Ergonomic Assessment of Work Position and Tools

Tech 481By: Kyle Malec and Alan Martineck

• Work area located in the warehouse of All-Together Transportation in Joliet, IL

Location

• Ergonomic assessment of various hand-held power tools to measure the exposure of vibration to the operator and work positions

Purpose

Work Area -Area is used to store parts and tools, as well as act as a workshop to maintain and modify company vehicles and projects.

-Currently being used for pre-season maintenance and modification to snowmobiles owned by the company owner and his employees.

Work Positions

• Commonly used tools include: screwdrivers, standard wrenches, ratcheting wrenches and pliers.

• These tools require much repetition and postures to the hand, wrist and arm that are anything but neutral.

• In some cases great force must be transferred from the body to the tool.

• Any number of MSDs can be caused by prolonged use of these motions and grips.

Hand Tools

• Lift can be purchased to bring the work piece up to a higher, more workable position

• Adjustable work stool can be purchased to bring the worker into a more comfortable, ergonomic work position

• Removing a part from the work piece to be brought to a more suitable work surface to avoid awkward postures and reaching

• Adjustable sit/stand chair can be utilized during prolonged standing work for support

Work Position Recommendations

• If hand tools must be used, choose tools that do not require wrist flexion, extension or ulnar/radial deviation, keeping a neutral hand, arm and wrist position.

• For tools that may require great force such as plier, substitute for a vice grip style plier that grips on its own, not requiring a prolonged strenuous grip.

• Where possible, substitute electric or pneumatic powered tools, provided that they do not emit too much vibration.

Hand Tool Recommendations

• Havex Tri-Axial Hand Arm Vibration Meter

Instrument Used

• Various musculoskeletal injuries on the bone, joints, and muscles and tendons

Bones- osteoporosis, cysts in the handsJoint- joint pathologyMuscles/Tendons- impaired grip strength (neuropathological effect)

Vibration Injuries

Hand-arm vibration syndrome• Blanched fingers• Tenderness or pain and swelling of the fingers and

forearm• Paresthesia or tingling in fingers• Cold intolerance• Weakness of the finger flexors or intrinsic muscles• Loss of muscle control• Reduced sensitivity to heat and cold• Discoloration and trophic skin lesions of the fingers• Loss of manipulative dexterity and finger

coordination

Injuries cont.

Where:- ahv is the vibration magnitude (in m/s2).- T is the daily duration of exposure to the vibration magnitude (in m/s2).- T0 is the reference duration of eight

hours.*Single tool use

Daily Exposure?

Where:- A1(8)2, A2(8)2, A3(8)2, etc. are the partial vibration exposure values from the various vibration sources.*Multiple tools used

Exposure cont.

• Hand arm vibration can also be simplified by using an exposure system that relies on “points”.

Where:- PE,1h is in points per hour- ahv is vibration magnitude in m/s2.

Exposure cont.

• To determine the number of exposure points, one should follow this equation

Where:- ahv is the vibration magnitude (in m/s2).- T is the daily duration of exposure to the vibration magnitude (in m/s2).

Exposure cont.

• After the amount of exposure points has been determine, one can determine the daily exposure by using the following equation

Where:- PE,1h is in points per hour

Exposure cont.

Exposure Points Table

Aeq Peak Vector Points

x: 15.05 m/s2 x: 42.55 m/s2 22.59 m/s2 Aeq 5m: 86

y: 12.42 m/s2 y: 29.98 m/s2 15m: 256

z: 11.37 m/s2 z: 42.30 m/s2 30m: 511

1hr: 1021

Tool 1: Pneumatic Air Chisel

Aeq Peak Vector Points

x: 0.61 m/s2 x: 1.94 m/s2 1.44 m/s2 Aeq 5m: 1

y: 0.98 m/s2 y: 2.51 m/s2 15m: 2

z: 0.85 m/s2 z: 2.09 m/s2 30m: 3

1hr: 5

Tool 2: Pneumatic Cutoff Wheel

Aeq Peak Vector Points

x: 2.05 m/s2 x: 9.26 m/s2 2.96 m/s2 Aeq 5m: 2

y: 1.92 m/s2 y: 6.46 m/s2 15m: 5

z: 0.95 m/s2 z: 7.16 m/s2 30m: 9

1hr: 18

Tool 3: Pneumatic Impact Gun

Aeq Peak Vector Points

x: 1.25 m/s2 x: 3.86 m/s2 1.50 m/s2 Aeq 5m: 1

y: 0.66 m/s2 y: 2.84 m/s2 15m: 2

z: 0.50 m/s2 z: 1.75 m/s2 30m: 3

1hr: 5

Tool 4: Pneumatic Ratchet

Aeq Peak Vector Points

x: 0.83 m/s2 x: 3.19 m/s2 4.19 m/s2 Aeq 5m: 3

y: 3.58 m/s2 y: 8.87 m/s2 15m: 9

z: 2.01 m/s2 z: 5.74 m/s2 30m: 18

1hr: 36

Tool 5: Electric Grinder Handle

Aeq Peak Vector Points

x: 0.85 m/s2 x: 2.86 m/s2 2.30 m/s2 Aeq 5m: 1

y: 1.90 m/s2 y: 5.40 m/s2 15m: 3

z: 0.99 m/s2 z: 2.59 m/s2 30m: 6

1hr: 11

Tool 6: Electric Grinder Body

Aeq Peak Vector Points

x: 0.11 m/s2 x: 0.48 m/s2 0.29 m/s2 Aeq 5m: 1

y: 0.21 m/s2 y: 0.85 m/s2 15m: 1

z: 0.71 m/s2 z: 0.63 m/s2 30m: 1

1hr: 1

Tool 7: Electric Drill

- Pneumatic Air Chisel *22.59 m/s2 Aeq Less than 5 minutes

- Pneumatic Cutoff Wheel *1.44 m/s2 Aeq8 hours+

- Pneumatic Impact Gun *2.96 m/s2 AeqUp to 5 hours

- Pneumatic Ratchet *1.50 m/s2 Aeq8 hours+

- Electric Grinder (Handle) *4.19 m/s2 AeqLess than 3 hours

- Electric Grinder (Body) *2.30 m/s2 AeqUp to 8 hours

- Electric Drill *0.29 m/s2 Aeq8 hours+

Results

• Do not exceed the suggested times of operation for any of the tools unless you are seeking injuries.

Vibration Recommendations

• 2005. Hand-arm vibration syndrome. [Internet]. [2005 Apr 12, cited 2015 Nov 22] Available from: http://www.ulib.niu.edu:3565/content/172/8/1001.full.pdf+html

• Hagberg M. 2002. Clinical assessment of musculoskeletal disorders in workers exposed to hand-arm vibration. International Archives of Occupational and Environmental Health [Internet]. [2002 Jan, cited 2015 Nov 22] Volume 75(1). Available from: http://www.ulib.niu.edu:2359/article/10.1007/s004200100283

• Griffin MJ, Howarth HV, Pitts PM, Fischer S, Kaulbars U, Donati PM, Bereton PF. 2006. Guide to good practice on Hand-Arm Vibration [Internet]. [2006 Dec 06, cited 2015 Nov 22] Available from: http://resource.isvr.soton.ac.uk/HRV/VIBGUIDE/HAV%20Good%20practice%20Guide%20V7.7%20English%20260506.pdf

References: