calibration of torque tools - atlas copco tools eastern...

Calibration of torque tools

1 INTRODUCTION ................................................................................2

2 WHAT IS CALIBRATION? ........................................................... 3-5 2.1 Why do we need calibration and determining of capability? ......3 2.2 How does calibration differ from service? ..................................5

3 CREDIBILITY OF RESULTS ........................................................ 6-9 3.1 Traceability of measuring equipment ..........................................6 3.2 Conditions for performing calibration .........................................7 3.3 Measurement uncertainty .............................................................8 3.4Calibrationcertificate .................................................................. 9

4 ACCREDITED AND NON-ACCREDITED CALIBRATION ... 10-12 4.1 Why use accredited calibration? ................................................10 4.2 Rules for performing calibration ..........................................11-12

5 ADVANTAGES OF THE ATLAS COPCO LABORATORY ......13-17 5.1 Who are Atlas Copco? ......................................................... 13-14 5.2 Services provided ................................................................. 14-16 5.3 Contact ....................................................................................... 17

6 APPENDIXES .............................................................................. 18-22 AtlasCopcos.r.o.accreditationcertificateandappendix ......... 18-19 Samplecalibrationcertificate 3-point calibration of a rise-and-fall pendant ..................................20 ISO9001,ISO14001certificates ...............................................21-22

Contents

CALIBRATION OF HAND TORQUE TOOLS 1

Using calibration services for torque tools, torque transducers and torque measuring tools (collectively torque measuring equipment) significantly contributes to compliance withprescribed parameters in all technical activities that require reliable tightening results. Increasing product safety requirements for are especially important in the automotive industry, but are alsoappliedinassemblyandotherindustrialfields.

The purpose of this publication is to provide information on the importance of accredited calibration services for torque measuring equipment. It presents the work provided by calibration laboratories and the range of information provided oncalibrateddevicestotheirusers.Thepublicationalsoexplainsimportant concepts associated with the work of calibration laboratories.

1. Introduction

Fig. 1 Sample use of a hand torque tool.

2 CALIBRATION OF HAND TORQUE TOOLS

2.1 Why do we need calibration and determining of capability?

Services for torque measuring equipment include maintenance and repair, as well as equipment adjustment. These services are needed wherever it is necessary to monitor the parameters of tight-ening tools. A good service organization will provide adjustments to meet the user’s requirements (and according the knowledge of its employees). However, this service is no substitute for independ-ent, impartial assessment of the equipment’s ability to achieve the required results.

A direct request for independent accredited calibration and deter-mining of capability may arise from a customer’s quality manage-mentsystemcertification.Chapter7.6ofISO9001referstocali-bration of measuring equipment according to standards associated with national or international standards. The stricter ISO/TS 16949 standard, in chapter 7.6.3.2, demands that a calibration laboratory be directly accredited according to ISO/IEC 17025 (although it alsoallowsforotherformsofverificationofalaboratory’scapa-bilities).

2. What is calibration?

Fig. 2 Mobile equipment for testing hand torque tools.



The quality cost of badly performing tools

Badly performing tool reported by the employee

“Quality control” detects that the joint is wrong

€10

€ ???

€ ???

€1000

€100

Final inspection detects that the assembly is wrong

Expense of warranty repair

Customer detects that the assembly is wrong

Losses mount tenfold

Let’s hope that the rest are OK!

On a properly working tool, a sensor measures tightening torque at 25 Nm, where ~24.8 Nm is the set torque and ~0.2 Nm is the friction on the gears and joints.

During work, the set torque gradually changes, but the sensor still shows

25 Nm. If internal friction reaches 5 Nm, the tool will tighten only to 20 Nm.

Are your tools really adjusted right?

25Nm or 20Nm?

SensorGears

Bearings

What problems can calibration detect?Electric and pneumatic wrenches and screwdrivers (Gear wear)

Variance(3σ)

Number of tightenings (Worn angle and planetary gears)

Tools live longer with regular preventative maintenance.

x x

70% max. tightening torque

Tool set to maximum tightening torque

Gear replacement needed

Failure

2.2 How does calibration differ from service?

Torque tools, torque transducers and torque measuring devices are calibrated by a calibration laboratory within the scope specified in a valid accreditation certificate, or more preciselyin its appendix. For accredited calibration (see chapter 4), thecalibrationlaboratoryisboundbyspecificrules,andviolationofthem can result in revocation of the laboratory’s accreditation. The calibration laboratory’s customer can be sure that an auditor and aprofessionalexpertconductstrictinspectionsofthelaboratoryemployees’ activities. The customer can also submit a complaint regarding the laboratory’s activities, and complaint resolution is the object of special attention by the supervisory authority.

