Technology & Engineering
Machine Guarding
Machine guarding refers to the protective barriers, devices, and practices implemented to ensure the safety of individuals working with or near machinery. It aims to prevent contact with moving parts, electrical hazards, and other potential dangers. Proper machine guarding is essential for minimizing the risk of accidents and injuries in industrial and manufacturing settings.
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10 Key excerpts on "Machine Guarding"
eBook - PDFSafety and Health Essentials
OSHA Compliance for Small Businesses
- William Martin, James Walters(Authors)
- 2001(Publication Date)
- Butterworth-Heinemann(Publisher)
14 Machine Guarding The National Safety Council estimates that nearly 20% of all permanent partial disabilities result from injuries associated with machinery. Machine Guarding is of the utmost importance in protecting workers from the hazards associated with machinery. In fact, the degree to which machines are guarded is a reflection of the company's interest in providing a safe workplace. The purpose of this chapter is to provide a general overview of OSHA requirements relative to guarding machinery and equipment and how guarding contributes to the total hazard control program. Workers cannot always be relied upon to act safely enough around machinery in motion to avoid injury. Even the well coordinated and highly trained worker may commit an error which could lead to injury and death. While an effective guard will allow workers to be more comfortable around machinery, a poorly designed or inadequate guard is very dangerous because workers falsely believe that it will protect them. The National Safety Council defines guarding as any means of effectively preventing personnel from coming in contact with the moving parts of machinery or equipment which could cause physical harm to the personnel. Machine Guarding prevents injury from the following sources: 9 direct contact with the moving parts of a machine 9 work in process making contact with personnel (kickbacks on a circular ripsaw, metal chips from a machine tool operation, or splash- ing of chemicals or hot metal) 9 mechanical failure 9 electrical failure 9 human failure from any cause (curiosity, distraction, fatigue, worry, anger, illness, zeal, laziness, or deliberate risk-taking) Machine Guarding is a mandatory part of the safety and health program. With the information derived from this chapter, small businesses can evaluate 234
eBook - ePub- John Ridley, Dick Pearce(Authors)
- 2006(Publication Date)
- Routledge(Publisher)
Part II Guarding TechniquesTo be effective, guards and safeguarding devices must be pertinent to the application and be applied in a manner that will ensure the desired levels of protection. This part looks at the different types of guards that can be used, the techniques to make their application effective and gives typical examples. It also considers techniques of non-physical protection through the use of trips, interlocks and layout of controls. Since most machines are now powered by electricity, electrical controls and control systems of increasing complexity are being developed to match the complexity of modern machinery. Perhaps one of the most unpredictable aspects of safety in the operation of machinery is the operator. By applying ergonomic techniques to the design of safeguards the temptation to by-pass or defeat them is greatly reduced. All these facets of safeguarding are considered in this part.
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Chapter 5
Mechanical Guarding
5.1 Introduction
The object of a guard is to prevent access into the danger zone or to parts of a machine that could cause injury. The type of guard used will depend on the type of machine, the process and operating needs. Generally the term ‘guard’ refers to a fixed barrier between the operator and the dangerous part of the machine.The particular hazards to be guarded against will be identified from the findings of the risk assessment and risk reduction investigation. A number of safeguarding techniques are available and it is incumbent upon the designer to select the one that will give the greatest protection within the parameters of the agreed operating procedures. When considering the most appropriate method of safeguarding to provide the required degree of protection, there are two main avenues of approach:
eBook - ePub- Ron C. McKinnon(Author)
- 2019(Publication Date)
- CRC Press(Publisher)
Unguarded or inadequately guarded machines cause a high percent of injuries which are normally serious, and many of them are permanent. Unguarded machines are also responsible for a number of accidental deaths each year.It is often asked, “How do we know if the machine is sufficiently guarded?” A rule of thumb is that if a person should stumble and fall with outstretched hands, could they be injured in a machine or unguarded pinch point? Machine guards should be fitted wherever rotating or operating machinery is within normal reach.Definitions
A machine guard is a device that prevents limbs and other body parts from contacting the dangerous moving parts of machinery.Guarding means effectively preventing people from coming into contact with the moving parts of machinery or equipment that could injure them.Enclosing means guarding by means of physical barriers which are mounted on a machine in an effort to prevent access to the hazardous parts.Fencing means erecting a fence or rail which restricts access to a machine.Classes of Machine Guards
