health and safety executive vibration solutions · 2014. 10. 1. · vibration solutions page 3 of...

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Health and Safety Executive

Vibration solutionsPracticalwaystoreducetheriskofhand-armvibrationinjury

This is a free-to-download, web-friendly version of HSG170 (First edition, published 1997). This version has been adapted for online use from HSE’s current printed version.

Youcanbuythebookatwww.hsebooks.co.ukandmostgoodbookshops.

ISBN 978 0 7176 0954 3Price £13.75

This book is aimed at managers in industry who experience problems with vibration tools, which can cause hand-arm vibration syndrome and vibration white finger. It features case studies to demonstrate how vibration levels can be reduced and by how much. It describes solutions which have been adopted by industry and how much they cost using charts, illustrations and photographs to accompany a description of the methods used.

HSE Books

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© Crown copyright 1997

Firstpublished1997

ISBN9780717609543

Allrightsreserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystem,ortransmittedinanyformorbyanymeans(electronic,mechanical,photocopying,recordingorotherwise)withoutthepriorwrittenpermissionofthecopyrightowner.

Applicationsforreproductionshouldbemadeinwritingto:TheOfficeofPublicSectorInformation,InformationPolicyTeam,Kew,Richmond,SurreyTW94DUore-mail:[email protected]

ThisguidanceisissuedbytheHealthandSafetyExecutive.Followingtheguidanceisnotcompulsoryandyouarefreetotakeotheraction.Butifyoudofollowtheguidanceyouwillnormallybedoingenoughtocomplywiththelaw.Healthandsafetyinspectorsseektosecurecompliancewiththelawandmayrefertothisguidanceasillustratinggoodpractice.


Vibrationsolutions Page3of107


ContentsIntroduction 5

How to approach a vibration problem 6

Avoiding pitfalls when introducing vibration control 10

Reduction in vibration exposure case studies 12Tableofcasestudiessortedbyvibrationsource 14

Case studies 181 Semi-automaticcutoffmachine 182 Off-linegrindingwheelpre-forming 193 Introductionoflow-vibrationanglegrinders 214 Crushingconcrete 235 Waterjetting 246 Burstingconcreteinsteadofbreaking 267 Diamondwirecutting 288 Pipelineinsertionmethodavoidstrenching 309 Directionaldrillingavoidstrenching 3210 Mountedroadbreaker 3411 Reduced-vibrationroadbreakers 3612 Maintainingchainsawanti-vibrationrubberbushes 3813 Chainsawmaintenanceandtrainingprogramme 4014 Reduced-vibrationchippinghammer 4215 Sleeveforchippinghammerchisel 4416 Isolatedcastingcutoff 4517 Automaticfettlingofcastings 4718 Air-carbonarcgougingreplacestraditionaltools 4819 Castingshellknockoutincabinet 5020 Maintenanceoflow-vibrationtools 5221 Reduced-vibrationneedleguns 5422 Shotblastingcabinetreplacesrotaryfiles 5623 Descalingwithabrasiveblasters 5724 Jobrotationanduseofpedestal-mountednutrunners 5825 Automaticboltfitting 6026 Automatedpalletstripping 6227 Low-vibrationpowersaw 6328 Outdoorpowertoolspurchasingpolicy 6429 Low-vibrationfastenersystem 6630 Nocontactcastingshellknockout 6831 Low-vibrationrivetersandreactionbars 6932 Specialformworkavoidsscabbling 7133 Paint-onmaterialavoidsscabbling 7334 Gritblastinginsteadofscabbling 7435 Reduced-vibrationpolescabbler 7536 Deburringwithrumbler 7737 Beltgrindingandpolishingofmetalfabrications 7838 Groupworkingwithsuspendedtools 7939 Installationofhydrauliccroppingmachine 8040 Excavatorreducesvibrationexposureinquarry 8241 Toolstockauditandpurchasingpolicy 8442 Hands-freelinishing 8543 Beltgrindingandpolishingofceramicware 8644 Isolationforgrindingoperation 8745 Lasercutterreplacesnibblingmachine 89



Maintaining blood circulation case studies 9146 Glovestowarmhands 9247 Ductawayexhaustair 9348 Heatedhandles 9449 Hotairtowarmhands 95

Health surveillance 9650 Healthsurveillanceonaconstructionsite 9751 Screeningandsurveillancemethodsinanaero-enginemanufacturer 98

Table of case studies by industry 100

Table of case studies by reduction method 101

References 102

Further reading 103

Glossary 104

Acknowledgements 106

Further information 107



IntroductionBackground

Vibrationexposurefromprolongedandregularworkwithpoweredhand-heldtools,equipmentorprocessescanhaveadverseeffectsonthehandsandarmsofusers.Withouteffectivecontrols,workersusingsuchequipmentmaysuffervariousformsofdamage,collectivelyknownas‘hand-armvibrationsyndrome’(HAVS).Thisisapainfulconditionandtheeffectscanincludeimpairedbloodcirculation,damagetothenervesandmuscles,andlossofabilitytogripproperly.Thebestknownformofdamageis‘vibrationwhitefinger’(VWF),whichisaprescribedindustrialdisease.

Legislation and HSE guidance

Underhealthandsafetylegislation1,2,3employersandmachinemakersmustconsiderwhatactionisnecessarytoreduceriskstohealth,sofarasisreasonablypracticable.HSEhaspublishedauthoritativeguidance,Hand-arm vibration(HS(G)88),4asasourceofreferenceforthoseinvolvedinidentifyingandcontrollingtherisksofHAVS.Itcontainsextratechnicaldetailstocomplementthecasestudiesandincludessectionson:hazardandcontrolprogrammes;technicalwaystoreducevibration;clinicaleffectsandthehealthsurveillanceprogramme;andmeasuringhand-armvibration.Alistofotherrelevantpublicationsisincludedinthe‘Furtherreading’section.

Aim of the book

Thisbookisaimedatmanagersandshowsthatvibrationproblemscanbesolvedinmanyways-butitisnotexhaustive.Itoffersrealexamplesofhowsomecompanieshavereducedvibrationatwork.Althougheachindustryhasitsownworkingpractices,manyvibrationproblemsandsolutionsarenotuniqueandarerelevantinseveralindustries.Vibrationreductionshouldbeconsideredattheprocessandproductdesignstages,whenselectingandpurchasingtools,andwhenindividualworktasksandworkstationsarebeingdesigned.

Check-list and advice for managers

Thisbookincludesacheck-listformanagersonapproachingtheproblemofvibrationandadviceonavoidingpitfallswhenintroducingvibrationcontrols.

The case studies

Thecasestudieshavebeenorganisedintothreesections,eachwithashortintroduction.Theseare:

(a) reductionofexposuretovibration;

(b) maintainingbloodcirculation;and

(c) healthsurveillance.

Thetablesatthebeginningandendofthebookprovideaneasycross-referencetocasestudiesforparticularindustriesandtoparticularmethodsofvibrationcontrol.

Someemployershavedevelopedthesolutionsin-house.Otherorganisationshavefoundthatemployingvibrationconsultantswithwideexperienceininvestigatinghand-armvibrationexposureatworkhasledtoeffective,value-for-money



solutions.Tohelpemployers,HSEhaspublishedguidanceonemployinghealthandsafetyconsultants.5

Someofthelanguageistechnicalandsoaglossaryisincludedattheendofthebook.Thecasestudiesaredesignedtogivemanagersanideaofwhatisachievableandarenotmeanttoreproducetechnicalmanuals.

Acknowledgements

HSEcommissionedAVTechnologyLimitedtogatherinformationforthecasestudymaterialinthisbook.Wewouldliketothankthemandthecompanieswhoagreedtobeinvolvedwiththispublication(listedonpage106).

How to approach a vibration problemAnyworkerwhousespoweredhand-heldorhand-guidedtoolsasamajorpartoftheirjobmaybeatriskofdevelopingvibrationinjurytotheirhandsandarms.Manyworkerswhoneedtoholdworkpiecesindirectcontactwithmachinerymayfacesimilarrisks.Inparticular,anyjobthatcausestinglingornumbnessinthefingers,orwherefingerblanchingoccurs,shouldberegardedassuspect.Onecourseofactioncouldbetomeasurethevibration,assesstheexposureandtakeactioninaccordancewithHS(G)88.4Forpoweredhandtools,itmaybeeasiertoassumethereisaproblemwhenthereisregularandprolongeduse.

Thecheck-listisdesignedtohelpyoudecidewhereproblemsmightoccur.Itisfollowedbyadviceonvibrationcontroltechniquesthatmightbeusedtogetthevibrationhazardundercontrol.Youmaywishtodiscussyourconclusionswithavibrationcontrolengineer.

Find out where the main problems are

Observetheworkprocessesandthetoolsused.Wherepracticableandsafe todoso,trythetoolyourself.

Howmanyemployeesusepoweredhand-heldtoolsandwheredotheywork? Isthereahighturnoverofpeopleinanydepartmentsusingpoweredhand- heldtools?

Askoperatorsaboutvibrationlevelswhenthetoolormachineisinuse. Dotheygetnumbnessortinglingintheirfingers?

Haveoperatorscomplainedaboutrecurrentpainorthrobbingintheirhands, ordifficultieswithgrippingobjects,orcompletingfiddlytaskssuchas fasteningorunfasteningabutton?



Look at the process

Couldyouredesigntheprocesstoavoidorreducetheuseofpowered hand-heldtools,egbysubstitutionormechanisation?

Arealternativelowervibrationprocessesormethodsavailable?

Couldyouintroduceremoteorpower-assistedcontrol?

Couldyouusemechanicalaidstohelpmovethecomponentsortools?

Look at the installation

Couldyoureducevibrationfromfixedmachinesbyimprovingthemounting?

Couldyouisolatethevibrationdirectly?

Couldyouusejigstoholdcomponentsfirmlyinplace?

Look at the task

Couldyoureduceormechanisetheforcewhichtheoperatorhastoexert todothejob?

Couldyouusebalancersortensionerstotaketheweightofthetoolfrom theoperator’shands?

Look at the tools

Areyouprovidingthemostappropriatetoolsforthejob?Checkwithsuppliers whetherlowervibrationtoolsorcomponentsareavailable.

Couldyouuseanalternativetypeoftool,forexampleagrinderinsteadofa chippinghammer,toreducevibrationexposure?

Couldyoubuybetter-balancedwheelsordiscsforcuttingorgrinding?

Areyouusingtheoptimumqualityandgradeofcuttingorgrindingwheels anddiscs?

Arethetoolsandmachineryperforminginaccordancewiththevibration valuesdeclaredbythemanufacturer?



Couldyoureducetheairlinepressureonhammeractiontoolsandmaintain cuttingrates?

Check maintenance requirements

Doyourmaintenanceschedulesconformtothemanufacturer’sspecifications?

Areyourmaintenancearrangementsadequatelysupervised,monitoredand recorded?

Doyouknowhowoftentoolsortheircomponentsshouldbereplaced? Doyouneedtoreplaceanti-vibrationmountsordampers?Askthe manufacturerorsupplierforinformation.

Couldyoumakebalancechecksonyourtoolsandmachines?

Doyoukeepthetoolssharp?Couldvibrationexposurefromtoolsharpening operationsbereduced?

