machinery and machine guarding

7/28/2019 Machinery and Machine Guarding

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7/3/2013 2003 Seton Identification Products 2

Introduction

Serious employee injurycan occur when usingmachinery.

This module is based onCFR 1910 Subpart O whichdiscusses generalrequirements for protectingemployees in the machinearea.

Employee protection onseveral specific types ofmachinery is alsodiscussed.


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Introduction

It is important tounderstand how Subpart Oapplies to machinery in theworkplace.

Section 1910.212 is ageneral (horizontal)standard that applies to allmachines not specificallymentioned in other sectionsof Subpart O.

The other sections arespecific standards thatapply to particular types ofmachines.


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Objectives

At the end of this Machinery and Machine

Guarding module, you should be able to:

Identify hazards associated in working with and

around machinery and the guards used to

protect the operator

Identify hazards and machine guards for varioustypes of specialized machinery.


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General Requirements

One or more methods of machineguarding shall be provided toprotect employees in the machinearea from hazards such as thosecreated by point of operation,ingoing nip points, rotating parts,flying chips and sparks.

The following are some generalguidelines that apply to allmachines:

Guards shall be affixed to the

machine where possible andsecured elsewhere if not possible

A guard shall not create anaccident hazard


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General Requirements

The point of operation ofmachines that exposes anemployee to injury shall beguarded

Revolving drums, barrels, and

containers shall be guarded by anenclosure which is interlockedwith the drive mechanism

When the periphery of the bladesof a fan is less than 7 feet abovethe floor or working level, theblades shall be guarded with aguard having openings no larger

than inch

Machines designed for a fixedlocation shall be securelyanchored to prevent walking ormoving.


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Woodworking Machinery

Requirements

The following guidelines are basedon 29 CFR Subpart O - 1910.213and generally apply to allwoodworking machinery:

Each machine must be free fromsensible (able to be felt) vibrationwhen the largest size tool ismounted and run at full speed withno cutting load

A mechanical or electrical powercontrol shall be provided on each

machine so that operators can cutoff the power from each machinewithout leaving their position at thepoint of operation.


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Requirements

It should be unnecessary for themto reach over the cutter to makeadjustments. This does not applyto constant pressure controls usedonly for setup purposes

Machinery must have devices toprevent automatically restartingupon restoration of power afterpower failures.

Provision of these devices willprevent possible injury to

operators from automatic restarts.


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Requirements

29 CFR Subpart O - 1910.213 contains guarding requirementsfor specific woodworking machines.

A discussion of some of these requirements follows.

All woodworking machinery such as table saws, swing saws,radial saws, band saws, jointers, tenoning machines, boringand mortising machines, shapers, planers, lathes, sanders,veneer cutters, and other miscellaneous woodworkingmachinery shall be effectively guarded to protect the operator

and other employees from hazards inherent to their operation.


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Requirements

The mention of specific machines "is not intended to excludeother woodworking machines from the requirement thatsuitable guards and exhaust hoods be provided to reduce to aminimum the hazard due to the point of operation of such

machines."

Specific machinery. Radial Saws

Table Saws

Swing or Sliding Cut-Off Saws

Jointers Bandsaws and Band Resaws


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Abrasive Wheel Machinery

This section discusses Subpart O- 1910.215.

This regulation covers onlyabrasive wheel machinery. It doesnot cover wire wheels, buffing

wheels, or the like. An abrasive wheel is made up of

individual particles that arebonded together to form a wheel.

The potential hazard is that animproperly mounted and usedwheel can literally explode causingserious or fatal injury to the

operator. The four topics of the Abrasive

Wheel Machinery section arelisted to the left.


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Mounting

Because of the possibility that the abrasivegrinding wheel could explode, the operatormust inspect the wheel and check the speedof the spindle.

Immediately before mounting, all wheels shallbe closely inspected and sounded (ring

tested) by striking the wheel and listening forany abnormal sounds. This is done to ensurethat the new wheel has not been damaged.

The spindle speed of the machine shall bechecked before mounting of the wheel to becertain that it does not exceed the maximumoperating speed marked on the wheel.

Always ensure that the manufacturers

instructions are followed to properly mount thewheel.

The operator should also always ensure thatthe machine guards are in place. Exceptionsare discussed on the next screen.


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Machine Guards

Abrasive wheels can only be used on machines that have safety guards whichnormally cover the spindle end, nut, and flange projections.

