Pinch Points - Don't Get Caught!


We take them for granted — the machines that complete production tasks with greater speed, accuracy, and efficiency than any manual method ever could. Machinery also reduces the physical demands of work that can lead to employee muscle strains and sprains. When much of the work is mechanical, the risk of personal injury is greatly reduced. 

However, there is a downside to using machinery. Although the benefits of machinery are many, they can also expose workers to potentially dangerous moving parts. Any machine part or process which could cause injury, must have safeguards to prevent that exposure. 

Hazardous Locations On Machines 

Dangerous moving parts are typically found in one or more of the following three locations. Some form of safeguarding is needed at these points: 

Point of operation: This is the point at which cutting, shaping, boring, or forming of the stock is accomplished. It also includes any other point that creates a hazard when operators insert or manipulate materials during the machine’s operation. A specific example would be the point of the process where a grinder comes into contact with the face of a weld. 

Power transmission apparatus: This includes all moving components of the mechanical system that delivers energy to the area of the machine that performs the work. Examples include flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, cranks, and gears. A specific example would be the belt and pulley apparatus of an air compressor. 

Other moving parts: This includes all other parts of a machine that moves while the equipment is functioning. Examples include reciprocating, rotating, and transverse moving parts. Other cases are feed mechanisms and auxiliary moving parts of the machine. 

Five Approaches to Machine Guarding 

— Stationary Guards 

Stationary guards are physical barriers that enclose dangerous machine parts and prevent contact. They must be strong and fastened by a secure method that prevents the guard from being inadvertently dislodged or removed, this is the preferred method of protection. 

— Safe Guarding Devices 

Safeguarding devices are controls or attachments that usually prevent inadvertent access by employees to hazardous machine areas. Examples include presence sensing, pullback, restraint, safety controls, and gates. 

These devices may perform one of several functions: 

  • It may stop the machine if a hand or any part of the body is inadvertently placed in the danger area. 

  • It may restrain or withdraw the operator's hands from the danger area during operation. 

  • It may require the operator to use both hands on machine controls, thus keeping hands and body out of danger. 

  • It may provide a barrier which is synchronized with the operating cycle of the machine to prevent entry to the danger area during the hazardous part of the cycle. 

— Secondary Safeguarding Methods 

Detection safeguarding devices, awareness devices, safeguarding methods, and safe work procedures are secondary safeguarding methods. These methods provide a lesser degree of protection than the primary safeguarding methods as they do not prevent employees from placing or having any part of their bodies in the hazardous machine areas. These methods are acceptable only when guards or safe-guarding devices cannot be installed due to reasons of infeasibility. This method must have prior approval by management and documented by the safety department. 

** Secondary safeguarding methods must not be used in place of primary safeguarding methods. 

— Location/Distance 

To consider a part of a machine to be safeguarded by location, the dangerous moving part of a machine must be positioned so that those areas are not accessible or do not present a hazard to a worker during the normal operation of the machine. A thoroughly documented hazard analysis of each machine and the particular situation is essential before attempting this safeguarding technique and must be approved by management and documented by the safety department. 

— Awareness Barriers (warnings) 

Awareness barriers do not give complete protection from machine hazards; however, they may provide the operator with an extra margin of safety. An awareness barrier does not provide physical protection but serves only to remind a person that he or she is approaching the danger area (an example is barricade tape). This method must have prior approval by management and documented by the safety department prior to work beginning. 

***Awareness Barriers are not considered adequate when continual exposure to the hazard exists. 

Infographic courtesy Premiere Safety Partners

Infographic courtesy Premiere Safety Partners

For more information on machine guarding and pinch points,
please see this edition of Wachs Weekly!