Part of the engineering phase of creating assembly processes in custom wire harness manufacturing involves pre-planning every detail and intricacy of a wire harness.
One of the core business avenues as a service based company in the wire industry is helping CSA & UL certified panel shops mass produce a standardized wire harness for the internal wiring of their product. Often, companies grow a product line from producing single custom-made units that are hand wired at the facility to the point of ramping up production to hundreds and even thousands of a single type of harness.
Although most contracts flowing through these channels are one-offs or small custom runs with differing designs, once a product is known well enough and starts selling in the market, there is an opportunity for creators to save on cost, produce faster, and enhance the quality of the wiring aspects of the product by having an OEM supplier who specializes in wire help manufacture the product.
In order to replicate the same harness repeatedly for clients, jigs & fixtures are created to mimic the real machine. As part of the design, various temporary holding devices are used to secure wires in their specific patterns so they can have a finish applied to them.
Clamps
The main tool we use on fixtures to route and secure wires are specialized clamps in different sizes depending on location and use (seen in figure 2). The assembler pushes wires through the clamp arms to hold them before using a more permanent securing technology to finish the harness. When a harness assembly process is designed, clamps are meticulously placed onto jigs with purpose to maintain critical section lengths, fittings, curves, shapes, any feature a client might need in their final design.
Larger clamps are sometimes needed when cross sections of harness reach the 1″ + mark. Alternative style clamps help to hold large harnesses as they are built.
Permanent Solutions
Once a harness is mocked up on a fixture/jig & tested for quality, a finish must be applied to the harness in order to:
a) remove it from the jig, and
b) keep the harness in the same shape for application into their product.
Below we will look at common solutions used standardly in the wire industry.
Zip Ties
Not all ties are created equal!
Did you know? There are many manufacturers of zip ties both certified by regulatory bodies & uncertified.
We believe, using a certified tie solution is far superior to others. Because zip ties are used for many binding actions in different industries, a high quality tie with performance characteristics might not be needed to for example: cable management for computers.
In the commercial certified wire industry, zip ties are used to confine wires within a harness or sleeving solution. they can also be used to secure down a wire harness to a panel box surface using zip tie mounting bases.
When selecting a zip tie for certified products, it is important to understand 3 factors of a zip tie:
- The Locking Tab
- Cross Section
- Grip
Locking Tab: There are many styles of locking tab from molded tabs to insertable metal clips. Often the overall holding strength is affected by the quality of this tab. Higher quality certified ties are more pliable and tend to hold the tensile weight of a tie more accurately.
Cross Section: Consider the amount of wire diameter you need to encompass. There are standard widths for ties from 2.5mm to 12mm with binding strength ratings for each. Certified ties meet this minimum holding spec whereas sometimes cheaper ties do not. Another fact most users do not know is, there are different innovations made to this cross section that enhances its abilities on higher quality ties. This feature of the tie is meant to stretch slightly when tightened to create an “elastic” forcing effect to the wire bundle.
Grip: Every tie has some sort of gripping teeth that bite onto the wire insulation surfaces being bound. The difference between a certified tie and a non-certified tie often lies in the design of this feature. Cheaper ties primarily design the teeth shape to lock to the holding tab at the end of the tie. Some certified zip tie brands take it a step further and engineer these teeth also for the holding performance of the wire bundle creating a tie that when properly applied, will not twist around a bundle of wires.
** ZIP TIES ARE MADE OF NYLON AND are HYGROSCOPIC. Click Here to read our article about the importance of this
Split Loom
A commonly used product to aesthetically finish a commercial wire harness is split loom. It is a bendable slinky-like sleeve usually made of semi-rigid plastics to cover a wire harness. It standardly comes with a slit down the side of the diameter for easy application. Split loom can also be purchase without the slit for applications requiring a sealed connection.
Many different diameters are available for covering multiple sizes of wire, as well as specialized pieces for creating breakouts from the loom.
Most sleevings require a way to secure them in place along the harness. Although we use zip ties internally to clamp wires together, it does not provide the most pleasing finish to a wire harness. In this case, to finish split loom, electrical tape cut to length is wrapped in a thin profile around its circumference at a prescribed interval to close off the loom and keep it around the harness.
On harness ends where split loom ends, electrical tape or glued heatshrink is used to secure the loom tip to the harness as shown in figure 6.
Usually split loom is used as a finish when the harness does not move from its installed position.
Spiral Wrap
A more industrial sleeving solution which can help protect a wire harness from physical cuts, mars and other abuses is spiral wrap sleeving. It is a semi-rigid plastic wrap with small spacing between its folds to allow for bending and movement of a wire harness. It is especially useful in control panel designs to allow a wiring harness to cross the hinging gap where the lid of the box attaches to the main box body.
Application of this type of sleeving is usually faster than looming or tying.
Spiral wrap has a stronger cross section permeability than split-loom for protecting the harness when it needs to move.
Cable Clamps
Another aspect of wire harness securing is box clamps. When a harness needs to go through a hole in a panel, box clamps are used to keep it safe from cuts and scrapes. Certified clamps are rated for securing weight as well as tolerance specs and material performances.
These parts are also HYGROSCOPIC! read about this here
We hope this article has been educational and informative!