Airupgrading
Polyurethane moulding
By Adam O ord
manufacturer Midas Pattern
Company provides a range
of prototype and production
volumes of ame-retardant
polyurethane moulding from its Bedfordbased
manufacturing facilities.
While its production is primarily
suited to the development of scienti c
equipment, other applications include
items such as solar panels and housings
for electric vehicle charging stations. All
items are moulded from the company’s
composite resin mould tools, which are
designed in-house from customer-input
CAD data. The mould tools are produced
from master patterns machined out via
the company’s extensive CNC facility,
which includes six Haas vertical CNC
milling machines and one ‘very large’
Correa horizontal CNC milling machine.
Compressed air plays a vital role within
the machining, moulding and product
nishing processes, in two ways.
Continuous supply of low-pressure
air (approx. 20 PSI) is needed for clearing
‘swarf’ (waste material) that is produced
from the soft tooling board surfaces.
Seven CNC units are at work machining
them out 24 hours a day, seven days a
week, and the low-pressure air helps
to prevent the build-up of the waste
material that might otherwise interfere
with metalcutting.
Low-pressure air is also involved in the
batch mixing of the polyurethane reaction
materials before pouring into composite
moulds. After curing, the moulded
items are removed to undergo nishing
operations, such as fettling (trimming
and cleaning) and shot blasting (removing
impurities), in preparation for epoxy or
acrylic spray painting. These processes,
especially the spray booths and shot blast
plants, require a constant and reliable
supply of compressed air.
AUDIT & RECOMMENDATIONS
As part of Midas’s Green Initiative (MGI),
the company called upon the services of
Atlas Copco premier distributor Anglian
Compressors to conduct a performance
survey of the compressed air system,
which had been installed for 10 years and
comprised two Atlas Copco 22 kW, xedspeed
rotary screw compressors, as well
as a small VSD unit. The MGI began in
April 2019 and was introduced by Midas
Digital art/stock.adobe.com
Midas Pattern Company has recently had a compressor system audit carried
out at its premises in Bedford, UK, as part of a green initiative project. This
has led to an equipment upgrade and has also helped the company to achieve
energy savings and reduce its carbon footprint
MD Alan Rance, who decided to bring
his personal and professional carbon
footprint down to zero. (Details can be
found at www.is.gd/hiyaho).
Anglian measured the usage patterns
of the air supply, learning that the
demand uctuated throughout the
week and had also changed considerably
over the 10-year period. This was down
to a combination of the production
equipment used, the number of sta and
the operating hours. Depending on what
process is running, di erent volumes of
air were required, causing a uctuation in
usage.
The minimum requirement needed by
the factory was 12 l/s, and the maximum
was 105 l/s. The VSD compressor also had
reliability issues and lower output than the
xed speed units, meaning that at times,
it did not have enough capacity to provide
the full air requirement needed. The xedspeed
compressors were, therefore, doing
most of the work, running on and o oad
and wasting energy. (A spokesperson
explains: “With xed speed compressors,
you are not able to start and stop them
continually because the motor will burn
out due to the starting currents. What
happens is when the compressor has
reached its upper pressure set point,
CHEMICAL & PROCESS – ENERGY
30 www.operationsengineer.org.uk Autumn 2020
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/hiyaho)
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