From  A Custom Wire Harness Manufacturer

As a custom wire harness manufacturer, C-T Wire Prep meets with many individuals each year who are usually employed as purchasing agents or buyers for various OEM’s. Many of these individuals have a limited knowledge scope of the basics about what they are attempting to purchase or find — a regular, repeatable supplier for their custom wire harness or custom cable assemblies. This informative article was put together for the sole purpose of helping out these individuals in their task.

So there you are in your purchasing role tasked to find a decent manufacturer who can supply you with custom wiring harnesses or cable assemblies. The reasons why you are searching could be many. From quality issues, cost reduction, or maybe a new product is coming on board and this is all new to you. Just keep on reading and we’ll get you up to speed on what you should look for in a supplier and the questions to ask potential candidates.

Prepare to search:

One of the very common things I notice when a purchasing agent contacts C-T Wire Prep Inc. is that the necessary drawings/documentation required to be able to quote a custom harness are either outdated, incomplete or non-existent. This can slow down the quotation process due to so many small but necessary questions that must be answered. Now as long as you are not in a hurry this may not be a huge problem. As an electrical engineer, I am able to visit your factory and see what requirements you may have and even build up a first off prototype. This is usually done for spec’ing brand new products. For existing products, drawings should be established and up to date.

Check with your engineering department to make sure you have what is needed. For larger companies this will likely mean well drawn fairly complicated renderings that look like Greek to an average purchasing agent. For smaller organisations I’ve seen hand drawn renderings that work just find. This is usually because there is no engineering department and the purchaser is likely the owner of the company. A true example of one of our present customers is a utility trailer manufacturer. The company is owned by a pair of partners and they build about 4 or 5 hundred trailers per year out of a 10,000 sq ft. factory. One partner is the purchaser and looks after the office area for the most part, while the other partner looks after the production side of things. When I initially met with these fellows they simply handed me a harness and said “please quote this”. As long as the harness isn’t too complicated that is a simple and typical way it happens many times. At C-T we usually do create a drawing for our own internal use and build a first off custom wire harness from the original one supplied. We get it approved and keep it at our factory for reference each time we do a build.

So to summarize, if you do have drawings be prepared and get them because that is one of the first questions you will be asked. If you don’t, a working sample is the next best thing. The absolute best is both drawings and sample if possible.

Understanding wire processing and building of a custom wire harness or cable assembly.

A basic understanding of just how a manufacturer builds the harness or cable you need is something that helps you as a purchaser, so we will delve into the terms that wire harness guys throw around. We will also explain good manufacturing techniques that should be employed by all decent wire harness manufacturers.

First term that I get asked that seems to confuse purchasers is “What’s the difference between a custom wire harness and a custom cable assembly?” Well not much really other than the wire harness usually has several breakouts while a cable assembly is kind of like an extension cord you’d buy at your local hardware store. Cable assemblies usually just have two ends or breakouts to plug into. So look at your requirements and decide what to call it based on the above definition.

No matter which type of harness or cable you are seeking both will require at the least blunt cutting to length a cable or wire. Usually there is more to it and likely stripping of wire or jackets of cables as well as stripping internal wire conductors inside a cable is necessary to prepare the assembly for the crimping of terminals onto the stripped ends of the wires.

Cutting Stripping, crimping Requirements:

Depending on how many harnesses or cables you require, the method of cutting/stripping could vary. Tools such as hand plier’s side cutters might be used for low volumes or higher volumes usually employ a wire processing machine of some type. Typical names you will hear thrown around are Artos, Amp/Tyco, Eubanks, Schleuniger, komax, carpenter, megomat, as well as many others but those ones are the main machines used by most reputable wire harness manufacturing companies.

But just because they have good machines doesn’t necessarily mean they create quality. A good quality plan should be in place to prevent mistakes from happening.   Checks and double checks should be set up throughout the manufacturing sequence to ensure quality.

I’ll go through the checks we do at C-T that we use on our shop traveller sheet which follows the work through our production process. Each step an operator signs for the process they set up and or processed

1. Our operators set up a machine for length of cut, they sign our shop traveller. Before the operator can go ahead with the cut, he or she must have the set up double checked and signed off on the shop traveller as well.
2. On the shop traveller there are check boxes to check for correct wire being used, length of cut, stripped ends specified and their length. As well a few wires get cut and checked that the machine set up is not nicking out any copper strands. This is very important for ensuring your wire harness can handle the current it was designed to do. I can’t stress enough that a good quality plan will have a check and double check to guarantee the copper strands are all there and not damaged
3. If there are any contacts or crimp terminals to be put on the shop traveller specifies which ones and on what end they are required. Also there is yet another sign off spot for any presses needing to be set up to do the crimping as well as an operator showing who actually did the crimping. A set up operator doesn’t necessarily do the crimping but must ensure the press is properly set up with the correct crimping die. This is confirmed by doing a destructive pull test.Again I can’t stress enough the importance of doing a pull test. Many wire processors will state they do a measurement of the crimp height rather than pull test. This is not good if you want quality. Pull testing a crimped wire is the only true measure of a good crimp.
4. The pull test results are collected as data on the shop traveller to create a traceable history.
5. If there is more processing to be done such as taking this wire that has been cut, stripped, and crimped and grouping it with other wires to build a custom wire harness, and this is where the drawings come into play. The drawings usually get put together with a kit bin of parts needed to build the entire product. Wires get processed each having their own shop traveller identifying them as to what they are part of. They get put into the kit bin. The drawing is referenced to identify the harness and a production procedure is developed to build the harness. If it is a complicated harness with many breakouts (connectors) there will usually be a harness build board developed to build the harness on as well as test it to make sure all connections are correct. A cable assembly may not need a build board but certainly must be put through a test to ensure all connections are correct and in place. Again I can’t stress enough this test must be done. Any company that suggests otherwise is not worth your efforts. They may come in with a lower price but I guarantee you will have issues with quality.
6. The first harness built should be checked over for correct build including ties placed properly and all connectors properly housed.Other considerationsFinally one of the things sometimes overlooked by purchasers is just how the harness or cable assembly will arrive at your factory. Harnesses can quickly turn into a rats nest with breakouts all tangled creating lost time for your employee’s. Harnesses should be separately packed in plastic bags and if appropriate bulk packed in boxes depending on their size. Another consideration that should be addressed if you have more than one type of custom harness assembly or custom cable assembly is identification. Imagine having a pile of boxes that wind up opened up and 3 or 4 generations or types of harnesses all mixed up.
7. Summarizing this article (what a purchasing agent should look for in choosing a custom wire harness company.
8. Best to have some type of part number and revision level marked on the harness. Alternately at least a part number and rev level on the plastic bag that separates them.

Summary

1. Make sure whoever you deal with addresses the checks and double checks. Have them show you a typical shop traveller sheet to verify.
2. Make sure they utilize pull tests for every set up to guarantee a proper crimp. All crimps should be visually inspected before being inserted into the connectors.
3. Make sure that all harnesses or cable assemblies are tested for correct placement and that they conduct properly. This is usually done with a harness test device.
4. Of course there are many other aspects of quality to check out for various suppliers such as workmanship and having a good quality system in place. Concerning the wire processing industry the 3 main criteria have been addressed here in this article.

I hope you’ve found this article informative and useful to your needs with choosing a quality custom wiring harness supplier.

If you have any questions or want to check out C-T for your needs feel free to call or email us using the contact form above.

Thomas Collins Eng. Dept. C-T Wire Prep Inc.