Crimp Pull Tester Calibration

Developed to replace the need to solder terminations, crimping technology provides a high-quality connection between a terminal and a wire at a relatively low applied cost. Crimp pull testers are devices used to determine the mechanical strength of a crimp termination. Pull testing is done with a Tester device that clamps the wire, pulls at a set speed, and measures force using a load cell. A pull tester also can be as simple as hanging fixed weights on the wire for a minimum of one minute.

 

Crimp Pull Testers – Types:

Tensile strength of materials is measured with universal testing machines (UTM), compared with the standard force and elongation data. Following are the two types of Crimp Pull Testers are used as industry standards:

1. Manual crimp pull testers: As the name suggests, manual testers involve manual cable pulling at a constant pull speed and recording the force and elongation values. Due to the operation complexity, manual testers are suitable to only a limited extent as long as the operator can hardly keep a constant pull-speed with increasing force. Hence, manual testers are recommended for quick and easy check of tensile strength only.
2. Motorized Pull testers: Due to disadvantages associated with Manual pull testers, Motorized benchtop pull testers were invented and can be used to measure the tensile strength of crimped connections as well as welded wire-to-wire connections. These pave the way for more comprehensive testing and type approval.

 

Motorized Crimp Pull Test – Operational Procedure:

Motorized Tensile Wire Crimp Pull Testers are used to test a crimp contact’s or terminal’s tensile strength, according to UL, ISO, SAE, MIL, and ASTM tensile test requirements. The testers typically have the range of 2.5 lbf to 250 lbf and include digital data logging capability for exporting test data to a PC via USB or RS-232 protocols. Following is the step-wise procedure to be followed for a Crimp pull test.

 

1. Cut wire length 6 inches (152 mm) long and strip one end to 1/2 inch (13 mm) or long enough, so no wire insulation is under the insulation grip, or loosen the insulation crimp so it has no hold on the insulation of the wire.
2. Terminate the appropriate terminal to the wire to the nominal crimp height. Visually inspect the termination for bellmouth, wire brush, and cut strands.
3. Set the Crimp pull tester to 2″ per minute (50 mm/min). If necessary, knot the UN-terminated end of the wire (If insulation slips on the wire).
4. Regardless of pull tester type, both wire and terminated end must be securely clamped and activate the pull test.
5. Record pull force readings. A minimum of 5 pull force measurements should be done to confirm each set-up. A minimum of 25 readings should be taken for capability.
6. Compare the lowest reading to minimum pull force specification.

 

Applicable Standards for Crimp Pull Testers:

The standards lay out procedures to determine the pull-out force of terminal and wire connections, although specific standards do not specify to capture the elongation. The following are standard procedures followed while performing Crimp pull tests:

1. SAE/USCAR-21: Performance Specification for Cable-to-Terminal Electrical Crimps USCAR21. This specification defines basic test methods and requirements for solder-less crimped connections.
2. VW-60330: Volkswagen Crimp Connections, stating the procedures to be followed for Solderless Electrical Connections
3. BS EN 60352-2:2006+A1:2013: Solderless connections – Crimped connections. General requirements, test methods, and practical guidance.

 

Crimp Pull Tester Calibration and Maintenance – Why is it essential:

All electrical equipment needs to be calibrated to ensure that the performance is restored to design standards. For Crimp Pull Testers following the OEM Standards, calibration is done every 12 months from the date of first use. This is further reduced based on the frequency of operations to ensure functions are error-free. The following procedure should be used while periodically calibrating the crimp pull testers using the calibration kit:

 

1. The calibration kit should be placed on a bench sturdy enough to withstand a weight of 200lbs.
2. Affix the calibration kit to the bench using screws and fasteners.
3. Remove the wire terminal turret grip using the socket head screw.
4. Mount the Crimp pull tester and faster using the screws.
5. Attach the calibration cage and tighten using screws.
6. Hang certified dead weights from the hook on the opposite end of the cage, and calibrate the tester at five or more even increments, such as 40, 80, 120, 160, and 200lb loads.

 

Though usage of Crimp pull testers seems straightforward, the equipment needs to be calibrated and maintained following OEM operation guidelines. To comply with international standards, an annual calibration process should support the repeatability and accuracy of crimp pull testers.

Calibration of Crimp pull testers also determines the offset values and the deviation from the actual reading. These readings are used as correction factors and evaluate if the crimp tester is fit for use.

 

e2b calibration offers industry-leading ISO-certified crimp pull tester calibration services. Our labs are ISO/IEC 17025 accredited and operated by a team of qualified calibration experts to test and calibrate your pull testers. Our verifiable services are unmatched in the industry. We are registered with ANAB. We are also ANSI/NCSL Z540-1-1994 certified. We have the NIST Traceable Wide scope of ISO/IEC 17025 accreditation. Contact e2b calibration for all your equipment calibration needs.