front of it, cutting precise shapes in conductive materials, regardless of hardness. The current is pulsed, with some generators switching on and off in units of nano-seconds with cutting speeds over 400 mm²/min. The wire electrodes used in the application are from bedra.

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Who uses spark erosion?

Spark erosion is the uncontested key technology in the production of sophisticated moulding and stamping tools for production of metal and plastic parts for all industries. Additionally, there is the direct machining of complex precision components. Geometric variety and accuracy are the decisive erosion advantage. Unconventional solutions are realised. Freeform surfaces with extreme tapers, small holes, near-sharp corners and fine finishes. Everyone profits from spark erosion: whether we look at our watch, use an electric shaver, board a car, train or airplane, make a phone call, play or sit on stacking chairs … bedra EDM wire always represents a link in the chain of process.

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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.

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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.

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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

Which spool sizes are bedra EDM wire available on?

In our spool overview you will find all spools available for bedra products. Using the spool overview quick button, you can filter our product range by “EDM”.  In addition to the spool images, you can also find the spool dimensions and the maximum filling weight per spool (in kg).  

Furthermore, details of spool sizes available can be found under each respective EDM product under the “Delivery program” tab.

To the spool overview

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.

Where can I find the current metal prices?

In our metal price information system you can find daily updated metal prices. Displayed are overviews of currencies and the prices of raw metals. The metal prices are displayed either as a graph, a table or as a monthly average.

To the metal prices

Wire application

Why do we recommend the gapstar® ONE when using coated wire?

gapstar® ONE delivers unparalleled performance, up to 60% faster cutting than brass wire, while maintaining a competitive price. gapstar® ONE boosts cutting speed for both the main cut and the trimcuts, enabling this new wire to cover a broad range of applications from simple cuts to highly complex contours. Numerous lab tests and real world applications prove gapstar® ONE raises your throughput. Taking into account wire consumption and hourly machine rates, your production cost could be lowered up to 37%.

Another major advantage of gapstar® ONE is the compatibility across all EDM machine manufacturers and machine types with both a hard (gapstar® ONE.9) and two soft wire variants (gapstar® ONE.5 and gapstar® ONE.4). This means that no cumbersome adjustments are necessary in order to achieve the high cutting performance deliverd by gapstar® ONE.

For more information please visit the gapstar® ONE product pages.

Go to gapstar® ONE.9

Go to gapstar® ONE.5

Go to gapstar® ONE.4

What are the differences between gapstar® ONE and coated wire?

gapstar® ONE is a completely new generation of coated EDM wire that utilizes TRIMPAC® technology, something new to the world of EDM. TRIMPAC® means “Triple Impact Sheath” which describes a unique, patented technology that delivers up to 60% faster cutting performance as compared to brass wire. The difference between gapstar® ONE and other coated wires lies in the performance across all cuts with high precision and good surface quality. TRIMPAC® performance increases benefit both the main cut and trimcuts. High cutting precision is also achieved (Ra = 0.25). gapstar® ONE thus covers a very wide range of applications, i.e. from simple cuts to precision work with up to 4 trimcuts.

For more information please visit the gapstar® ONE product pages or check the next question (What advantages does gapstar® ONE offer compared to coated wire?).

Go to gapstar® ONE.9

Go to gapstar® ONE.5

Go to gapstar® ONE.4

What advantages does gapstar® ONE offer compared to coated wire?

gapstar® ONE cuts significantly faster than all wires of the previous generations and is the first product of our new TRIMPAC® wire generation. It offers plug and play compatibility on all machines, i.e. the wire works on machines with bare wire technologies as well as on machines with coated cutting technologies. gapstar® ONE operates with existing standard technologies of your machine. This means that no complicated adaptations are necessary in order to achieve high cutting performance.

gapstar® ONE is also characterized by good stability under poor flushing conditions, which can often occur in the manufacturing process.  Additionally, gapstar® ONE achieves significant performance at a very attractive price-performance ratio. In numerous laboratory tests as well as practical applications, gapstar® ONE demonstrates increased throughput by up to 60% compared to brass wire. If the wire consumption and the machine hour rate are taken into account, costs are reduced by up to 37%.

gapstar® ONE is available in 3 different versions : Type ONE.9 is suitable for cylindrical and slightly conical cuts on all EDM machines. The types ONE.5 and ONE.4 have been specially developed for taper machining.

