R.F. Bevan & Co.


Frequently Asked Questions

General Information

What is wire-erosion?
Wire-erosion is a machining process that cuts metal by creating an electrical spark between the workpiece and a thin brass wire. As the wire moves along a computer-controlled path the spark removes material, similar to cutting with a very thin piercing saw but without the mechanical contact.
What thickness can be cut?
We can cut thicknesses up to approximately 150mm. Very thin materials may need to be sandwiched in layers to increase rigidity and prevent them from deforming.
Can you cut through a stack of several sheets at once?
We can cut through a stack of sheets to produce multiple identical items. This can work out more economical in many cases; however, the increased thickness of the stack increases cutting time, and so the extra items are not zero cost. There is also a limit to the size of the stack, particularly for items with small holes and apertures.
Does wire-erosion burn or corrode the metal?
The heat generated by wire-erosion is very localised and does not cause a general work-hardening of the part. It may cause the production of a small amount of tarnish on the metal surface that is easily removed from most metals.


What materials can be cut?
Most electrically conductive metals can be cut, provided that they are free of non-conductive coatings or impurities. Suitable metals include:
  • Steel (including heat-treated and hardened steels)
  • Copper
  • Brass and bronze
  • Aluminium
  • Titanium
  • Silver
  • Gold
What materials cannot be cut?
  • Non-metallic items, such as wood or plastic
  • Metal that is coated in paint, laquer or other non-conductive surface, such as anodising
  • Welded areas that contain pockets of welding flux
  • Heavily corroded iron or steel.
Can I supply my own metal, or do you supply it?
You are welcome to supply your own metal. We do not hold stock of precious metals and so you would need to supply those. We can supply other metals if required; however, certain materials may have extended lead times and can therefore delay production. Advance payment may also be necessary.


What shapes can be cut?
Most 2d shapes with parallel sides can be cut provided that they do not require a tool diameter smaller than 0.3mm.
How much detail can be achieved?
A 0.3mm diameter cut can produce fairly detailed work. While internal corners will, by necessity, have a small radius, external corners will remain sharp.
What shapes cannot be cut?
Some paths cannot be cut because the workpiece itself may become too fragile as the supporting material is removed. Other designs may fail because the material that falls away when an internal hole or aperture is cut may get trapped within the machine. If a design seems problematic then we will advise you beforehand.

Metal loss / Scrap

How much metal is lost?
The approximate width of the cut is 0.3mm. This material is reduced to microscopic particles by the process and cannot be reclaimed. While we do try to retrieve all other scrap some small pieces may get flushed into the filtration system. Also, if holes or apertures have to be cut in the workpiece then this material may be lost as swarf.
Do I get my scrap metal back?
All scrap metal is available for collection from our workshop. Non-precious metal scrap is not automatically returned by post; however, it can be returned to you if you wish to pay any additional carriage charge.


How much does it cost?
Each job is priced individually, based on several factors (shown below).
What factors affect the cost?
In addition to any material costs, several factors contribute to the overall price. These include:
  • Setup time
  • Cutting time
  • Material type — different metals cut at different speeds: aluminium, copper and silver cut faster than steel and titanium.
  • Material Thickness — increasing the metal thickness also increases the cutting time.
  • Internal holes and apertures — For each internal hole or aperture it is necessary to drill a hole in the workpiece before cutting can begin. This is to allow the wire to be threaded through the workpiece. The machine must also be manually stopped and started for every aperture, with a consequent increase in the time required. Reducing the number of internal apertures in a design can be a major factor in reducing cost.
  • Very small apertures — tiny apertures require more accurate drilling and setup to ensure that they cut correctly, with a corresponding increase in the time required.