A calibration laboratory’s management system involves a number of monitoring instruments. These include upgrading employees’qualifications,inspectionofthetechnicalequipmentused, managing disputes and taking systematic measures, all thewaytointernalauditsconductedbyaqualifiedemployee.

Thebasicdifferencebetweenadjustmentinaservicecontextand calibration of torque tools is the reliability and credibility of the parameters required when using the tools.

Fig. 3 Sample equipment for testing dynamic torque tools.



3.1 Traceability of measuring equipment

The laboratories use only measuring equipment that are metrologically traceable to international standards. Traceability canbeachievedthroughcalibrationofstandardsbyanexternalcalibration laboratory, or through calibration using one’s own accreditation. Traceability through one’s own calibration is secured through participation in programs for inter-laboratory comparisonandverificationwithinthecontextofaccreditation.

3. Credibility of results

Fig. 4 Sample calibration performance, including measuring set (measurement unit, cable and standard) and measured set (tool, cable and control unit).

3.2 Conditions for performing calibration

A laboratory’s activities include calibration conducted under laboratory conditions and calibration conducted externally onthe customer’s premises. Monitored values include the ambient temperatureandhumidity.Forthismonitoring,thelaboratoryhasbarometers and thermometers calibrated at accredited calibration laboratories. The standard environmental condition for obtaining proper measuring results is a temperature between 18°C and 28°C (preferably between 20ºC and 22ºC) and a maximum of 90%humidity. The temperature during calibration must be recorded. If, during measurement, there is a deviation of more than ± 1°C, measurementmustbe repeated. If thecustomerdefinesdifferenttemperature conditions for using calibrated measuring equipment, the uncertainty must be adjusted. Based on the manufacturer’s data, the uncertainty caused by the temperature difference during calibration and ordinary use must also be added.

To obtain reliable results, treatment of the calibrated equipment is also essential.

In laboratory calibration, equipment is inspected upon receipt. (An ineligible equipment cannot be accepted for calibration and is sent for service or returned to the customer.) Throughout the process, thorough marking and monitoring of the course of the activities are ensured.

Forcalibrationonthecustomer’spremises,theequipmentisinspectedand accepted for calibration, but the customer is responsible for its condition.

If there is any damage to the tool, the situation is recorded, the customer is immediately informed, and after evaluation, corrective action is taken.



3.3 Measurement uncertainty

Theappendixtothelaboratoryaccreditationcertificatespecifiesthe BMC value (Best Measurement Capability). Why is this data important? It gives the minimum percentage of the measured value by which a calibration result can vary under standard conditions.

For judging the level of the laboratory, it is also essential totake into account the contribution of the standard (wtcm) to the uncertainty. In such a case, during calibration the calculation methodology allows assessment not only of deviations in the equipment themselves, but in the entire chain (from the torque converter to the imaging unit). It also allows assessment of theequipmentabilitytoworkwithinthecontextofdeviationsascertained.

Data on measurement uncertainty (also including deviations in thestandard)areincludedonthecalibrationcertificate.

To achieve reliable calibration results, it is best to use specialized calculation software, which undergoes annual testing and inspection by the accreditation authority.

3.4 Calibrationcertificate

Acalibrationcertificateisalistofresultsofcalibrationperformed.It guarantees adherence to the approach and accreditation rules duringcalibration.Thedataonthecalibrationcertificateprovidespecifically achieved values, but it does not assess whether acustomer’s required parameters have been achieved. Calibration laboratory employees cannot monitor the conditions under which the calibrated equipment is used, and in many cases they don’t know thecustomer’s specifications.The information in thecalibrationcertificatemustallowthecustomertomakeaqualifiedjudgementastowhethertheequipmentusedfulfilshisrequirements.

Upon customer request, a professionally qualified laboratoryemployeecanprovideanexpertopiniononthecalibrationresults.This statement is not a product of the accredited laboratory’s activities.

Fig. 5 Sample calibration certificate.



4.1 Why use accredited calibration?

What are the main differences between accredited and non-accredited calibration?