For more information please visit the gapstar® ONE product pages.

Go to gapstar® ONE.9

Go to gapstar® ONE.5

Go to gapstar® ONE.4

What does TRIMPAC® mean?

TRIMPAC® is bedra's latest patented coating technology. From the strengths of the wire generations cobracut®broncocut® and topas® bedra developed the new coating technology TRIMPAC®. TRIMPAC® stands for "Triple Impact Sheath", which points out that the TRIMPAC® coating combines three effects:

1. The wire has a thin oxide layer that acts like a semiconductor and prevents faulty discharges, which improves the cutting quality.

2. The increased zinc content of the sheath increases abrasion, while at the same time improving wear resistance.

3. The surface has a special structure, which has a positive effect on the cutting performance and cutting quality.

As a result of the three effects, wires with TRIMPAC®  coating technology achieve significantly higher cutting performance levels than the wires of the predecessors.

TRIMPAC®  coating technology can be found in our new EDM high-performance wire generation gapstar® ONE.

Go to gapstar® ONE.9

Go to gapstar® ONE.5

Go to gapstar® ONE.4

Why do we recommend the betterbrass when using brass wire?

We recommend our new and innovative betterbrass for standard applications, as it usually offers an increased performance in eroding, which is even more effective with increasing workpiece height.

Furthermore, betterbrass is characterized by the following features in addition to the very good price-performance ratio:

  • Absolute process reliability 24/7
  • Plug-and-Play function on all machine types
  • Up-to-10% faster cutting speed
  • High cleanliness
  • Easy automatic threading

Faster eroding. Less wire consumption. Reduced wire costs

For more information please visit the betterbrass product page.

Go to betterbrass

What are the differences between betterbrass and a standard brass wire?

The differences of betterbrass compared to a standard brass wire are in the specialized development of the alloy. The innovative heat treatment generates the increased performance speeds up to +10%.

For further information please visit the betterbrass product page or check the next question (What advantages does the betterbrass offer compared to a standard brass wire?).

Go to betterbrass

What advantages does the betterbrass offer compared to a standard brass wire?

The key to the realization of betterbrass was innovation in our core continuous casting and heat treatment technologies. Through this, our engineers have succeeded in generating a wire electrode from a new type of alloy and thus raising performance to a new level.

For  betterbrass, alloy and casting technology are the basis for high process performance and stability already created during the original forming process. The specially developed heat treatment then completes the desired material structure.

The result is an increase in cutting performance of up to 10%. Thus, less wire is used and costs are reduced immediately. The improved results become even more apparent with lager workpiece heights. Reliability and precision meet the highest demands on bright brass wires.

betterbrass combines a lean manufacturing process with a performance characteristic that has never been achieved before:

  • Absolute process reliability 24/7
  • Plug-and-Play function on all machine types
  • Up-to-10% faster cutting speed

Faster eroding. Less wire consumption. Reduced wire costs

For further information please visit the betterbrass product page.

Go to betterbrass

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 Japanese machines?

In general, for Japanese machines such as Sodick, Fanuc or Mitsubishi, we recommend our betterbrass for the standard and our gapstar® ONE.9 with the new TRIMPAC® technology for high performance. For Makino, we recommend our topas® H.E.A.T. for high productivity in addition to betterbrass for the standard.

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

Complaint

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.

How long is the warranty period for bedra EDM wires?

The warranty period for all our EDM wires is 12 months after date of manufacturing. (See question: What is the best way to store bedra spools? and What is the best way to store a used spool?) You can find more information on the EDM product page.

EDM product page

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

Sustainability

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

Holger Seyock

Holger Seyock

Sales Director 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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