October 10, 2006
Laser machine users know it, but often ignore it. Laser manufacturers swear by it, but often don't push it. It's maintenance, and it should be the watchword of anyone who owns and operates a laser.
Laser machine users know it, but often ignore it. Laser manufacturers swear by it, but often don't push it.
It's maintenance, and it should be the watchword of anyone who owns and operates a laser. With lead-times decreasing, margins thinning, and raw material prices always proving to be unpredictable, proper machine maintenance can save a shop plenty of headaches at crunch time.
Instead of aspirin, these three tips can help laser operators avoid pounding head pains and keep their equipment operating at top performance.
All laser machines are manufactured identically, but the shop environments they enter once they are purchased influence the laser cutting devices in completely different ways. Many factors, such as ambient temperature, the type of material being cut, operator knowledge, shop cleanness, and air quality, make each setting unique.
For instance, one shop's air source—perhaps a defective air dryer or an old compressor—might contaminate focal lenses faster than in the shop next door. In another example, the type of cutting, such as nitrogen-assisted cutting of aluminum or stainless steel, might require more frequent equipment maintenance checks.
Once a laser operator has studied these factors, a preventive maintenance program can be tailored to the individual shop.
|By not checking a nozzle for proper alignment, an operator runs the risk of having the machine produce bad cuts.|
For those fabricators new to laser cutting, laser technology vendors can help them establish their own internal maintenance programs and provide on-site training. If a fabricating shop wants to outsource maintenance, arrangements can be made with laser technology specialists to perform maintenance checks on a reccurring basis.
Checking the alignment of inner and outer nozzles in the shop is not that difficult, but it is very important. Operators simply can look at the nozzles and see whether or not they are centered. Two nozzles that look aligned usually are. No formal measurement is needed.
If an operator chooses not to check the nozzles and runs the equipment with them misaligned, a poor-quality cut is almost ensured, and nozzle damage is a possibility.
Laser operators can rely on their eyes for another routine check. To check the focal lenses for cleanness, an operator only has to pull the cartridge out and hold it up to the light. A breath test can help make this judgment. By breathing on the lens, the laser operator can tell if it is clean (a frosty look) or it is dirty (a glazed or spotty look).
|The type of material being cut represents just one factor that goes into planning an appropriate laser machine maintenance program.|
Checking basic laser components such as nozzles, focus lenses, and assist gases should be as much of an operator's routine as punching in. Good communication between workers leaving from a shift and others arriving for a shift is an ideal way to keep track of regular maintenance updates throughout the day, week, or month.
Of course, there's more to a laser than the cutting torch. Other components of the laser equipment require proper attention too.
For instance, if a laser cutting machine is idle for a long weekend, the water in the chiller unit tends to build up conductivity—or, more simply stated, its ability to conduct an electrical current. This occurs because water is naturally conductive. When conductivity in the chiller is high, the machine's self-diagnostic features will prevent the resonator from starting until the level is more suitable for efficient operation. To lower the chiller's conductivity level, the operator should run the chiller unit for a few minutes before laser cutting.
New control technology in laser cutting equipment has eliminated the need for a laser operator to be cognizant of ambient temperature and its effect on the chiller. In the past variations in operating temperatures could affect a machine's performance, such as causing optics to sweat, and lead to unscheduled downtime. Today chiller units can be set to hold a constant temperature in any climate or region, with the laser circuit at an ambient 50 degrees F and the optics circuit at a constant 86 degrees F.
|Laser consumables also can affect laser cutting machine performance if not replaced as needed.|
If consumables are even slightly out of spec according to the manufacturer's specifications, a company could be sacrificing performance.
Aftermarket suppliers sometimes reverse-engineer an OEM component, which may result in a replacement part that is not within factory specifications. For the two-piece torch nozzle configuration commonly used now, aftermarket nozzles sometimes can have fit, beam centering, and assist gas flow problems, which can decrease accuracy and production uptime. If the outer nozzle isn't made according to the specifications, an alignment problem most likely will occur between the two nozzles.
That's why a regular maintenance program always should include a critical look at the consumables to see if they are affecting machine performance.
The bottom line is preventive maintenance programs lead to extended machine life, higher resale value, top productivity, and greater machine accuracies.
So now you know it, don't ignore it, and you'll learn to swear by it. Proper preventive maintenance will push your laser cutting operation to the next level.
|Keep up to Speed|
|Cut corners on maintenance, and you ultimately may be slowing a laser's cutting speed.
For instance, a clean machine that runs at 100 inches per minute through carbon steel may run at only 80 or 90 IPM when dirty, simply because a dusty optic or nonconcentric orifice conducts a less-than-optimal cut. Multiply that lost time by a thousand parts, and pretty soon total production time suffers.
In some cases, when the machine needs maintenance but it is neglected, a fabricating shop starts sacrificing feed rate. Before you know it, jobs are quoted at one speed, but because maintenance has been delayed, the laser cutting equipment may be cutting slower than the quoted speed.
Another way to keep up to speed is to keep replacement consumables, such as breakaway bolts on the cutting head, in stock and ready to install, minimizing downtime.
Minimum stock levels should be established, and when inventory falls below that number, the part can be reordered automatically to avoid having to wait for parts from the vendor.
Jeff Hahn is senior laser product manager, Bernie Olguin is Consumable Products Group laser consumables expert, and Dru Schwartz is laser senior applications engineer with MC Machinery Systems Inc./ Mitsubishi Laser, 1500 Michael Drive, Wood Dale, IL 60191, 630-616-5920, www.mitsubishi-laser.com.
The FABRICATOR® is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971. Print subscriptions are free to qualified persons in North America involved in metal forming and fabricating.