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1 PAGE 4 COPYRIGHT 2002 DANIELS MANUFACTURING CORP., ORLANDO, FL PHONE 407-855-6161 FAX 407-855-6884 E-MAIL: TTS Systems CD Pages 1/14/03 2:47 PM Page 4 PAGE 5 COPYRIGHT 2002 DANIELS MANUFACTURING CORP., ORLANDO, FL PHONE 407-855-6161 FAX 407-855-6884 E-MAIL: TTS Systems CD Pages 1/14/03 2:47 PM Page 5 Alphatron TTS Systems CD Pages 1/14/03 2:47 PM Page 6 There are several steps in the process ofterminating wires that must be followed in order toassure quality and longevity in the service life of awire harness. These include compliance with engi-neering and customer requirements, maintenanceand gaging/inspection of crimping tools, dies, appli-cators, and presses. If the termination is beingmade by ultrasonic welding, there are calibrationand verification measures that must be followed. Crimp height and crimp pressure measurementsmay indicate a condition that requires further atten-tion, but when all is said and done, the tensilestrength of a crimped connection is the final answerwhen a pass/fail decision is on the table.

2 A good connection starts with the correct selec-tion of wire, contacts, terminals, or other crimp tool, or press, and the correct accessory(die, locator, applicator, etc) should meet all thespecified go/no-go gaging requirements. Operatorabilities and safety must always be consideredwhen selecting a certain tool (or press) for thevolume and size work that is being HEIGHTis a valuable data point in theoverall wire harness quality assurance process, butit should not be relied upon as the ultimate pass/failcriteria. The measured height of a crimped or weldedconnection may verify that it was crimped in the cor-rect die cavity and the minimum pressure wasachieved, but it will not reveal a more illusive defect;like broken strands, failure to remove the wire insu-lation properly, cracked or fractured metal or severalother possible problems. Since crimp height is anon-destructive test, and it is relatively simple toperform, it should be considered as a component ofmost wire harness quality assurance PRESSUREis another good indicator ofthe performance of the operator and the equipmentin the wire harness fabrication process, however,the crimp pressure monitor (sometimes called crimpquality monitor) is available on relatively few pressesand no hand tools that are utilized in the NorthAmerican wire harness industry.

3 Where they areused, they produce another good data point, butoverall, pressure monitors are not commonplace,and may not be cost effective in a small or mediumwire harness TESTINGto the minimum tensile value, orto the breaking strength of a terminated wire samplewill resolve all concerns about the mechanicalproperties of the crimped or welded termination,and it will indicate,with reliable accu-racy, the electricalintegrity of a con-nection. So, whatfactors should beconsidered whenselecting a pulltester, and decid-ing how often it willbe used?FREQUENCY isthe most com-monly asked ques-tion. How often dowe pull test a termi-nated wire sam-ple? Of course, theanswer will differfrom one companyto the next, andsometimes will varywith type of job or customer. TheBy Dave Kelly, Standards and Industry Liaison, Daniels Manufacturing Corporation, Orlando, Florida (USA)June 2003 Pull TestingTHE FINAL ANSWERPullTestingBro 9/8/03 5:20 PM Page 1 PULL TESTING, THE FINAL ANSWER2critical questions are usually the following:1.

4 Are there any specific pull test requirementsin the contract or customer process docu-mentation?If the harness is being made for anautomotive or aerospace application, it is likelythat pull test requirements are called-out in thecontract or referenced process for industrial and appliance applica-tions are also candidates for the contract/process pull test Are there any industry specifications thatapply to the inspection and acceptancetesting of this harness (or the equipment towhich it applies)?In most commercial and automotive applications the UL486 AStandard will apply. In aircraft/aerospaceapplications the terminal specification (SAE/AS7928), the contact specification (MIL-C-39029), or NASA STD What are the manufacturers recommen-dations?Usually the manufacturer of the con-nector, contact, terminal, wire or terminatingequipment will not specify the level of inspec-tion and pull test requirements in their literature,but if you are looking for guidance, don t over-look this valuable What is my experience with this particular(or this type of) wire termination?

5 Is the wiretermination user-friendly? Is the terminationequipment reliable, or does it have user adjust-ments that must be maintained? Have I previ-ously had failures on this termination?5. Will acquiring test data on this terminationimprove my quality program?The reasonsome tests are performed is to gather uniformdata that may (or may not) be useful How critical is the end use of this wireharness?Another judgement call. If it will beused in an engine harness, a higher level ofquality assurance is needed. If it connects anengine to an electronic tester, maybe that isn tas What is the cost of testing, verses the costof making a mistake?The highest possiblecost to your company is reworking harnessesthat have been returned (or rejected in-house).The most valuable asset that your companyhas is the relationship and reputation with itscustomers. A sensible pull test inspection pro-gram can be the difference between a good ora bad experience when it comes to designing,building, and supporting the wire harness pro-duction operations in your company.

