Injury Reduction Ergonomics in the Development of an Automated Squeezer
Molder Line in a Gray and Ductile Iron Casting Facility
Angela Galinsky, University of South Dakota Carryl Baldwin, Western Iowa Technical Community College T. Dell,
J. Berkhout, University of South Dakota
In the course of a company-wide ergonomic evaluation of workstations, three squeezer-molder
stations in the casting division of the foundry were found to generate an unacceptably high rate of
musculoskeletal injuries. OSHA 200 logs for these workstations provided documentation of strains, tears
and back injuries dating back to 1981.We conducted a detailed inventory of all discrete operator tasks performed at these stations. Each
task was further analyzed for its effect on operator safety, productivity, machine integrity, and for the
derivation of design requirements for possible automation of the squeezer-molder stations.Extensive automation of these workstations was determined to be the most cost-effective way of
reducing the physical hazards to the operators.This foundry produces gray and ductile iron castings of up to 1,500 pounds. Approximately 150
employees work in the casting facility. Most of the workstations require considerable physical effort.
Forklifts move pallets of molds, cores and castings. An overhead conveyor moves crucibles of molten metal.
Other lifts and displacements are human powered, some using wheeled carts.The company is known for its low scrap rate (less than 2%), and its aggressive quality control
procedures. The company has an active safety committee, and its safety policies and procedures are well
documented and implemented.
Ergonomic hazard inventory
Seventeen years of accident records were reviewed. Workstations were flagged for extensive
analysis if they met any of the following tests:
|a frequency of accidents above norms for the metal working industry;|
|any severe accidents involving lost time;|
|any injuries related to repetitive stress or chronic musculoskeletal disorders;|
|any upper extremity disorders;|
|any accidents suggesting the presence of noxious environmental conditions.|
Minor injuries tended to occur to the most recent hires, while serious injuries were distributed among
employees without regard to tenure. This suggests that experience reduced exposure to minor injuries, but
that major workstation changes would be needed to reduce the more serious incidents.
Tables 1 and 2 below are excerpted from Dell and
Berkhout ( 1998), who published an extensive
review of injuries by work category at this same metal working facility.
One startling statistic is that less than one-fourth of all the molders working at the three sand mold
stations escaped injury. This was due to their low turnover rate and long tenure at the shop, as well as the
nature of the tasks they performed.