Look at the work schedule

Couldyoureduceexposurebyintroducingjobrotation?

Arethereenoughbreaksintheworkforrecoveryduringtaskswithariskof highvibration?

Check operator usage

Areoperatorsusingthetoolscorrectlyinaccordancewithmanufacturer’s instructions?

Doyoutrainoperatorstousethecorrecttoolforthejob?

Arethecorrecttoolsavailable?

Shouldyouintroducea‘permittouse’systemfortoolsandprocesseswith ahigh-vibrationrisk?

Wouldclosersupervisionhelp?



Consider operator protection

Dooperatorsknowwhattheycandotominimisevibrationrisks?

Couldyouimproveoperators’information,instructionandtraining?

Istheworkplacewarmenoughtomaintaingoodbloodcirculation,so preventinghandsandfingersfrombecomingcold?

Dooperatorsneedglovesorclothingtohelpkeepthemwarm?

Doestheexhaustairfrompneumatictoolsneedtobedivertedawayfrom theoperator’shands?

Look at the costs and benefits

Comparethecostsandbenefitsofthevariouscontrolmeasures.How manyemployeeswillbenefit?

Arethereotherbenefits,egreducednoiseorimprovedproductivity?

Whatwillbethecostperemployeeprotected?

Look for symptoms

Haveyouinstitutedaprogrammeforidentifyingearlyadversehealtheffects?

Doyouhaveaccesstoamedicalpractitionertosupervisetheprogramme andforreferralofsymptoms?

Doworkersknowwhattolookoutforandaretheyencouragedtoreport symptomssuchasfingerblanching?

Doyoukeepadequaterecordsofthesereports?

Doyouinvestigateanyadversehealtheffectsreported?

Doyoufeedyourfindingsbackintoyourriskassessmentandcontrol measures?



Avoiding pitfalls when introducing vibration controlThefollowingvibrationcontroltechniquesaredescribedinoneormoreofthecasestudies.

Process redesign

Waysofimprovingtheprocesscanoftenbefoundwhichnotonlyreduceexposuretohazardousvibrationbutalsoimproveproductivityandquality.However,considerthefollowingpoints:

Ensurethatwheneliminatingonehazard,egbyintroducinganewtechnique orproductsuchaschangingfrommechanical(buffing)tochemicalpolishing methods,youdonotcreateadifferenthazard.

Beawarethatimprovementsinproductivityresultingfromprocessredesign couldincreasethevibrationexposureofindividualemployees.

Redesignmaytaketimeandrequiresomeinvestment.Other,possibly temporary,measuresmaybeappropriatetointroduceuntiltheredesign hasbeencompleted,egintroducingjobrotation.

Theproductoftendeterminestheprocess.Forexample,thechoiceof decorativefinishforbuildingsurfacesandtheprocessusedtoachieveitcan affecttheexposureofconstructionworkerstovibration.Cancustomer requirementsbevariedtominimiseworkerexposuretovibration?

Isolation

Isolationisthereductionofvibrationpassingfromthevibratingmachine,toolorcomponenttotheoperator’shands.Thiscanbeachievedbytheuseofrubberbushes,sleevesandanti-vibrationmounts.Considerthefollowingpoints:

Thismethodisonlylikelytobepracticalinalimitednumberofcasesandwith expertadvice.Eachworksituationshouldbeassessed.Askforspecialist advicefromtheanti-vibrationmountormaterialsupplier.

Incorrectapplicationofthistechniquecouldincreasevibrationlevelsandmay createadditionalphysicalhazards.

Ifyouapplyittonewmachines,youshouldcheckthemanufacturer’s guaranteestomakesurethattheywillnotbeinvalidated.

Checkthatanti-vibrationhandlesaresuitableforthemachineinquestion andwillnotaffecttheoperationofthemachine.



Ensurethatresilientsleevesarecapableofreducinglow-frequencyvibration. Isthesleeveorwrappingthickenough?Getadvicefromthesupplieror vibrationexpert.

Theresonantfrequencyoftheanti-vibrationmountmustbewellbelowthe mostimportantmachinefrequencies-usuallytheoperatingspeedandrelated frequencies.Getadvicefromthesupplierorvibrationexpert.

Makesurethatthemountsarenotsosoftthatthetoolormachinebecomes uncontrollable.

Makesurethatamountoranti-vibrationhandlefailurecannotcreatea hazard.Getadvicefromavibrationexpert.

Gloves Glovescanplayanimportantroleinreducingtherisksfromhand-armvibration.Incoldconditionsgloveswillkeepthehandswarm,helpingtomaintaingoodcirculationtothefingers.Glovesmayalsobenecessary,oradvisable,forphysicalprotectionofthehands.Ifyouwishtosupplyglovestoyourworkers,youwillneedtoensurethattheyareappropriateforthetoolsandthetasksothatthewearerfindsthemcomfortableandisabletomanipulatethetoolsandcontrolsproperlywithoutincreasinggriporforce.

Variousgloveswithspecialsoftliningsintendedtoprovidevibrationisolationarecommerciallyavailable.Theseglovescanoftenreducehigh-frequencyvibrationbuthavelittleeffectatmidandlowfrequencieswhicharethosemostlikelytodamagebloodflowinthehand.Anti-vibrationglovesshouldbeassumednottoreducevibrationexposureunlessyouhavetestdatathatshowsotherwiseforthecombinationofgloveandtoolused.Manufacturerscontinuetoconductresearchtodevelopbetterperformingmaterialstoreducevibrationatthehazardousfrequencies.

New tools

Askforvibrationdataforanytoolsthatyouareconsideringusingorbuying.SomehelpfulquestionsaresuggestedinAppendix1ofHS(G)88,4andtheyarereproducedonpage12.

Doyouknowwhatthesupplier’svibrationdatameans?Rememberthatthedatawhichthesupplierhastoprovideisintendedtohelpyouchoosetherightmachineforthejobandyouremployees.

Thevibrationmagnitudesquotedbymanufacturers/machine-makersareintendedtoenablethepotentialpurchasertocompareonemaker’smachineswithmachinesofasimilartypeofferedbyanothermanufacturer.Thevibrationmagnitudesofthemachineswheninnormalusemaybedifferent.Askthemanufacturerformoreinformation.

Ensureemployeesareawarethatsomelow-vibrationtoolswillfeeldifferentinuseandmayrequireadifferentoperatortechniquetothetraditionaltoolswhichtheyreplace.Trainingandaperiodforemployeestogetusedtousingthenewtoolsmaybenecessary.



Purchasing new tools and equipment

Whenpurchasingnewtoolsandequipment,employersshouldasksuppliersforinformationonvibration.Thefollowinglistsuggestssomepossiblequestions.

1Isthevibrationofanyhandleorothersurfacetobeheldbytheuserlikelytoexceedanaccelerationof2.5m/s2,innormaluse?

Iftheanswertoquestion1isYES,

2Whatisthefrequency-weightedacceleration:(a)underoperatingconditionsproducingthehighestvibration?(b)undertypicaloperatingconditions?(c)underotherstandardconditions?

3Underwhatoperatingconditionswerethemeasurementsmade?

4Ifthetestswereinaccordancewithapublishedstandard,providedetailsandindicatetheextenttowhichthevibrationmaydifferfromthequotedvaluesundernormalconditionsofuse.

5Whatmeasureshavebeentakentominimisevibration?

6Areadditionalvibrationreductionmeasurespracticable?Givedetailsofanydesignchanges,theadditionalcostandanyproductionpenalties.

7Whatisthemaximumfrequency-weightedaccelerationthatthetoolorequipmentcanbeguaranteednottoexceed?

8Whattestswouldbecarriedouttoconfirmanyclaimsmadeinanswertoquestion7?

9Whatothermeasuresarerequiredtominimisethevibrationhazardtowhichemployeesareexposedwhenusingthetoolorequipmentinquestion?Givedetailsofanyspecialmaintenancerequirements.

Reduction in vibration exposure case studiesThesestudieshavebeenplacedinorderbyvibrationsource.Eachcasestudyinthissectiondescribesthenatureofthevibrationproblem,thesolutionappliedbythecompany,thecost(at1995prices)andthevibrationreductionandotherbenefitsgained.Vibrationreductionshavebeenachievedbyusingtoolsormachineswhichproducelessvibration,byreducingtheamountoftimespentusingthetoolormachine,orbyintroducinganewwayofworkingwhichremovesallexposuretovibration.

Thevibrationdataforeachcasestudyissummarisedinatable.

Understanding the vibration measurements and data tables

Vibration magnitude

Hand-transmittedvibrationmagnitudeismeasuredintermsoftheaccelerationofthesurfaceincontactwiththehand.Theaccelerationofthesurfaceisnormallyexpressedinunitsofmetrespersecondsquared(m/s2).Hazardtohealthisusuallyassessedfromtheaverage(root-mean-squareorrms)accelerationlevel,usinganinstrumentwithastandard‘frequencyweightingnetwork’orfiltertoreduceits

ExtractfromHS(G)88Hand-arm vibration



sensitivityatthehighfrequencies.Thisgivesthe‘frequencyweightedacceleration’(ah,w)inm/s

2,where‘h’indicateshand-transmittedvibrationand‘w’indicatesthatthemeasurementhasbeenfrequencyweighted.BritishStandardBS6842:19876describesaprocedureformakingthesemeasurements.

Thevibrationmagnitudefiguresquotedinthestudiesrelatetospecifictoolsinspecificcircumstances.Eachsituationshouldbemeasuredseparately.Thefiguresmayofferaguideonlytothelikelyvaluewhensimilartoolsareusedinsimilarprocesses(seeHS(G)884).BS6842:1987hassincebeensupersededbyBSENISO5349-1:2001,butthevibrationmagnitudesinthisbookwereobtainedusingBS6842:1987.

Daily vibration exposure

Thevibrationexposure,or‘dose’,ofaworkeroveraworkingdaydependsonthedurationofexposureaswellasthevibrationmagnitudeatthegrippedsurface(s)ofthetool(s)used.Exposureshouldbeadjustedtoastandardreferenceperiodof8hours(A(8))toallowdifferentexposurepatternstobecomparedandfortheassessmentofhealthrisk.Programmesofpreventativemeasuresandhealthsurveillancearerecommendedwhereworkers’dailyvibrationexposureregularlyexceeds2.8m/s2A(8).

Vibration data table

Vibration magnitude ah,w in m/s

2

Time before daily exposure exceeds 2.8 m/s2 A(8)

Daily exposure time

Daily exposure (m/s2 A(8))

Before 5 2.5hours 3hours 3

After 0 - 0 -

Thetablegivesthevibrationmagnitude(ah,w)anddetailsofdailyexposurebeforeandafteractiontoreducevibrationexposurehasbeentaken.Inmanycasesthevibrationisreducedtozerobythemodification.TheseverityofthevibrationhazardisindicatedincolumnBwhichshowsthepermittedtimebeforethedailyexposureexceeds2.8m/s2A(8):theshorterthetimeindicated,thegreaterthevibrationhazard.Actiontoreducetheriskmayberequiredafteronlyafewminutesdailyexposureforsomehigh-hazardtools.Therelativeriskofdevelopinghand-armvibrationinjurycanbegaugedbycomparingeithertheactualdailyvibrationexposuretime(columnC)withthetimebeforethedailyexposureexceeds2.8m/s2(columnB),ortheactualdailyvibrationexposure(columnD)with2.8m/s2A(8).

