Walsall-based Presscare has succeeded in breathing new life
into two 600t power presses for Covpress using Pilz PNOZ
multi configurable safety relays with diagnostic operator
screens – improving press reliability, output, operator
usability and safety

Covpress is a manufacturer of parts for
UK-based automotive companies
such as Renault, Vauxhall / General
Motors, Jaguar Landrover, Honda, Nissan
and Toyota. It also makes parts for nonautomotives
such as Sky and Landis & Gyr.

Recently it needed to overhaul a pair of 35
year old automatically coil-fed 600t Wilkins
& Mitchells sister presses to meet increased
demand for pressed parts and turned to local
press expert, David Walls of Presscare UK, to
develop a solution which would improve
reliability, in-feed speed and output capacity,
and, of course, safety.

Safety-critical components
Initially the Covpress job involved
deciphering old diagrams and reviewing the
machine to see what could be re-used; this
culminated in the need to redesign the
complete control system and rewire both
presses. Physically the upgrade involved the
use of dual channel solenoid valve control of
the clutch and brake which are critical to the
safe control of the moving part of a
mechanical press, cam box monitoring for
stopping within 15° of top dead centre
(TDC), front and rear rising screens
monitored by heavy duty Fortress interlocks,
and multiple emergency stop pushbuttons –
all linked to a programmable controller
which would monitor these devices.

Other operational parameters affecting the
reliability and usability of the presses, such as
air pressure and lubrication over/under
pressure needed to be monitored and
displayed in an easy to read format for
operators. All of this had to be done in
compliance with the requirements of the Cstandard
for mechanical presses, EN 692.

Previously Presscare had used an old
DOS-based controller in such applications,
but when this was discontinued it turned to
Pilz and the PNOZmulti m2p expandable,
software configurable safety relay. This is a
Type Approved device for such press
applications and the software contains precertified
press-safety application function
blocks. This makes the production of the
Technical File for the machine easier, as well
as providing peace of mind to both designer
and user.

The Pilz PNOZmulti m2p is easily
expandable so there is no daisy chaining,
which leads to a reduction in cabling; each
safety function also has its own input which
provides individual diagnostics for each
function. The PNOZmulti configurator
software permits integrated real time
monitoring via Pilz PMImicro diagnostic
human machine interface screens, permitting
operators to quickly identify faults, such as
lubrication under-pressure or a guard left
open, thus improving uptime and
productivity. This was a major benefit for
Covpress, who previously had to refer to a
bank of flashing pilot lights to determine the
cause of a fault.

Productivity boost
Carl Osborn of Covpress was impressed with
the quality of the job: “The machine is now
more reliable and faster. We’re getting 3 to 4
more strokes per minute, resulting in a
previously unachievable 20 strokes per
minute. This has definitely improved our
productivity, but both presses are now also
safer to operate, maintain and quicker to
fault find.

“The customised text signals on the Pilz
screen fitted to the local control panel
provide easily understood fault finding
information which our operators can act
upon immediately – far easier than
deciphering banks of flashing lamps.”