6 Somecontact samples are expensive, and of courseyour employees time is valuable, but it s allcheap compared to rework and BEST RULE TO FOLLOWis: start out witha high sample test frequency plan, and back off asyour experience allows. By that we mean, If you pulltest two samples from a crimp press every fourhours, and you maintain this schedule for sixmonths without a failure, then you can look atreducing the test to once a day, and follow that forsix WITH SPECIFICATIONS ANDSTANDARDS begins with understanding theprocess. Applying a controlled longitudinal force toa terminated wire sample, and measuring the hold-ing strength of the termination device is the mostsimplistic definition of tensile testing as it relates tothe wire harness industry. Beyond this simpledefinition, there are other factors that are required inorder to comply with the various standards. UL486A Wire Connectors and Soldering Lugsfor use with Copper Conductors(UnderwritersLaboratory, Inc.)

7 Is required or referenced in many commercial and automotive with the Pullout Test requirementsspecified in Section 12 of this document requiresthat the minimum pullout force be maintained for 1minute. There are two ways to maintain a continu-ous force on a test sample. One way is to attach oneend of the sample to a stationary point, and theother end to a certified weight of the preciserequired value. Further into this article we define theshortcomings of using individual weights for pulltesting wire samples (look that up if you are consid-ering the use of individual weights). The other way is to use a motorized pull testerequipped with a continuous force hold option. Thismethod is more versatile, practical, and safer foryour employees. A tester with the continuous forcehold option is equipped with a method of presettingthe test force, and the motor controller will jog themotor during the test to maintain the continuousforce for the duration of the test.

8 As the test sampleis being stressed, it will relax and stretch. The motor jog pulses will restore and maintain therequired force for the specified test duration. Thisrequirement cannot be met with a non-motorizedmanual :Some process documents and contractsrequire UL486A pullout test minimum values .Generally, this is interpreted as a requirement tomeet the value specified in the table, but not neces-sarily for the one minute time duration. This extendsthe option to use a manual or motorized tester forcompliance with minimum test values only. Evenwhen production lots are tested for either minimumvalue or full breaking strength, it is good to have thecapability in-house to do the one minute continuousforce test periodically. If you are presently usingUL486A as a test standard, be sure the one minutecontinuous force requirement does or does notapply to your SPECIFICATIONS aremostly based on the test procedure that is called outin EIA TP-08B CRIMP TENSILE STRENGTH TESTPROCEDURE FOR ELECTRICAL test procedure replaces MIL-STD-1344,PullTestingBro 9/8/03 5:20 PM Page 2 PULL TESTING, THE FINAL ANSWER3 METHOD Tensile strength testing in accor-dance with this document requires a motorized pulltester (not weights) that is capable of moving at arate of 1 inch (plus or minus 1/4 inch) per minute,and gripping jaws that hold each end of the sample,without distorting the crimp following specifications are generallyreferenced for minimum test values.

9 CONTACTS Mil-C-39029 (AS39029 pending release), TERMI-NALS AS7928 (replaces MIL-T-7928), CRIMPTOOLS MIL-DTL-22520, and SPACE APPLICA-TIONS Charts showing acomparison between the UL486A tensile values and the corresponding values of AS7928 terminalspecification is included for your reference. Alsoincluded in this article are the charts that appear in MIL-C-39029, MIL-DTL-22520, and :The aircraft/aerospace tensile test valuesare somewhat higher due to the high performancedesign of the tools, contacts/terminals, conductors,and 9000 QUALITY SYSTEM COMPLIANCE isbased either on your quality assurance manualrequirement, or your customer s if a higher than normal level of pull testingis required, it will be stipulated as a contract or pur-chase order line item. NON-DESTRUCTIVE PULL TESTINGas a partof ISO9000 compliance is discussed frequently, andthere sometimes is a misconception that as muchas 100% of production wire assemblies should bepull tested using a fraction of the minimum pull testvalue that would apply to a destructive test.

10 This isnot a recommended practice, and should be dis-couraged. Any pull force that is exerted on a wiretermination will take service life from the harness,and the danger of physical damage to the terminalplating or wire insulation is not worth the small ben-efit (if any at all) of doing the TESTINGis the only type of pulltesting that should be relied upon to determine thenecessity to adjust or replace termination equip-ment, or to select another method of tests should be either to the minimum pullstrength from the table in the controlling specifica-tion/process document, or to separation. Whentesting to separation, the description of the type ofseparation should be included in the test , the types of separation are defined in thechart below that was copied from CRITERIAmay change from oneapplication or industry to another. Usually the onlypass/fail requirement is that the actual tensile valuemust exceed the minimum specified value for thatparticular wire size and contact size before thesample breaks or the test is stopped.