laser ablation
essential. But there are distinctions in these areas. For ex- ample, although Rollomatic does not otherwise build ma- chines with linear motors, the LaserSmart uses linear mo- tors for X and Y and torque motors for the two rotary axes. Peter said that in addition to superior precision, only linear/ torque motors deliver the speed and acceleration needed to effi ciently create small radii and similar features. EWAG uses linear/torque motors on all mechanical axes. In another twist, Rollomatic started with its highly re-
garded V-block toolholding system on the LaserSmart, but since laser machining doesn’t impart any signifi cant pressure on the tool (there are no grinding forces after all), the company can achieve excellent results with a standard collet system or (more commonly), a standard HSK63 toolholder. EWAG does likewise. And of course, both companies have to remove the vapor coming off the tool, rather than deal with coolant and mist. Evacuating and fi ltering the vapor prevents laser diffraction as the process continues and maintains a healthy environment in the shop. In an interesting analogy to grinding with the face of the wheel on the OD, EWAG achieves extremely fi ne fi nishes by using the side of the laser beam, essentially using just a line of photons. They call this “tangential machining.” Dold said, “The number of free electrons you have to generate to ablate diamond is 10 to the power of 21 and the same ap- plies to the photons. For a typical cutting tool application, we’d start with roughing, removing quite a bit of material— in the range of 0.1 to 0.2 mm. Then for fi nishing we would
switch to tangential machining in which we are using the side of the beam. The advantage is that you can do very fi ne surfaces with this. But the material removal rate goes practically to zero.” Everyone agrees that getting good results in super-hard
tooling requires more than just “the laser.” “The key,” said Peter, “is delivering an entire process that combines excel- lent mechanics with the best means of guiding the beam, controlling the pulses, overlapping the pulses on the tool surface, turning the tool during machining, and so forth.” Because this process is signifi cantly different from tool grinding, Dold said, “EWAG’s strategy is to explain how things work and why some things work better so the cus- tomer is able to manufacture whatever he wants. We think the faster people understand what laser can do for them, the faster the market will grow.”
Astonishing Results When it’s all put together, the results can be astonish- ing. Both companies say their machines can reliably de- liver a cutting edge as sharp as a one micron radius. While general practice within the cutting tool world would sug- gest that an extremely sharp edge is brittle and needs to be rounded to achieve satisfactory tool life (referred to as edge preparation), Peter said if you can guarantee a con- sistent edge (i.e. without any chipping), an extremely sharp tool performs better in many applications. Just as important and even more challenging, these machines can also control the cutting edge to deliver a
Á The Rollomatic LaserSmart 500 and EWAG Laser Line Ultra: The two leading contenders in this fi eld. The Ultra uses a picosecond laser while EWAG also offers a nanosecond version called the Precision.
LF16
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