PLEASE NOTE: I’heat generation in metal cutting pdf really not competing to win the laser, a t-shirt would be fine, thanks. I saw the competition and thought it would be fun to show off my system. The general idea of this CO2 laser system is that a beam is directed down to a part for cutting.
The part sits on a computer controlled platform which moves the piece around the stationary laser beam. Cutting is acheived by passing the beam through a focusing lens. A focused beam exits through the bottom of a cutting head nozzle. Gas, such as oxygen, is fed into the side of the chamber below the focusing lens. To give you an idea, this is a comprehensive diagram describing the basic components of a CNC laser cutting system. This is a picture organizing many of these components around the central control unit and includes other sub components such as the motors, encoders, solenoids and flow sensors. What other systems have to be on-line in order to have a cutting operation?
Two 110VAC 20 amp lines were run to operate ancillary equipment, a 220VAC 20 amp line services the laser power supply, a 220VAC 20 amp line services the chiller outside of my house, and another 110VAC 15 amp line runs room lighting. It was also useful to make boxes like this that have 110VAC entering into them and also had relays system that could be driven by TTL levels to run various appliances like ventilation. A ventilation system has yet to be installed in the work area. This will be required to remove fumes and reduce smoke that will contaiminate the optics inside the beam delivery system.
The laser has the capability to cut a number of different materials like wood and plastic. Ventilation will be essential to remove the fumes produced by these materials. The laser cutting system can use either oxygen or nitrogen depending on the cutting application. This required that a couple tanks get installed and I ended up mounting the tanks up off the wall. This is to conserve floor space so I can cut larger sheets of metal.
The brackets came from the welding supplier. The plastic chameleon has a couple magnets embedded in it for sticking to the tank. Here’s a pic of the gas set up. The laser head needs to be suspended about 48 inches away from the nearest wall. Another design criteria was that it has to be able to change the height of the laser along the z-axis. A CAD drawing was put together, and I bought a pile of channel iron, angle iron, and flat stock then went to work with my chopsaw. Note the lag bolts attaching the angle iron to wall and floor.
My system is based the Coherent G-100, an RF excited sealed industrial C02 pulsed laser. It consists of 100 watt laser resonator and solid state RF amplifier integrated into an all aluminum enclosure. The RF amplifier provides pulsed RF power to the laser to ionize the CO2 gas mixture in the tube. A modulation signal applied to the laser head controls the output pulse width and period. The amplifier produces 3000 watts of RF power. Input power: 48 volts DC at 50 amps.
Cooling requirements: 2500 watts, water based. The power supply was specifically designed for the G-100. It is air-cooled and digitally controlled. The supply produces 48VDC at 50 amps and requires 220VAC input.
The G-100 has a DB25 connector that supplies control and input modulation signals to the RF amplifier and supplies status information from the amplifier. This allows monitoring of the temperature, duty cycle, and supports digital control of the overall power output of the laser. The table was probably made in the 90s. It has a total of 18 inch movement in X and Y directions. The lead screws have a . The motors that came with the table were too old to be used, and some new servos were retrofitted. The servos also came from on ebay.
Maximum Continuous Stall Torque At Max Motor Temp 300 Oz-In. US digital motor encodersencoders were used to detect the position of the motor relative to turns of the lead screw. The new motors were so large that they dont fit the nema 34 sized system on my table. I had to make an educated guess about the length of the belts, so using the data from the sdp site I put the geometry of the motors, pulleys and ballscrews in autocad and figured out the number of teeth required for the correct length belt. The CNC table also needed to have a rack added that would support parts that are getting cut by the laser.
The rack has to be level, because the distance from the laser that can develop the power density to cut metal can only vary by a less than a millimeter. The first tablefirst table was machined aluminum, very flat, and served as a good platform for the rack. I tried putting neodymium ring magnetsneodymium ring magnets attached with small bolts in on each bar. The neodymium rings came from ebay. If you search on neodymium you’ll get a million hits.
Nice stuff, but you cant machine it, so the ring variety was purchased for easy bolting. I went to a newer version of the table that supports parts to be cut by the laser more effectively. It was constructed with 12 power hack saw blades. They have 4 teeth per inch. 4 inch threaded rod through the holes at the end of the blades. One and a half inch long spacers were placed between each blade. The only other construction item was the bracketsbrackets that were placed in the assembly to bolt the blade-unit to my cnc table.