The term “wire processing” typically refers to preparing wire from the spool for it’s end use, and includes things such as measuring and cutting to length, stripping, twisting, and solder tinning. Processing wire by hand is very time consuming and difficult to do accurately, which is why even for low volumes this work is typically done by machine. A machine can do simple wire processing (cutting and stripping) very quickly and prepare thousands of pieces per hour to incredibly tight tolerances.
Materials. Once of the most important factors in wire processing is the raw materials themselves. The wire used should be of high quality, and be delivered on as large of spool core as possible or be pulled from a wire barrel. Wire that is too tightly wound will be difficult to straighten before being fed into the machine. Another important factor in choosing wire is that the wire conductor is centered, and round inside of the insulation material. Wire with strands outside the expected conductor area is easily nicked or cut by automated equipment and can make removing the insulation around strips more difficult. If the conductor is an oval shape the stripping blades can only cut as deep as the shallowest point to the conductor, meaning it will not cut all the way through the insulation and make removing the insulation slug more difficult and possibly cause some strands of conductor to pull out with it.
Pre-feeding. After a proper material is chosen you must feed that wire into the machine properly, meaning at the correct tension, and after straightening the wire as much as possible. A pre-feeder is often used to dereel the wire from the spool and take up any slack so that the wire processing machine gets wire at a constant tension even though it will often alternate between rapidly feeding wire and completely stopping the wire feed to perform operations on it. The pre-feeder acts as a buffer that can speed up the wire pull from the spool and brake the spool as well as having a supply of wire already available for the machine to pull at any given moment.
Straightening. Wire that isn’t straight will not get processed very well, the machines do everything possible to minimize the distances between a feeder and a blade or wheel, but if the wire has a lot of curl to it, it may not get placed in exactly the right spot for whatever operation is taking place. Most wire processing machine include a set of wire straighteners on them, but if your wire is particularly difficult to work with you may need to add additional straighteners to get acceptable results.
Cutting and stripping. The heart of any wire processor is cutting and stripping. While typically done with a single set of blades for both operations, there are special circumstances where multiple blade sets are used, this can extend the life of a set of
blades, or allow for stripping operations on difficult material such as PTFE where a more concentric cut may be required than standard V-blades can produce. While most machines can be programmed to cut and stip both ends of a piece of wire, there are also machines that can strip out a “window” in the middle of a piece of wire, but for cost purposes it is usually better to spec your harness without these types of strips and instead do a splicing operation to keep costs down. Stripping can be done in two ways, either a full strip where an entire lug of insulation is pulled off, or a partial strip, where the insulation is cut and pulled back part way but left on the end of the conductor. Partial strips are great for when the wire won’t be immediately terminated and will prevent the strands from fraying out during transport or packaging.
Other operations. Today’s wire processing machines can do some amazing things but some of the more common secondary operations include twisting pairs of wires, stripping multi-conductor wire and cable, tinning stripped wire with solder, and even being integrated into other operations through automation. While these additional features can cost quite a bit up front in equipment, they can save amazing amounts of time on higher volume jobs and should be considered if you are doing more than 10,000pcs.