Hazards

1
Hazards

• Any part of a machine that moves presents a
  mechanical hazard.

2
Where are there hazards?

• Rotating parts
• Reciprocating and transverse motions
• In-running nip points
• Cutting, sanding, and grinding actions
• Punching
• Shearing
• Bending, etc.

3
In-running nip point

• OSHA 3067 1981

4
Types of hazards

• Mechanical
• Non-mechanical
• electrical
• chemical
• thermal

5
How to make hazardsless dangerous.

• Design
• Guard
• Warn
• Train

6
It is best to design against hazards. Engineers
can design a product so the hazards do not exist
in the first place.
7
When hazards cannot be eliminated by design,
physical guards and guarding devices are used if
possible.
8
Types of guards

• Fixed
• Interlocked
• Adjustable
• Self-adjusting

9
Fixed guards

• OSHA 3067 1981

10
Interlocking guard

• Removal of this type of guard causes the power to
  the system to shut off.
• 
  
  OSHA 3067 1981

11
Adjustable guard

• OSHA 3067, 1981

12
Self-adjusting

• OSHA 3067, 1981

13
Types of guarding devices.

• Presence Sensing
• Pullback
• Restraint
• Safety Controls
• Gates
• Others distance and automatic systems

14
Photo-electric presence-sensing deviceon a power
press.

• OSHA 3067, 1981

15
Design based on hand speed

• The human hand can move at
• 63 inches per second.
• Example A device located 2 inches from a
  grinder must be able to sense the hand and stop
  the grinder in under 0.03 seconds.
  T2(in)/63(in/s).032s

16
Warning and training are least effective because
people will always make mistakes.
17
Total system design includes design for
inspection and repair.
18
Lockout/ Tagout

• When a machine or some other source of stored
  energy is being repaired, the energy must be
  released to the extent possible and the machine
  locked so that further energy release cannot
  occur. Also, the system must be tagged to warn
  others of the dangerous situation.