Manufacturing Machinery World June 2018

ROBOTICS
FEEDING THE MACHINE
When manufacturers in low-cost economies
such as the Far East and Eastern Europe first
began to threaten the market share of machine
shops in the west, many looked to automation in
the hope that it would level the playing field.
Certainly, the rationale makes sense: eliminating
the labour cost negates the sole advantage of
competitors able to leverage a low-cost
workforce. However, how many UK machine
shops have actually adopted such a strategy?
Among those able to raise their hand is
Rousant Sherwood Manufacturing (RSM), a
family-owned company based at Henley-on-
Thames that specialises in the subcontract
manufacture of complex machined components
for industries such as medical, aerospace and oil
and gas.
RSM has 11 Nakamura-Tome multi-axis,
multi-turret, twin-spindle turn-mill centres,
complemented by the latest 13-axis sliding-head
turning and four-axis milling capability. As a
result, the company has minimised both cycle
times and the number of set-ups required.
However, faced with an increasingly
competitive global marketplace, the 35-
employee company wanted to make further
efficiency gains, deciding to focus its attention
on automation.
Surveying the entire range of industrial
robots available, RSM concluded that six-axis
Universal Robots from RARUK Automation
were the ideal match for its machine-tending
requirements, largely due to their ease-ofprogramming,
competitive price and
collaborative operating capabilities.
Collaborative robots (‘cobots’) use sensor
technology (programmed with a predetermined
force) to stop safely in the event of
human contact. As a result, around 80% of the
thousands of Universal Robots in use
worldwide operate with no safety guarding
(after risk assessment).
“The ability to use the robots unguarded was
something that appealed, as was ease-ofprogramming,”
states general manager Robin
Salter. “Programming is very intuitive; it can
take as little as 10 minutes to program one of our
robots for a new part. What’s more, we recently
trained one of our apprentices and he picked it
up in an hour.”
In total, RSM has invested in five UR5 (5kg
payload) and two UR10 (10kg) Universal
Robots. The robots are busy tending the
company’s 14 CNC machine tools, and are
relocated to different machines in line with
customer/contract demands. One of the UR10
robots is currently serving a Nakamura-Tome
Super NTJX multi-tasking turn-mill centre on a
24-7 basis. The robot loads square billets of
aluminium into the machine, where they are
turned into aerospace components as part of a
40-minute cycle.
“Just to be clear, we have not invested in
robots to save on headcount, we’ve done it to
win contracts,” says Robin Salter. “We could
never have tendered for this job without
automation. Using a robot makes us profitable
on work where we wouldn’t normally be able to
compete.”
To aid automated machining even further,
investing in the latest workholding solutions can
make a genuine difference. Indeed, some
automation systems combine robots with vices,
such as the Lang Robo-Trex automatic handling
system from Thame Workholding. Robo-Trex
operates a machining centre from an automation
trolley, which serves as a storage medium for
the vices. Depending on the component size, the
trolley can store up to 42 vices. Robo-Trex is
optionally available with up to four trolleys,
which means that the storage capacity can be
increased to up to 168 vices.
The patented vertical positioning of the vices
ensures maximum space utilisation and
guarantees best accessibility when being picked
up the robot. Furthermore, external pre-loading
of the automation trolleys allows Robo-Trex
Automation to be re-equipped within seconds.
Continuing the machining centre theme,
recently introduced by 1st MTA is a new zeropoint
clamping system from V-Tech. For
clamping workpieces on CNC machining
centres, this pneumatic quick-change system
features 24kN retraction of the clamping pin in
each receiver, and a positioning accuracy of
better than 5µm.
Mechanical vices, clamping chucks and bars,
and special workholding fixtures, can be
accommodated in the receivers, while
positioning slots allow precise 90° indexing. The
self-clamping mechanism, which uses highpower
springs to secure the workpiece and
fixture, ensures that the force is still applied after
the air has been disconnected. Pneumatic power
is only required again for release. Clamping
bases are available to hold one, two, four or six
receivers, which are 135mm in diameter but
only 41mm high, so little Z-axis travel is lost.
Elsewhere, now added to the portfolio of
Leader Chuck Systems is the Piranha Clamp
range of centring vices. The Swiss-manufactured
vices replace the usual dovetail guides found on
many vices with parallel twin-cylindrical jaw
guides that are said to offer better precision and
clamping force.
Designed to act much like a hydraulic press,
the hardened and coated spindle guides provide
an increased surface area for load distribution,
while the drive spindle has been tested to
withstand pressures above 1300 Nm². This
capability supports high-pressure workpiece
clamping with a minimal depth of just 3 mm, so
material waste is kept to a minimum.
A built-in zero-point clamping system on the
base of the Piranha Clamp provides the interface
with the machine tool’s work table and achieves
a repeatable loading accuracy of 0.01mm.
However, the quick-change location system can
be specified to fit any zero-point design, with
adapter plates making the vices totally
interchangeable.
Of course, not all workholding devices rely
on mechanical gripping force to secure
components. Leader, for example, now offers
freeze clamping plates from AMCC, which the
company says are an excellent alternative to
magnetic fixtures when securing non-metallic
and non-magnetic components. At the MACH
exhibition in April, visitors were able to see the
plates in action so they could fully appreciate the
holding strength available with ice.
For those required to hold thin-walled or
fragile ferrous parts, the latest Magnos magnetic
chucks from Schunk are designed to offer lowdeformation
workpiece clamping, accessibility
and fast workpiece changeovers. To improve
ease of operation, the company has recently
released Magnos square pole plates equipped
with a status display by default. The display
shows the current clamping status continuously,
even when the magnetic chuck has been
disconnected from the control and is in pallet
storage with a clamped workpiece, for instance.
Schunk is also launching a modular control
unit that gives users a high degree of flexibility
and operating comfort. The Magnos KEH Plus is
suitable for all Schunk square and radial pole
plates. One, two, four or eight magnetic chucks
can be actuated at the same time, depending on
the base version.
To ensure process reliability in automated
applications, users can monitor each individual
magnetic chuck, an action that is facilitated by
transmitting the individual clamping state via a
PLC interface to the system control.
12 Machinery World, June 2018