SUBCONTRACTING ROUND-THE-CLOCK INVESTMENTS
Stonewood Precision is employing
Hermle automation to provide a
capacity boost
and at weekends. Kingsbury UK (https://
is.gd/exevoc) is the UK agent for Hermle.
Says Stoneswood Precision’s managing
director, Charles Day: “We looked at four
options before deciding to buy the Hermle
cell. Its major differentiator is the ability to
stop automatic production quickly and use
the machine in manual mode to manufacture
a one-off part. The other solutions we looked
at could not achieve that easily.
“The exibility it provides is already
proving useful, as it is allowing us to
machine xtures during the day and
simultaneously set up the HS Flex for lightsout
running overnight. The cell’s connectivity
also ts well within the Industry 4.0
environment that we are creating in our
factory.”
The machine has axis travels of 850 by
700 by 500 mm, +91/-139° trunnion swivel,
500 by 400 mm pallet size and capacity for
12 of them on two levels in the HS Flex
store, which is served by a 3-axis pallet
handling unit with rotary, lift and linear
motions.
The store is controlled and managed by
Hermle’s proprietary Automation Control
System, which enables smart order
management via a touch panel. It is
currently being interlinked with an MES
(manufacturing execution system), recently
installed in Dukin eld by Forcam (https://
is.gd/ucodag), which is compatible with
Stoneswood Precision’s SAP ERP (enterprise
resource planning) software. It allows
production orders to be
sent directly to all
machines for improved
job sequencing,
leading to optimised
production output. The
resulting provision of enhanced data,
including of machine utilisation, is taking the
subcontractor’s operation further along the
road of Industry 4.0.
Stoneswood Precision’s current facility
was set up in 2004 to produce 450 different
aluminium and titanium parts for a military
aircraft, involving machining of mainly wing
details. Already a user of several multi-pallet
production systems based around horizontal
machining centres, the subcontractor
needed an additional system to ful l a
different contract for the manufacture of
aluminium control boxes.
Initially, an older 5-axis VMC with a B-axis
spindle was employed to produce the suite
of 48 bodies, sides and lids for the control
box variants, which range in area from 75 by
150 mm to 300 by 300 mm and from 5 to
20 mm deep. The components are smaller
and more complex than most of the
predominantly aerospace parts produced at
the Dukin eld facility and the HMCs are too
large to machine them ef ciently.
The original process route required the
use of a coolant-driven, right-angle
attachment for drilling holes in the sides of
components to avoid further set-ups. The
tool, while in many ways t for purpose,
could not hold the positional tolerances
required, down to 100 microns true position.
Drilling was not suf ciently repeatable over a
batch of components and therefore a new
engineering solution was sought, resulting in
the installation of the new production cell
based on the trunnion-type Hermle C 400
5-axis machine.
Continues Day: “Apart from the control
box work dictating the use of a 5-axis VMC,
there are parts of other aerospace contracts
that lend themselves to a vertical-spindle
production platform and many new enquiries
we receive also require such capacity. So
the choice of a second VMC, particularly
with automation, made business sense.
“I had never heard of the Hermle
brand but Paul Mellor, technical
director of the Hyde Aero Products
division, of which we are a member,
was familiar with the manufacturer.
“Some of our staff travelled to a
user of a smaller HS Flex system in
the North East and came back with
very positive reports, including from
the shop oor, so we decided to place
the order.
“Luckily the C 400 was in stock at
Kingsbury, so it was available quickly to
solve a looming production bottleneck,
whereas other potential suppliers were
quoting lead-times of up to one year.”
SMOOTH INSTALLATION
The machine was brought into service
quickly, due to preparations. Final
commissioning was achieved within nine
days, after which the machine started
producing components straight away. This
was down to the prior provision from the
supplier of a CAD model of the C 400, which
allowed early 3+2 axis programming of parts
in Catia (Dassault Systemes UK, https://is.
gd/zetoxu), cycle simulations in Vericut
(CGTech, https://is.gd/ohezat) and the
design and production of xtures. The latter
exercise was helped even further by
Kingsbury’s delivery to Dukin eld of an
actual machine pallet.
The advance preparation made the onsite
training provided by a Kingsbury
engineer over a period of ve days more
productive than had the subcontractor’s
staff still been at the start of developing the
processes.
28 www.machinery.co.uk @MachineryTweets December 2019
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