Exceptions to the above machine guarding requirement includes machineswith:

Wheels used for internal work while within the work being ground

Mounted wheels, used in portable operations, 2 inches and smaller in diameter

Type 16, 17, 18, 18R, and 19 cones, plugs, and threaded hole pot balls where thework offers protection

Safety guards may be constructed so that the spindle end, nut, and outer flange areexposed on all operations where the work provides a suitable measure of protectionto the operator

Work practices that entirely cover the side of the wheel. Then, the side covers of theguard may be omitted

The spindle end, nut, and outer flange may be exposed on machines designed asportable saws.


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Work Rests

On offhand grinding machines,there must not only bemachine guards, butadjustable work rests of rigidconstruction to support the

work.

Work rests shall be adjustedclosely to the wheel with amaximum opening of 1/8 inchto prevent the work from beingjammed between the wheel

and the rest.

Breakage could result ifjamming were to occur.


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Angular Exposure and

Exposure Adjustment

The presence of an abrasivewheel safety guard is not enough.

Specific requirements concerningthe safety guard are discussedbelow.

Abrasive wheel safety guards forbench stands, floor stands, andcylindrical grinders shall notexpose the grinding wheelperiphery for more than 65degrees above the horizontalplane of the wheel spindle.

The protecting member of theabrasive wheel safety guard shallbe adjustable for variations inwheel size so that the distancebetween the wheel periphery andthe adjustable tongue or the endof the peripheral member at thetop shall never exceed 1/4 inch.


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Mechanical Power Presses

This section deals with 29 CFR Subpart O - 1910.217 whichdiscusses mechanical power presses.

This is a specialized, complex topic that is beyond the scope

of this discussion.

There are, however, some basic rules that are listed below:

The employer shall provide and ensure the usage of point-of-operation guards or properly applied and adjusted point-of-

operation devices to prevent entry of hands or fingers into thepoint of operation by reaching through, over, under, and aroundthe guard on every operation performed on a mechanical powerpress. This requirement shall not apply when the point-of-operation opening is 1/4 inch or less


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Mechanical Power-

Transmission Apparatus

This section deals with 29 CFR SubpartO - 1910.219 which contains detailedrequirements for the safeguarding of allthe power-transmission components.

Mechanical power-transmission

apparatus refers to all components ofthe mechanical system which transmitenergy from the prime mover (powersource) to the part of the machineperforming the work.

These components include flywheels,pulleys, belts, connecting rods,shafting, couplings, cams, spindles,

chains, cranks, and gears.

The primary focus of this regulation isto ensure that employees cannot beinjured by rotating members, in-runningnip points, sprockets or pulleys, and thelike.


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Some of the detailed requirements for Mechanical Power-Transmission Apparatus are presented below:

Guards for mechanical power-transmission equipment shall be

made of metal or other suitable material. Wood guards may be used in the wood working and chemical

industries, in industries where atmospheric conditions wouldrapidly deteriorate metal guards, or where temperature extremesmake metal guards undesirable

All pulleys, belts, sprockets and chains, flywheels, shafting andshaft projections, gears, and couplings, or other rotating or

reciprocating parts, or any portion thereof, within 7 feet of thefloor or working platform shall be effectively guarded


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All guards for inclined belts shall conform to the standards forconstruction of horizontal belts, and shall be arranged in such amanner that a minimum clearance of 7 feet is maintainedbetween the belt and floor at any point outside the guard

Flywheels protruding through a working floor shall be guarded

The guard shall extend at least 15 inches above the belt whereboth runs of horizontal belts are 7 feet or less from the floor orworking surface

Gear guards, where required, shall extend 6 inches above themesh point by a band guard covering the face, or be completelyenclosed

Couplings with bolts, nuts, or set screws extending beyond theflange of the coupling shall be guarded by a safety sleeve.


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Belts, pulleys, and shaftinglocated in rooms used exclusivelyfor power-transmission apparatusneed not be guarded when all ofthe following requirements aremet: Basement, tower, or room

occupied by transmissionequipment is locked againstunauthorized entrance

Vertical clearance inpassageways between the floorand power-transmission beams,ceiling, or any other objects is notless than 5 feet 6 inches

Intensity of illumination conformsto the requirements of ANSIA11.1-1965 (R1970)

Route followed by the oiler isprotected in such a manner as toprevent accidents or injury.


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Quiz Question:

All fans must be guarded and have

openings in the guard no larger than

1/2 inch.

True

False


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Quiz Question:

Woodworking machinery must be free

of sensible vibration when the largest

tool size is run at full speed with nocutting load.

True False


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Quiz Question:

This module discusses inspecting the

abrasive wheel machinery to ensure

that the operators will not be cut by thegrinding wheel during normal

operations.

True

False


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