The procedures for conducting accredited calibration and for calculating the deviation and uncertainty of measurement are regularlyverifiedbyauditorsandspecialistsoftheaccreditationauthority. The laboratory’s employees must pass repeated training in torque measuring equipment calibration and metrological regulations. However, also important is the system of equipment traceability for verifying a calibrated tool’s compliance with thedefinedparameters,orstandards.Thecustomerdeliversthetorque measuring equipment to the calibration laboratory trusting that the stability and precision of the tightening process’s results willbereliablyverified.Howisthereliabilityofnon-accreditedcalibration ensured? It is based on the customer’s trust in the reliability of the equipment at the laboratory he uses. However, thisreliabilityisnotindependentlyverifiedandisnotbasedon

4. Accredited and non-accredited calibration

Fig. 6 Calibration of precise equipment (torque transducers), as dynamic also stationary.

afirmmethodologyforimplementingthecalibrationconditions,for evaluating measurement or determining uncertainty.

Accreditationcannotbereplacedwithanyformofcertificationor other calibration laboratory authorization. CertificationaccordingtoISO9001,forexample,showsalaboratory’sabilityto meet its obligations, but it is no indication of technological reliability.Certificationespeciallydoesnotverifythecorrectnessof the approach for calculating the reliability and precision of the results of measurements conducted in the laboratory. It does not even include the procedures for testing a laboratory’s capabilities, or so-called inter-laboratory comparison (comparing the results achieved by various accredited calibration labs).

Credibility is enhanced by direct monitoring of the calibration lab’s activities by auditors from the accreditation authority in the lab’s place of operation and by evaluation of calibrations conductedinoperation(called“witnessauditing”),forexternalcalibrations, on the laboratory customer’s premises.

4.2 Rules for performing calibration

The difference between service adjustments to torque tools and calibration isdefinedproceduresandparameters-standardiza-tion. The basic standard for assessing conformity - the capabilities of the accredited calibration laboratory - is international standard EN ISO/IEC 17025. Technical requirements for calibrating hand torquetoolsaredefinedbystandardENISO6789.Methodsofdetermining, calculating and expressing measurement uncer-taintyaredefinedbyEA4/02.EA10/14isamanualpublishedby European Accreditation for calibrating torque measurement equipment. International standard ISO 5393 describes Perform-ance test method of Rotary tools for threaded fasteners.



Theentirecalibrationfieldisalsosubjecttotherequirementsofnational laws on metrology. When providing services abroad, a calibration laboratory must provide its employees with the metrological legislation of the country where the customer operates. In some countries, the national metrological authorities make information on legal requirements available on the Internet.

To get the right results when conducting calibration (even for non-accredited calibration), it is essential to have proper calibration procedures and internal methodologies that are maintained in practice.Stepbystep,calibrationproceduresforspecifictypesof equipment determine the approach to performing calibration. They start with stabilizing the equipment’s temperature, and continue with inspecting it, actual measurement and recording the calibration and labelling the equioment. The calibration methodology is an essential internal document specifying the conditions for performing calibration, the general principles for all calibration procedures, the method for evaluating measurement and determining measurement uncertainty, and the calibration certificaterequirements.

All documents must be accessible to the customer on demand. The right calibration procedure is chosen during the actual orderingphaseforcalibrationservices.Forthisreasoneventhequalifications of sales employees are essential. They must beinformed enough to support the customer in choosing the right calibration procedure.

5.1 Who are Atlas Copco?

Atlas Copco is a group of industrial companies with worldwide leadership in thefieldofcompressors,constructionandminingvehicles, pneumatic tools and assembly systems. In industrial tools,itisaworldleader,settingtrendsinthefield.

The Atlas Copco group delivers sustainable solutions for increasing its customers’ productivity through innovative products and services. The company was founded in 1873 and is headquartered in Stockholm, Sweden. Around the world, Atlas Copco is represented in more than 170 countries and had 30,000 employees in 2009. In industrial tool calibration, it can therefore use its knowledge from production. It has access to precise technical information and specifications and the latest findingsfrom research and development.

Atlas Copco’s accredited calibration laboratory operates in several countries of Europe, and North and South America. This allows internationalknowledgeexchangeamonglaboratoriesaccreditedunder the same accreditation standards, ISO/IEC 17025. However, their experience and national conditions differ. The group’sorganizational structure allows clear establishment of independent calibration laboratories, emphasizing the monitoring mechanisms of the company’s information system.

The Atlas Copco calibration laboratory is accredited by the Czech Accreditation Institute, o.p.s. It has offered its services since 2007 and operates in Central and Eastern Europe. Inclusion

5. Advantages of the Atlas Copco laboratory



of accreditation approval under international agreements on recognizing accreditation (EA MLA and ILAC MRA) allows publicationofcalibrationcertificatewithoutregardtoworkshoplocation.

