1. Machine Guarding
Subpart O
1910

2. Trainer Objectives
Explain the general requirements for guarding the hazards of machines.
Describe precautions to be taken around woodworking machinery.
List fundamental requirements for abrasive wheel machinery.
Identify important terms associated with operation of mechanical presses.
Describe the requirements for guarding moving parts of machinery.

3. General
Requirements

4. 1910.212(a)(1) Types of guarding
One or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by:
Point of operation,
Ingoing nip points,
Rotating parts,
Flying chips and sparks

5. Standard Interpretations Machine-guarding requirements
This standard requires that machine guards be provided to protect employees (e.g., points of operation, ingoing nip points), but does not specify the type of machine guard. The standard recommends several types of machine guards, including barriers, tripping devices, and electronic safety devices, but leaves to the employer the decision regarding which machine guard best suits the working conditions.

6. Standard Interpretations Machine-guarding requirements
By not specifying the types of guards this standard is referred to as a "performance" standard (i.e., the employer is free to adopt a guard that "performs" or meets the objective of protecting employees from the hazards).
If OSHA had specified the types of machine guards that must be used, the standard would be a "specification" standard.

7. 1910.212(a)(2) General requirements for machine guards
Guards shall be affixed to the machine where possible and secured elsewhere if attachment to the machine is not possible
The guard shall be such that it does not offer an accident hazard in itself

8. 1910.212(a)(3) Point of Operation
(i)Point of operation is the area on a machine where work is actually performed upon the material being processed
(ii)The point of operation of machines whose operation exposes an employee to injury, shall be guarded

9. 1910.212(a)(3) Point of Operation
(ii)The guarding device shall be in conformity with any appropriate standards therefor, or, in the absence of applicable specific standards, shall be so designed and constructed as to prevent the operator from having any part of his body in the danger zone during the operating cycle

10. (a)(3)(iii) Hand Tools
Special hand tools for placing and removing material shall be such as to permit easy handling of material without the operator placing a hand in the danger zone*
*Such tools shall not be in lieu of other guarding, but can only be used to supplement protection provided.

11. 1910.212(a)(3)(iv) Examples of machines
Types of machines which normally require point of operation guarding:
Mills
Drills
Grinders
Power presses
Shears
Saws

12. 1910.212(a)(4) Barrels, containers, and drums
Revolving drums, barrels, and containers shall be guarded by an enclosure which is interlocked with the drive mechanism, so that the barrel, drum, or container cannot revolve unless the guard enclosure is in place

13. Standard Interpretations Interlock requirements for centrifuges
Centrifuges are not specifically mentioned in the machine-guarding regulations and are not covered by the particular provision at (a)(4), the general provision at (a)(1) does cover hazards created by rotating parts or the point of operation.
Accordingly, centrifuges that present such hazards must comply with the provisions of (a)(1), (a)(2), and (a)(3).

14. 1910.212(a)(5) Exposure of blades
When the periphery of the blades of a fan is less than seven (7) feet above the floor or working level, the blades shall be guarded
The guard shall have openings no larger than one-half (1/2) inch.

15. 1910.212(b) Anchoring fixed machinery
Machines designed for a fixed location shall be securely anchored to prevent walking or moving
This pedestal grinder is designed for anchoring, and is not anchored, creating a potential hazard

16. CPL 2-1.35 National Emphasis Program on Amputations
Identify and reduce workplace hazards likely to cause amputations
top five machines that cause amputations are:
Saws, Slitters, and
Slicers, Shears,
Presses

17. Saws Used primarily in woodworking and manufacturing shops Two types
Table
Radial arm
Other types include:
Hand held
Band saw
Miter saw

18. Shears Self-contained machines using a mechanically driven ram
Ram moves a nonrotary blade at a constant rate past the edge of fixed blade

19. Slicers Commonly used to slice meat and food Use rotary blade
Guillotine cutters used in other industries
Most injuries occur in restaurants and grocery stores

20. Power Presses NEP covers all types of power presses
Presses consist of stationary bed, and slide
Used in a variety of industries

21. Program Procedures NEP includes three activities:
Outreach
Targeting/selection
Inspection
If present, a thorough inspection will be conducted focusing on:
Nip points
Pinch points
Shear points
Cutting actions
Point(s) of operation

22. Woodworking
Machinery
CFR

23. 1910.213 Woodworking machinery requirements
(a)(1)Each machine shall be so constructed as to be free from sensible vibration when the largest size tool is mounted and run idle at full speed.

24. 1910.213 Woodworking machinery requirements
(a)(11)The frames and all exposed metal parts of portable electric woodworking machinery operated at more than 90 volts to ground shall be grounded.
Portable motors driving electric tools which are hand held shall be grounded.
The ground shall be a separate ground wire and polarized plug and receptacle.

