Date: 20 June 2005
Advances in laser profiling resonator technology make for a complex investment decision.
Full Story:
Matt Orford; Technical Manager of Yorkshire Laser and Fabrication compares the current benefits of three types of laser profiling method:
“When looking into the purchase of a Laser Profiling System, there are many configurations to be taken into account including bed size, resonator power, rotary axis chucks and service package, to name but a few. On the scientific side is the choice between a DC (Direct Current) and RF (Radio Frequency) powered resonator. The fundamental choice of laser beam generation method may have significant impact on productivity and life cycle costs.
DC resonators have internal electrodes situated within glassware. The main benefit is that DC resonators are about thought to be about 30% more power efficient than RF. As the electrodes are encapsulated they are also safer and more robust during maintenance. Drawbacks in comparison with RF are 30% increased used of gas and replacement glassware requirement at between 20-25,000 hours, costing about £30,000. The saving on power is greater than the cost of additional gas but not much.
The alternative, RF resonators have external electrodes. Electrode wear is less and glassware is uncontaminated by what is considered to be a cleaner process of laser generation. It is argued by some that this gives a better quality of beam however profiling performance is not noticeably improved. On the downside RF resonators are less easy to work on and may need returning to the manufacturer for repair, potentially causing downtime. Servicing costs include replacement of end stop valves for approximately £4000 every 2,000 hrs. The life of the RF generator is finite and may require replacement at some point after 30,000 hrs at an approximate cost of £20,000.
Fast Axial Flow Resonators generate a laser beam using power emitted from electrodes in an atmosphere of exited lasing gas. The mixture of Carbon Dioxide, Helium and Nitrogen is forced to circulate the glassware by a turbine. Turbine bearing wear is an issue to be considered. Non contact bearings may outlast the machine whereas contact bearing wear may require turbine exchange at a cost of between £10-15, 000 at uncertain intervals.
There has been a recent surge in interest in Slab Resonators the alternative to Fast Axial Flow featuring RF resonator technology. Slab laser profilers have a static gas field that requires no pressurisation or glassware hence savings on replacement turbines and glassware. Drawbacks of slab laser profilers are reduced performance with stainless steel and aluminium plate; although they will cut, productivity is less.
Investment in capital equipment ultimately comes down to estimating life span costs and weighing this up against potential benefits including perception of reliability, quality of service, performance and actual effect on production of new technologies.”
