NO MORE WAITING FOR CLEAN PAINT-MIX VESSELS
The task of cleaning mixing vessels at the Harrow, Middlesex, plant of
artists' materials group ColArt was transformed by the introduction of
a new computer-controlled cleaning system based on a Spraying Systems
automatic motorised tank wash unit.
What threatened to become a constant and stressful struggle to keep
up with demand for clean vessels is now a smooth operation coping
comfortably with an increased workload. The process became faster,
safer, more effective and more economical. Production bottlenecks at
'pot washing' stage were eliminated; and there have been environmental
benefits, notably a sharp reduction in water usage. Moreover, the
installation was developed in-house and commissioned by ColArt's own
engineering department, at a fraction of the cost of solutions put forward
by specialised cleaning system consultants.
ColArt is best known to artists world-wide through its historic brands
Winsor & Newton, Lefranc & Bourgeois and Reeves, which were founded in
the 18th and 19th centuries. ColArt’s reputation as the world leader in
its field was further enhanced following the acquisition of the American
acrylic paint specialist Liquitex. However, the transfer of the production
of Liquitex from the US to ColArt’s Harrow factory posed new problems in
the pot wash area, and frequent shortages of clean mixing vessels began
to hamper manufacturing operations.
ColArt were using their existing wash station to clean a variety of open-top
vessels, ranging from 120 litre polyethylene storage drums to 300 litre
stainless steel mixing pots. All were inverted over a fixed spray head
at the centre of a raised drain grid, the heavier vessels being turned
over and manoeuvred into position with the help of a balance crane - an
awkward operation that sometimes damaged the spray head.
Mixing acrylics demands careful temperature control and the new
water-jacketed mixing vessels, with double skins in stainless steel,
were simply too heavy to handle on the old wash station. The only
option for the time being was manual cleaning with spray gun and brush.
"We needed a new system that would handle all our mixing vessels with
no need to invert them," said project engineer Rob Crellin, "but
two specialist firms we consulted were talking prices around
£50,000 excluding installation. Also we thought that oil colour
could clog the brushes they planned to use. We felt high pressure
spraying was the way forward."
After successful 'worst case' trials on oil colour pots, and following
further costing and development, a complete system designed around a
Spraying Systems high pressure tank washer came into full operation in
September 2002.
Mixing vessels are wheeled into position beneath the washer, model 190AGH, which is
mounted on a raise/lower mechanism adapted from an old mixing machine. The air motor
for driving the washer is integral with the shaft and rotating spray head, which would
normally be inserted in a closed tank through a narrow port. To seal their own open-top
vessels ColArt fitted the washer with a 'universal' steel lid designed to close any of
the several types and sizes of vessel in use. A rubber air bag on the underside of the
lid automatically inflates as the assembly is lowered, providing an effective seal
compatible with a variety of vessels and individual differences in the condition of
their wheels.
The 190AGH washer, with twin solid-stream nozzles and capability for
working at up to 70 bar liquid pressure, maintains very high impact
cleaning performance with economical water usage. The spray head
rotates in two planes giving progressive 360° coverage of all tank
surfaces.
For cleaning, ColArt use a caustic solution heated to 70°C. This is
returned to tank for re-use, while rinsing water is pumped to drain.
The whole system (high-pressure pump, drain/return pump, directional valves
and other elements) is programme-controlled for one-man operation.
The operator chooses from four cleaning cycles and can do other jobs as
cleaning goes on. For instance, lightweight storage drums can be cleaned
on the old fixed spray head nearby.
All stainless steel mixing vessels are handled on the new system, on which
average throughput is 50% higher. Meanwhile, vessels previously cleaned by
hand, taking up to 40 minutes, are now turned round in 10-12 minutes.
Among the benefits noted by Rob Crellin were that safety has been improved
because heavy stainless steel vessels can be cleaned without inverting
them; also that the operation is using far less water, which is in line
with the company's environmental policy. And higher productivity means
that the cleaning facility has been able to take on 30 additional new
mixing vessels without hiring extra staff or risking disruption through
work piling up.
After the new system was installed, one of the supervisors summed up the
general verdict.
"It puts everyone in a better temper when things go smoothly," he said,
"and now no-one has to wait for a clean mixing pot, even though we're
busier than ever."
Printer Friendly Acrobat Format. (pdf)
|
|
 |
| Lowering the washer into position for cleaning a mixing vessel. |
 |
| Job completed. The whole operation is computer controlled once the operator
has selected a cleaning programme. |
 |
| Project engineer Rob Crellin checks results. |
|