There are two basic classes of machine guards: transmission and point-of-operation guards. Transmission guards are guards which guard all mechanical components including gears, cams, shafts, pulleys, belts, and rods that transmit energy and motion from a source of power to a point of operation. Point-of-operation guards effectively shield the area on a machine where the material is positioned for processing and where an exchange of energy takes place.Types of Machine Guards
There are four main types of machine guards: fixed guards, interlocking guards, automatic guards, and point-of-operation guards.A fixed guard is preferable and should be used in all cases where possible. It prevents access to the danger areas at all times and is normally a part of the machine.Interlocking guards
eBook - ePubSurviving an OSHA Audit
A Management Guide
- Frank R. Spellman(Author)
- 2020(Publication Date)
- CRC Press(Publisher)
Concepts and Techniques of Machine Safeguarding , published by OSHA (publication No. 3067), 1992. Although dated, this remains an excellent reference source, which is available from the Superintendent of Documents, U.S. Government Printing Office, Washington, DC.Basics of Safeguarding Machines
OSHA points out that any mechanical motion that threatens a worker’s safety should not remain unguarded. The reasoning behind this point is quite clear and is reinforced often—anytime the safety and health professional investigates on-the-job injuries involving crushed hands and arms, severed fingers, blindness, and other horrifying machinery-related injuries. For the safety and health professional, the goal is quite clear: when the operation of a machine or accidental contact with it can injure the operator or others in the vicinity, the hazards must be either controlled or eliminated.Safeguarding Defined
Application of appropriate safeguards keeps people and their clothing from coming into contact with hazardous parts of machines and equipment. Safeguards also prevent flying particles from an operation and/or broken machine parts from striking or injuring people. Guards may also serve to enclose noise or dust hazards.The National Safety Council (1987) defines Safeguarding as follows:“Machine safeguarding is to minimize the risk of accidents of machine-operator contact.” The contact can be:- 1. An individual making the contact with the machine—usually the moving part—because of inattention caused by fatigue, distraction, curiosity, or deliberate chance taking.
- 2. From the machine via flying metal chips, chemical and hot metal splashes, and circular saw kickbacks, to name but a few.
- 3. By the direct result of a machine malfunction, including mechanical and electrical failure.
According to Brauer (1994), guards should have certain characteristics. They should be a permanent part of the machine or equipment, must prevent access to the danger zone during operation, and must be durable and constructed strongly enough to resist the wear and abuse expected in the environment where machines are used. Guards should not interfere with the operation of the machine—that is, guards must not create hazards. Finally, machine guards should be designed to allow the more frequently performed maintenance tasks to be accomplished without the removal of the guards.
- Charles D. Reese(Author)
- 2008(Publication Date)
- CRC Press(Publisher)
17 Machine Guarding 17.1 Machine Guarding Machine Guarding is an integral part of safety and health for those working in the infrastructure section of the service industry. It matters little what piece of equipment or machinery is found in the workplace, but it does matter if it is not properly guarded to protect workers from making errant contact, which could result in injury, amputation, or even death. All machines or equipment should have a hard guard, but at times this is not possible and other safeguards are place upon machines or equipment to protect workers. Amputations are among the most severe and disabling workplace injuries. They are widespread and involve various activities and equipment (The U.S. Bureau of Labor Statistics 1996 annual survey indicated that there were approximately 10,000 amputations for all industry sectors). About one-half of all workplace amputations occur in the manufacturing sector and the rest occur across the construction, agri-culture, wholesale and retail trade, and service industries. These injuries result from using stationary machines such as saws, presses, conveyors, and bending, rolling, or shaping machines as well as from powered and nonpowered hand tools, forklifts, doors, and trash compactors; and during material-handling activities. The information will help employers protect their employees. It will help in the recognition, management, and control of the potential hazards form machines and equipment in the workplace. The chapter cannot possibly cover all machines or Example of an enclosure interlocking guard that disengages the machine ’ s operation when raised. 259 equipment and their associated hazards, but it provides the principle approaches need to assure safeguarding machines and equipment. Although this chapter recommends work practices and ways to safeguard machinery, there are legal requirements in OSHA standards that need to be complied with.
