From The Ergoweb® Learning Center

Ergonomics- Skin Stapler Assembly and Welding Operation


Longmate, Arthur R., and Hayes, Timothy J., March/April 1990, Making a Difference at Johnson & Johnson: Some Ergonomic Intervention Case Studies, Industrial Management, 32(2).

Task Prior to Abatement (Description)

This task was performed by a four-man crew (two assemblers, one welder, and one cleaner/packer). With the tote upright on the table, the assembler would reach into the pan each time and get a single component (total five components) for each assembly. Workers needed to reach near the bottom of the tote when the pans were less than half-full. The welding operation involved welding the instrument in an ultrasonic welder and then firing it five times to test staple formation and staple feed in the magazine.

Task Prior to Abatement (Method Which Verified Hazard)

The welding operation steps were:

1)Get one instrument from tray with the left hand

2)Position and insert into welder nest using the same hand

3)Close manual clamp on welder nest with left hand

4)Push and hold welder activation buttons to cycle welder

5)Get instrument from weld nest using right hand

6)Fire instrument once by striking trigger forcefully with palm of left hand

7)Place instrument aside for final cleaning or destroy it if not acceptable

8)Record the defect type on sheet

If the welder station became backed up, one of the assemblers would swing over and assist the welder by performing the test-firing function.

Task Prior to Abatement (Method Which Identified Hazard)

The ergonomic-related medical incidence rate was extremely high in this department. These incidences include various forms of tendinitis and hand/wrist related disorders.

Many employees were placed on medical restrictions.

Ergonomic Risk Factor (Force)

High mechanical force concentrations to the hands and fingers and high hand force is required to dig the parts out.

Ergonomic Risk Factor (Posture)

Longer reach than necessary and difficulty in grasping is required to grasp the parts.

Ergonomic Risk Factor (Repetition)

High repetitive wrist flexion and ulnar deviation is required in order to strike the trigger forcefully with the palm of the left hand five times to fire each instrument for approximately 4,000 instruments per day.

Ergonomic Solution (Administrative Controls)

A structured job rotation sequence was established to reduce the exposure to the high repetitive and forceful tasks.

Ergonomic Solution (Engineering Controls)

Assembly stations with adjustable V-stands were provided to tilt up tote pans to the most accessible angle without allowing parts to spill out onto the table.

New, adjustable ergonomic chairs were purchased and footrests were provided for shorter employees to reduce the risk of posture related injuries and increase comfort.

A presence sensing activation button system was provided and an adjustable angle mounting bracket was developed to attach the activation buttons to the side of the welder in order to reduce the high repetition and forceful task of activating buttons using the thumbs (reducing the thumb tendinitis).

A pneumatic clamp was used to automatically clamp the instrument in order to eliminate repetitive striking of a manual De-sta-co clamp to retain the instrument for welding.

Ergonomic Solution (Benefits)

All workers that perform this task now have reduced exposure to various forms of tendinitis and other hand/wrist related disorders.

Productivity has increased up to 10-12 percent.

Employee response to the modifications has been extremely positive and they can perform the task with less risk of injury.

Ergonomic Solution (Method Which Verified Effectiveness)

There has been a 10-12 percent increase in productivity.

New medical problems have greatly diminished.


Providing a conveyor to automatically transport trays of assembled instruments between the assembly and welding workstations is under consideration, although from an ergonomic view, the positive influence of a conveyor is not as clear because of the low weight (about five pounds) of the full trays of instruments. Due to the relatively high cost of the conveyor (about $8,000 per line) and due to the questionable ergonomic impact, justification is in question.