Environmental Health & Safety

Machine SafeGuarding

Each piece of machinery has its own unique mechanical and non-mechanical hazards. Machines can cause a variety of injuries ranging from minor abrasions, burns or cuts to severe injuries such as fractures, lacerations, crushing injuries or even amputation. Machine guards are your first line of defense against injuries caused by machine operation. Each machine must have adequate safeguards to protect operators and other employees in the immediate work area from hazards created by ingoing nip points, rotating parts, sparks and flying debris.

The University of California, Riverside EH&S/General Safety staff developed the campus Machine Guarding Safety Program to manage the safe selection, procurement, use of and safe work practices, inspection and record keeping for all machine guarding equipment and devices. Included are guidelines for identification and correction of locations with machine guarding hazards that may endanger faculty, staff, students, and the public.

This Machine Guarding Safety Program applies to any department on campus, at field stations, or on leased property where any type of activities could result in injuries from machine operation. The campus Machine Guarding Safety written program outlines roles and responsibilities for users of machinery (including full-time employees, contract employees and graduate students performing research related activities in field stations and remote research facilities) as well as those of EH&S/General Safety staff in managing this program, and “Owner Departments” that purchase, maintain and/or manage an inventory of shop, scientific, maintenance or repair machinery. Additionally, this document describes all aspects of machine guarding use, inspection, personnel accountability for the condition and use of the equipment, safe work practices, training requirements, and record keeping.

Having an understanding of how a machine works, and how the guards can protect you, will result in a reduced risk of injury. In order to be in compliance with Cal/OSHA requirements, all guards must:

·         Prevent contact – machine guards must provide a physical barrier that prevents the operator from having any part of his/her body in the “danger zone” during the machine’s operating cycle;

·         Be secured in place or otherwise be tamper proof – machine guards must be secure and strong so that workers are not able to bypass, remove, or tamper with them. They must be attached to the machine where possible. If the guard cannot be physically attached to the machine it must be attached elsewhere;

·         Create no new hazard – A safeguard defeats its own purpose if it creates a hazard of its own such as a shear point, a jagged edge, or an unfinished surface which can cause a laceration. The edges of guards, for instance, should be rolled or bolted in such a way that they eliminate sharp edges. Machine guards should not obstruct the operator’s view; Allow for lubrication with the guard still in place - If possible, one should be able to lubricate the machine without removing safeguards. Locating oil reservoirs outside the guard, with a line leading to the lubrication point, will reduce the need for the operator or maintenance worker to enter the hazardous area.

·         Not interfere with the machine operation - Any safeguard which impedes a worker from performing the job quickly and comfortably might soon be overridden or disregarded. Proper safeguarding can actually enhance efficiency since it can relieve the worker’s apprehensions about injury.


A wide variety of mechanical motions and actions may present hazards to workers operating or working around machinery. The three basic types of hazardous mechanical motions and actions are:

·         Hazardous Motions – including rotating machine parts, reciprocating motions (sliding parts or up/down motions), and transverse motions (materials moving in a continuous line);

·         Points of Operation – the areas where the machine cuts, shapes, bores, or bends the stock being fed through it;

·         Pinch Points and Shear Points – the area where a part of the body or clothing could be caught between a moving part and a stationary object. This would include power transmission apparatuses such as flywheels, pulleys, belts, chains, couplings, spindles, cams, gears, connecting rods and other machine components that transmit energy.

There are also non-mechanical hazards that can injure machine operators or personnel working in the vicinity of machinery. These hazards include flying splinters, chips or debris; splashes, sparks or sprays that are created when the machine is operating. These hazards can be prevented through the use of machine guarding and wearing/use of required personal protective equipment (PPE).


There are five (5) general types of machine safeguards that can be used to protect workers and personnel in the immediate vicinity of machinery. They are:

·         Guards – these are physical barriers that prevent contact. They can be fixed, interlocked, adjustable, or self-adjusting.

·         Devices – these limit or prevent access to the hazardous area. These can be presence-sensing devices, pullback or restraint straps, safety trip controls, two-hand controls, or gates.

·         Automated Feeding and Ejection Mechanisms – These eliminate the operator’s exposure to the point of operation while handling stock (materials).

·         Machine Location or Distance – this method removes the hazard from the operator’s work area.

·         Miscellaneous Aids – these methods can be used to protect both operators and people in the immediate vicinity of operating machinery. Examples include shields to contain chips, sparks, sprays or other forms of flying debris; holding tools that an operator can use to handle materials going into the point of operation; and awareness barriers to warn people about hazards in the area.



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