Insomeofthecases,forexampleCaseStudies11and40,theexposurevaluesafterthecontrolmeasureshavebeenappliedremaininexcessoftherecommendedHSEactionlevel.Inthesecases,additionalactionshouldbetakentoaddresstheriskstohealth,forexample,increasingthefrequencyordetailofhealthsurveillance.

Explanation of ‘before’ and ‘after’ terms

‘Before(estimated)’-thismeansthatthedataisbasedonestimatesoftheexposurethatwouldhavebeencausedbyaprocessnolongerinexistence,orthatthedatahasbeenprovidedtogiveanindicationoftheexposurethatwouldhaveoccurredifahigh-vibrationprocesshadbeenused.

Exampleoftable A B C D



‘Before(potential)’-thisisbasedontheworstcasehypotheticalprocessthatcouldhavebeenusedtodothework.

‘Before(typical)’-thisreflectsthefactthattheoldtechniquecouldproduceawiderangeofexposuresduetodifferentvibrationmagnitudesandvaryingexposuretimes.Thefiguresinthetablegiveagoodaverageforthetypeofwork.

‘After(potential)’-thisisestimateddatawherethesolutionwasnotcompleteatthetimeoftheresearch.

‘After(typical)’-thisiswherethesolutionmayleadtoarangeofvibrationexposuresduetovariationsinvibrationmagnitudeandexposuretime.

Table of case studies (sorted by vibration source)

Case Title Vibration source Industry Exposure reduction technique

1 Semi-automaticcutoffmachine Abrasivedisccutter Investmentfoundry Process automation

2 Off-linegrindingwheelpre-forming Grindingwheeldresser Precisionengineering Process automation

3 Introductionoflow-vibrationangle Handtool Shipbuilding Tooldesign grinders (anglegrinder)

4 Crushingconcrete Handtool(breaker) Construction Changeofmachine

5 Waterjetting Handtool(breaker) Construction Changeofprocess

6 Burstingconcreteinsteadof Handtool(breaker) Construction Changeofprocess breaking

7 Diamondwirecutting Handtool(breaker) Construction Changeofprocess

8 Pipelineinsertionmethodavoids Handtool(breaker) Utilities Changeofmachine trenching

9 Directionaldrillingavoidstrenching Handtool(breaker) Utilities Changeofprocess

10 Mountedroadbreaker Handtool(breaker) Utilities Isolation

11 Reduced-vibrationroadbreakers Handtool(breaker) Utilities Tooldesign




12 Maintainingchainsawanti-vibration Handtool(chainsaw) Forestry Maintenance rubberbushes

13 Chainsawmaintenanceand Handtool(chainsaw) Watercourse Management trainingprogramme maintenance

14 Reduced-vibrationchipping Handtool(chipping Foundry Tooldesign hammer hammer)

15 Sleeveforchippinghammerchisel Handtool(chipping Steel Isolation hammer) 16 Isolatedcastingcutoff Handtool(disccutter) Foundry Isolation

17 Automaticfettlingofcastings Handtool(grinder) Foundry Process automation

18 Air-carbonarcgougingreplaces Handtool(grinder) Powerengineering Changeofprocess traditionaltools

19 Castingshellknockoutincabinet Handtool(hammer) Investmentfoundry Isolation

20 Maintenanceoflow-vibrationtools Handtool(needlegun) Construction Maintenance

21 Reduced-vibrationneedleguns Handtool(needlegun) Construction Tooldesign

22 Shotblastingcabinetreplaces Handtool(needlegun) Shipbuilding Changeofprocess rotaryfiles

23 Descalingwithabrasiveblasters Handtool(needlegun) Shipbuilding Changeofprocess

24 Jobrotationanduseofpedestal- Handtool(nutrunner) Automotive Isolation mountednutrunners

25 Automaticboltfitting Handtool(nutrunner) Automotive Process automation

26 Automatedpalletstripping Handtool(powersaw) Palletrepair Process automation




27 Low-vibrationpowersaw Handtool(powersaw) Palletrepair Tooldesign

28 Outdoorpowertoolspurchasing Handtools(outdoor) Watercourse Management policy maintenance

29 Low-vibrationfastenersystem Handtool(rivetinggun) Aerospace Changeofprocess

30 Nocontactcastingshellknockout Handtool(rivetinggun) Investmentfoundry Isolation

31 Low-vibrationrivetersandreaction Handtool(riveter) Aerospace Tooldesign bars

32 Specialformworkavoidsscabbling Handtool(scabbler) Construction Changeofprocess

33 Paint-onmaterialavoidsscabbling Handtool(scabbler) Construction Changeofprocess

34 Gritblastinginsteadofscabbling Handtool(scabbler) Construction Changeofprocess

35 Reduced-vibrationpolescabbler Handtool(scabbler) Construction Tooldesign

36 Deburringwithrumbler Handtool(straight Turbinemanufacture Changeofprocess grinder)

37 Beltgrindingandpolishingof Handtool(straight Turbinemanufacture Changeoftool metalfabrications grinder)

38 Groupworkingwithsuspended Handtools(various) Automotive Management tools

39 Installationofhydrauliccropping Handtools(various) Foundry Changeofprocess machine

40 Excavatorreducesvibration Handtools(various) Quarrying Changeofprocess exposureinquarry

41 Toolstockauditandpurchasing Handtools(various) Shipbuilding Management policy




42 Hands-freelinishing Linishingmachine Investmentfoundry Isolation

43 Beltgrindingandpolishingof Pedestalgrinder Ceramics Changeofmachine ceramicware

44 Isolationforgrindingoperation Pedestalgrinder Foundry Isolation

45 Lasercutterreplacesnibbling Sheetmetal Turbinemanufacture Changeofprocess machine

Note:CaseStudies46to51donothaveavibrationsource.



1 Semi-automatic cut off machineThe task

Cutting multiple cast components from their runners and risers.

The problem

Oneofthetraditionalmethodsforcuttingoffcastcomponentsistouseanabrasivecuttingdiscmountedinacircularsawbench.Inatypicaldayatonefoundrytheoperatorofsuchamachinecouldspendupto3hoursexposedtovibrationmagnitudesofupto5m/s2.Theoperationisalsoverynoisyandthereispotentialriskofinjuryfromcontactwiththeexposedcuttingdisc.

The solution

Twofully-enclosed,semi-automaticcut-offmachineswerebought,principallytoimprovequalityandefficiency.Themultiplecastingsareclampedinrotatingfixtures,trunnionmounted,andcutoffwithanabrasivedisc.

The cost

Thetotalprojectcostswereapproximately£70000.

The result

n Theoperatordoesnotneedtotouchanyvibratingcomponents.n Theoperatorcontrolsthepositionandalignmentofthecastingsandcutting

discsatadistance.n Manualhandlingofthecomponentsandexposuretonoise,dustandsparksis

reduced.n Thecycletimeiscut.n Lessmetalhastobegroundoffafterwards,whichalsosavestimeinthefettling

shop.n Theriskofinjuryfromcontactwiththecuttingwheeliseliminated.


2


Daily exposure time


Before 5 2hours30minutes 3hours 3

After 0 - 0 -

Automaticcut-offmachine

Automaticcut-offmachinesavailablefromFlexovit(UK)Limited



2 Off-line grinding wheel pre-formingThe task

Dressing precision grinding wheels.

The problem

Somecompanieshavetogrindcomponentstopreciseshapes,dimensionsandsurfacefinishes.Thisisoftendonewithgrindingwheelsthatareprofiledtogivetherequiredshape.Duringuse,thesewheelshavetobefrequentlydressedtorestoretheircorrectshapeandsurfacequalities.Thisisusuallydonewithadresserattachmentmountedonagrindingmachine,whicheithersemi-automaticallyorfully-automaticallyprofilesthesurfacewithadiamondtool.

Newgrindingwheelsaresuppliedinsetwidths,withnoprofiling.Cuttingacompletenewprofilewiththedresserattachmentisverytimeconsuming,somostcompaniespre-formtheirwheelsbeforethedresserisused.Thetraditionalmethodofpre-formingistouseahand-heldpieceofcarbide.Thisisextremelydangerous,bothbecauseoftheriskofcontactwiththegrindingwheelandbecausetheoperatorisexposedtohighvibrationmagnitudes.Theactualvibrationexposurevariesdependingonthesizeofthewheelandthepieceofcarbideinuse.Operatorsreportedseverewristpainandnumbnessofthehandsafterjustafewsecondsofthework.

Off-linegrindingwheeldresser/pre-former

CasecourtesyofIndustrialMachineToolServicesLimited



The solution

Thewheelsarepre-formedanddressedonanoff-linedressingmachine,whichusesamechanicallydrivendiamondtoolguidedbyaspeciallyprofiledsteelfixturetocuttheprofileintothegrindingwheel.Themachineisfullyautomaticwithalidwhichmustbeclosedbeforethecuttingcyclecanbeginandcannotbeopeneduntilthecycleiscomplete.

The cost

Anoff-linedressingmachinewouldcostabout£12000.

The result

n Theoperatorsarenotexposedtovibration.n Thereislittleriskofcontactwiththegrindingwheel.n Productivityisincreasedbyavoidingproductionmachinedowntime.n Theoperators’exposuretonoiseisalsoreduced.


2


Daily exposure time


Before(estimated)

40(estimated) 2.4minutes 5minutes 4.1(estimated)

After 0 - 0 -



3 Introduction of low-vibration angle grindersThe task

Weld dressing and fettling of metal fabrications.

The problem

Atoneshipyardthebulkofthisworkisdonewith225mm(9in)electrichigh-frequencyanglegrinders.Thesearelargeheavytoolswhichoftenhavetobeheldoverheadorinawkwardpositionsbytheoperatorforanaverageof1to3hoursaday.Thecompanyhasjustunder200ofthesetoolswhichproduceaveragevibrationmagnitudesof7m/s2,givingapotentialexposureofover4m/s2A(8).

The solution

Thecompanyintroducedatemporarysolutiontorestrictthetimeforwhich225mm(9in)grinderscouldbeused,andtoencouragetheuseoflesspowerfultoolswithlowervibrationvaluesforsmalljobs.

Thelong-termrequirementwastouseagrinderwithbothhighperformanceandlowvibration.In-houseengineersreviewedallthegrindersavailableonthemarketatthetimeanddecidedthatanewdesignofpneumatic225mm(9in)grinderfeaturingautomaticcorrectionfordiscimbalanceshouldbebought.Initialtestsshowedthatthesenewtoolsusingthecompany’susualgrindingdiscsachievedalowermetalremovalratecomparedwiththeoldelectricgrinders.Furthertestingrevealedthatbychangingtoasoftergradeofdisc,thepneumaticgrinderscouldgiveametalremovalrate40%higherthanthatachievedbytheoldtool/disccombination.Theuseofthenewtoolssignificantlyincreasedtherequirementforcompressedairintheshipyardanditwasnecessarytoupgradetheairdistributionsystemtocopewiththeextrademand.

The cost

Self-balancingpneumatic225mm(9in)anglegrindersareapproximately£700each.Theresearchanddevelopmenttook1month.Thealterationstotheairdistributionsysteminvolvedsignificantexpenditure.