The range of activities is not tied only to Atlas Copco brand tools. Wealsouseourcalibrationexperiencewithtoolsofotherbrands.The important thing is to comply with the scope of calibration specifiedintheappendixtotheaccreditationcertificate.

Atlas Copco also provides its customers with Internet access to its specialized calibration database. There anyone can check the calibration dates of their tools, and the associated data. If the customer is connected to this database, he is automatically informed ahead of time of his tool’s calibration deadline.

5.2 Services provided

Angle calibration

Forequipmentcapableofmeasuringtheangleofscrewrotationduring tightening, ITS can conduct inspection and non-accredited calibration of the rotation angle, including settings.

Other Atlas Copco servicesAtlas Copco and its sister service company Industrial Tools Service (ITS) can provide you with a full range of services for industrial tools of various brands and assembly applications.

You can choose from one of our various service programs. They can be further adapted to your needs and requirements.

ITS service representatives (see paragraph 5.3) can discuss and propose optimal service programs based on the customer’s own needs.

More than 60 specialists in industrial tool and application services in all regions of Eastern Europe are then ready to fulfil thecustomers’ requests.

Full Coverage ServiceYou can delegate all your service needs to ITS, who will choose the best preventive maintenance plan and provide a full range of services(repairs,calibration)foryourtoolsforfixedcosts.

This program provides the following advantages: - less production downtime, higher productivity - consistently high production quality - afixedservicebudgetwithnosurpriseexpenses - lower administrative and production costs - less need for investment in inventories of replacement parts andbackupequipments

It allows customers to concentrate fully on increasing production efficiency.

ToolScan RCM – Reliability Centered MaintenanceThis program establishes an optimal system of preventive or predictive maintenance tailored to the customer’s needs and requirements. It can be part of Full Service Coverage. Theprogram ensures that the system’s user can be sure that it will workthewayitsuserdemandsitto,withoutirregular,unexpectedinterruptions and breakdowns. It allows the customer to optimize production processes and minimize manufacturing interruptions or slowdowns while lowering administrative costs.

Preventive maintenanceThis program allows users to keep their industrial tools at top performance. As a service partner, ITS can provide preventive maintenancethatensuresmaximumreliabilitywhilemaintainingtools’ stable high performance. The program allows users to plan a



large portion of their necessary service activities for manufacturing downtimes, thus minimizing production line breakdowns.

Fixed-price repairsThis program allows fast repairs while decreasing administrative costs. Tools receive priority repair service based on a system previously agreed upon between the user and ITS. Transport to theservicecentreandbackishandledwithspecialserviceboxes.Full-servicerepairsatITSensuremaximallifeandperformancefor repaired tools. After repair, the tools are tested according to ITS global standards.

Training, consulting services and installation of assembly systemsITS provides a full range of training and consulting services for tightening technology, ergonomics and pneumatic and electronically operated industrial tools and systems. ITS also performs installation (including all necessary documentation) and modificationofindustrialapplications.

Advantages of Atlas Copco calibration and ITS maintenance services - Preventive maintenance is performed along with tool and equipmentcalibration. - Part of calibration of ordinary tools is their adjustment accordingmanufacturerspecifications. - ITS and Atlas Copco perform services during customer downtime(suchasweekends). - CalibrationservicescanbepartofaFullServiceProgram thatincludesacompleterangeofservices. - ITS is a part of the worldwideAtlas Copco network and is therefore integrated into the supply system of all important industrialmanufacturers.

5.3 Contact

FormoreinformationaboutofferingsfromtheAtlasCopcos.r.o.accredited calibration laboratory and other ITS-services, please, contact your local from the following representatives:

Tomasz Biernat ...............................................western PolandTel: +48 510 025 974, email: [email protected]

Krzysztof Karolak ........................................... eastern PolandTel: +48 784 345 402, email: [email protected]

David Tydlitat ................................................ Czech RepublicTel: +420 724 853 538, email: [email protected]

Martin Krynský......................................Moravia & SlovakiaTel: +420 725 483 562, email: [email protected]

Csongor Tomos ..........................................................HungaryTel: +36 204 179 964, email: [email protected]

Remus Cosmin Stangu ............................ Romania, BulgariaTel: +40 730 075 909, email: [email protected]

Formoreinformation,visitwww.its-ee.com.



6. Appendixes

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