1. Safeguarding Machinery and Tools

Question 1

What is machine guarding?

Answer 1

An engineering control that places a barrier between a worker and a source of harmful energy.

Question 2

Define “safeguard”

Answer 2

Measures that protect workers from hazards.
Examples:
barrier guards
safety devices
shields
awareness barriers
warning signs
safe work procedures
PPE

Question 3

Define “guard” - context, safeguarding.

Answer 3

A physical barrier type of safeguard.

Question 4

List 9 classes of actions associated with the operation of a machine that are hazardous to workers.

Answer 4

Entanglement
Abrasion
Cutting
Shearing
Stabbing/puncturing
Impact
Crushing
Drawing in
Other (compressed air, high pressure fluid, etc.)

Question 5

While there may be as many types of safeguards as there are machines, what are three hazardous mechanical motions that are generally recognized as requiring safeguards?

Answer 5

Rotational Hazards
potential for crushing, abrasions, shearing, entrapment

Reciprocating
back/forth or /up/down motion. may cause blunt trauma, shearing, crushing.

Transverse
motion in a continuous line. may cause entanglement, blunt force, crushing, shearing.

Question 6

Of the three common mechanical motions, which are usually associated with:

• Crushing/bending injuries
• Cutting
• Puncture

Answer 6

-Crushing/bending injuries
Transverse, most common
(also rotational and reciprocating)

-Cutting
Transverse, rotational, and reciprocating.

-Puncture
Reciprocating is most common

Question 7

What is a device, in the context of devices that safeguard machines?

Answer 7

A device is a mechanical or electrical mechanism that reduces the risk of a machine hazard.

Question 8

Of the many systems used to classify safeguarding systems, what are the 4 categories in the simplest?

Answer 8

• Point-of-operation guards
• Point-of-operation devices
• Power transmission guards
• Miscellaneous

Question 9

Define and list four types of point of operation guards.

Answer 9

Fixed POO Guards
Fixed barriers in place. Shouldn’t be easily circumvented/removed.

Adjustable POO Guards
Adjusted by the user to allow for function while guard remains mostly in place

Self-Adjusting POO Guards
Retractable, or other automatically adjusting guards that change during use for safe function.

Interlocked POO Guards
Machines that will not function without the guard being in place.

Question 10

List 6 features all POO guards should have.

Answer 10

Point Of Operation guards should all:

Be integrated (not cumbersome add-on)

Be durable for long-term use

Be functional for the machines purpose (permit appropriate material to be used properly with the machine)

Effectively provide the appropriate protection required, based on risk assessment.

Be easy to inspect & maintain.

Be reasonably tamper-proof.

Question 11

What are POO devices?

List four types.

Answer 11

Point Of Operation devices are mechanisms of control that limit the operation of a machine when a person is in the path of hazardous energy.

Presence-Sensing Devices
Done form of proximity detection that limits use of machine.

Two-Hand Controls
Ensure workers hands in two locations, away from hazard.

Safety-Trip Controls
Some form of trip (bar, wire, sensor) that will stop machine if worker enters area of hazard.

Holdbacks & Pullbacks
Straps or harnesses that limit the workers ability to enter the area of hazard.

Question 12

Explain what power transmission is and discuss power transmission protection.

Answer 12

Power transmission refers to any parts of a mechanical system that transmit energy to another part of the machine.

Examples: flywheel, pulley, belt, chain, gears.

PT components are most often guarded by fixed guards.

Question 13

Discuss some miscellaneous safeguarding methods.

Answer 13

This category covers anything that does not fall into the categories of POO guards, POO devices, and PT safeguards.

Awareness Barriers
painted on floor, caution tape, signage.

Feeding and Ejection Methods
Devices that perform all or part of the task to feed materials into a machine. This removes or reduces the workers approach to the POO. These devices can introduce new hazards.

Question 14

Discuss safeguards and regulations.

Answer 14

Safeguards are required in most jurisdictions.

Saskatchewan and Manitoba have performance-based requirements for safeguarding.

BC has prescribed standards for safeguarding.

In addition to required standards that may be in jurisdiction-specific standards, there are also voluntary standards that are commonly used by engineers.

Question 15

What is the key machine guarding standard in Canada?

Answer 15

CSA Z432-04 (R2009)

Safeguarding of Machinery.

Question 16

What are the four principles that are recognized in CSA Z432-04?

Answer 16

1)
Machine safety is a combination of implementation at design stage and end user.

2)
Machine designers should
-Identify hazards/assess risks
-Remove hazards when practicable
-Design guards & safety devices to protect against remaining hazards
-Inform/warn users about residual risk

3)
It is the owner’s responsibility to inform manufacturers of needs & use conditions.

4)
It is the owner’s responsibility to inform manufacturer of planned modifications to allow for manufacturer input on safety.

Question 17

What ANSI standards are important in machine safety?

Answer 17

The ANSI B11 group of standards covers Machine Tool Safety.

Question 18

Discuss Safeguarding Programs

Answer 18

Safeguarding programs should be implemented when safeguards interfere or frustrate workers. The goal is to ensure that work can continue practically while remaining safe. (avoid workers simply disabling safeguards)

-Formal Inspection
(hazard identification/risk assessment, guard/device inventory)
-Review manuals
-Supervisor training
-Worker training
-Reference mandatory/voluntary standards during purchasing
-Solicit input from supervisors/workers during purchasing
-Manufacturer approved modifications
-In-house built devices, only used with careful/thoughtful/documented consideration