Reduced-vibrationanglegrinder

EquipmentprovidedbyAtlasCopcoToolsLimited



The result

n Vibrationmagnitudesarelower.Inextendedtestingonrealjobsintheyard,thenewgrindersproducedanaveragevibrationmagnitudeof3.5m/s2.

n Efficiencyisimprovedbecauseofthehigherrateofmetalremoval.n Thetoolsaremuchlighterandsotheyareeasierandlesstiringtooperate.n Therearefewerrisksassociatedwithtrailingelectricalleadsintheworkingarea.


2


Daily exposure time


Before 7 1hour17minutes 3hours 4.3

After 3.5 5hours7minutes 3hours 2.1



4 Crushing concreteThe task

Demolishing concrete structures.

The problem

Aspartoftherefurbishmentofahospitalmaternityblock,itwasnecessarytodemolisha15mlongsectionofconcretewall.Thiscouldhavebeendonewithsmallpneumaticbreakerswhichmighthavecausedtypicalworkervibrationexposuresof7m/s2A(8)andcreatedintrusivelevelsofnoise.

The solution

Thewallwascutawayfromthebuildingpillarsbydrillinglinesofoverlappingholes(stitchdrilling)usingadiamonddrill.Thediamonddrillingmachinewasheldinaclampandsotheoperatorswerenotexposedtovibration.Eachsectionwasthenbrokenupby‘biting’offpieceswithahydraulicconcretecrusher.Thejawsofthisdevicecloseslowly,allowingtheoperatorstoloosentheirgripbeforecrushingtakesplace.

The cost

About50%morethanthecostofusingpneumaticbreakersonthesamejob.

The result

n Theoperator’sexposuretovibrationisnegligible.n Verylowvibrationispassedintothestructurewhichhelpstoreducedamage

andstructure-bornenoise.n Thismethodislessmessythanusingbreakersasthedebrisisinlargerpieces

andlessdustisproduced.n Noiselevelsareverylow,bothfortheoperatorsandtheenvironment.


2


Daily exposure time


Before(typical)

12 26minutes 3hours 7

After 0 - 0 -

Left Demolishingconcretestructures.

CasecourtesyofSpecialistServices(CuttingandDrilling)Limited

Right Concretecrusherdemolishingawall



5 Water jettingThe task

Removing damaged or weathered concrete surfaces.

The problem

Thedeckandsidewallsofareinforcedconcreteroadbridgehaddecayedtotheextentthatsurfacerepairswereneeded.Thetopfewcentimetresofconcreteneededtoberemovedandreplacedwithnewmaterial.Thetraditionalmethodofremovingtheoldmaterialistousehand-heldpneumaticbreakers,whichcanexposeworkerstotypicalvibrationmagnitudesof12m/s2forabout3hoursperday.Theuseofpercussivetoolscanalsodamagethereinforcementbar,whichthenhastoberepairedorreplaced,andcausecrackinginthebaseconcretewhichmayweakenthestructure.Theoperatorsworktoaspecifieddepth,oftenunnecessarilyremovingsoundmaterialandleavingareasofdeepdamagedmaterial.Thesurfacealsorequiresthoroughcleaningbeforenewconcretecanbeapplied.Thejobwouldhavetakenabout60workerdayswiththebreakers,aswellasadditionaltimetorepairthereinforcementbarandotherdamage.

The solution

Thejobwasdonewitharobot-mountedwaterjettingmachine.Thisprocessusesanextremelyhighpressurewaterjettowearawaytheolddamagedconcrete.Thejetremovesallconcreteuptoacertainstrength,regardlessofdepth,leavingthegoodmaterialandremovingallofthedamagedmaterial.

The cost

Acontractorusingthewaterjettingmachinetook15daysatapproximately£1200perdaytocompletethejob(totalcost£18000).Todothejobusinghand-heldbreakerswouldhaveinvolved60workerdaysatapproximately£150perday(totalcost£9000),plusthecostofrepairstothereinforcementbarandbaseconcrete.Thesereinstatementcostsoftenresultintotalprojectcostssignificantlyhigherthanthoseforthewaterjettingmethod.

Robotmachinewaterjettingabridgesidewall

Concretesurfaceafterwaterjetting



The result

n Operatorsarenotexposedtoanyhand-armvibration.n Thereinforcementbarwascompletelyunaffectedandtherewasnodamageto

thebaseconcretestructuresoitwasimmediatelyreadyfortheapplicationofnewconcrete.

n Thenewconcreteadheresbettertothejettedsurface.n Airbornedustlevelsareverylowasthedebrisiswashedawaybythewater.


2


Daily exposure time


Before(typical)


After 0 - 0 -



6 Bursting concrete instead of breakingThe task

Demolishing concrete structures.

The problem

Duringtherenovationofalargewarehouse,atemporaryconcreteretainerwasbuilttosupporttheexternalwallswhilethefloorswereremovedandreplaced.Whenthestructuralworkwascomplete,theretainer,whichwas1mx1minsectionandranroundtheentire300mperimeterofthebuilding,hadtoberemoved.Traditionallythisisdoneusingsmallhand-heldpercussivebreakers,asthevibrationsfromlargerplantcoulddamagethebuildingstructure.Suchsmalltoolshavelowmaterialremovalratesandexposeoperatorstovibrationmagnitudesintherangeof5to20m/s2.

The solution

Themaincontractorhiredasmallspecialistcompanytobreakuptheretainerusinghydraulicbursting.Thisinvolvesforcingtheconcreteapartwithaspecialhydraulictoolinsertedintoholesspeciallydrilledforthepurpose.Althoughtheburstingprocessitselfdoesnotexposetheoperatortoanyvibration,inthiscasetheholesweremadewitharockdrillwhichwouldhaveexposedtheoperatortovibrationmagnitudesashighas15m/s2.Therockdrillworksfast,sothetotaldailyexposuretimewasonlyabout10minutes,whichwouldgiveapotentialvibrationexposureofabout2m/s2A(8).Vibrationexposurecouldbeeliminatedaltogetherbyusingaclamp-mounteddiamondcoredrilltomaketheholes.Thiswouldtakeslightlylongerthantherockdrill.

The cost

Therockdrillandburstingmethodcostapproximately30%morethanusingbreakers.Thediamonddrillandburstingmethodcostapproximatelytwicethatofusingbreakers.

Hydraulicburstingtoolbeingusedtodemolisharetainingwall




The result

n Thedailyexposuretimeoftheoperatorsisreduced.Thismethodismuchquickerthanequivalentlowimpactmethods.

n Verylowvibrationmagnitudesaretransmittedtothebuildingstructure.n Burstingproducesverylownoiselevelsandlessdustandflyingdebristhan

pneumaticbreakers.


2


Daily exposure time


Before(typical)


After(actual)

15 17minutes 10minutes 2.2

After(potential)

0 - 0 -



7 Diamond wire cuttingThe task

Removal of sections of brick or concrete structures.

The problem

Aspartoftherefurbishmentofarailwaystation,anewstairwellwastobecutthroughthetopofabrickarchedtunnel.Directlyabovethetunneltherewasasolidfloor,whichwas1mthickinthemiddleofthetunneland4mthickatthesides.Theaperturewastobecutthroughallofthismaterialacrossthefull7mwidthofthetunnelforalengthofapproximately3m.Thisjobcouldhavebeendonewithhand-heldpneumaticbreakers.However,toavoiddamagetothebasestructure,onlylow-poweredunitscouldhavebeenusedandthejobwouldinvolvefrom40to60workerdaysofwork.Astoolsofthistypeproducetypicalvibrationmagnitudesintherange5to20m/s2andmaybeusedforlongperiods,vibrationexposuresof7m/s2A(8)orgreaterarepossible.

The solution

Theaperturewasmadewithalargepercussivebreakermountedonanexcavator.Normallythiswouldhaveledtoseveredamagetotheremainingarchstructure,butthiswaspreventedbycuttingrightthroughthebrickworkalongtheedgesoftheareatoberemoved.Thisisolatedthedelicatepartsofthestructureandallowedthematerialtobebrokenupinapproximately2hours.Thecutsweremadeinfoursectionswithadiamondwiresaw.Thisconsistedofadiamond-toothedsawwirewhichwaswrappedaroundthestructuretobecutanddrivenbyatrack-mountedmechanism.Asthewirecuts,itispulledthroughthestructurelikeacheesecutter.Forthisjobthewirewasthreadedthroughpilotholesdrilledthroughtothetunnelfromthefloorabove.Thiswasdonewithaclamp-mounteddiamondcoredrill.

The cost

£4500,comparedwithabout£5000forthesamejobusinghandbreakers.

Diamondwirecutter(NBThesafetyguardshavebeenremovedforthephotograph)

Mountedbreakerknockingaholethroughabrickarchshowingdiamond-drilledpilotholes




The result

n Theoperatorsarenotexposedtoanyvibrationfromthecuttingordrilling.n Thismethodismuchquicker,whichmeanslessdisruptiontotheoverallwork

programme.Inthiscase,thetotaltimeonsitewasreducedtoatotalof3days,ie1.5daysdiamonddrilling,1daydiamondwiresawingand2hoursbreaking.

n Thereislessnoiseandlessdamagetothestructure.


2


Daily exposure time


Before(typical)


After 0 - 0 -



8 Pipeline insertion method avoids trenchingThe task

Replacing old cast-iron gas and water mains.

The problem

Thetraditionalmethodofreplacingoldutilitymainsistodigatrenchdowntotheoldpipeandlayanewonebyitsside(knownasfull-lengthtrenching).Thisinvolvesalotofworkbothindiggingthetrenchandinreinstatementafterwards.Thereisalsoachancethatotherburiedservicesmightbedamagedintheprocess.Inurbanareasitisalsonecessarytobreakroadandpavementsurfaceswithpercussivetools,whichmayresultinhighhand-armvibrationexposures.

The solution

Itisnowpossibletoreplaceoldpipeswithoutfull-lengthtrenching.Onetechnique,whichcanbeusedinareaswithcompressiblesoil,involvessplittingtheoldpipeundergroundandinsertinganewoneinthevoid.Twoholesaredugabout3mwideand100maparttoexposesectionsoftheoldpipe.Alargepneumatichammerfittedwithapipesplittingbladeisthenpulledfromoneholetotheotheralongtherouteoftheoldpipewithapowerfulwinch.Thebladebreaksupthepipewhilethehammerbodyforcesthefragmentsaparttomakespaceforthenewpipelinewhichispulledalongbehindthepipesplittingblade.Additionalsmallholesaredugdowntoreconnectbranchestothenewpipeandtoremoveoldleakrepaircollarswhichthebladeoftencannotsplit.Ittookoneutilitiescompanyapproximately2hourstoreplaceabout100mofpipe.

Pipelinereplacementequipment



The cost

About£10000forpneumaticequipmentor£30000forhydraulicequipment.Thisequipmentisalsoavailableforhire.