- Charles D. Reese(Author)
- 2008(Publication Date)
- CRC Press(Publisher)
Couplings with bolts, nuts, or setscrews extending beyond the fl ange of the coupling are to be guarded by a safety sleeve. 18.17 SUMMARY Machine Guarding is visible evidence of an employer ’ s interest in promoting safety, and it is to the employer ’ s bene fi t, for unguarded machinery is a principle source of accidents that cause injuries for which compensation must be paid. A guarded machine is a safer machine; and when operators have no fear of a machine, they can better contribute their effort to production. FIGURE 18.6 If the gate is lifted during operation, an interlocking system will de-energize it. Machine = Equipment Safeguarding 289 An effective machine guard should have certain characteristics in design and construction. Such a guard should . Be considered a permanent part of the machine or equipment . Afford maximum protection . Prevent access to the danger zone during operation (see Figure 18.6) . Be convenient: it must not interfere with ef fi cient operation . Be designed for the speci fi c job and speci fi c machine, with provisions made for oiling, inspection, adjusting, and repairing machine parts . Be durable and constructed strongly enough to resist normal wear . Not present a hazard in itself Safe machine operating conditions depend on the detection of existing and potential hazards and on taking immediate actions to remedy them. Management should develop and keep its own machine-guarding checklists. Employees should follow safety precautions and be trained on the machines that they are required to operate. 290 Industrial Safety and Health for People-Oriented Services
eBook - PDF- Keith Dinwiddie(Author)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
Guards , for our purposes, are devices designed to protect us from the dangers of a system. The two types we will explore are guards installed directly on the equipment and those placed a set distance from the device. No matter the placement, a guard’s main purpose is to keep people safe; only rarely do they improve the operation of the equipment. In fact, there are many situations where guards will limit the operation of the equipment and/or make it more difficult to work with. Guards that protect us from moving parts such as chains, pulleys, belts, or gears mount directly to the robot and are part of the system. Usually this guarding is supplied by the manufacturer in the form of the outer structure of the robot (see Figure 2-5). This guarding will often be made of a sturdy plastic or light metal that will allow for removal during repairs and preventative maintenance. Depending on how the guarding fits together, it may be necessary to move the robot into specific positions to remove certain pieces. If you are having trou-ble removing a piece of guarding, look for hidden screws or other pieces that may be holding it in place. Trying to force a piece of guarding off is a good way to break it and possibly damage parts underneath. Always repair or replace damaged guarding to ensure proper operation of the system and the safety of those who work around it. Guarding that encloses the work area or envelope of a robot, as mentioned earlier, can be made of vari-ous materials, though expanded metal or metal mesh is the most common. Expanded metal guarding is metal that is perforated and then stretched to create diamond-shaped holes with eighth-inch pieces of metal around it (see Figure 2-6); metal mesh consists of thick wire welded and/or woven together to create a strong bar-rier that is easy to see through (see Figure 2-7). We weld these into metallic frames, usually angled iron pieces, which make up the panels of the robot cage.
eBook - ePubHealth and Safety at Work
An Essential Guide for Managers
- Jeremy Stranks(Author)
- 2016(Publication Date)
- Kogan Page(Publisher)
Some machines actually emit particles of metal. Grinding machines are a classic example, where there is a risk of ejection of metal particles, particularly into the face and eyes or, alternatively, of the abrasive wheel actually bursting without warning.OTHER HAZARDS ASSOCIATED WITH MACHINERY OPERATION
While the above items are classed as the principal machinery hazards, there are many other hazards which need consideration at the design stage of a machinery-based work system, and during the operation of machinery. In certain cases people not actually involved in machinery operation may be exposed to risk of injury. Any assessment of the relative safety of a machine should take into account the following:- procedures for job loading and removal;
- systems for changing of tools;
- safe removal of scrap and waste material;
- procedures for routine maintenance and adjustment, gauging, trying out following adjustment or setting, and in the event of breakdown;
- the potential for unexpected start-up or movement, uncovenanted stroke of the machine or mechanical failure;
- safe access to and egress from the machine and machine area;
- cleaning and housekeeping procedures in the machine area;
- availability of operating space; and
- potential risks to other persons passing through the machinery operating area.
