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Machine Guarding

Machine Guarding

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Machine Guarding

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  1. Machine Guarding MODULE 19

  2. What hazards exist? • Crushed by or drawn into equipment • Struck by moving parts • Struck by failed components or particles

  3. Key parts of machines • Point of operation: where work is performed on the material, such as cutting, shaping, boring, or forming of stock. • Power Transmission Device: transmits energy to the part of the machine performing the work • Includes flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, cranks, and gears.

  4. Key parts of machines • Operation Controls: Control mechanisms • Other moving parts: can include reciprocating, rotating, and transverse moving parts, feed mechanisms, and auxiliary parts of the machine

  5. Hazards to be Guarded • Things to guard include • In-running nip points • Rotating equipment • Flying chips or sparks • Belts or gears • Parts that impact or shear

  6. Rotating Parts • Can grip hair or clothing • Can force the body into a dangerous position • Projecting pieces increase risk

  7. In-Running Nip Points • Between 2 rotating parts • Between rotating and tangential parts • Between rotating and fixed parts which shear, crush, or abrade

  8. Reciprocating Parts • Risk of being struck between stationary and moving part

  9. Transverse motion • Continuous straight line motion • Worker struck or caught in pinch or shear point

  10. Cutting action • Direct injury from cutting action • Flying chips or sparks • Saws, drills, lathes, mills

  11. Punching action • Ram stamps materials • Danger at point of operation

  12. Shearing action • Powered blade that shears materials • Hazard at point of operation

  13. Bending action • Power applied to a slide to stamp/shape materials • Hazard at point of operation

  14. Guarding Principles • Prevent contact between hazardous moving parts and body or clothing • Secure guard: not easily removed • Protect from objects falling into machinery • No new hazards: sharp/rough edges • No interference with job/comfort/speed • Allow safe lubrication: without removing guards if possible

  15. Guarding Methods • Location / distance • Guards • Fixed • Interlocked • Adjustable • Self-adjusting

  16. Guarding Methods • Devices • Presence sensing • Pullback • Restraint • Safety controls (tripwire cable, two-hand control, etc.) • Gates

  17. Guarding Methods • Feeding & ejection methods • Automatic and/or semi-automatic feed and ejection • Robots • Miscellaneous aids • Awareness barriers • Protective shields • Hand-feeding tools

  18. Fixed Guard • Barrier is a permanent part of machine • Preferable over other types

  19. Interlocked Guard • Stops motion when guard is opened or removed Interlocked guard on revolving drum

  20. Adjustable Guard • Barrier may be adjusted for variable operations • What are the drawbacks? Bandsaw blade adjustable guard

  21. Self-Adjusting Guard • Adjusts according to size/position of material Circular table saw self-adjusting guard

  22. Pullback Device • Cables attached to operator’s hands or wrists • Removes hands from point of operation during danger period • What are the drawbacks?

  23. Restraint Device • Cables attached to fixed point and wrists or hands • Adjustable to let hands travel in predetermined area • May be accompanied by hand-feeding tools

  24. Safety Tripwire Cable • Device located around the perimeter of or near the danger area • Operator must be able to reach the cable to stop the machine

  25. Two-Hand Control • Requires constant pressure on both pads to activate the machine • Hands on controls at safe distance while machine is in dangerous cycle

  26. Gate • Must close fully to protect user before cycle will start Gate Open Gate Closed

  27. Safeguarding by Location/Distance • Location of hazardous parts that is inaccessible or not a hazard during normal operation • Must maintain safe distance • Training, warning, communication necessary

  28. Protective Shields • Protection from flying particles or splashing fluids • Do not protectcompletely frommachine hazards

  29. What regulations apply? • 29 CFR 1910 Subpart O • 29 CFR 1910 Subpart P for hand and portable power tools • API RP 54 6.8 Machinery and Tools

  30. Machinery and Machine Guarding 29 CFR 1910 SUBPART O

  31. Organization • Definitions • General requirements for all machines • Woodworking machinery requirements • Abrasive wheel machinery • Mills and calenders in the rubber and plastics industries • Mechanical power presses • Forging machines • Mechanical power-transmission apparatus

  32. General Requirements 29 CFR 1910.212

  33. 1910.212(a) Machine guarding • One or more types of guarding to protect from hazards. • Barrier guards • Two-hand tripping devices • Electronic safety devices • Etc. • Affixed to machine where possible • Guard must not cause its own hazard

  34. 1910.212(a) Machine guarding • Point of operation guarding: • Guarded if exposes employee to injury • According to standards or • Keep any part of body out of danger zone • Hand tools to permit material handling – in addition to guards, not instead • Examples of machines requiring guards on point of operation

  35. 1910.212(a) Machine guarding • Revolving barrels, drums, containers guarded by interlocked enclosure (cannot turn without guard in place) • Exposure to fan blades: guard openings 1/2 inch

  36. 1910.212(b) Anchoring fixed machinery • Machines designed for fixed location must be anchored to prevent moving This pedestal grinder is designed for anchoring, but is not anchored

  37. Abrasive Wheel Machinery 29 CFR 1910.215

  38. 1910.215(a) General requirements • Abrasive wheels must be guarded, with exceptions • Guard design dependent on type of work and type of wheel

  39. 1910.215(a) General requirements • Work rests: • Rigid, clamped in place securely • Adjusted to within 1/8 inch of wheel • Never adjusted while in motion Work rest is closely adjusted

  40. 1910.215(b)(9) Exposure adjustment • For type where operator stands in front of opening: Adjustable for decreasing wheel size • Adjustable tongue guard must never be more than ¼ inch from wheel

  41. 1910.215(d) Mounting • Inspect for damage and ring test immediately before mounting • Tap with light nonmetallic implement (screwdriver, wooden mallet) • If sound is dead, cracked ring may not be used • Check spindle speed against maximum for wheel

  42. Ring Test

  43. Mechanical Power-Transmission Apparatus 29 CFR 1910.219

  44. Organization of 1910.219 (a) General requirements (b) Prime-mover guards • Flywheels • Cranks and connecting rods • Tail rods or extension piston rods (c) Shafting (d) Pulleys

  45. Organization of 1910.219 (e) Belt, rope, and chain drives (f) Gears, sprockets, and chains (g) Guarding friction drives (h) Keys, setscrews, and other projections (i) Collars and couplings (j) Bearings and facilities for oiling (k) Guarding of clutches, cutoff couplings, and clutch pulleys

  46. Organization of 1910.219 (l) Belt shifters, clutches, shippers, poles, perches, and fasteners (m) Standard guards-general requirements (o) Approved materials (p) Care of equipment

  47. Hazards on Oil and Gas Sites Machine Guarding

  48. Parts Requiring Guarding • Drive belts and shafts – mud pumps and tank area • Pony rods • Rotating parts • Shale shaker • Agitator shafts & couplings • Moving generator parts • (explore)

  49. Mud Pumps

  50. Shale Shaker