Motion control for laser inscription
Laser inscription is a rapidly growing field and an important component of many industrial production processes. In order to achieve the most precise results, repeatably precise motion control systems are essential. These systems provide the exact positioning accuracy and speed needed to keep up with the demands of high-volume and high-precision laser inscription applications. However, not all motion control systems are created equal.
Having recognised that most laser marking systems are restricted to operating in two-dimensions, and can therefore only scan on the and x and y axes (and in addition also lack the ability to process materials that have a high hardness of low ignition point) ALIO created a range of multi-dimensional motion control systems ideal for demanding inscription applications.
Bill Hennessey, President of ALIO Industries, says: “There are several drawbacks to using a laser inscription motion control system that only works in two dimensions. First, the system is limited in the types of objects it can engrave or cut. Basically, it can only add inscriptions to surfaces facing the marking system, so objects with complex shapes or raised surfaces cannot be engraved with the precision and therefore the quality needed by many customers. Second, 2D systems are also limited in the height of features they can engrave or cut. In addition, 2D systems are also limited in the accuracy of the engraving, as the laser beam is not always able to follow the contours of an object accurately, so the inscription may not be precise.”
A particular and important application is the inscription of diamonds. Without causing any damage, a micro-laser beam is used to etch a microscopic inscription on the girdle of diamonds. The often complex shapes of diamonds mean that 2D inscription machines struggle to provide neat engravings. The need for a 3D or 3D+ solution that is at the same time speedy, precise and repeatable is obvious. Such a solution would also after initial capital outlay save money by reducing the potential for scrap and through improved inscription quality reduce the need for costly post-processing.
There are many reasons why 3D and 3D+ motion control systems are superior for laser inscription applications. For one, they allow for more precise and accurate laser beam positioning, using as they do a three-dimensional axes of movement, which means that the laser beam can be positioned more precisely on the surface of the material being inscribed.
Another reason is that they offer a greater degree of flexibility in terms of the size and shape of the inscribed area, there being no limitations, as the laser beam can be moved freely in three-dimensional space. This allows for much larger and more complex inscribed shapes and designs.
Finally, they also offer a higher degree of speed and efficiency in terms of inscription. With a high-quality 3D or 3D+ motion control system the motion profile is optimised promoting straight parallel movements, and ‘real’ corners rather than curves.
Hennessey concludes: “To overcome the limitations of traditional 2D inscription machines, ALIO has developed compact x, y, z motion control systems, gimbal systems with up to 5 axis, and Hybrid Hexapods that exhibit smooth travel, high stiffness, and low dither which all enhance the clarity and versatility of the inscription. Our compact x,y,z motion control systems are designed to provide high performance and precise positioning capabilities in a small footprint. Gimbals and Hybrid Hexapods are meant to maximise flexibility, and improve quality on complex forms and hidden spots. These systems utilise precision motors for each axis of travel, providing high thrust force and low inertia for rapid acceleration and deceleration. Integrated position feedback sensors ensure precise positioning and repeatability, while programmable motion controllers allow for custom movement profiles to be created. They are suited to laser inscription applications where fast and precise motion control is required in a limited space.”
