Heat Shrink Tubing Processing Machine - KINGSING

  1. Home page
  2. Services
  3. Industry News

Terminal Crimping Force Standard - Kingsing Machinery Co., Limited

2022-10-13 14:27:02 美工

The quality of a crimp joint depends on the strength of the joint as well as its electrical conductivity. Crimp joint testing ensures the integrity of the final product but, more importantly, it ensures the effectiveness of the crimping tool itself, since it can be calibrated according to test results. Calibration is best carried out in response to Statistical Process Control (SPC) data which can be gathered as joint integrity degenerates over a period of time.

Pull Force Testing

  1. Cut wire length to approximately 150mm (6") long.

  2. Strip one end to 13mm (.50"), or long enough so no wire insulation is under the insulation grip, or loosen the insulation crimp so it has no grip on the insulation of the wire.

  3. Terminate the appropriate terminal to the wire to the nominal crimp height.

  4. Visually inspect the termination for bell mouth, wire brush and cut strands.

  5. Set pull tester to 254mm per minute (1.00" per minute). For most applications, a higher rate will not have a significant impact on the data. The slower rate prevents a sudden application of force or jerking that snaps strands. Verify higher pull rates with data taken at 1.00” per minute.

  6. If necessary, knot the un-terminated end of the wire (If insulation slips on wire).

  7. Regardless of pull tester type, both wire and terminated end must be securely clamped. (Note: Clamp terminal contact interface, do not clamp conductor crimp)

  8. Activate pull test.

    Note: High variability and lower value of Cpk (see section 8 for explanation of Cpk) are common when two wires are crimped together. The variability is due to more variation in conductor brush, conductor bell mouth and fewer strands of one wire being in contact with the serrations on the terminal barrel. A double wire crimp is considered no better than the smallest wire crimped. Higher pull force readings can be seen if both wires are gripped and pulled exactly together. Pulling each wire individually will result in a much lower pull force reading. If both wires are of the same size, the top wire will normally result in a lower reading than the bottom wire due to the effects of the terminal serrations.

    1. a. Record pull force readings. A minimum of five pull force measurements should be done to confirm each set-up. A minimum of 25 readings should be taken for determining process capability.

    2. b. Compare lowest reading to minimum pull force specification.

Wire Chart

Note: Pull force has only a minimum specification. For Cpk calculations, the average reading is assumed nominal and the upper specification limit is set so Cp and Cpk are equal. High pull force readings that increase the standard deviation can lower Cpk even if the mean and lowest reading are increased.

Test Values for Pull Force Test (UL486A)
Size of ConductorPullout Force
AWGmm2LbfN
300.051.56.7
280.0828.9
260.13313.4
240.20522.3
220.324835.6
200.5191357.9
180.8232089.0
161.3130133.5
142.0850222.6
123.3170311.5
105.26180356.0
88.36790400.5

Crimp Height Testing

  1. Complete tool set-up procedure.

  2. Crimp a minimum of five samples.

  3. Place the flat blade of the crimp micrometer across the center of the dual radii of the conductor crimp. Do not take the measurement near the conductor bell mouth.

  4. Rotate the micrometer dial until the point contacts the bottom radial surface. If using a caliper, be certain not to measure the extrusion points of the crimp.

  5. Record crimp height readings. A minimum of five crimp height readings is necessary to confirm each set-up. A minimum of 25 readings is necessary to determine capability.

  6. Check crimp height every 250 to 500 parts throughout the run.

Note: Crimp height is usually control charted because it is a quick, nondestructive measurement and is critical for the termination's electrical and mechanical reliability. There are three primary purposes for control charting. One, the number of setup samples is normally small, and its statistical value is limited. Two, since special cause/effects on a process are irregular and unpredictable; it is necessary to have a means of catching changes in the process as soon as they occur. This prevents having to scrap thousands of terminations after the run is over. Three and this is most important, the data is necessary to assess and improve the crimp process.

