^ Laser Cutting (Source: http://www.maximumind.com/laser-cutting-maximum-industries.html)
Laser Cutting Machines
Because it can cut a wide range of materials to almost any shape, laser cutting is globally acknowledged as a fundamental, indispensable technology. Numerous experts believe the next few years will witness radical developments in the world of laser cutting.
Laser cutting machines employ an acutely-focused, high-power light beam for accurate cutting of metals, plastics, fabrics, paper, and wood. Engineers select Computerized Numerical Control (CNC) or manually operated laser cutters based on task requirements.
Kemplon Engineering is a proud owner of the Mazak Super Turbo X 612 High-Pro Supercharger Laser Cutter. Its constant-beam-length delivery cuts diverse materials of varying thicknesses. Its refined features enable automatic operation, minimize operational costs and failures, and lower setup time to provide strikingly precise cuts.
Evolution of Laser Cutting & Computerized Numerical Control (CNC)
For a long time after Albert Einstein first theorized them in 1917, lasers were a solution seeking a problem. It was only in 1965 that Western Electric Engineering Research Center built the first production grade laser cutter.
With high-coherence and large power per-unit-area, lasers rapidly cut through materials without substantially heating the workpiece. This minimizes distortion i.e. expansion-contraction of the workpiece. Laser cutters are installed inside radiation-proof casings to minimize radiation hazards.
Most laser cutters are automatic. Large automatic cutters come equipped with headstock and tailstock positioners, gear-driven positioners, and turning rolls. Smaller and portable semi-automatic cutters are used in restricted, difficult-to-reach spots.
Both CNC and laser cutters are profoundly accurate. The combination therefore is superbly precise. CNC laser cutters offer better results as compared to plasma cutting, conventional cutting, flame cutting, and abrasive waterjet cutting.
CNC is the use of computers to guide machine tool operations. The CNC concept is the brainchild of John Parsons who, in 1947, developed a control system that successively directed a spindle to multiple locations. Presently, microprocessors have drastically cut CNC machine costs. Now we have such machines for hobbies and personal use as well.
Quality, accuracy, safety, economy, repeatability, speed, and simplicity are the distinctive features of CNC. The fact that the Society of Manufacturing Engineers named Mr. Parsons as the Father of the Second Industrial Revolution in 1975 speaks volumes of CNC’s groundbreaking potential.
Lasers & the CNC Laser Cutting Process
After Western Electric Engineering Research Center built the first production grade laser cutter in 1965 to drill holes in diamond dies:
- the British employed laser-assisted oxygen jets to cut metals in 1967
- development of CO2 lasers enabled cutting of non-metals such as textiles
- aerospace sector practiced laser cutting of titanium in the 1970s
LASER stands for Light Amplification by Stimulated Emission of Radiation. Laser machines excite electrons of certain materials to higher energy levels (orbits in the atom) using electricity. When coming back to their original orbit, these electrons emit laser, a supremely powerful, coherent, and intense light beam.
Lasers are ideal for cutting due to their:
- High Power Per-Unit-Area
- High Focus or Coherence between the electric and magnetic components of light imparts it greater energy
- Mono-Chromaticity i.e. single-colored, more-focused light beam
- Minimum Diffraction or bending around sharp corners maintains its energy levels over a distance
The resonator of a laser machine generates lasers. Mirrors guide the beam in the required direction. Lenses focus it at the necessary point. Such focusing multiplies its cutting power. For best quality cuts, position the workpiece at the focal point of the lens.
CNC laser cutters employ capacitive height control to maintain an accurate gap between the workpiece and the nozzle-end. The nozzle-end is the exit point for the laser beam as also for compressed gases that blow away molten debris. This gap determines the cut quality.
Laser cutters cut by melting, vaporizing, or burning action. Compressed gases such as oxygen and nitrogen flush the molten debris off the kerf i.e. the zone on the material where the laser makes the cut.
Laser cutting is most compatible with stainless steel, mild steel, and other hard materials that absorb lasers and have low kerf widths. Aluminum and copper are not so friendly because they reflect lasers.
