ACQUIRING A SECOND-HAND LASER: GAS AND EQUIPMENT SAVVY ARE REQUIRED FOR HASSLE-FREE SET UP
By John Karpus
A factory-reconditioned or second-hand laser is a good way to increase shop productivity at a fraction of the cost of a new machine. Incorporating these principles and pointers into the purchase and installation of a second-hand laser should assist you in achieving first-class efficiency and operation.
Steel fabricators in this country have been staying competitive by using CO2 cutting lasers for more than ten years now. Names like TRUMPF, Mazak, Mitsubishi, Cincinnati, Strippit, and Prima have all become synonymous with high-tolerance CO2 laser-cutting systems.
Industry research tells us that 80 percent of new laser customers will purchase a second laser within 24 months of their initial purchase. As new laser owners become more familiar with the capability of their machines, the trend is to expand into thicker material and higher capacity systems.
This evolution is driving the market for used CO2 cutting lasers that become available for resale as fabricators and job shops upgrade. For companies wanting to acquire their first laser, the rationale for the move to used equipment, of course, is value and function. As the cost of a new CO2 cutting laser can easily run $250,000 to $500,000, a factory-reconditioned or second-hand laser is a good way to increase shop productivity at a fraction of the cost of a new machine.
BREAKING IT DOWN
The resonator is the part of the laser that creates the cutting beam. The gases required are high-purity grade 5 or better, CO2, nitrogen, and helium. Carbon monoxide will sometimes be added into the resonator gas mix depending on the resonator manufacturer. Inlet purging of resonator gases when hooking up a new cylinder must be done to remove ambient air, moisture and contamination prior to gas entering the resonator.
If moisture or particulate contamination enters the resonator chamber with the resonator gases, these impurities will damage the resonator. The first symptoms that indicate this has happened are poor cut quality and high-power consumption by the laser. Some laser manufacturers have developed resonators that use such small amounts of these gases that they come supplied with the machine and don’t require replacement for a year or more. High-purity two-stage regulators equipped with inlet purging capability are recommended (see Figure 1).
If customers have invested in material-handling systems, they are probably intending on running the laser unattended and will require an uninterrupted source of gas. If the laser will be run unattended, you will need a continuous supply of these gases or the laser will turn itself off when the gas runs out. Outfitting the laser with a high-purity gas switchover system equipped with inlet purges is the best way to keep this from happening (see Figure 2). Normal operating pressure to the back of the laser ranges from 50 psi to125 psi. Resonator gas consumption is low, so it normally takes several months to empty a 200 cu ft or 300 cu ft cylinder.
Some other items that are often ignored when setting up resonator gas systems are: (1) relief valves to protect from a regulator failure, and (2) in-line filters to insure clean, non-contaminated gas. Most laser manufacturers recommend the use of two-micron inline filters and appropriate relief valves installed in the line between the outlet of the resonator gas switchover or regulator and the back of the laser.
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