The result

n Thismethodreducesthetimetheoperatorsareexposedtovibration.n Itismuchquickerthanfulltrenching(about25%ofthetime)anditreducesthe

chanceofdamagingotherburiedutilitiesortreeroots.n Thereislessdisruptiontootherroadusersandresidentsasthereisless

excavationandreinstatement.n Inareaswithsuitablesoilitispossibletoinsertapipe25%largerthantheold

onewhichreducestheneedforridermains(ieextrapipesonthesameroutetocopewiththeadditionalvolume).


2


Daily exposure time


Before(typical)


After(potential)

12 26minutes 30minutes 3



9 Directional drilling avoids trenchingThe task

Laying new utility mains.

The problem

Thetraditionalmethodforlayingutilities,egwater,gasandtelephonelines,istodiganopentrenchoverthefulllengthofthejobandplacethepipeinthetrenchinsections.Thetrenchingoperationcausesconsiderabledisruptionandmess,andcanbeexpensive.Roadandpavementsurfacesneedtobebrokenupandreinstatedusingpercussivetools.Workersareexposedtotypicalvibrationmagnitudesintherange5to20m/s2foranaverageof3hoursperday.

The solution

PipesforanewwatermainwerelaidwithouttrenchingacrossamotorwayinnorthernEngland.Theutilitycompanyhiredacontractorwhouseddirectionaldrillingtolaythepipe.Thistechnique,whichcanbeusedinareaswithsoftground,involvesdiggingapitateachendofthepiperunanddrivingasteerableboringtoolhorizontallyundergroundfromonepittotheother.Theheadofthetoolissteeredfromthesurfaceusingamobiletransmitter.Aftertheboringiscomplete,thenewpipeispulledbackthroughthehole.Smallholesaredugfromthesurfacedowntothenewpipetoconnectthesidebranchestothemain.Thereisariskofdisturbingotherburiedutilities,whichcanbeavoidedbyfollowingtheHSEguidancebook,HS(G)47, Avoiding danger from underground services.7

Directionaldrilling



The cost

Equipmentcostsabout£30000.Thetotaljobcostsabout75%offulltrenching.

The result

n Vibrationexposuretimeisreducedfromanaverage3hoursto15minutesperday.

n Thismethodismuchquicker(about25%oftimeforfulltrenching).n Thereislessreinstatementandlessdisruptiontoroadusersandresidents.


2


Daily exposure time


Before(typical)


After 12 26minutes 15minutes 2



10 Mounted roadbreakerThe task

Breaking road surfaces.

The problem

Themostcommontoolusedtobreakuproadandpavementsurfacesisthehand-heldpercussivebreaker.Thesetoolstypicallyproducehand-armvibrationmagnitudesofbetween8and25m/s2withanaverageofaround12m/s2.Afull-timebreakeroperatorworkingonaroadexcavationjobmightbeexposedtothisvibrationforanaverageof3hoursperdaywhichwouldgiveatypicalexposureof7m/s2A(8).Theamountofworkthatanoperatorcandowithoneofthesetoolsinadayvariesdependingonthedepthandhardnessofthesurfacetobebrokenup.

The solution

Insomecircumstancesitispossibletogreatlyreducethevibrationexposurebyusingalargerbreakerattachmentmountedonthearmofanexcavator.Thismethodwasusedbyautilitiescontractorfordiggingtelecommunicationstrenchesintheroadinabusyurbanarea.Therewasalreadyanexcavatoronsitefordiggingoutthetrenchesoncethesurfacehadbeenbroken,andthebucketwasreplacedwithabreakerattachment,whichtookabout5minutes,wheneverrequired.Thebreakerispoweredusingtheexcavatorhydraulicsandisactivatedbyafootpedal.Thearmpositioniscontrolledbyapairoflevers,passingverylittlevibration(vibrationmagnitudeislessthan1m/s2)totheoperator’shands.Ahand-heldbreaker,fittedwithasharpcuttingtool,wasusedforabout5minutesatthebeginningofthedaytoscoretheedgesoftheareatobebrokenupwiththemountedbreaker.

The cost

Mountedbreakerattachmentsstartataround£3000.

Mountedbreakerbeingusedtobreakroadway



The result

n Thismethodreducesthetimetheoperatorsareexposedtovibration.Theexposureforthehand-heldbreakeroperatorwasreducedtolittlemorethan1m/s2A(8).

n Onthetypeofsurfacefoundinthisexample,themountedbreakerworksapproximately10timesasfastasonepersonwithahand-heldtool.

n Theattachmentsontheexcavatorcanbechangedveryquickly.n Overallthereislessdisruptionandnoise.


2


Daily exposure time


Before(potential)


After 12 26minutes 5minutes 1.2



11 Reduced-vibration roadbreakersThe task

Breaking concrete and asphalt road surfaces.

The problem

Wheninstallingormaintainingundergroundservicesitisoftennecessarytodiguproadways,pavementsandotherareasofhardstanding,whichusuallyinvolvesbreakingthesurfacewithpercussivepneumaticorhydraulicbreakers.Oneutilitycontractoremployedteamsofworkerstodothisusingarangeofbreakersofvarioustypesandages.Onetool,whichwasoldbutstillinregularuse,producedavibrationmagnitudeof23m/s2measuredwhilebreakingaroadsurface.Onaverage,toolsfromthecompany’sstocksproducedvibrationmagnitudesofabout12m/s2.Theworkershadavarietyoffunctionstoperformsotheactualexposuretovibrationfrombreakersvariedfromdaytoday.Takingatypicalexposuretimeof3hours,anexposureofover7m/s2A(8)couldbeexperienced.

The solution

Manybreakermanufacturersnowmaketoolswhichtheyclaimproducelowervibrationmagnitudesthanoldertypeswithnolossofperformance.Thesemayfeatureredesignedmechanismsorsomeformofvibrationisolationinthehandle.Thecompanyboughtorborrowedaselectionofreduced-vibrationtoolsfromitsregularsuppliersandallowedaroadgangonarealjobtotrythemoutandcomparethem.Thevibrationmagnitudesproducedbythetoolsweremeasuredandtheoperatorswereaskedtocommentontheirperformanceandeaseofuse.

Oneofthenewtools,whichfeaturedsoftlysprunghandles,producedthelowestmeasuredvibrationmagnitudeof5m/s2.Theoperatorfeltthatthesoftspringsmadethetooldifficulttocontrolsothathehadtoholdthehandlesmoretightlythantheothertools,increasingfatigue.Thenextlowestvibrationmagnitudemeasuredonanotherofthenewtoolswithstiffer(risingrate)springswas8m/s2.Theoperatorfoundthistoolcomfortabletouseandeasiertocontrolthanalloftheothertoolsontest.Infuturethistoolwillbeboughtbythecompanyastheyfeltitofferedaconsiderablereductioninvibrationexposureovertheexistingtoolswhilestillhavinggoodperformanceandcontrollability.

Left Aselectionofbreakers

Right Oneofthepreferredbreakersinuse



The cost

Vibration-reducedbreakerscost25%morethantheequivalentstandardtypes.

The result

n Thevibrationmagnitudeisreduced.n Tooloperatorsareinvolvedinchoosingthepreferredtool.n Operatorsfoundthepreferredbreakerlesstiringtouseanditallowedgreater

precisionthantheothers.


2


Daily exposure time


Traditionalbreakerdesign(typical)

12 26minutes 3hours(estimated)

7.3

Newbreakerdesign

8 1hour 3hours(estimated)

5



12 Maintaining chainsawanti-vibration rubber bushesThe task

Cutting wood with chainsaws.

The problem

Mostmodernchainsawsarefittedwithrubberbusheswhichisolatethehandlesfromthevibratingpartsofthemachines.Overtimethesebushesdeterioratethroughcontactwithoilandhightemperatures.Generallytheyarereplacedwhentheyhavesplitorfailedcompletely.Theirabilitytoprotecttheoperatorfromharmfulvibrationwillbereducedsignificantlywellbeforecompletefailureoccurs.Oneforestrycompanyhadachainsawthathadbeenininfrequentuseforapproximately3years.Thesawhadbeenwellmaintained,withregularinspectionandservicingandwiththechainkeptsharpandatthecorrecttension.Theanti-vibrationbusheswerestillintactbuthadbecomesoftenedtotheextentwheretheycouldbe‘bottomedout’bypressureonthehandles.Inanormalwoodsawingoperation,avibrationmagnitudeof9.7m/s2wasmeasuredwhichwouldleadtoavibrationdoseof2.8m/s2A(8)beingreachedinabout40minutes.Thetypicalusageofsuchatoolmightbe2hoursperday.

The solution

Thebusheswerereplacedonaregularbasisaspartofamonitoringandmaintenanceprogramme.

The cost

Typicalbushescostabout£5eachandcanbereplacedinabout1hour.

Vibrationaccelerationmeasuredonachainsawbeforeandafteranti-vibrationbushreplacement



The result

n Thevibrationmagnitude,measuredwiththesameoperatorcuttingthesamepieceofwoodasbefore,wasreducedto5.4m/s2.Thiswouldallowover2hoursuseinadaybeforereachinganexposureof2.8m/s2A(8).

n Theoperatorhadmorecontrolofthetoolandfounditmorecomfortabletooperate.


2


Daily exposure time


Before(typical)

9.7 40minutes 2hours 4.8

After 5.4 2hours 2hours 2.7

Dismantledchainsawwiththefiveoldanti-vibrationbushes



13 Chainsaw maintenance and training programmeThe task

Use of chainsaws for cleaning river banks and watercourses.

The problem

Riverbanksandwatercoursesareclearedusingchainsawsandotherpowertools.Onecompanyintroducedatoolpurchasingpolicydesignedtoreducethevibrationexposureofstaffto2.8m/s2A(8).Thiswasdonebybuyingchainsawswithamaximumvibrationof5.6m/s2,basedonatypicaldailyexposuretimeof2hours(seealsoCaseStudy28).Theeffectivenessofthispolicydependedonthisvibrationperformanceandworkratebeingachievedinthefield,anditispossiblethatpoormaintenancemayleadtoanincreaseinthevibrationproducedbychainsaws.Forexample,inatestitwasshownthatpartiallyperishedanti-vibrationbushesincreasedthevibrationmagnitudeproducedbyonesawfrom5.6m/s2to9m/s2.Inanothertest,abluntchaincutatapproximatelyathirdofthespeedofasharponefittedintothesamesaw,operatedbythesameperson,cuttingthesamepieceofwood.Sincetheworkershaveafixedamountofworktodo,itwaspossiblethatusingbluntchainscouldtriplethevibrationexposuretime.

The solution

Theorganisationapproachedtheproblemintwoways.Firstly,theydevelopedaplannedmaintenanceprogrammewhereeverytoolwasservicedbyacompetentmechanicevery12months.Foreachtoolthereisaservicerecordsheetwhichhastobecompletedshowingtheconditionofallmajorcomponentsincludinganti-vibrationequipment.Thisshouldensurethatpartsarereplacedbeforetheystopworkingandthattoolsarekeptingoodcondition.Secondly,thetooloperatorsthemselvesweregiventraininginthecorrectmaintenanceoftheirtools(suchaschaintensioningandregularsawsharpening),therisksofhand-armvibrationandtheconsequencesofpoormaintenanceandbluntchains.Thiswasdoneaspartofthegeneralchainsawsafetytrainingtheoperatorsreceive.

Chainsawinuse



The cost

Toolservicingcouldcostapproximately£50.Additionaltrainingcostswereminimalasitwasdoneaspartofanexistingtrainingprogramme.