KINGSUN

Bell Mouth and Cut-off Tab Length

SymptomCauseSolution
Low pull force
(Figure 9-6 and 9-7)
Excessive bell mouth, no cut-off tabAdjust track position for small cut-off tab
Excessive bell mouth, cut-off tab alrightCheck for worn or incorrect punch tooling and replace
Cut or nicked strands
(Figure 9-8)
No bell mouth and/or excessive cut-off tabAdjust track position
Check for camber in terminal strip
Long cut-off tab
(Figure 9-9)
Good bell mouth and excessive cut-off tabCheck for worn cut-off and replace if necessary
Check for worn punch tooling, replace, and re-adjust track

KINGSUN

Conductor Brush and Insulation Position

SymptomCauseSolution
Insulation under conductor crimp,
good conductor brush (Figure 9-10)
Strip length too shortCheck specification, adjust strip length longer
Insulation under conductor crimp,
long of transition area conductor brush length (Figure 9-11)
Bench top crimping - Wire stop position incorrectAdjust wire stop to centerof transition area
Wire Processing – Press position incorrectAdjust press position away from wire
Insulation under conductor crimp,
short or no conductor brush (Figure 9-12)
Strip length too shortCheck specification, adjust strip length longer
Re-adjust wire stop position for bench top applications OR re-adjust press position for wire processing applications
Insulation edge centered in transition area,
conductor brush too long (Figure 9-13)
Strip length too longCheck specification, adjust strip length shorter
Re-adjust wire stop position for bench top applications OR re-adjust press position for wire processing applications
Irregular wire cut-off or strands pulled from insulation bundleCheck for worn stripping tooling
Insulation edge centered in transition area,
conductor brush too short (Figure 9-14)
Strip length too shortCheck specification, adjust strip length longer
Re-adjust wire stop position for bench top applications OR re-adjust press position for wire processing applications
Insulation edge under insulation crimp,
Good or long conductor brush (Figure 9-15)
Strip length too longCheck specification, adjust strip length shorter
Re-adjust wire stop position for bench top applications OR re-adjust press position for wire processing applications
Insulation edge under insulation crimp,
short or no conductor brush (Figure 9-16)
Bench top crimping - Wire stop position incorrectAdjust wire stop to center of transition area
Wire processing - Press position incorrectAdjust press position away from wire
Verify operators wire placement abilityOperator training, reduce crimping rate

KINGSUN

Insulation Crimp

SymptomCauseSolution
Terminal surrounds less than 88% of a large diameter wire (Figure 9-21)Crimp too loose, not enough terminal insulation barrelTighten insulationcrimp height
Evaluate terminal
Terminal contacts less than 50% of a small diameter wire (Figure 9-22)Too much terminal insulation barrelEvaluate terminal
Insulation crimp barrels cut through insulation in o conductor strands (Figure 9-23)Crimp too tightAdjust insulation crimp height
Insulation not firmly gripping insulation, fails bend test (Figure 9-24)Crimp too looseAdjust insulation crimp height tighter

Inexpensive hand tools provide no adjustment for the insulation crimp. A hand tool is intended for low volume applications. Although you are not able to adjust the insulation crimp on a hand tool, an insulation crimp, which pierces the insulation, may still be considered acceptable for many applications. This criterion only applies to hand tools due to their low speed crimp cycle. If the insulation crimp pierces the insulation, the wire strands tend to move aside without damage.

KINGSUN

Crimp Height

SymptomCauseSolution
Crimp height off target
(Figure 9-26)
Changed wire type vendor or strandingAdjust toolingback to target
Changed insulation color or durometer
Changed crimp tooling
Changed crimp press (shut height)
Changed press type (manufacturer)
Changed terminal reel (lot code)
Changed tooling set-up
Damaged or worn toolingReplace tooling
Crimp height variability too high
(Figure 9-27)
Wire variabilityInspect incoming product
Terminal variability
Damaged, loose or worn toolingTooling replacement or tightening
Measurement errorGauge capability analysis
Terminal spring-back too great, over crimpingCrimp height adjustment
Cut or missing wire strandsStripping process adjustment

KINGSUN

Pull Force

SymptomCauseSolution
Wire breaks before conductor
crimp - low pull force
(Figure 9-29)
Cut or nicked strandsCheck the stripping process
Crimp height too lowAdjust crimp height
Small or no bell mouthAdjust tooling track
Insulation crimp through insulation wallRaise insulation crimp height
Wire pulls out of conductor
grip - low pull force
(Figure 9-29)
Crimp height too highAdjust crimp height
Small or no conductor brushIncrease strip length
Conductor bell mouth too bigAdjust tooling track
Gold terminal applicationEvaluate the terminal application
Terminal material thickness too small
Light serrations on terminalContact your local sales engineer

KINGSUN