25. 1910.213(a)(12) Guarding blades under tables
For all circular saws where there is a possibility of contact with the portion of the saw beneath or behind the table, that portion of saw shall be:
Covered with an exhaust hood, or, if no exhaust system is required,
With a guard that shall be arranged as to prevent accidental contact with the saw

26. 1910.213(b) Machine controls and equipment
A mechanical or electrical power control shall be provided on each machine to make it possible for the operator to cut off the power from each machine without leaving his position at the point of operation

27. 1910.213(b)(3) Non-restart devices
On applications where injury to the operator might result if motors were to restart after power failures, provision shall be made to prevent machines from automatically restarting upon restoration of power

28. 1910.213(b)(4) Location of controls
Power and operating controls should be located within easy reach of the operator while at his regular work location, making it unnecessary to reach over the cutter to make adjustments

29. (c) Ripsaws
Each circular hand-fed ripsaw shall be guarded by a hood which shall completely enclose that portion of the saw above the table and that portion of the saw above the material being cut.

30. (c)(2) Spreaders
Each hand-fed circular ripsaw shall be furnished with a spreader to prevent material from squeezing the saw or being thrown back on the operator
Spreader

31. 1910.213(c)(3) Non-kickback fingers
Each hand-fed circular ripsaw shall be provided with non-kickback fingers or dogs so located as to oppose the thrust or tendency of the saw to pick up the material or to throw it back toward the operator

32. 1910.213(g)(1) Swing cutoff saws
Each swing cutoff saw shall be provided with a hood that will completely enclose the upper half of the saw, the arbor end, and the point of operation at all positions of the saw

33. 1910.213(g)(2) Swing cutoff saws
Each swing cutoff saw shall be provided with an effective device to return the saw automatically to the back of the table when released at any point of its travel

34. (h) Radial saws
The upper hood completely encloses the upper portion of the blade, including the end of the saw arbor
Radial saws used for ripping shall be provided with nonkickback fingers or dogs located on both sides of the saw so as to oppose picking up the material or throwing it back toward the operator

35. (i) Bandsaws
All portions of the saw blade shall be enclosed or guarded, except for the working portion of the blade between the bottom of the guide rolls and the table

36. 1910.213(i) Bandsaws Bandsaw wheels shall be fully encased
The outside periphery of cover shall be solid
The front and back of the band wheels shall be either enclosed by solid material or by wire mesh

37. Treadle
Each operating treadle shall be covered by an inverted U-shaped metal guard, fastened to the floor, and of adequate size to prevent accidental tripping

38. 1910.213(j) Planers and Jointers
Each hand-fed planer and jointer with horizontal head equipped with a cylindrical cutting head, the knife projection of which shall not exceed one-eighth inch beyond the cylindrical body of the head
The opening in the table kept as small as possible

39.
Abrasive Wheel
Machinery

40. Definitions
"Flanges" means collars, discs or plates between which wheels are mounted and are referred to as adapter, sleeve, or back up type.
"Off-hand grinding" means the grinding of any material or part which is held in the operator's hand.

41. (a)(2) Guard design
The safety guard shall cover the spindle end, nut, and flange projections
The safety guard shall be mounted so as to maintain proper alignment with the wheel

42. (a)(2) Guard design
The strength of the fastenings shall exceed the strength of the guard, except:
Where the work provides suitable protection, the guard may expose the spindle end, nut and flange
Where the work entirely covers the side of the wheel the side cover(s) of the guard may be omitted

43. (a)(4) Work Rests
On off hand grinding, work rests are required, to support the work
Rigid construction, and adjustable with wheel wear
Must be kept closely adjusted, max gap = 1/8" to prevent work from jamming & breaking wheel
Work rest is closely
adjusted

44. For bench / floor stand grinders
Angular exposure for wheel periphery
Maximum angle of exposure above the horizontal = 65º
Maximum wheel exposure = 90º
Horizontal plane of the spindle
For bench / floor stand grinders

45. 1910.215(b)(9) Exposure adjustment
Safety guards of the type where the operator stands in front of the opening, shall be adjusted to the constantly decreasing size of the wheel
The distance between the periphery and the adjustable tongue guard shall never exceed one-fourth inch

46. 1910.215 (d) Mounting Inspection:
Immediately before mounting, all wheels shall be closely inspected and sounded by the user (ring test) to make sure they have not been damaged in transit, storage, or otherwise
The spindle speed of the machine shall be checked before mounting of the wheel to be certain that it does not exceed the maximum operating speed marked on the wheel

