There are a variety of methods available to wire and harness designers and assemblers in order to properly strip wire insulation. Each of these wire stripping approaches has its advantages and disadvantages.
The typical wire insulation or “stripping” removal of the insulating jacket from wires and cables can be accomplished via several methods. The oldest and most common method involves mechanical wire stripping. In this method, either a manual tool or an automated machine feeds wire into a pair or more of mechanical shears. These shears pinch or “bite” through the insulation. Once the insulation is cut in this manner, the insulation is pulled off leaving the exposed conductor core. In another method, a heated wire melts the insulation much the same way thereby cutting through the insulation. Liquid chemical stripping agents can also be used in some applications to dissolve the jacketing material. The wire then needs to be neutralized to stop the process. In some applications, abrasion wheels grind away the insulating jacket.
Laser wire stripping was developed in the 1970s as part of a NASA and other defense programs. The need was for a method to strip wires without the potential for damaging inner conductors. In the 1990s laser wire stripping grew in usage as ever smaller devices need to be connected to including mobile phones, laptop, and other consumer devices.
There are several advantages to using laser sources to perform wire stripping. Inherent in the laser wire stripping process is its repeatability. The laser sources can be precisely defined as a sophisticated system of “beam steering” mirrors which steer the laser beam precisely and repeatability. There are no wearing parts or wearing devices. The beam is precisely steered as well as the energy is delivered via a sophisticated electronic control system. This causes the material to ablated or “burned away”. In some set-ups, the laser energy is absorbed by the jacket or insulating material whereas it is reflected by the conductor strands. This means that a C02 laser has a stop-gap limit that is set by the material making laser wire stripping a repeatable process even with variations in cable and insulation thicknesses. Properly set up laser wire insulation stripping systems will not damage the wire or the insulation. This is advantageous to industries requiring a high degree of precision as well as process control and verification such as the medical device and defense industries.
When the job calls for out-of-round, flat ribbon cable or other odd-shaped cable cross-sections, laser wire stripping is a good flexible answer. Through the use of proper tooling and programming and laser source selection, these wires and cable can be stripped repeatably using a laser source. Since the process is non-contact and the tooling is programmable, laser wire stripping is the way to go when odd-formed cables for wires need to be stripped.
Another area where laser wire stripping shines is in cases where window pane or slitting patterns are required. Again because the cutting source is programmable, precise ablation techniques using a laser are an advantage. There are no mechanical blades or fixtures. The set-up is done via programming and by waiting on long lead time, custom-made tooling that needs to be figured into the project budget.
The versatility of laser wire stripping machines makes them a very flexible tool. Different wavelength lasers as part of the wire stripping system are tuned to different materials. Therefore, having a supplier with multiple wavelength machines is key to the custom wire harness and cable assembly houses, as these vendors have the greatest flexibility when different wire stripping projects with different materials arise.
Laser wire stripping is finding its way into many medical applications. Typical laser wire stripping applications in the medical industry include but are not limited to catheter-delivered devices and implantables, both application requiring very fine gauge wires that require the precision of lasers to remove the outer jacket material. In addition, very fine diameter coax cables, like are found in ultrasonic devices, are well-suited for the precision of laser wire stripping.
Micro co-ax cables are well-suited for laser wire stripping. They are made up of a metallic conductor with a dielectric insulation. This, in turn, is covered by a braided shield and a polymer jacket. Laser wire stripping starts to make the most sense when cables are smaller than 26 AWG sizes, as this is when more traditional mechanical stripping methods begin to not be as repeatable. Ribbonized versions of the micro-coax are also a good application for laser wire stripping, especially when window pane stripping is required. The control of the laser source in laser wire stripping allows window stripping and slitting along individual insulators.
Whether in the military, space or medical fields laser wire stripping has advanced as a technology which can very precisely and very repeatably strips the insulation from the wire jacket. The advances in smaller, specialty cables will keep laser wire stripping here for years to come.