When consigning parts to a contract manufacturer, you will need to provide either a “kit” that includes all required materials, or a list of all necessary components for the CM to purchase on your behalf. In either case, these best practices will ensure fast and accurate turn-around.

If You Provide a Kit

If you plan to provide your CM with a kit, you will want to do some up-front work to ensure that your CM has everything it needs – and in the correct format – needed to meet your production expectations. Ask yourself the following:

1. Are our parts in machine-ready format? If your prototype requires machine assembly, parts must be provided in particular formats. The last thing you want is to learn that you need to re-order, hand assemble, or re-package your parts before they can be assembled. Common materials problems that can delay production include:
   – Non-panelized boards: Manufacturing one board at a time is more time-consuming and expensive than manufacturing boards in a 4-up configuration, so panelized boards are preferred.
   – Irregularly shaped boards or boards with parts near the edges: These boards can’t be line-run since they lack the borders required to carry them through the machines. If your prototype has these characteristics, it will need to be panelized or manually assembled (if possible).
   – Dirty/damaged boards: While boards do not need to be sealed in their original packaging, they must be free of damage, debris, and oxidation. Snapping a few out of the panel means that panel cannot be readily assembled.
2. Are your part numbers properly documented? For fast and accurate turn-around on a prototype, it helps to provide your CM with more than the original manufacturers’ part numbers. To speed the process, assign internal part numbers to your design and reference those numbers to the parts in your kit. This will ensure that your manufacturer can process the parts and subsequent revisions in a timely and efficient manner with a minimum chance for error. This is particularly important if you will ever need more than one design or version.

If you revise your prototype for a second round of production, be sure to maintain the existing internal part numbers. If the part numbers on your bill of materials (BOM) change from one round of production to the next, your CM will need to review, search and re-align existing parts with the new BOM. This can add extra time and cost, and increases the risk of production errors.

If Your Contract Manufacturer Purchases the Parts

If you your CM will be purchasing the parts for your prototype, be sure to consider the following:

1. The CM will need adequate lead time to acquire the parts. You will likely only be able to grant your CM approval to purchase parts late in the design cycle. If your CM needs to order parts before the design is complete, you will need to clearly communicate the specific parts required and when they should be ordered. Most CMs will also require you to sign a contractual arrangement to ensure that they will be compensated for the parts ordered. If you get your CM involved in the design process, they can offer guidance on parts and alternates that may be more readily available or lower risk than others.
2. Your prototype may be machine-run or manually assembled. You might have a preferred assembly method in mind for your prototype, but the decision will probably come down to economics. For low-volume prototypes with low complexity, manual assembly is usually most cost-efficient. You may prefer not to have human intervention, but machines need to be programmed and set up for production, which takes time. This has a cost, as does taking a working machine off-line to setup your prototype.

Machine assembled prototypes require additional parts to be purchased —some parts are used to “teach” the machine and some can be lost during feeder setup or production (attrition). Minimum purchase volumes will likely exceed the quantity actually required for your prototype. Instead of buying 10 pieces “neat” for manual assembly, your CM may need to buy 35 machine ready pieces at extra cost. Your CM will take these costs into account when proposing the best assembly option for your particular prototype.

Communication is Key

A good contract manufacturer can lay out the options available to you and help you choose the best assembly method for your prototype. The key is to establish a communication channel as early as possible with your manufacturer. This will enable the CM to ask the right questions, help you avoid unexpected delays or SNAFUs, and will give you a clear indication of the materials and lead time needed to produce your prototype.
In particular, take care of these details in advance:

• If you are using a turnkey prototype service, prepare a purchase order concurrently with your design. The prototype house needs to start working with you early to procure materials. A “cost plus” approach is one option that can smooth out issues.
• Provide adequate assembly documentation as early as possible and follow our guidance for best practices for preparing documentation.
• Give the prototype manufacturer as much heads-up as you can, along with any available documentation – it’s almost never too early to get the CM involved!

These measures will help ensure that your CM is able to get started on your prototype as soon as your design is ready, and to provide fast turnaround.

Fast Prototyping

OCM Manufacturing’s Fast Prototypes service is a dedicated prototyping practice. We offer fast turnaround, high quality, and invaluable design for manufacturability (DFM) feedback that is critical to a product’s success once it enters the market.

We will work directly with you and your designers to ensure that your plans and prototypes are manufacturable and therefore marketable. Contact one of our Program Managers for details about how we can help.