Page 25
For 12,000 rpm and more spindle speed, with 130mm diameter cutter.
Energy Containment - 12 mm Polycarbonate
0
200
400
600
800
1000
1200
0
2
4
6
8
10
Years
J
oul
e
s
The diagram above is typical for a 12mm thick polycarbonate window, as fitted
to a Bridgeport Machining Centre. Given that a Bridgeport Machining Centre has
a possible maximum cutter of Ø130mm (with adjacent tool pockets empty) and
that the maximum projectile energy that the window is likely to see will be a
fractured piece from the periphery of the cutter, then using the projectile mass
of 0.1kg (as used in the Safety Standard EN12417), then the impact energy
and potential window useable life will be:
Maximum Spindle Speed
(rpm)
Projectile Energy
(Joules)
Window replacement period
(years)
12000 334
7
15000 521 5.1/2
For 20,000 rpm spindle speed, with 95mm diameter cutter.
The diagram above is typical for a 12mm thick polycarbonate window, as fitted
to a Bridgeport Machining Centre. Given that a Bridgeport Machining Centre has
a possible maximum cutter of Ø95mm (with adjacent tool pockets empty) and
that the maximum projectile energy that the window is likely to see will be a
fractured piece from the periphery of the cutter, then using the projectile mass
of 0.1kg (as used in the Safety Standard EN12417), then the impact energy and
potential window useable life will be:
These charts are for guidance only and must be used with caution. Life of the
window of the machine will also be determined by the use to which the machine
is put. The analysis of window life is based upon the predicted maximum cutter
used. It can be foreseen that the customer can load a larger cutter than 130mm.
It is also possible for the cutter to be of special design, with a large tip
(although it is unlikely this would ever weigh more than 0.1kg). The customer
must complete his own risk assessment to determine the potential of exceeding
the impact resistance of the windows.
Maximum Spindle Speed
(rpm)
Projectile Energy
(Joules)
Window replacement period
(years)
20000 495 5.1/2
