Pulltester / Measuring tensile strength of crimped terminals with pulltester

Pull Tester

In the wire and harness manufacturing for the electrical & electronic industry, the reliability of each electrical connection determines the life span and quality of the final product. For testing the tensile strength of crimped, welded or soldered terminals we offer special instruments for standarized pull test.

Industrial Application

A wire and harness manufacturer with customers in the field of automotive industry, space and aircraft industries or medical devices need state of the art manufacturing and testing equipment as well as reliable testing methods to become an approved supplier. The most important mechanical testing is the measurment of tensile strenght of the terminal connection, most commonly called pull testing or wire terminal testing.

 

Definition Pull-Out Force

Acceptance criteria for tensile strength (Pull-out Force)

The acceptance criteria for tensile strength (in some standards also called pull-out force) are depending on the conductor size and the applied industry standard for the final product. If there are no product specific standards available IEC 60352-2 can be apply or for UL-listed products UL 486 C. Both standards require testing until the rupture of the connetor. For automobil industry tensile strength or pull-out force  is mostly specified according SAE-USCAR-21 or manufacturer standards such as VW-60330.  Space and aircraft industries have the own (higher) requirements stated in NASA-STD-8739-4.

Auszugskraft - Diagramm mit normabhängigen Grenzwerte der Zugfestigkeit

 

Our PC-software FMT-W_Connect for data transfer and test protocols for all Alluris pull tester include the acceptance critera of several standards for limit settings.

 

Reference pull speed

Usually tensile tests are performed with universal material testing machines, with force and elongation as measuring data. Non of the related standards for pull out tests of conductor terminals require the elongation of the specimen as test result. Therefore (motorized) benchtop pull tester are used to capture the tensile strength of terminals or welded wire-to-wire connections commonly.  

 

Pull test with highest accuracy

A Load-cell of highest quality designed for the specific requirements in force measurement is used in each Alluris force gauge. Therefore the load cells are made in-house to assure the fine tuning between the sensor and the amplifier electronics to reach highest accuracy of the measuring instrument. The entire design considers the perfect positioning of the force sensor in the center-line of applied force. This is to achive a minimum of torque influence and force vectoring which have negative impact on the measuring reproducibility and overall accuracy.

Most important for a high reproducibility is a constant pull speed at increasing force as stated in all a.m. standards. This pullspeed can realted to the specific standard be setted from 25mm/min to 250mm/min. Therefore our motorized pull testers are equipped with a strong stepper motor.

Auszugskraft - Zuggeschwindigkeit bei Prüfen der Abzugskraft nach unterschiedlichen Normen

As the pull speed may vary due to the limited control capabilities of an operator with manually operated pull-testers, those instruments are limited to  non-conform tests related to the strict standards. Therefore we recommend manual wire terminal tester for quick check of machine or crimp tool settings only. For approval testing of crimped conductor terminals, motorized pull-tester with selectable constant pull-speed are strongly recommended.

 

Data Interface

The Alluris pulltester are equiped with USB 2.0 - Interface and 10-pin I/O - Interface. These two interfaces serve devices for OK / NOG indication, or combined with a foot-switch and approbiate software they are used to transfer data straight into any PC application, such as CAQ, SAP, Oracle, SAGE or automated crimp presses. The USB 2.0 interface also transfers data to MSExcel.

With the related software (AddIn for MSExcel) the captured measuring results can easily be organized and within minutes a comprehensive report can be generated as PDF. All relevant test settings according the a.m. international standards are stored in the software and can be used for setting of force limits at the pull tester accordingly.

 

Measuring range and calibration

Range and terminal adapters

The measuring range of 0...500N and 0...1000N (for conductor size up to 10mm² / AWG 8) as well as the ergonomic design based on a heavy duty hardened steel plate are layed out for slipfree table top use. The test specimen (terminals) are hold in a interchangable terminal adapter with 12 different slot width from 0,5...6,0 mm to cover standard wire diameters. Alternative adapters can be found as accessories on the related product pages of the wire terminal tester.

Calibration and tracability

Pull testers should be, as all force gauges recalibrated after 12 month latest. As manufacturer of force and torque measurement devices we operate an accredited calibration laboratory with highest quality and traceability to the standard of the german national metrology institute PTB (Physikalisch-Technische Bundesanstalt).

As the only ISO 17025:2005 accredited calibration laboratory in the world, we have a force reference standard measuring device (K-BNME) to calibrate pulltesters in horizontal position, applying DAkkS validated procedures. The calibration certificates therefore fulfill the high requirements of the IATF 16949:2016.

 

Applicable Standards

BS EN IEC 60352-2 Solderless connections. Crimped connections. General requirements, test methods and practical guidance (to obtain from: BSI Shop)

SAE-USCAR-21 Performance Specification for Cable-to-Terminal Electrical Crimps (to obtain from: SAE International)

VW-60330 Crimpverbindungen (to obtain free of charge from: Volkswagen AG - B2B Lieferantenportal)

NASA-STD-8739-4 Crimping, Interconnecting Cables, Harnesses and Wiring (to obtain free of charge from: NASA Technical Standard)

UL 486 C Splicing wiring connectors (to obtain from: UL Standards)

 

 


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