47. 1910.215 (d) Mounting -Ring Test
Sound the wheel by tapping around the wheel periphery with a wood handled screwdriver*
Good wheel portions will “ring” like a bell
Cracks will sound “dead”

48. (d) Mounting
The spindle speed of the machine shall be checked before mounting of the wheel to be certain that it does not exceed the maximum operating speed marked on the wheel.
Compare this number to the
spindle speed on the grinder
motor

49. Mechanical
Power Presses

50. Definitions
"Antirepeat" means the part of the clutch/brake control system designed to limit the press to a single stroke if the tripping means is held operated
"Antirepeat" is also called single stroke reset or reset circuit

51. Definitions
"Brake" means the mechanism used on a mechanical power press to stop and/or hold the crankshaft, either directly or through a gear train, when the clutch is disengaged.

52. Definitions
"Clutch" - coupling device on a mechanical power press between the flywheel and crankshaft, direct or through a gear train.
"Full revolution clutch" - Type of clutch that cannot be disengaged until the crankshaft has completed a full revolution and the press slide a full stroke.

53. Definitions
"Part revolution clutch" - Type of clutch that can be disengaged at any point before the crankshaft has completed a full revolution and the press slide a full stroke.

54. Definitions
"Continuous" means uninterrupted multiple strokes of the slide without intervening stops (or other clutch control action) at the end of individual strokes*
*Should generally only be used for auto-feed operations where the operator does not enter the point of operation (Stamping for example)

55. Definitions "Device" means a press control or attachment that:
Restrains the operator from inadvertently reaching into the point of operation, or
Prevents normal press operation if the operator's hands are inadvertently within the point of operation, or

56. Definitions "Device" means a press control or attachment that:
Automatically withdraws the operator's hands if inadvertently within the point of operation as the dies close
Prevents the initiation of a stroke, or stops of stroke in progress, when there is an intrusion through the sensing field by any object

57. Definitions
"Hand feeding tool" - Hand held tool designed for placing or removing material or parts to be processed within or from the point of operation.
"Jog" - Intermittent motion imparted to the slide by momentary operation of the drive motor, after the clutch is engaged with the flywheel at rest.

58. Definitions
"Inch”* - Intermittent motion imparted to the slide (on machines using part revolution clutches) by momentary operation of the "Inch" operating means
*"Inch" is a function used by the die setter for setup of dies and tooling, but is not intended for use during production operations by the operator

59. Definitions
"Point of operation" - Area of the press where material is actually positioned and work is performed

60. Definitions
"Press" - Mechanically powered machine that shears, punches, forms or assembles metal or other material by means of cutting, shaping, or combination dies attached to slides.
A press consists of a stationary bed or anvil, and a slide (or slides) having a controlled reciprocating motion toward the bed surface, the slide guided in a definite path by the frame of the press.

61. 1910.217(a)(5) Excluded machines
Press brakes, hydraulic and pneumatic power presses, bulldozers, hot bending and hot metal presses, forging presses and hammers, riveting machines and similar types of fastener applicators are excluded from this section

62. (b)(2) Brakes
Friction brakes provided for stopping or holding a slide movement shall be inherently self-engaging by requiring power or force from an external source to cause disengagement

63. 1910.217(b)(3) Full revolution clutches
Machines using full revolution clutches shall incorporate a single-stroke mechanism*
*That means after one complete cycle the press returns to the full open position, and will not re-engage until another cycle is initiated

64. 1910.217(b)(4) Foot pedals (treadle)
The pedal shall be protected to prevent unintended operation from falling or moving objects or accidental stepping onto the pedal
A pad with a nonslip contact area shall be firmly attached to the pedal
Treadle

65. 1910.217(b)(6) Two-hand trip controls
Hand controls protected against unintentional operation
Two-hand trip systems on full revolution clutch machines shall incorporate an antirepeat feature

66. 1910.217(b)(7) Part revolution clutches
The clutch shall release and the brake shall be applied when the external clutch engaging means is removed, deactivated, or de-energized
The stop control shall override any other control, and re-actuation of the clutch shall require use of the operating (tripping) means which has been selected

67. 1910.217(b)(7) Part revolution clutches
A red color stop control shall be provided with the clutch/brake control system
Momentary operation of the stop control shall immediately deactivate the clutch and apply the brake

68. 1910.217(b)(7) Part revolution clutches
A means of selecting Off, "Inch," Single Stroke, and Continuous (when the continuous function is furnished) shall be supplied with the clutch/brake control to select type of operation of the press

69. 1910.217(c)(2) Point of operation guards
It shall prevent entry of hands or fingers into the point of operation by reaching through, over, under or around the guard;
It shall conform to the maximum permissible openings of Table O-10;

