Understanding SLO: Safe Laser Off
90
Arex™ 400
Example 2
Risk Analysis of a fully automatic laser processing machine that operates only
when protection system is disengaged.
• Operative cycle: 500 pcs/hour, 3 shifts
(8h/shift) 350 days /year
• Dedicated enclosures prevent laser emission also during parts loading /
un
loading
• An interlocked door is d
edicated to maintenance and blockage recovery
• Operator are NOT SK
ILLED on laser risks and do NOT have DPI
• In case of access line is
stopped and restarted
LASER RISK ASSESSMENT: H
AZARD, direct scattered laser radiation:
• RISK SEVERITY: SEVERE (irreversible eye damage)
• RISK FREQUENCY: SELDOM (1/week)
• AVOIDANCE PROBABILITY: NO
T POSSIBLE
RISK REDUCTION: INTELOCKED DOOR
Estimation of PLr for door
interlock safety function
• SEVERITY: SEVERE S2
• FREQUENCY: SELDOM F1
• POSSIBILITY OF AVOIDING HAZARD: NOT POSSIBLE P2
Severity of injury (S)
S1 Slight (normally reversible injury)
S2 Serious (normally irreversible injury or death)
Frequency and/or exposure time to hazard (F)
F1 Seldom to less often and/or exposure time is short
F2 Frequent to continuous and/or exposure time is long
Possibility of avoiding hazard or limiting harm (P)
P1 Possible under specific conditions
P2 Scarcely possible
PLr = PLd
Restart: manual reset
Door Switch
Safety Controller Arex™ 400 SLO - Safety Circuit
Input
Subsystem
Logic
Subsystem
Output
Subsystem
PLr=PLd
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