How to Qualify and Choose Wire Harness Assembly Contract Manufacturers

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This article will point out key factors to consider when choosing wire harness manufacturers in the distribution and contract manufacturing industry. Being born into the wire and cable manufacturing market by-way-of our family-owned business, over the years I’ve learned what it takes to find a quality vendor that accepts your terms, instead of dictating their own. Your customers depend on your quality products, so it’s important to qualify a vendor that can support your exact needs and desires, on your terms. Be tough, be strong, be confident, be fair, and when you get what you want, be appreciative.

A cable harness is very similar to a wire harness, which can also be interchanged with the terms cable assembly and wiring assembly. They are all comprised of multiple wires or cables to transmit signals from Point A to Point B. They are held together with cable ties, heat shrink tubing, sleeving or a combination of each.

Can You Outsource Wire and Cable Assemblies to Save Money?

Outsourcing is beneficial to companies that not only complete the wire harness assembly processes manually instead of using expensive equipment, but also for those that only have a few machines that run at a third of their full potential, or capacity. Contract manufacturers use one piece of equipment for multiple customers and run the equipment all day, they buy the similar products in higher quantities and they focus on improving production on a daily basis.

Close up photo of wire cutting machine

Therefore, the additional savings obtained by purchasing in bulk and using equipment at full capacity is passed on to you, the customer, currently doing these things by hand. When companies such as General Electric continue to outsource assemblies to wire harness contractors you can trust that it saves them money or they would bring it in house. In fact, even during recessions and depressions over the last 50 years you’ll see that companies continued to outsource rather than buying equipment, hiring employees, creating quality control procedures and setting up production schedules.

Photo of wire harness assembly employee at WesBell Electronics

You’ll have to search for these vendors online which may or may not offer their services with a few clicks of the mouse. Perhaps, if you only need cut wire, twisted pairs or a spiral stripe you’ll be able to find an online retailer. However, as specifications get more complicated it’s important that you qualify this manufacturer before placing a large order for something that might lack your quality standards.

How to Qualify a Wire Harness Manufacturer to Ensure a Successful Contract


In order to save you money you need to find a company that has equipment that you don’t currently have. Outsourcing harnesses that you produce manually to a vendor that will produce them manually won’t save you any money. It might save you a few headaches if you can manage less employees but you’ll want to discuss the type of equipment that will produce products faster and more efficiently than you can currently do manually. Equipment will also provide more consistency of cut lengths and insulation removal which can turn into a marking advertisement to your customers even though you aren’t producing the products yourself.

Assembly worker seting up wire machine.

Delivery Lead Times

How quick do you require, or do your customers require, you to deliver your products? Customers have demands and you need to get an assurance from your new contract manufacturer that they can produce a certain amount of products in a certain amount of time or else the relationship isn’t going to work. There are also plans that can be implemented to be sure you’ll get quick deliveries such as blanket orders, Kan-Ban systems, buffer quantities and consignment inventory that many vendors will entertain for certain customers.

ISO 9001 Quality Standards and Procedures

ISO 9001 is the International Standards Organization which stresses quality and structures a company of any size to continuously improve processes and procedures for all parts of the company. For instance, a quarterly ISO audit of compliance will review all of the documented errors and request documentation as to how you addressed those errors to be sure they won’t happen again. They will ask for your safety manual and request documentation as to how you’ve improved the safety of employees throughout the organization, and they will request information as to how all of the other processes and procedures have been tweaked or improved to benefit their customers. The ISO 9001 certification isn’t just a check off the list, it’s a continuous battle to pass audits and stay approved as a quality company that improves (on paper) every quarter.

Can You Purchase On Terms?

Purchasing on terms allows you to pay the invoice at least 30 days after the product is shipped and there is usually a discount offered (such as 2%10 Net 30 – Pay within 10 days for a 2% discount). The more business you have to offer the vendor the better your chances are of demanding your own terms, however, if you only have a small amount of business you might choose to ask nicely for favorable terms. When you set up orders to ship monthly you have 30 days to pay the invoice after each shipment, rather than making a large purchase online and receiving it all at once.

Do They Accept Blanket Orders?

Employee picking wire spool from storage

Many wire harness manufacturers allow you to purchase 1,000 pieces and ship 250 pcs per month, and you only have to pay the invoice for each shipment after it ships. Ideally, you’re committing to purchasing 1,000 pieces without paying so that your vendor can buy in bulk (cost savings) and offer you a better price. This is an ideal situation for the vendor as well as the customer because the vendor can plan their production schedule better when inventory is readily available.

Will They Produce Buffer Quantities?

When fast deliveries are a main concern it can help to have an extra buffer quantity produced and sitting on the shelf for immediate release. Perhaps you can increase your normal order from 1,000 pieces to 1,250 pieces, ship and pay for 1,000 pieces and wait to release (and pay) the balance when you’re ready. Or, if you buy monthly quantities of 250 harnesses at a time, you can request that 250 pieces are made on the shelf for quick shipment. Once you release the harnesses on the shelf the vendor will immediately start building the next batch of 250 pcs for the next time you call.

Do They Pay for Shipping?

Wire order being packaged for shipping.

Ask your potential vendors if there’s a threshold for free shipping. Perhaps you need to place an order for $1,000 to get free shipping and that’s easy for you to do. When you add free shipping together with a 2% discount, outsourcing to a vendor with machine produced product and bulk purchasing they add up to serious savings over time. It’s important to take advantage of every opportunity to save money and increase quality. It’s much more organized to buy completed wire assemblies than it is to measure the costs of inventory, waste, employees, overhead, and equipment. The nature of the business in contract wire assembly is to measure all of those costs and to improve quality and output for their customers. After all, you research and develop a product, then you have someone else make it for you at the level of quality that you demand.

Ask for a List of Wire Assembly Services from the Potential Contractors

Employee crimping a welding lug on to a cable

Can the contractor produce cut wire and cable as you expect? Can they tin dip, solder, terminate, meet tight tolerances and follow difficult specification sheets? Do they provide quality control checks and balances before shipping products to you, or are you forced to double check everything that arrives? Feel free to ask them about their quality processes to see how quickly and easily they supply you with that information. If you get an email within 10 minutes with 5 PDF’s showing the detailed process of quality control, then you know you’re in good hands. If you get a written email 2 weeks later trying to explain that they double check their work, you might not be in the best hands. Use your judgement based on the item you want produced, compare it to the cost, delivery method, terms, etc. and make your decision with a list of pros and cons.

Review First Articles

Once you find a manufacturer with all of the qualifications you desire you should request a few samples of a standard product you build in house in order to compare it to your own work. It seems customary to say that your business has top quality products and first class customer service, but take a test drive first to see for yourself. Also, if you have concerns, give the vendor a chance to address them once or twice. Are they willing to work with you without a fuss, or do they complain about the $5 cost of shipping and say that they produced a perfect product?

Start with a Small Order

Photo of magnified wires with soldered eyelets

Start by placing a small order of wire and cable products that aren’t too complicated to produce. See how quickly they complete the job, how often they need to ask you additional questions, if they push the delivery date out because of their own production schedule issues, and conduct any other tests you want them to pass before placing a bigger order. Complete this process with multiple vendors to see which was the easiest to work with.

Gradually Grow Your Business with the Relationship

You should have a couple of vendors to start with in case something goes wrong. As you develop a stronger relationship with a vendor that you like you’ll be able to push more business, and hopefully savings, through them. But until you have a solid relationship that meets all of your terms, you should keep a few vendors in the mix. I hope this helps you successfully find a wire harness contractor that meets your needs.