Why is it so important to engrave at high speed?
Simply put, if the marking speed is faster then the job time will be shorter and this provides for the following advantages:-
- Higher throughput; more parts per hour.
- Higher hourly profits and/or lower operating costs.
- Shorter lead times.
- Increased capacity to supply
- Higher competitiveness; the ability to charge lower unit costs without compromising profit.
- Savings on capital expenditure
So long as there are no significant decreases in output quality the aim should always be for greater throughput.
So how fast is fast?
I’m often told by people who already own a laser that their machine is incredibly fast for engraving.
In almost all cases this comment comes from somebody who has experience with using a CO2 (10.6µm) plotter system and often some of these people are already my customers!
There are now several well designed machines from a number of manufacturers that can truly claim to be fast.
But by what benchmark do we determine if something is engraved fast or slow?
Assuming that both systems are capable of producing the same job, if we are comparing a high end CNC engraving system to an average performance modern day plotter laser, then in many cases the laser is a faster tool for producing the job.
However, have you ever wondered if there’s another machine that could produce the same job even faster than a plotter laser?
In many cases there is and it’s not just an even faster plotter laser again: sometimes this could be a micro-percussion (dot peen) machine but such a machine has limited application. Where non-contact marking is required in most cases it will be another form of laser; one which delivers the beam not via a plotter mechanism but by high speed galvanometers or ‘galvo’ for short.
What is a galvo laser?
For basic beam delivery a galvo laser will have just two moving parts with a combined weight of just a few grams. By contrast a plotter mechanism can contain dozens of moving parts weighing several kilograms.
Furthermore, as plotters become larger they are inherently more cumbersome, therefore, when trying to move faster any tolerance in the belts, bearings, etc will be magnified into poorer quality output as the speed increases. For this reason many plotter machines use firmware/software to provide for longer delays as the speed is set faster so that the mechanism can recover from acceleration and deceleration. For small area work such machines never achieve their potential top speed even if the user sets full speed in the software
With galvo technology, having fewer moving parts not only contributes to faster output without any significant loss of quality, it also minimises downtime and unnecessary ownership costs due to wear and tear. It’s almost always the case that galvo lasers are significantly more reliable than their plotter based alternatives.
The optic of a galvo laser will be static (not moving) above the work piece. The beam will be focused through a complex optic called an F-Theta lens. The lens holds the beam in focus over a defined flat field marking area. By interchanging the lens it is possible to vary the available marking area and the size of the focal point (spot).
There are many advantages to this design;
- The lens sits further from the material so it’s possible to engrave inside things like bowls, cylinders, etc
- Contamination is almost non-existent; meaning longer part life and lower maintenance
- For some models it’s possible to engrave the surface of a 3d object at high speed with the focal point following the curve of the surface.
So what’s your angle?
Plotter lasers can only engrave at speed in one axis: the X-axis. This is otherwise known as ‘raster mode’ or ‘raster engraving’ and is similar in function to how an office inkjet printer will deliver ink to paper with the head scanning the material from left to right. With this process the angle of the beam delivery is always in the zero plane (at zero degrees or in other words from left to right).
For galvo lasers the terminologies for ‘raster mode’ are ‘hatch angle’ or ‘scan angle’.
For many jobs a better quality of output and/or an even higher process speed can be achieved by marking at an alternative angle such as 90 or 60 degrees. By simply changing the scan angle it’s possible to save large percentages off of the process time.
Because a galvo laser can move both the X and Y axis simultaneously it possible to deliver the beam at absolutely any angle.
Almost all galvo lasers are designed with industrial applications in mind. So when it comes to software in most cases a galvo laser will have many more functions for marking than the best of the plotter lasers could ever have. For example, automatic/variable data input, all forms of 2d and bar-coding, image marking, date/code marking, etc.
How big a difference can it be?
The answer to this question very much depends on the application and the job at hand, however, taking the example of marking something like a key fob the process speed of a good quality plotter laser will be in the region of 30 seconds. By contrast an entry level galvo laser would be capable of producing a higher quality result in less than 5 seconds; at least 6 times faster.
Can you rely on a galvo?
A galvo laser will not only deliver exceptional quality at high speed. It will also deliver millions of marks with amazing reliability even when work continuously over a number of years.
We have installed many such systems to customers who operate them faultlessly 24/7 well in excess of 5 years
Can you handle it?
Built to work with industrial applications you would expect a galvo laser to be connectible with some form of automated handling. This isn’t always the case for some machines on the market, so if you are now interested to look in more detail at galvo laser marking technology then look very carefully about how adaptable it will be if the needs of your business grow.
A good machine will connect to almost any handling device without any form of significant upgrade; hardware or software. You’d be amazed by how much a good handling device can increase throughput as well as minimise operator errors.|