The result

n Thevibrationmagnitudeproducedbythetoolswasreduced.n Efficiencyimprovedandtherewasareductioninunexpectedtoolbreakdown.


2


Daily exposure time


Poorlymaintainedtools


Correctlymaintainedtools

5.6 2hours 2hours 2.8



14 Reduced-vibration chipping hammerThe task

Removing mould materials from the cores of large castings.

The problem

Manyofthecastingsmadeinthefoundryofapumpmanufacturingcompanyarehollow.Theyarecastaroundasandcorewhichhastoberemovedwhenthemetalhascooled.Thisisdonewithahand-heldimpulsivechippinghammer.Thecompanyhadseveraloldtoolswhichtypicallyproducedvibrationmagnitudesof8m/s2.Althoughtheworkwasnotdoneeverydayitwaspossiblethatonsomeoccasionsworkerswereexposedtovibrationfromthesetoolsforupto4hoursperday.Thisgaveapotentialvibrationexposureofabout6m/s2A(8).Theextendedperiodsofusewerealsoquitephysicallytiring.

The solution

Theworkisnowdonewithavibrationreducedchippinghammerwhichexposestheworkertoavibrationmagnitudeof3.7m/s2.Thevibrationhasbeenreducedbytheredesignoftheinternalcomponentsofthetoolusingspringsandcompressedairtoisolatethetoolbodyfromtheimpactingparts.

Low-vibrationchippinghammerknockingoutacasting CasecourtesyofSvedalaLimited

Cross-sectionoftoolshowingthemetalandairspringsusedforvibrationisolation



The cost

Thelow-vibrationchippinghammerusedinthiscasecostabout25%morethanthepriceofanequivalentnormalone.

The result

n Thevibrationmagnitudeproducedbythetoolhashalved.n Thenewtoolismuchmorecomfortabletouseforlongperiods.n Toolperformanceisasgoodasequivalenthigh-vibrationunits.


2


Daily exposure time


Before(potential)

8 59minutes 4hours 5.6

After(potential)

3.7 10hours 4hours 2.6



15 Sleeve for chipping hammer chiselThe task

Removing defects in steel castings using a chipping hammer.

The problem

Atalargesteelworks,defectsinsteelcastingsareremovedusingpneumaticchiselsorchippinghammers.Generallythetoolpiece(chisel)isheldinonehandwhilethetriggerisoperatedbytheother.Bothhandsareexposedtovibrationbutthechiselhandisexposedthemost.Ononetoolavibrationmagnitudeofapproximately26m/s2wasmeasured.Theexposuretimeforthesetoolscannotbepredictedasitvariesfromdaytoday.However,theHSErecommendedactionlevelof2.8m/s2wouldbeexceededifthetoolwasusedforabout5minutesinoneday.

The solution

Workingtogetherwithasupplierofindustrialrubberproducts,thesteelcompanyhasdevelopedaresilientsleevetowraparoundthechisel.Thisismosteffectiveatreducingvibrationalongthelineofthechisel.

The cost

Sleevescostapproximately£5each.

The result

n Theoverallvibrationmagnitudehasreducedto13m/s2,halfofitsoriginalvalue.

n Thesleeveprovidesthermalinsulationbetweenthechiselandtheoperator’shandandismorecomfortablefortheoperator.

Note:Inadditiontothedevelopmentofthechiselsleeve,thecompanyhasintroducedreduced-vibrationgrinderswhichareabletoremovemostdefects.


2


Daily exposure time


Before 26 5minutes Varies Varies

After 13 20minutes Varies Varies

Chiselfittedwithresilientsleeve

CasecourtesyofBritishSteelPLC,SwindenTechnologyCentre,Rotherham



16 Isolating casting cut offThe task

Cutting runners and risers from cast components.

The problem

Inasmallalloysteelfoundry,runnersandrisersusedtobecutfromcastingsusing225mm(9in)pneumatichand-helddisccutters.Overatypicalworkingcycle,thisoperationproducedanaveragevibrationmagnitudeof5m/s2.Operatorscouldhavebeenexposedtothisvibrationforupto5hoursaday,givingapotentialvibrationexposureof4m/s2A(8).Theeightworkersinthefettlingareaused25000cuttingdiscsperyear.Theworkalsoresultedinhighnoiseexposureandalotofmanualhandling.

The solution

Aspartofageneralprogrammetoimproveergonomicsandreducevibrationexposureinthefettlingarea,thecompanyboughtanenclosedremote-controlledcut-offmachine.Thecastingismountedinasimplefixtureandcutbyalargeabrasivedisconapneumaticarm.Theoperatorwatchesthecuttingthroughawindowintheenclosureanddoesnotcomeintocontactwithanyvibratingcomponents.

The cost

£135000forthecut-offmachine.Disccostshavereducedbyapproximately80%.Themachinepaidforitselfin2yearsboththroughimprovedproductivityandgreatlyreduceddiscconsumption.

Cuttingoffacastingwithahand-heldtool

Automaticcut-offmachineshowingacastinginafixture

CasecourtesyofTerrillBros.(Founders)Limited



The result

n Theoperatorsarenotexposedtoanyvibration.n Ithashelpedintheprogrammetoreducebackinjuriesatthefoundry.n Theexposuretonoise,dustandfumeshasreduced.n Theriskofinjurybycontactwiththecutterorhotmetalisreduced.n Moreworkcanbeprocessedbythesamenumberofworkers.


2


Daily exposure time


Before 5.5 2hours 5hours 4

After 0 - 0 -



17 Automatic fettling of castingsThe task

Fettling spheroidal carbon steel castings.

The problem

Thecompanyoperatesafoundrythatcastscomponentsinspheroidalcarbonsteels.Thesematerialsareveryhardand,asaresult,fettling(theremovalofexcessmaterialaftercasting)hastobedonewithhigh-performancetools.Peopleworkinginthefettlingareacanbeexposedtogrindervibrationforupto3.5hoursaday.Thelargehigh-frequencyelectricgrindersusedatthefactorycanproducetypicalvibrationmagnitudesofaround7m/s2,soitispossiblethatpeopledoingthisworkreceivedavibrationexposureofabout5m/s2A(8).

The solution

Muchofthefettlingisnowdonewithafully-automatedrobot-basedmachine.Thecastingsaremountedonspecialfixturesandplacedontoaconveyorsystem.Arobotarmthenpicksupthefixtureandmanipulatesthecastingsothattheunwantedmaterialisremovedbylargegrindingandcut-offwheels.Thecontrolsequencesarepre-programmed,soalltheoperatorhastodoismountthecastingsontothefixtures.

The cost

About£250000foreachautomaticfettlingmachine.

The result

n Theoperatorsarenotexposedtoanyvibration.n Thereisimprovedproductivityandmoreconsistentquality.n Thereisreducedexposuretonoise,dustandfumes.


2


Daily exposure time


Before 7 1hour17minutes 3.5 4.6

After 0 - 0 -

Insidethefettlingmachine,showingacastingmountedinafixtureandthegrindingwheel

CasecourtesyofTriplexWilliamsLimited



18 Air-carbon arc gouging replaces traditional toolsThe task

Rectifying defects in large castings.

The problem

Anengineeringcompanyneededtorefurbishtwosteamchests,whicharelargespecialiststeelcastingsweighingabout20tonneseach.Theyhadbothbeeninserviceforsomeyearsandhadmanydefectsfromuseandpreviousrepairs.Non-destructivetestingtechniqueswereusedtodetectandlocatethedefects,whichincludedcracksandholesinthesurface,hiddenvoids,andareaswhereanincorrectmaterialhadbeenadded.Torepairthedefects,approximately2tonnesofmaterialneededtoberemovedfromeachcastingbygouging.Traditionaltools,suchaschippinghammersandgrinders,wouldhavetakenateamofworkersseveralmonthstocompleteandtheywouldhavebeenexposedtoahighvibrationmagnitude.

The solution

Thecompanyremovedthematerialusingair-carbonarcgouging.Thisprocessusesanarcweldingpowersourceandaspecialhandsetwithanozzlethatblastscompressedairontothearc,blowingawaythemoltenmetal.

Steamchestcastingshowinglargearearemovedbythermalgouging

Air-carbonarcgouginginprocess

CasecourtesyofMitsuiBabcockEnergyServicesLtd



The cost

Air-carbonarcgougingequipmentcostsapproximately£7000perset.

The result

n Theoperatorswerenotexposedtoanyvibration.n Thismethodgaveahighermaterialremovalratethanchippingandgrinding,

whichledtolargesavingsintimeandcost.Forexample,thejobwascompletedbyfourmeninabout1month.

Note:Theprocessproducedcopiousvolumesofairbornefumeandspatter.Operatorsmustbeprotectedandotherpeopleremovedfromthearea.Failuretodosowillputthehealthofoperatorsatseriousrisk.Companiesshouldperformadetailedassessmentoftheriskstothehealthandsafetyofoperatorsandensurefumelevelsarecontrolledtotheappropriatelevel.Thismayresultinadditionalcosts.Itmayalsoproducehighnoiselevelsfromwhichoperatorsmustbeprotected.

Therearevariousothermethodsofthermalgougingwhicharesuitablefordifferentapplicationsandmanyhavelowerexposuretotheseotherhazards.Thetwomainalternativesareoxy-fuelgasflamegougingandplasmagouging.

Operation Vibration magnitude ah,w in m/s

2


Daily exposure time


Before(potential)

GrindingChipping

913

46minutes22minutes

3hours3hours

5.58

After - 0 - 0 -



19 Casting shell knockout in cabinetThe task

Removing ceramic mould shells from precision cast components.

The problem

Atonesmallfoundry,ceramicmouldshellsusedtoberemovedbyhandusingalumphammer.Thiswasverytimeconsumingandnotparticularlyeffectiveatremovingallofthemouldmaterial.Handhammeringoperationslikethisexposeworkerstohighmagnitudesofshockvibration-overatypicalworkingcycle,valuesashighas27m/s2arecommon.Eachmouldshelltookabout2minutestoknockout.Thenumberdoneperdayvariedandtheworkwassharedbetweentwoorthreepeople.Ifonepersonknockedouttenmouldsinadaytheirvibrationexposurewouldhavebeenabout6m/s2A(8).

The solution

Thecompanyboughtaknockoutcabinet.Thisconsistsofachippinghammermountedinasteelframeinsideanacousticallytreatedenclosure.Thecastingisplacedinthecabinetandthechipperwillonlyoperatewhenthedoorisclosed.

The cost

£5000topurchaseandfitoutthecabinet.

Left Castinginsidecabinetbeforeoperationbegins

Right Castinginsidecabinetaftermouldremoval

Automaticknockoutcabinetandoperator



The result

n Theoperatorisnotexposedtovibration.n Thereisasmallreductioninmanualhandling.n Itisamuchfastermethod(eighttimesfasterthantheoldmethod)andmore

effective.n Noiseexposuresarelowerthanalternativemethods.n Thereislessmessaroundtheworkshopastheremovedceramicisallinone

place,reducingcleanuptime.


2


Daily exposure time


Before(typical)

27 5minutes 20minutes 5.5

After 0 - 0 0



20 Maintenance of low-vibration toolsThe task

Using a needle gun.