70. 1910.217(c)(2) Point of operation guards
It shall, in itself, create no pinch point between the guard and moving machine parts;
It shall utilize fasteners not readily removable by operator, so as to minimize the possibility of misuse or removal of essential parts;

71. Table O-10
[In inches]
___________________________________________________ |
Distance of opening from point | Maximum width of
of operation hazard | opening
____________________________ |__________________
1/2 to 1 1/ | /4
1 1/2 to 2 1/ | /8
2 1/2 to 3 1/ | /2
3 1/2 to 5 1/ | /8
5 1/2 to 6 1/ | /4
6 1/2 to 7 1/ | /8
7 1/2 to 12 1/ | /4
12 1/2 to 15 1/ | /2
15 1/2 to 17 1/ … | /8
17 1/2 to 31 1/ | /8
____________________________ |__________________

72. 1910.217(c)(2) Point of operation guards
Preventing and/or stopping normal stroking of the press if the operator's hands are inadvertently placed in the point of operation;
Presence sensing device

73. 1910.217(c)(2) Point of operation guards
Requiring both of the operator's hands to use controls and locating such controls at a safe distance from the point of operation that the slide completes downward travel or stops before the operator can reach into the point of operation

74. Presence sensing devices
The device may not be used on machines using full revolution clutches!

75. 1910.217(c)(3)(iv)(d) Pull-out device
Each pull-out device in use shall be visually inspected and checked for proper adjustment at the start of each operator shift, following a new die set-up, and when operators are changed.
Necessary maintenance or repair or both shall be performed and completed before the press is operated.
Records of inspections and maintenance shall be kept in accordance with paragraph (e) of this section.

76. Pullback
device
Adjustable
wrist
straps

77. 1910.217(c)(4) Hand feeding tools
Hand feeding tools are intended for placing and removing materials in and from the press
Hand feeding tools are not a point of operation guard or protection device and shall not be used in lieu of the "guards" or devices required in this section

79. 1910.217(d) Setting and feeding dies
Furnish and enforce the use of hand tools for freeing and removing stuck work or scrap pieces from the die, so that no employee need reach into the point of operation for such purposes

80. Belt, Rope & Chain Drives
Prime Mover Guards
Flywheels
Pulleys
Belt, Rope & Chain Drives
Gears &
SHAFTING
Sprokets

81. (b)(1) Flywheels
Flywheels 7 feet or less above the ground shall be guarded
Sheet, perforated, or expanded metal or woven wire, or with
Guard rails between 15 to 20 inches from flywheel rim
Toe board if within 12 inches of floor or extends into a pit
All projections shall be covered

82. *Particularly inclined idler shafts
(c) Shafting
Each continuous line of shafting shall be secured in position against excessive end movement
Inclined and vertical shafts* shall be securely held in position against endwise thrust
*Particularly inclined idler shafts

83. (c) Shafting
All exposed parts of horizontal shafting 7 ft. or less above the floor shall be guarded (except: runways used for oiling or running adjustments) by a stationary casing, or trough
Troughs must enclose sides and top, or sides and bottom of shafting as location requires

84. (c) Shafting
Projecting end shafts shall present a smooth edge and project not more than 1/2 the diameter of the shaft
Unused key ways shall be filled up or covered

85. (d) Pulleys
Pulleys, which are seven feet or less from the floor or working platform, shall be guarded in accordance with the standards specified in paragraphs (m) & (o)
Pulleys serving as balance wheels (e.g., punch presses) on which the point of contact between belt and pulley is more than six feet six inches from the floor or platform may be guarded with a disc covering the spokes

86. Example Belt width = three inches Distance between pulleys = 2 inches
Guides must be placed
in this area

87. Guard
Unguarded portion
seven ft. minimum
Floor

88. 1910.219 (f) Gears sprockets and chains
Gears, sprockets and chains shall be guarded by one of the following methods:
By a complete enclosure; or
By a standard guard as in paragraph (o), at least seven feet high, extending six inches above the mesh point of the gears; or

89. 1910.219 (o) Approved Materials
(1)(i)(a)All guards shall be rigidly braced every three (3) feet or fractional part of their height to some fixed part of machinery or building structure.
Where guard is exposed to contact with moving equipment additional strength may be necessary.

90. (o)(2) Wood guards
Wood guards may be used in the woodworking and chemical industries, in industries where the presence of fumes or where manufacturing conditions would cause the rapid deterioration of metal guards
In construction work and outdoors where extreme cold or heat make metal guards and railings undesirable

91. 1910.219(o)(2) Wood guards If wood, 2"x 4" toprail
midrail half way in-between
height 42"
Posts not more than 8' apart, permanent, substantial, smooth, w/ no protruding nails, bolts or splinters
Toeboards at least 4" high