Laser Ablating / Laser Wire Stripping

Bob Wettermann

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There is a multitude of different methods for wire stripping, each with their own benefits and shortcomings. During wire stripping the insulation, media is removed from the conductor or conductors. This allows for an electrical and mechanical connection to be made. Traditional methods of this insulation removal process include mechanical, chemical, thermal and laser wire stripping. The mechanical wire stripping methods ae the most flexible and most common.

In this method, a hand tool cuts the insulation with the grippers pulling the cut insulation away from the wire. This method, when done manually is an uncontrolled process and is a function of the operator’s method and the maintenance of the cutting and pulling tools.This method has made its way into high-speed production equipment with cutting and unspooling and sometimes tinning functions built into the tool. Chemical stripping is generally performed on hard-to-strip or specialty insulation materials. In this case, the properly-designed chemical “east away” at the insulation. Controlling the length of the strip and neutralizing the media post stripping are challenges of this stripping method. Thermal stripping involves small heated wires “burning off” the insulation at a defined length from the end of the wire. This is not always a neat strip rather may be prone to remnants still being attached to the wire. Many production floor supervisors do not want a heated source on the hand of their production personnel. Laser wire stripping is a clean and fast method for wire stripping. Very tight tolerancing, very clean insulation cutting and the ability to selectively strip off the insulation in the center of a wire run are the benefits of laser wire stripping. Laser wire stripping equipment is capital intensive.

Laser wire stripping methods can be done in one of two methods. In one case the insulation is sliced along the length of the wire as well as around the circumference of the insulation material. After this, the insulation can be “pulled free”. In a second laser wire stripping technique, the insulation is ablated or completely vaporized/melted away along the strip length. C02 laser sources are used often to perform this insulation ablation. Equipment either manipulates the material into fixed laser source or the laser source is rastered around the periphery of the insulation, thereby the laser ablation to remove the insulation around the wire. Most insulation material absorbs this part of the laser spectrum. In addition, the conductors reflect the C02 wavelength thereby not damaging the conductors. Another commonly-used laser source for laser wire ablation is the 355nm YAG source. This source has a very small spot or laser cutting cross-sectional area thereby offering greater precision than the C02 laser making it well-suited for very fine gauge medical wire applications.

No physical force is imparted on the wire during the wire ablation process, so delicate wires down to 50 microns (2 mils)can be stripped using the laser wire ablation process. A directed focused beam is directed rapidly via a galvanometer. These galvanometers are small fully programmable X/Y mirrors. This precision control along with a small beam diameter allows for very small areas of the cable, whether at the end of the conductor run or in the middle (window paning) can be removed. The cycle time is very rapid.

Wires can be laser stripped in one of several laser machining configurations

Reel to reel- In this method, a spool of tension wire is unspooled and feed into the cutting/ablating area. If the material requires the center of the run insulation removal or “window panning” then the processed wire can re-reeled on to a take-up spool. The control system takes care of the counts and length of wire and in some cases includes an inspection station.

Reel to cut: A spool of wire is advanced through the laser wire stripping system, stripped at the required locations and then cut to length. It is critical that the individual cutting process does not create unacceptable irregularities at the ends of the part. In some cases lasers are used to cut the finished material to length with a different laser is used for cutting than for stripping.

Individually process- In this method, which has already been cut to the correct specified length, is laser stripped.

To strip short wires, longer wires can be used so that they can be tensioned, laser-stripped and then cut to the final length.

One step that cannot be overlooked in laser wire stripping is the post wire ablation cleaning process. While laser systems employ a vacuum system in close proximity to where the beam meets the wire insulation at the ablation process point to vacuum away the burnt insulation there still remains remnant destroyed wire insulation on the surface of the wire. Many times there needs to be some post wire ablation cleaning process. This will help to ensure that the tinning process is reliable and does not contain contamination that may impact the operating environment of the wire or the integrity of the solder joint.

More About the Author

I am the principal of BEST Inc and I have the passion for teaching in a variety of life skills as well as in soldering and PCB repair as well in Social Media Marketing.