The problem

Aspartofaprogrammetoreducehand-armvibrationexposure,oneconstructioncompanytriedoutanewvibration-reducedneedlegun.Themanufacturerclaimedavibrationmagnitudeof4m/s2(testedtotherelevantlaboratorystandard).Thiswasconsideredacceptablebythecompanyasthetoolswouldnotbeusedformorethan4hoursperdayandtheoperatorswouldnotbeexposedtovibrationfromothersources.Thetoolwasusedonalargesiteforafewmonthswithoutanyregularmaintenance.Duringacheckonvibrationlevelsperformedon-site,theneedlegunproducedavibrationmagnitudeof15m/s2.Thecompanyreturnedthetooltothemanufacturersforrepairsandcomment.

The solution

Thetoolwasdismantledanditwasdiscoveredthatonlysixoftheoriginal28needleswerestillintactandthatpartofoneofthebrokenneedleswasjammingthevibrationisolationsystem.Therewasnodamagetotheotherinternalcomponentsofthetoolwhichhadstillbeenusableeveninitsdamagedstate.Theneedlesandneedleguidewerereplaced,thetoolwasreassembledandtestedforvibrationagain.Undersimilarloadconditionstobefore,amagnitudeof4m/s2wasmeasured.Thevibrationexposurecausedbythepoorly-maintainedtoolwillbeavoidedinfuturebymorerigorousmonitoringofthetool’scondition.

The cost

Basicmaintenancecanbedonein-house.Thecostofamanufacturer’sservicewilldependonthetypeoftool.

Vibrationaccelerationmeasuredonaneedlegunbeforeandafteritwasrepaired



The result

n Thevibrationmagnitudeisreduced.n Properlymaintainedtoolstendtolastlongerandretainperformanceand

productivity


2


Daily exposure time


Before 15 19minutes 4 10.6

After 4 4hours 4 2.8

Therepairedneedlegun



21 Reduced-vibration needle gunsThe task

Large-scale concrete construction.

The problem

Thebuildingoflargeconcretestructuresofteninvolvesscabbling.Thisinvolvesroughingupconcretewithpercussivetoolstoformabondingsurfacewhichwillmakeagoodjointwhereadditionalconcreteistobeadded.Thiscanbedonewithavarietyoftoolsdependingonaccessrequirements.Ononesite,hand-heldneedlegunswereusedtoscabblearangeofsurfaces.Someofthesetoolsweretestedatthesiteandproducedvibrationmagnitudesofbetween9and13m/s2whilescabbling.Asthetoolsmaybeusedforupto2hoursinatypicalday,thiswouldgiveamaximumvibrationexposureof6.5m/s2A(8).

The solution

Thereareseveralmethodswhichcouldreducevibrationexposureduetoscabbling.Oneinvolvestheuseofnewlow-vibrationneedlegunswhichwereusedasdirectreplacementsfortheoldtools.Ononeofthenewtools,avibrationmagnitudeof4m/s2wasmeasuredwhilescabblingconcrete,whichwasasignificantimprovementovertheoldertoolsonthesite.Theinternaldesignofthetoolusessprings,rubberandcompressedairtoisolatethevibrationfromtheoperator.

The cost

Thetoolinthiscasecostsabout10%morethanthepriceofanequivalentnormaltool.

Vibration-reducedneedlegun

Cross-sectionoftoolshowingvibration-isolatingspringsandfloatingcylinderbody



The result

n Thevibrationmagnitudehasreduced.n Operatorsreportthatthetoolismorepleasanttouse.


2


Daily exposure time


Before(potential)

13 22minutes 2hours 6.5

After(potential)

4 4hours 2hours 2



22 Shot blasting cabinet replaces rotary filesThe task

Descaling very large castings.

The problem

Submarinebuoyancytankscontainlargeintricatelyshapedventscalledgrillagesthroughwhichwaterandairarepumpedinandout.Thesegrillagesaregenerallymadeofcastmetalandrequirefettlinganddescalingbeforetheycanbefittedtotheship.Becauseoftheircomplexshape,atoneshipbuildingcompanythisjobwasdonebyateamof30peoplewithrotaryfiles.Theywouldworkalldayforseveralweeksoneachgrillageandcouldbeexposedtovibrationmagnitudesover5m/s2.Noiseanddustlevelswerealsoextremelyhigh.

The solution

Thecompanyalreadyhadaverylargeshotblastingcabinetwhichwasusedforsurfacepreparationofotheritems.Thiscabinetwasadaptedsothatthegrillagescouldpassthroughonaconveyorsystem.Amachineusescompressedairtoblastsmallmetalballs(shot)atthesurfacesofthegrillage.This‘shot-blasting’dislodgesandremovesthescale.Oneoperatorisrequired,whostandsawayfromthenoiseanddust,andisnotexposedtoanyhand-armvibration.

The cost

Approximately£50000.

The result

n Theoperatorisnotexposedtovibration.n Thereisreducedexposuretonoiseanddust.n Whatusedtotakeateam3weekscannowbedonebyonepersonin1day.


2


Daily exposure time


Before 5 2hours30minutes 6hours 4.3

After 0 - 0 -



23 Descaling with abrasive blastersThe task

Cleaning the insides of large storage tanks to remove rust, scale and other impurities after fabrication.

The problem

Alargeshipbuildingcompanyusedtocleanouttanksusingneedlescalers.Thisoperationexposedstafftovibrationmagnitudesintherange11to23m/s2oftenformorethan7hoursaday.Conditionsinsidethetankwerealsoextremelyunpleasantwithhighnoiselevelsandcloudsofdust.

The solution

Theneedlescalerswerereplacedwithportablevacuumblastingmachineswhichcleanthesurfacesbyblastingthemwithanabrasivematerialandthensuckingitandanydebrisawaytoaholdingtank.Theoperatorisexposedtovibrationmagnitudesbelow1m/s2.

The cost

About£1000forthevacuumblastingmachine.

The result

n Areductioninvibrationmagnitudefromupto23m/s2tolessthan1m/s2.n Alargereductioninbothnoiseanddustlevels.Thevacuumactionofthe

equipmentremovesdustanddebriswhichpreviouslymadetheworkenvironmentveryunpleasant.

n Asmallerteamofoperatorsisrequiredtocleanthetankswhichhasledtoimprovedproductivityandcostsavings.


2


Daily exposure time


Before 23 7minutes 7hours 21

After 1 Morethan24hours 7hours 1

Vacuumblastingmachine

Educt-o-maticmachineavailablefromHodge-ClemcoLimited



24 Job rotation and use of pedestal-mounted nutrunnersThe task

Tightening threaded fastenings and attachments.

The problem

Ononeengineassemblyline,atemporaryadapterisnecessaryforfeedingoiltotheenginesumpduringon-linetests.Itisscrewedintoathreadedholeonthesideoftheengineblock.Itdoesnotneedtobetightenedtoaspecifictorquebutneedstobequitetight.Thisusedtobedonewithahand-heldpneumaticratchetgunofthetypeusedingaragestotightenwheelnuts,whichcouldproducevibrationmagnitudesupto8m/s2.Amaximumof2400enginesareassembledperday,which,withperhaps3secondsratchetingoneach,wouldgiveanexposureof4m/s2A(8).Theworkwasdonebyagroupofaboutfivepeople.

The solution

Thecompanyimplementedajobrotationschemewherebyoperatorsmovedbetweenfourorfivedifferenttasksallaroundthesameareaoftheproductionline.Someoftheotheractivitiesinvolvesomevibrationexposure,butingeneraltherotationhashalvedindividualexposuretime.Tofurtherreduceexposure,thecompanyoptedtousepedestal-mountednutrunnersinsteadofratchetgunstodothejob.Theseareverysolidlymountedandsopassverylittlevibrationtotheoperator.

Ahand-heldratchetguninuse

Apedestal-mountednutrunner

CasecourtesyofFordMotorCompany



The cost

About£5000forthepedestalmountingandtool.

The result

n Vibrationmagnitudeisreduced.n Lessnoiseisproducedbythepedestal-mountedtoolthantheratchetgun.n Operatorsreportthatthegroupworkingreducesboredomandfatigue.


2


Daily exposure time


Before 8 1hour 2hours 4

After Lessthan1 Morethan24hours 1hour Lessthan1



25 Automatic bolt fittingThe task

Fitting main bearing caps to car engines.

The problem

Thecompanyusedtofitmainbearingstoengineblocksmanually.Usingthismethod,theretainingboltsarestartedbyhandandthenrun-upandtightenedup,or‘torqued’,usinghand-heldpneumaticorelectrictools.Thesetoolsoftenproducedhighvibrationmagnitudesupto8m/s2andwereinalmostconstantuseasenginespassedontheproductionline.Ittooktwopeopletofitthebearingcapsquicklyenoughtokeepupwiththeotherpartsoftheline.

The solution

Inoneplanttheprocesshasbeenautomated.Thebearingcapsareplacedinafixturebyrobotarmsandfittedbyadedicatedmachinewhichpicksandplacesallfivecaps.

The cost

Tenspindleautonutrunnerscost£100000.

Themachineinoperationshowingarowoffivebearingcapsabouttobeliftedontoacylinderheadandfasteneddown

Multipletighteningspindlesofthetypeusedtosimultaneouslytightenthetenbearingcapbolts

CasecourtesyofFordMotorCompany



The result

n Theoperatorsarenotexposedtoanyvibration.n Thenoiseexposureofoperatorshasreduced.n Consistencyandproductivityhasimproved.Forexample,whatwasdoneby

twofull-timepeoplecannowbedonebyone,whoalsohashandsfreeforothertasks.


2


Daily exposure time


Before(potential)

8 1hour 6hours 7

After 0 - 0 -



Left Hand-heldnailsawusedtodismantleapallet

Right Stringerstrippingmachine

26 Automated pallet strippingThe task

Repairing wooden pallets.

The problem

Thecompanyownandleaseoutpallets.Whenthepalletsaredamagedtheyarerepairedinspecialdepotsaroundthecountry.Onarrivalatthedepot,thepalletsaresortedandtheirdefectsidentified.Damagedpartsarethenremovedbyprisingapartthejointsandcuttingthroughthenailswithapneumaticsaw.Thesawsusedhaveareciprocatingactionandareusedinshortburstsforatotalofabout1hourperday.Thecompanywantedtoreducetheresultinghand-armvibrationexposurebyasmuchaspossible.

Themosttime-consumingpalletelementstoremovearethestringers.Thesearethestrongpieceswhichrunacrossthepallettosupportthetopplanksandareheldinplacewithmorenailsthantheotherparts.Thestringernailsarealsomoredifficulttoaccess,whichresultsinalotofmanualhandling.

The solution (BRISTOL DEPOT)

Aspartofanoverallprogrammetoreducearangeofhazardsandimproveefficiency,approvedbyanergonomist,thecompanydecidedtoautomatethestringerstrippingprocess.Theyintroducedspeciallyconstructedstringerstrippingmachineswherethepalletsareclampedtoabenchandacircularbladeisforcedthroughthenails.Workersintheplantrotatejobs,sosomevibrationexposureisstillexperiencedduetotheuseofthesawsonthenon-stringerparts.

The cost

Nocostsavailable.

