Machine Guarding

Machine Guarding Subpart O 1910 211-219

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.

General Requirements 1910.212

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

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.

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.

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

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

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

1910.212(a)(3)(iii) Hand Tools *Such tools shall not be in lieu of other guarding, but can only be used to supplement protection provided. • 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*

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

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

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 1910.212(a)(4), the general provision at 1910.212(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 .212(a)(1), (a)(2), and (a)(3).

1910.212(a)(5) Exposure of blades • The guard shall have openings no larger than one-half (1/2) inch. • 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

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

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

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

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

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

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

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 Program Procedures

Woodworking Machinery CFR 1910.213

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.

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.

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

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

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

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

1910.213(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.

1910.213(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

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

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

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

1910.213(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

1910.213(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

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

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

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

1910.215 Abrasive Wheel Machinery

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.

1910.215(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

1910.215(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

1910.215(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

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

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

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

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”

1910.215 (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

Mechanical Power Presses 1910.217

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

Machine Guarding