Safety Study of OSHA's Experimental Variance on Self-Tripping of Power Presses: Phase II: Machine Actuation Devices: The Ergonomics of Making Hand Contact, Foot Contact, and Non-Contact Devices Safe Man-Machine Interfaces.
Ergonomic aspects of machine press actuators are discussed, including human reliability, control devices, rules and checklists for safe machine control design, and advantages and disadvantages of various safety features. Human error can be reduced by considering human factors in design of equipment and facilities, and by developing procedures to contribute to safety and training personnel in the use of such procedures. System reliability is a combination of human and equipment reliability. Injuries which can occur in punch press operators are discussed, and their widespread prevalence suggests a need for machine actuator reevaluation and design. Types of actuators include hand contact devices, foot contact devices, and photo optic non contact devices. Factors contributing to human/actuator system design include noise levels; sitting posture; reach distance; leg room; after reach phenomena; fatigue, stress, and strain of movements; and hand and arm movements in relationship to safe distances. Types and aspects of control devices are discussed. Hand controls are compared to foot controls, and two/hand controls are compared to self tripping devices. Criteria of reliability at the control interface involve design allowances for human reliability; rules for designing safe machine controls are presented.