EDM | Electrical Discharge Machining (Spark erosion)

In operation since July 2022 | Savings approx. 400,000 € / year
(of consumables / filter cartridges)

A world-leading manufacturer of precision scales focuses on quality and sustainability in its production chain. Electrical discharge machining (EDM), also known as spark erosion (DIN 8580) or electroerosive machining, is a thermal, erosive manufacturing process for conductive materials. The process is based on electrical discharge processes (sparks) between the electrode as a tool and the conductive workpiece (here the aluminum components).

During the machining of aluminum components (wire EDM), very fine particles are removed from the workpieces. The particles that are introduced during this process are <1μm.
The material removed must be continuously removed from the process water circuit. Typically, consumables (disposable cartridge paper filters) are used for this purpose. This process causes a corresponding effort in terms of procurement and stocking. At the same time, the used filters must be continuously replaced and disposed of.

Project history
After a trade fair discussion, at the Parts2clean in Stuttgart, a project for glass bead assisted filtration was set up. In the first step, laboratory tests for process water analysis were carried out. Based on the results of the process water analysis and taking into account the requirements for the process water quality, a 3-month test operation of a SiLibeads Filter Pack test plant was carried out on-site (at the manufacturer). Here, a partial flow of the process water was treated in by-pass operation. The test operation was continuously accompanied by sampling and analysis. Subsequently, the test results were evaluated and assessed. After successful testing of the SiLibeads Filter Pack Particle Filtration, planning, construction and installation of a large-scale plant took place.

As a central unit, this system handles the process water treatment of 15 EDMs (EDM machines) with fully
automatic feed and return of the process water.

• Return tank Collecting tank Unfiltrate – from EDM to reprocessing
• Feed tank collecting filtrate – to EDM
• 2 x 4 SiLibeads Filter Pack filter battery, multilayer glass beads filter bed
• Solids discharge via a chamber filter press
• Commissioning of the large-scale plant with the rinsable, regenerable SiLibeads glass beads filters took place in July 2022

Readings process water analysis
Detailed measured values can be provided on request.

Comparison of filtration efficiency
Paper filter vs. SiLibeads® Premium Filter Packs

Flow diagram process water treatment EDM

Project example EDM system | Process water treatment/recovery
Starting point: Process water inlet unfiltered 13,900 μg/l (aluminum)

SiLibeads Premium Filter Pack vs. paper cartridge filter performance characteristics
The SiLibeads Filter Pack achieves a 20 times better performance in the retention of dissolved aluminum and a 3.4 times better separation performance, related to the total concentration of aluminum, compared to the previously used paper filter cartridges. Prior to the conversion of the process water treatment to backwashable SiLibeads Filter Packs, the existing situation was as follows:

• Each of the 15 EDM units required 4 paper filter cartridges.
• The replacement interval for the disposable cartridges was 2-3 days.
• An average of 120 paper filter cartridges were required weekly.
• The cost per cartridge was approximately 75.00 €. Thus, the costs for the disposable car tridges used in the process water treatment amounted to about 36,000.00 € per month.
• In addition to the consumption and disposal costs, the cartridge changeover required extensive manpower.
• There was also no sustainability effect, as the cartridges used were disposable and could not be regenerated.

Since the large-scale plant was put into operation in July 2022, over 5,000 disposable cartridges have been saved. The process of recirculating water treatment and recovery, as well as the supply of the 15 EDM units, is automated to the greatest possible extent. The maintenance and handling effort has been significantly reduced. Over 400,000.00 € were saved within 1 year.

Test system images