Poor ergonomic design of sewing machine systems can lead to many health problems for all users, although users with disabilities can encounter additional problems. The angle of the head is lower than its natural position causing strain on the neck and shoulder muscles that may lead to headaches and some cumulative trauma disorders (CTDs). The required reaches are also greater than normally recommended and can lead to back pain and strain on the shoulder and elbow joints. Repetitive motion caused by the foot pedal can lead to CTDs in the foot. Excessive noise and poor lighting can also lead to hearing and vision problems.
Additional problems encountered by people with disabilities include inability to use the traditional foot pedal, greater limitations in reach distances, need for magnification, and improper seating.
Four aspects of the sewing station were addressed:
The table was modified to be adjustable between 24" and 28" high and the depth of the table limited to about 19". All containers were placed within 15" to the right or left of the user, to limit reach requirements. Also, the sewing machine platform is tiltable to 10-15 degrees below the horizon to keep the workpiece in the normal line of sight.
For any seated work, a footrest is recommended. For a traditional sewing station, a double footrest with a foot pedal incorporated for use by either foot was designed. For a non-traditional sewing station, a hand pedal was used. A forearm pad was added to keep the wrist in a neutral position and the force required to depress the pedal was reduced.
Appropriate seating was also addressed. Users of sewing machines traditionally sit on the front of their chairs to more easily operate the foot pedal. With the foot pedal modifications, a full-size seat was used. Proper seating requires adjustable height, seat depth, lumbar support, and armrests. An additonal posture aid was a front pad attached to the table to allow the user to lean forward with the workpiece and still maintain proper posture.
The final consideration was environmental, lighting and noise. An adjustable task light was added with the brightness at 1000lx, and an optional magnifier would also be added to the light. The noise level of industrial sewing machines could exceed the 90db limit for safe exposure, depending on the type of material and speed of stitching. Proper hearing protection, earplugs in this example, was used.
(No cost analysis included)
These design changes would be applicable for any user, regardless of disability, to improve the ergonomics of the sewing station. Users without foot control would benefit from the addition of the hand pedal. Also, users without good trunk control would benefit from the addition of the front posture pad.
Click on a link below to see the associated image: