References – Industrial plants

A renowned manufacturer of precision scales relies 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, abrasive manufacturing process for conductive materials. The process is based on electrical discharge (sparks) between the electrode as the tool and the conductive workpiece (in this case, aluminium components).

When machining aluminium components (wire EDM), extremely fine particles are removed from the workpieces. The particles produced during this process are <1μm. The removed material must be continuously removed from the process water circuit. Typically, consumables (disposable paper filters) are used for this purpose. This process involves a corresponding amount of effort in terms of procurement and stocking. At the same time, the used filters must be continuously replaced and disposed of

Following a discussion at the Parts2clean trade fair in Stuttgart, a project was launched to develop glass bead-based filtration. The first step involved laboratory tests to analyse the process water. Based on the results of the process water analysis and taking into account the process water quality requirements, a three-month trial run of a SiLibeads filter pack test system was carried out on site (at the manufacturer’s premises). During this test, a partial flow of the process water was treated in bypass mode. The test operation was continuously monitored with sampling and analysis. The test results were then evaluated and assessed. Following the successful test run of the SiLibeads Filter Pack particle filtration system, a large-scale plant was planned, built and installed.

As a central unit, it handles the process water treatment for 15 EDMs (electrical discharge machines) with fully automatic supply and recirculation of the process water.

• Return tank Collection tank Unfiltered – from EDM to treatment
• Feed tank Collection tank Filtered – to EDM
• 2 x 4 SiLibeads filter pack filter battery, multi-layer glass bead filter bed
• Solid discharge via a chamber filter press (KFP)
• Commissioning of the large-scale plant with the rinsable, regenerable SiLibeads glass bead filters took place in July 2022

Detailed measurements can be provided on request.

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

The SiLibeads filter system achieves 20.6 times better performance in retaining dissolved aluminium and 3.4 times better separation performance in terms of total aluminium concentration compared to the paper filter cartridges previously used. Before switching the process water treatment to backwashable SiLibeads filter systems, the situation was as follows:

• Each of the 15 EDM units required four paper filter cartridges.
• The replacement interval for the disposable cartridges was two to three days.
• An average of 120 paper filter cartridges were required each week.
• The cost per cartridge was around £65. This meant that the cost of the disposable cartridges used in process water treatment amounted to around €36,000 per month.
• In addition to the consumption and disposal costs, replacing the cartridges required a considerable amount of manpower.
• There was also no sustainability benefit, as the cartridges were disposable and non-regenerable.

Since the large-scale plant went into operation in July 2022, over 5,000 disposable cartridges have been saved. The operation of the recirculating water treatment and recovery system and the supply of the 15 EDM units is largely automated. Maintenance and handling costs have been significantly reduced. Within one year, savings of over €400,000.00 have been achieved.