The result

n Thestringerstrippersdonotexposetheiroperatorstoanyvibrationandtheygreatlyreducetheamountofmanualhandling.

n Thetimetheoperatorsareexposedtovibrationduringthedayhasreduced.n Overalltheintroductionofthestringerstrippershasreducedthevibration

exposureofworkersby13%andreducedtheoccurrenceofupperlimbandbackinjuries.

Twodepotsinthecompany-BristolandBirmingham-introduceddifferentsolutionstotheproblem.

CasecourtesyofChep(UK)LimitedBristol depot



27 Low-vibration power sawThe solution (BIRMINGHAM DEPOT)

Atoneofitssitesthecompanyhastakenadvantageofadvancesintooldesignandboughtnewsawsofsimilarperformancewhichproducemuchlowervibrationmagnitudes.Thenewsawshavebeencarefullydesignedtohaveamorebalancedandsmoothoperationthantheoldertypes.

The cost

Anewlow-vibrationsawcostsabout11%morethantheoldtype.

Summary - the combined effect Inthefuture,thecompanyintendstointroducethebenefitsofbothsolutionstotheirotherdepotstofurtherreducetheexposureofoperatorstovibration.Wherebothsolutionsareusedtogether,thetotalreductioninvibrationexposurewillbe60%.

The result

n Thenewsawsproduceavibrationmagnitude53%lowerthanthetypicaloldsawsandtheycanbeintroducedwithoutanychangetotheworksystem.

n Thenewtoolisdesignedtoreduceinternalwearofpartsandsomaintenancecostsarereduced.

CasecourtesyofChep(UK)LimitedBirmingham depot

Explodeddiagramofthenewsawshowingpivotmechanismandcounterbalanceweights

SawsmanufacturedbyCengar,UniversalToolCompanyLimited



28 Outdoor power tools purchasing policyThe task

Using chainsaws and strimmers.

The problem

Themaintenanceofwatercoursesofteninvolvesusingchainsaws,strimmersandbrushcutterstoclearvegetationfromriverbanksandsimilarareas.Localdepotsofanationalorganisationwerefreetopurchasetoolsoftheirchoicefromlocalsupplierswhenrequired,whichresultedinthecompanyowningalargerangeoftoolsfromavarietyofmanufacturers.Atestsessionwasheldatwhichthevibrationproducedbyaselectionofthetoolsinusewasmeasuredundersimulatedworkconditions.Thechainsawsproducedanaveragevibrationmagnitudeof13m/s2withseveraltoolsreportedtoproducevaluesabove25m/s2.Thestrimmersgaveanaveragevibrationmagnitudeof8m/s2withasignificantnumberproducingmorethan15m/s2.Itwasverydifficulttodeterminearepresentativevibrationexposuretimeforthetools,however,discussionbetweentooloperatorsandotherstaffrevealedthatdailyexposuresofmorethan2hoursforachainsawand4hoursforastrimmerwereunlikely.Thismeantthatpersonnelhadpotentialexposuresof13m/s2A(8)forchainsawsand11m/s2A(8)forstrimmers.

The solution

Acommittee,includingrepresentativesofmanagement,theunionsandtheoperators,reviewedtheexistingsituationanddiscussedthemostappropriatemeasurestoreducevibrationexposure.Theobjectivewastoreduceitto2.8m/s2A(8),which,usingtheestimatedexposuretimes,couldallowchainsawstoproduceamaximumvibrationmagnitudeof5.6m/s2andstrimmersamaximumof4m/s2.Therewasalengthyperiodofconsultationwithtoolsuppliers,toolusersandotherstoensurethatasufficientrangeoftoolsmeetingthesecriteriawouldbeavailableandthatalloftheorganisation’sneedsandobligationscouldbemet.Apurchasingpolicywasthenprepared,underwhichallofthechainsawsandstrimmersinstockwouldbereplacedwithtoolswhichmetthecriteriawithin4years.Thechangeswillbephasedinwithtoolsproducingvibrationmagnitudesofmorethan20m/s2beingwithdrawnfromuseimmediately,alltoolsproducingmorethan12.5m/s2within1year,andtheultimateobjectiveachievedwithin4years.

Strimmerinuse



The cost

Minimalastoolswouldbereplacedattheendoftheirlifeanyway.

The result

n Ageneralreductioninvibrationmagnitudesproducedbythetoolsused.n Thenewertoolsareoftenbetterdesignedandlessnoisy.n Theoperatorsofthetoolswereinvolvedinthedevelopmentofthepolicywhich

helpedtoincreasetheirawarenessoftheproblem.

Tool Vibration magnitude ah,w in m/s

2


Daily exposure time


Old ChainsawStrimmer

2615

6minutes17minutes

2hours4hours

1311

New ChainsawStrimmer

5.6maximum4maximum

2hours4hours

2hours4hours

2.82.8



29 Low-vibration fastener systemThe task

Assembling lightweight structures.

The problem

Aircraftwingsproducedatonefactorywereassembledusingnutsandbolts.Withthismethod,toensuretheintegrityofthejoint,theboltsareslightlylargerthantheholesdrilledinthewingtotakethemandhavetobeforcedintoplacewitharivetinggun.Inasimulatedworkingcycle,arivetinggunproducedanaveragevibrationmagnitudeof9.5m/s2.Aworkermightbeexposedtothislevelforupto1houradaywithasimilarperiodspentusinganutrunner(vibrationmagnitudeofapproximately3m/s2)andtherestofthedaydrilling(vibrationmagnitudeoflessthan1m/s2).

The solution

Thewingsarenowassembledusingapin/collarfastenersystem.Thissystemusesswagedmetalcollarstosecurepins(bolts)withsimpleparallelgroovesratherthanspiralthreads.Thepinsarestillslightlylargerthantheholesinthewingbutarepulledintoplacewithaspecialpneumatictoolratherthanpushedthroughwitharivetinggun.Ametalringorcollaristhenplacedovereachpinandasecondspecialtoolsimultaneouslypullsonthetailofthepinandpushesaconicaldieover

Theoperationofthepin/collarfasteningsystem

CasecourtesyofBritishAerospace,AirbusLimited



thecollar.Thisactionclampsthejointtogetherandlocksitbydeforming(swaging)thecollarintothepingrooves.Thetailofthepinthensnapsoff,leavingitflushwiththenewlyswagedcollar.Theonlysourceofvibrationinthisprocess,otherthandrillingtheholes,istheshockproducedbythepintailbreaking.Thisresultsinanaveragevibrationmagnitudeof1.5m/s2overatypicalworkingcycle.Eachoperatorspendsbetween1and2hoursadayfittingthefastenersandtherestofthetimedrillingholes.

The cost

Thefastenersaresimilarincosttothenutsandboltspreviouslyused.Toolscostabout£1000each.

The result

n Thereisareductioninboththevibrationmagnitudeproducedandthetimetheoperatorsareexposed.

n Thenoiselevelsaregreatlyreduced.n Thecycleisfasteroverallwhichincreasesproductivity.n Thequalityofworkhasimprovedbecausetheclampingforceishigherand

moreconsistentandthefinishedjointismoreresistanttolooseningfromvibration.

Tool Vibration magnitude ah,w in m/s

2


Daily exposure time


Before RivetinggunNutrunnerDrill

9.53Lessthan1

42minutes7hoursMorethan24hours

1hour1hour6hours

Totalof3.6

After Pin/collartoolsDrill

1.5Lessthan1

Morethan24hoursMorethan24hours

1hour30minutes6hours30minutes

Totalof1.1



30 No contact casting shell knockoutThe task

Knocking out multiple-component ceramic moulds used in the ‘lost wax’ casting process.

The problem

Aprecisioncastingcompanyusedahand-heldrivetinghammer,ofatypeusedinshipyards,toknockoutcastingsfromtheceramicshellsinwhichtheyhadbeencast.Thisprocesstakesapproximately20minutestocompletepermultiplecomponentmould,exposingtheoperatortovibrationmagnitudesofupto12m/s2.Typicallyanoperatorwouldknockout18suchmouldsadaygivingapossibleexposureof10m/s2A(8).

The solution

Thecompanydevelopedanin-housesolutionbymountingapneumaticbreaker,similartothetypeusedtodiguptheroad,inacustom-builtsteelsupportframe.Themouldtobeknockedoutisheldintheframewithpneumaticjawsandvibratedbyaspecialtoolpiecefittedinthebreaker.

The cost

Approximately£2500forthebreaker,steelworkandpneumaticsplusengineer’stime.

The result

n Theoperatordoesnotcomeintocontactwithanyvibratingparts.n Thetimetoknockoutonemouldtreereducedfrom20minutesto5minutes.n Thereisareducedriskofbackproblemsaslessliftingisrequired.n Themachinecanbepartiallyorfullyenclosedtoreducetheoperator’s

exposuretonoise.


2


Daily exposure time


Before 12 25minutes 6hours 10

After 0 - 0 -

Knockoutmachineshowingbreakermountedinsupportframe



31 Low-vibration riveters and reaction barsThe task

Riveting aeroplane wings.

The problem

Aircraftwingsareoftenassembledusingrivets.Aholeisdrilledthroughthecomponentstobejoinedandarivetinserted.Thejointisthenmadebyflaringthepointoftherivetwithanimpulsivetool(rivetinggun)whiletheotherendissupportedwithareactionbar.Inatypicaloperationatonefactorythewingcomponentswereheldinajigwhiletherivetingwasdonebytwoworkers.Oneworkeroperatedtherivetinggunandtheotherheldthereactionbar,asolidblockofmetal,inplace.Afullday’srivetingrequiresabout2hoursuseofthetools,givingvibrationexposuresofabout2m/s2A(8)and9m/s2A(8)forrivetingandreactingrespectively.

The solution

Thecompanyinvestedinnewtoolswiththespecificintentionofreducinghand-armvibrationexposure.Theyboughtvibration-reducedrivetinggunsandvibration-isolatedreactionbarswhichhavereducedthevibrationmagnitudeexperiencedbybothoperatorsto3m/s2.Thegunhasanimprovedinternaldesignandthereactionbarfeaturesapassivespring/dampersystemtoreducethevibration.

The cost

Low-vibrationriveterscostabouttwicethepriceofnormalones.Vibration-dampedreactionbarscostabout£300.

The result

n Vibrationmagnitudehasreducedforboththerivetingandreactingoperations.n Thenewtoolsaremorecomfortablefortheoperatorstouse.

CasecourtesyofBritishAerospaceAirbusLimited

Low-vibrationtoolsbeingusedtorivetanaircraftwing



Operation Vibration magnitude ah,w in m/s

2


Daily exposure time


Before RivetingReacting

517

2hours30minutes13minutes

2hours2hours

2.58.5

After RivetingReacting

33

7hours7hours

2hours2hours

1.51.5



32 Special formworkavoids scabblingThe task

Construction of large concrete structures.

The problem

AconstructioncompanywasawardedacontracttobuildoneofthestationsfortheLondonUndergroundJubileeLineExtension.Thestationdesignincludedareinforcedconcretebaseslab300mlong,25mwideand3mdeep.Theslabwascastin situin43sections,each7mlong.Thesectionswerecastoneafteranotherusingtheprevioussectiontosupportonesideandaspeciallyconstructedformworkstopendtosupp

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