cleaning & finishing
IT’S estimated that around 50% of
manufacturing companies in the UK are still
using trichloroethylene and similar solvents
for degreasing. If they’ve continued to do so
after 31st October this year, they could face
prosecution under the Solvent Emissions
Regulations 2004. However, using high
purity water in aqueous based washing
machines can produce results as good as
solvent cleaning systems, as Renishaw has
discovered.
Renishaw uses Mecwash Midi 400 washing
machines to remove cutting oils from
precision machined components. ‘We noticed
that some of our parts, particularly satin
chrome plated components, suffered staining
even when they were rinsed in demineralised
water,’ explains development engineer Neil
Wood. ‘We now use ELGA Process Water
Aquaclean service exchange cylinders to
improve the quality of our demineralised
water by an order of magnitude, and that
eliminates the staining.’ Renishaw uses two
ELGA Process Water Aquaclean cylinders in
series, the first containing activated carbon
and the second containing a mixed bed of
cation and anion exchange resins. There are
also environmental benefits; Renishaw now
Renishaw is using pure water to deliver high performance
aqueous washing, thereby reconciling compliance on
solvent emissions legislation with component quality.
Cracking down
on solvent abuse
recirculates water from the rinse tank, which
used to be discharged to waste at a
conductivity of about 100μS/cm. Passing the
water from the rinse through an ELGA
Process Water Aquaclean exchange cylinder
upgrades its quality to about 5μS/cm and
allows recirculation - thus reducing mains
water consumption and eliminating the need
to discharge into the local sewerage system.
Service exchange users like Renishaw have
a duty of care to ensure that their wastes are
disposed of safely. In the case of resin
disposal, this means having a fully
documented audit trail to trace their resin’s
route from the process finishing areas to its
ultimate fate. Some service exchange
suppliers simply dispose of spent resin to
landfill, but regeneration is a much more
sustainable solution. ELGA operates the UK’s
largest regeneration centre at Stoke-on-Trent,
where it handles ion exchange resins from
many different industries. Its Environmental
Management System ensures that every batch
of resin that comes into the centre is
identified and fully traceable back to its
previous regeneration, and that includes a
record of compliance of regeneration wastes
with the discharge consent. Disposing of
TTI Group is the first heat treatment business in the UK to respond to the Solvents Emissions Directive (SED) legislation
by installing an EVT hermetically sealed solvent degreasing system.
UK’s largest sealed trike system
FORMERLY known as Senior Heat Treatment, TTI is part of the materials technology division
of Aalberts Industries NV, with nine sites in the UK. A Group-wide review of component
cleaning systems concluded that for heat treatment processes such as nitriding, Nitrotec
and vacuum treatment, effective pre-process cleaning demanded solvent degreasing.
The upshot was that in January EVT Eiberger Pfohler’s UK distributor IB Industries,
installed a hermetically sealed trichloroethylene solvent system with a charge weight of
up to 4 tonnes, making it the highest capacity degreaser trike degreaser in a UK heat
treatment facility. This has provided TTI Telford with the equivalent capacity to its
nitriding facility using a solvent spray and vapour process, with a regenerating carbon
absorption system removing the last traces of solvent from the chamber prior to the finish
of the cleaning cycle.
To comply with SED the system monitors solvent concentration in the working chamber at regular intervals - the sliding door can be opened only after the
concentration has fallen below the legal limit. www.ibindustries.co.uk
84 MWP november 2007
exhausted resin into a landfill simply doesn’t
provide the same level of traceability.
Compliance with the Solvent Emissions
legislation by moving to aqueous based
washing techniques need not be any more
expensive than solvent degreasing; but water
quality is of paramount importance in
ensuring a high quality finish. Service
exchange is both convenient and cost
effective, so long as the service provider can
provide full traceability for the resin’s life.
ELGA Process Water is part of Veolia Water
Solutions & Technologies (VWS), a subsidiary
of Veolia Water. VWS is one of the world’s
major designers of technological solutions
and constructor of facilities for water
treatment. With over 6,500 employees, the
company has operations in more than 50
countries. VWS recorded revenue of ¤1.6
billion in 2005. Veolia Water, a division of
Veolia Environnement, is the world leader in
providing outsourced water and wastewater
services for municipal authorities, as well as
industrial and service companies. It serves 110
million people worldwide. With over 67,800
employees, its 2005 revenues amounted to
¤8.9 billion.
www.elgaprocesswater.com
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