Types of Laser Cutters
Laser Cutter Systems can be:
- Gantry Systems: slowly cut material that is placed at right angles to the beam. They are used to make prototypes
- Galvanometer Systems: rapidly cut material placed at various angles to the beam by using angled mirrors. With speeds up to 100 feet-per-minute, it is used to cut final parts
Based on the chemical used to generate beams, laser cutters can be:
- Nd-YAF Lasers: high-power cutting applications
- Nd Lasers: high-power-low-repetition boring
- CO2 Lasers: cutting, engraving, and boring
Merits & Limitations
Being a precise, contact-less, and automated process, CNC laser cutters offer:
- Top Cutting Precision and Positional Accuracy
- Improved Edge Quality and Surface Finish
- Strong Repeatability
- Cut Materials not cut by Conventional Cutting Processes
- Negligible Workpiece Contamination
- Cost-Effective because top accuracy eliminates reworking and the associated time and cost overruns
- Minimal Thermal Stress Zone in Workpieces
- Cuts Complex Shapes
- Zero Tool Wear
- Better Material Utilization
In order to harness these merits, the CNC laser cutter must utilize technological features such as:
- Following Control: maintains constant gap between the cutter head and the workpiece
- Laser Power Control: adapts the laser power levels to varying traverse speeds to enable uniform cuts without excessive heating of the workpiece
- Leapfrog: manages cutter movement between two separate cutting zones
- Gantry Axis: moves heavy laser cutters using two synchronous motors on a single axis
- Scan Cutting: shuts off the laser gun while moving between cutting zones
- Multi-Axis Interpolation: coordinates simultaneous movement along all three axes
Of course, the process suffers from:
- Incompatibility with Laser-Reflecting Materials viz. aluminum and copper
- Incapacity to Cut Thick Material with present technology, for lasers lose energy after cutting through material
- Excessive Movements of Laser Bevel Cutters when Piercing Corners
- High Power Consumption
- Harden Heat Treated Material that hampers further machining
- Creates Tapered Holes as the laser beam’s entry diameter is slightly greater than its exit diameter
- Unsuited for Cutting Coated Materials such as galvanized steel or rusted plates
CNC Laser Cutting Vs Plasma Cutting
Heating a gas to very high temperatures transforms it to plasma, the fourth state of matter. At such elevated temperatures (30,0000F/16,6490C), gases such as oxygen, nitrogen, argon, and hydrogen possess tremendous energy. Plasma cutters cut by directing such charged gases at velocities of 20,000 feet-per-second (6,096m/s).
Laser Cutting in Shipbuilding
Shipbuilding involves cutting of large panels of over 12m width. Clients demand low turnaround time, high production levels, and significant uptimes. CNC laser cutting addresses these requirements. Japanese shipyards reported a 10% productivity boost by using laser cutters in 2001.
Although military research first made laser cuts in 1967:
- Shipyards first used laser cutters in 1995 when they employed the 6KW CO2 laser system to slice through large, thick parts
- First used in 1997, Laser Bevel Cutting Machines made cuts at angles other than 900
This was a major milestone, for bevel cutters enabled the cutting of complex shapes so necessary in shipbuilding
- Shipyards first used CNC ink-jet marking machines to rapidly mark machine trajectory on large parts in 2005
- In 2006, 5KW Gantry CO2 Laser Cutter was first used
Shipyards typically utilize lasers to cut:
- vessel skeleton and skin
- drains, pipes, and manholes
- block parts, hatches, and parts of stiffener plates
Mazak Super Turbo X 612 High-Pro Supercharger Laser Cutter
Kemplon Engineering delivers sterling laser cuts with the Mazak Super Turbo X 612 High-Pro Supercharger Laser Cutter. With its constant-beam-length delivery and automatic operations, the X 612 is capable of continuous operations.
Mazak’s Super Turbo X 612 High-Pro Supercharger Laser Cutter
Eminent features that reduce operational costs and failures while lowering setup time include:
- Non-Contact Laser Head eliminates the need for complicated jigs and allows operations with light clamping only
- Sequence Controller enables program as well as manual activation
- Orion Chiller prevents overheating during non-stop operations
- Dedicated Load-Unload Facilities
Finally, the Future
Recent development of a Hybrid Laser-Assisted Oxygen Cutting Technology that cuts over 50mm thick plates with a 2kW cutter promises new capabilities. CO2 lasers were widely used for a long time before fiber lasers entered the scene. Although faster, they cannot cut as deep as CO2 lasers.
Now we have Direct Diode Lasers that:
- offer better electrical efficiency
- generate less heat
Direct diode lasers are presently used more for heat treating and cladding than for cutting steel. The next few years may change this. In fact, many expert observers expect revolutionary developments in laser cutting in the near future.
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