07 22 Crimp Termination Technology Guide for Harness Manufacturers📖

Posted at 07:41h in Digital column by 희정 최

Crimp Termination Technology Guide for Harness Manufacturers

Crimping Termination

It is one of the most reliable wiring techniques, creating an electrical connection by joining wires and terminals through mechanical crimping force. It is an essential process used in almost every field involving wiring, including automotive, aerospace, home appliances, and industrial equipment. In this Crimp Termination Technology Guide, we will cover everything in detail, from basic principles and work standards to defect types and inspection methods.

1. Basic Principles of Crimp Termination

Crimping is not merely bending a wire to secure it inside a terminal. The core lies in plastic deformation and the cold welding effect.

When a crimping tool applies strong force to the terminal barrel, the following changes occur:

🟢 Breakdown of Oxide Film :
The microscopic oxide layer on the wire strands and terminal surface is broken down by pressure and friction.

🟢 Elimination of Voids:
The empty spaces between the strands completely disappear, adhering tightly to form a single, solid mass of metal.

🟢 Formation of a Cold-Welded State:
Bonding occurs at the metallic atom level, minimizing electrical resistance while maximizing mechanical strength.

2. Key 4Ms for Proper Crimping

For a successful crimp, the following four elements must be perfectly matched:

✳️ Material (Wire): The specifications, strand count, and insulation thickness must conform to the terminal specifications.

✳️ Machine (Tools & Equipment): Prescribed dies must be used with tools such as hand tools, semi-automatic applicators, or fully automatic crimping machines.

✳️ Method (Work Standards): Strip length, insertion depth, and crimp height standards must be strictly followed.

✳️ Man (Operator Skill): Precise wire alignment and accurate equipment operation skills by the operator are required.

3. Standard Crimping Process

Step 1. Wire Stripping → Step 2. Wire Insertion → Step 3. Crimping Execution

Note:
During the stripping process, ensure that internal wire strands are not nicked, cut, or excessively twisted. In addition, when using dedicated hand tools, crimp completely until the ratchet releases; when using automated equipment, allow it to complete the full single cycle.

4. Crimp Quality Inspection and Defect Types

Detailed inspections are performed to verify crimp quality.

When a properly crimped cross-section is cut and inspected, the wire strands should be densely deformed into a hexagonal or distinct compact shape with zero void space. Additionally, the ends of the terminal barrel must curl inward symmetrically toward the center. The main defect types and their causes can be broadly categorized into three groups: Incorrect Crimp Height, Strand Protrusion (Flared Strands), and Banana Defect (Terminal Bending).

* Incorrect Crimp Height: If the crimp height is too low, strands may be severed or the terminal damaged, leading to reduced tensile strength. Conversely, if the crimp height is too high, voids remain, increasing contact resistance and causing the wire to pull out easily.

* Strand Protrusion (Flared/Uncaptured Strands): A condition where some wire strands fail to enter the barrel and protrude outside. This can cause electrical short circuits.

*Banana Defect (Terminal Bending): A phenomenon where the terminal bends upward or downward like a bow after crimping. This makes it impossible to insert into the connector housing.

Today, a single vehicle we drive contains
approximately 2 to 3 kilometers of wiring and more than 3,000 crimped terminals.

If even a single terminal is improperly crimped, autonomous driving sensors can freeze or the engine can cut out. Compared to flashy industry buzzwords or massive equipment, crimp termination technology is easily overlooked. Yet, what fundamentally supports the systems of vast, cutting-edge industries at their very core is ultimately the solid foundational technology that perfectly secures a single wire to a single terminal.

Crimp Termination Technology Guide for Harness Manufacturers📖