What are the three types of machine safety?

The three types of machine safety are often described as engineering controls, administrative controls, and personal protective equipment, following the hierarchy of controls, or alternatively as safeguarding, complementary protective measures, and information for use per machinery safety standards. Engineering controls include fixed guards, interlocking guards, light curtains, safety mats, and two-hand controls that physically prevent access to hazards or stop hazardous motion. Administrative controls include training, safe operating procedures, warning signs, lockout tagout procedures, and supervision that rely on people following rules. Personal protective equipment includes safety glasses, gloves, hearing protection, and safety shoes that protect the individual but do not remove the hazard. In functional safety, three types might be described as prevention of unexpected startup, stopping and braking safety functions, and protection against mechanical hazards. Effective machine safety programs combine all three, prioritizing engineering controls that eliminate or reduce risk at the source, then administrative measures, then PPE as last resort, as defined in ISO 12100 and OSHA guidelines.