MACHINERY GUARDS
BS EN ISO 12100 Safety of Machinery is the authoritative guidance on machinery safety in the United Kingdom, and is revised at regular intervals. The following forms of guard are specified in BS EN ISO 12100.Fixed guard
This guard has no moving parts associated with it, or dependent upon the mechanism of any machinery, and, when in position, prevents access to a danger point or area. Generally, a fixed guard should not be removable other than through use of a hand tool. Fixed guards are generally used to guard transmission machinery, such as belt drives to machinery.
eBook - PDF- George T. Halmos(Author)
- 2005(Publication Date)
- CRC Press(Publisher)
In the United States, the OSHA Act of 1970 regulates the installation and use of Machine Guarding. In addition to OSHA, other organizations provide information on proper Machine Guarding. The ANSI publishes the B11 standards to provide information on the safety requirements for the construction, care, and use of machine tools. The National Safety Council’s safety manuals and data sheets are good sources for safety of machine tools. It is in the manufacturer’s and user’s best interests to understand and agree upon their legal and moral responsibilities regarding the safeguarding of machines. Manufacturers want to produce a competitive machine, while users want a machine that increases productivity. However, before any of these goals can be met, both parties must first determine how to engineer the machine using safe design principles to minimize operator’s risks. 13 -1 Investing in a safer workplace will also reduce the expenses of treating injured workers, will help companies to control insurance premiums, prevent workplace accidents, and will help boost employee morale by conveying the message that the company cares about its employees and wants to protect their health and safety. This chapter is intended to give the reader a brief overview of safety requirements for equipment, which are based on ANSI B11.12 and related standards. 13.2 Common Safety Related Definitions Definitions listed here are based on B11.12 standards. Safety is the ability of a machine to perform its function while being transported, installed, adjusted, maintained, dismantled, and disposed of under conditions of intended use specified in the instruction manual without causing injury or damage to health. Risk is a comprehensive estimate of the probability and the degree of the possible injury or damage to health in a hazardous situation in order to select appropriate safety measures. Hazard is a condition or set of circumstances that can cause physical harm to exposed personnel.
eBook - PDF- John R. Ridley(Author)
- 2014(Publication Date)
- Butterworth-Heinemann(Publisher)
26.5 Risk reduction Essentially reduction of risk can be achieved by technical, procedural or behavioural measures, or most notably by a mixture of all three, as shown in Table 26.2. Each machine or process should be studied and arrangements for its safe operation developed in the context of the criteria set out in the Table. Table 26.2. Risk reduction checklist (Ί) Technical measures (to make the machinery inherently safer) Dangerous parts: eliminate, or reduce capacity to cause harm: - reduce speed of movement; - reduce forces, torques, pressures, and inertia; - reduce or eliminate rough or sharp surfaces and projections; - reduce, or when appropriate, increase the size of clearances/gaps; Dangerous parts: seek ways of making the dangers more obvious Machine and guard design: -reduce need for access (e.g. remote lubrication/adjustment) - improve component and system design (reduce probability of failure and/or failure-to-danger) Guard design: - reduce ease of access to imminent danger (e.g. safeguards which allow safe access, but prevent access at other times) Machine controls: improve ergonomie layout to reduce unintended errors (2) Procedural measures (to make the work tasks safer) Planned maintenance and inspection of machines and guards Systems of work (which minimise needs for dangerous access) Permit-to-work procedures (to formalise precautions for imminent danger) (3) Behavioural measures (to ensure that personnel wish, or are obliged, to work safely) Training: basic skills; systems and procedures; knowledge of hazards Instruction and supervision (Note that the absence of 'risk taking' is only attainable when the inconvenience of defeating the safeguard or system exceeds the benefits which accrue for so doing.) 562 Part IV General science 26.6 Description and selection of safeguards It should be remembered that guards are only required where the designer has failed to achieve intrinsic safety through not avoiding trapping and similar dangers.
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