Pillar One: Crimp Elements
The process of crimping a terminal to a wire seems simple enough. Take a connector and a crimp tool and press that terminal around a wire. Do you assume that as long as it is secure on the wire, it is a quality connection?
But is it a Quality Crimped Connection?
This is the first of a four part deep dive into the pillars of a Quality Terminal Crimp. This article will introduce Crimp Elements as the initial pillar.
A crimp is characterized by five elements: Wire, Terminal, Application Tooling, Crimping Press and Operator (or automated processing machine).
The wire construction as well as the processing (cut and strip) quality are critical to crimp quality.
Wire Construction includes the wire OD, Insulation, Concentricity, Strand Count and Internal Wire Twist. Process variables include cut and strip quality, strip length (and strip length repeatability).
The terminal construction (material type and thickness) is important as is the proper wire/terminal match. We will dive deeper into the implications of a mis-matched wire in part 3 of this series.
An applicator is the heart of the mechanical part of the crimp process. Tooling rated for the terminal and wire match, the applicator set up and maintenance are all critical to a repeatable crimp process. A poorly maintained applicator can cause poor crimp results.
The crimp press is subject to thousands if not millions of crimps per year. Like the applicator, the press is subject to wear over time. Wear parts include the base plate and ram adaptors and moving components like the ram and crank shaft.
Keeping the press lubricated and checking for wear should be regularly scheduled. These tasks assure that the press provides repeatable press force and shut height.
Presses should also be calibrated annually. Using a digital press analyzer combines press calibration along with capability studies of press shut height and force. This provides evidence of press repeatability and allows maintenance to prioritize press maintenance.
The operator of the crimp press has a critical role in crimp quality. The operator must inspect the wire to ensure there are no defects in the wire. Then the wire is crimped to the terminal and a visual inspection is needed. Training on machine operation and quality inspection is essential.
In the case of an automated machine, the operator is replaced by robotic arms that must be aligned to assure the wire is presented in the correct orientation (front to back and side to side).
Crimp Quality: The sum capability of all elements.
Crimp Quality depends on all elements being in full statistical control. For example:
- Wire gauge is within rated specification of the terminal.
- Wire is stripped to the specified strip length with no nicks, strands or scrapes.
- Crimp Tooling is properly maintained and correctly set up.
- Crimp Press has been inspected for wear, lubricated, calibrated and capability studies show press shut height and force repeatability is within statistical limits.
- Operators and Maintenance are trained in the set up and operation of crimping equipment.
Pillar One represents the basic elements of crimping, their relationship to one another and the importance of all elements being in control. Crimp Quality Solutions is your source for training, crimp validation services and consulting on crimp quality. Watch for Part Two coming soon.
From WireProcess Specialties, providing solutions for wire harness assembly for over four decades.