Observation and Quantitative Evaluation of Wiring Harnesses and Crimped Connectors

The wire and sheath are crimped with respective barrels of the terminal, which uses the barrels' plasticity. The barrels are bent by crimping with a tool or automatic machine on a production line.

Tips:Crimp height, a criterion to determine the crimping quality of terminals
Crimp height is the cross-section height of a core barrel or sheath barrel after crimping. Failure to crimp to a specified height causes defective continuity or displacement of the wire.

Pass/fail examples of crimp height of the sheath
A crimp height larger than the specified height causes the wires to be disengaged when pulled, due to poor crimping. On the other hand, a crimp height smaller than the specified height causes the barrel to dig into the core due to excessive crimping, thereby leading to wire damage.
Crimp height is simply a judgment criterion used to estimate the conditions of the sheath and core wire. In recent years, wiring harnesses have become smaller and have been made of an increased variety of materials. To detect all defects that occur in the crimping process, the conditions of the core wires need to be inspected quantitatively on cross sections of crimp terminals.

A terminal used in this method is connected by squeezing a sheathed wire into a slit. When the wire is pushed into the slit, the blade on the slit strips the sheath to establish a connection.

There are two typical methods: one is solder pot, in which the wire is inserted into a terminal, and the other is eyelet, in which the wire is passed through a hole.

Conventional microscopes do not fully focus on three-dimensional wiring harnesses, which makes complete and comprehensive observations and evaluations difficult.
The VHX Series performs depth-composition to capture fully-focused images of targets that have complex shapes and geometries.

Magnified image of a crimped core wire using the VHX Series 4K Digital Microscope

Conventional warpage measurement requires multiple measuring instruments in addition to microscopes. This inevitably lengthens the measurement processes, requiring more effort and time. Conventional microscopes also require measurements to be taken in a separate software, further decreasing throughput.
The VHX Series 4K Digital Microscope has a wide range of 2D measurement tools, which enables measurements such as wiring harness angle and crimp height of terminal cross sections. The VHX Series allows users to quantify measurements, store and manage measured values, and create reports; dramatically improving work efficiency. Images stored on the VHX Series can be recalled to perform additional measurements at a later date.

Observation with conventional microscopes can be difficult due to reflection from metal surfaces.
With the glare removal function and ring reflection removal function, the VHX Series 4K Digital Microscope removes reflection from glossy metal surfaces, making it possible to accurately observe and understand the crimping conditions of the core wire.

Observation of a crimped core wire using the VHX Series 4K Digital Microscope

In appearance inspection using conventional microscopes, it is difficult to focus on and observe small targets, such as three-dimensional crimped connectors of wiring harnesses.
The motorized revolver and high-resolution HR lens of the VHX Series 4K Digital Microscope enable a seamless zoom function that automatically switches magnification from 20x to 6000x. This enables quick magnified observation with a mouse or handheld controller.

With conventional microscopes, inspection of wiring harnesses requires the target to be fixed at different angles, and the focusing must be readjusted for each angle.
The VHX Series 4K Digital Microscope uses a free-angle observation system and a high-accuracy XYZ motorized stage, thus supporting flexible movements of the head and stage that were conventionally impossible.
3-axis adjustment mechanisms enable easy field-of-view alignment, rotation, and oblique axis motion, allowing users to observe from any angle. Furthermore, eucentric design ensures that the target stays centered in the field of view, even if the lens is tilted or rotated, making visual inspection of three-dimensional targets much more efficient.

Tilted observation of a connector using the VHX Series 4K Digital Microscope

In conventional appearance observation of crimp terminals, it is necessary to focus on each part of a three-dimensional target. Furthermore, such observation cannot eliminate the issues of defects going undetected and variations in evaluation occurring among operators. Moreover, there is no other way to perform evaluations than to use 2D measurements, even for three-dimensional targets.
The VHX Series 4K Digital Microscope not only allows for magnified observation and 2D measurements, but it also capable of capturing 3D shapes and performing 3D profile measurements. 3D shapes can be analyzed and measured with simple operations, regardless of the skill level of the operator, which enables advanced and quantitative appearance evaluation of crimp terminals with higher work efficiency.

3D shape analysis of a crimp terminal using the VHX Series 4K Digital Microscope

The VHX Series 4K Digital Microscope has a wide range of measurement tools, allowing users to perform various automatic measurements on a captured cross section image.
For example, as shown in the following images, the area of the wires can be automatically measured on the cross section of the crimped core wire. This allows users to inspect the conditions of the crimped wires quickly and quantitatively, which cannot be achieved by crimp height measurement and cross-section observation.

Automatic area measurement of a crimped core wire cross section using the VHX Series 4K Digital Microscope