Analysis of Crimping Challenges for DualCore Shielded Wire Harness Terminals
Dualcore shielded cables (such as twistedpair + foil shielding or braided shielding) present higher precision requirements during terminal crimping. The main challenges arise from their complex structure, shielding integrity, twist preservation, and impedance stability.
一. Key Structural Challenges in DualCore Wire Terminal Crimping
1. Twisted pairs easily loosen or shift after stripping
After the jacket is stripped, dualcore twisted pairs often face issues such as:
Twisted conductors spreading apart
Uneven conductor height
Misalignment when entering the terminal window
These cause inconsistent crimp height or weak crimps.
2. Multilayer shielding is difficult to maintain during crimping
Common shielding structures include:
Foil + braid
Multilayer foil
Dense copper braided mesh
Crimping challenges:
Inner conductors may be scratched during shielding removal
Braided mesh is difficult to spread and stabilize
Shielding may tear, shift, or deform
Any damage affects signal integrity.
3. Smaller conductor diameters require extremely tight terminal tolerances
Dualcore signal wires often use:
28 AWG
30 AWG
32 AWG
The crimp window is extremely narrow. Slight misalignment may cause:
Crimp deformation
Terminal cracking
Conductor breakage
This demands highprecision tooling and fixtures.
4. Shielding termination requires independent, stable grounding
Shielding typically needs:
A dedicated shield terminal
Or grounding to the shell
Challenges include:
Consistent shield length control
Stable compression for proper conductivity
Preventing braid breakage or discontinuity
Poor shield grounding may cause EMI issues.
二. Process Challenges: High Accuracy Required During Crimping
1. Very tight crimp height tolerance
Dualcore signal terminals require crimp height tolerances of ±0.02 mm – ±0.05 mm.
Any deviation may lead to impedance instability or poor electrical contact.
2. Twistedpair geometry must remain intact
If the twist angle is not preserved, it can result in:
Increased crosstalk
Reduced signal integrity
Especially critical for:
LVDS
USB
CAN
Highspeed differential pairs
3. Shielding materials differ in hardness, making stripping control difficult
Shield materials include:
Soft foil (easy to tear)
Hard braided copper mesh (easy to cut accidentally)
Challenges lie in selecting the proper:
Blade depth
Stripping speed
Stripping angle
To avoid conductor damage or shield breakage.
三. Equipment Challenges: High Requirements for Precision & Tooling
1. Specialized fixtures needed for dualcore positioning
Fixtures must:
Clamp conductors without damage
Maintain twist geometry
Prevent terminal misalignment
Poor fixture design drastically reduces yield.
2. CFM crimp force monitoring is essential
Because dualcore wires are thin, visual inspection cannot reliably detect defects.
CFM detects:
Weak crimps
Overcrimps
Offcenter crimps
Missing conductor insertion
Greatly improving stability and quality.
3. Highprecision tooling required for micro terminals
Micro terminals require precisionstamped dies with:
High blade accuracy
Smooth, symmetric crimp wings
Zero eccentricity
Any tolerance error leads to severe terminal deformation.
