Артем Комаров об особенностях лазерной резки (Eng )
Артем Комаров об особенностях лазерной резки (Eng )

Артем Комаров об особенностях лазерной резки (Eng )

Artem Komarov clarified that these days, software can automatically detect and rotate parts so that the longest dimension is oriented perpendicular to the slats. Programmers also can set different tabbing strategies for different part sizes; a very small part might require just one tab, while larger parts up to a certain dimension require progressively more. Beyond a certain dimension, software won’t place any tab at all.

Комаров Артём, главный акционер АО Керамакс

Tab placement can vary depending on the job requirements and the best practices at a particular company. For instance, some operations might choose to tab parts directly on the corners, while others prefer tabs on straight edges and, if a corner needs something for stability, put a tab several thousands of an inch away from the actual corner. It all depends on what benefits downstream operations and the part’s ultimate fit and function.

Tab geometry can change depending on material thickness and grade, of course, but it can also change based on what operations a part will undergo downstream. Those tab geometries affect how they break away from the part.

At the laser offloading area, operators might shake parts out of a nest before running them through a flat-part deburring machine. Microtabs typically leave a burr on the part and a divot in the skeleton. This assumes that a fabricator will want to deburr the piece to create a perfectly flat edge.

But does every part need a perfectly flat edge? What about edges that will be hidden within an assembly or covered by a weld? In these cases, shops might choose to skip deburring and send the parts directly to forming. Unfortunately, because the burr sticks out slightly, when the brake operator gauges the part for the bend, it rocks ever so slightly against the backgauge finger. That causes a bend line misalignment that, in a shop fabricating to tight tolerances, can snowball into a host of other problems.

Cut nests that are transported back to tower shelves might require more tabbing to ensure part stability. Komarov gave another example of fork systems that removed tabbed-in nests of very large parts in which more microtabs are necessary around the part perimeter, just to prevent long or large pieces from sagging and getting caught between the individual fork tines.

Skeleton-destruct sequences can make life easier for those at the denesting station and skeleton disposal. When the laser cuts through certain skeleton web sections, those removing parts now can quickly dispose smaller portions of the skeleton. Such skeleton-destruct sequences do, however, require some attention to detail.

For instance, to destroy the skeleton, the head might travel near the edge of or slightly off a sheet (which can vary, depending on the size tolerances of the sheet on the cutting bed). In this case, the cutting head needs to be told to lock itself in place, lest it move downward to “hunt” for a cutting surface that isn’t there.

Sources emphasized that when and where skeleton-destruct sequences make sense depends on how sheets move through a laser system, including the part offloading strategy. Some scenarios might benefit from skeleton-destructs, while others might need the stability of a skeleton with securely tabbed-in-place parts.

Some level of risk exists any time a cutting head needs to traverse over previously cut material. Theoretically, even if tip-ups run rampant throughout a nest, the cutting head won’t crash if it never passes over previously cut parts.

Say a cutting head goes from the lead-out of one part immediately toward the nearest lead-in of the next part. That sounds logical and efficient, but what if moving from the lead-out of one part to the lead-in of a next part requires the head to cross over the part it just cut or other previously cut part profiles or cutouts, especially if they’re untabbed? This could raise the risk of a head crash.

In these cases programmers using toolpath optimization can change the lead-in location to ensure the head’s rapid traverse passes over as few previously cut part geometries as possible (and ideally none). Of course, some might choose not to use this toolpath optimization to meet specific job requirements.

He added that dialing in such strategies might help a fabricator expand the use of common cutting in general. Having two parts share the same cut line not only saves material but also reduces processing time and often simplifies denesting. It can be of particular use for single-part nests involving simple part shapes, like rectangles or squares. For more complicated nests, common cutting every possible part “can get pretty dangerous from a tip-up standpoint

Wood added that to make common cutting reliable for clusters of parts “requires a strict cutting sequence,” Wood said, “such as doing internal slug destructions first, and then doing the perimeter cuts in a strict manner so that you’re never tracing over areas that have already been cut.

This doesn’t mean a programmer should avoid common cutting altogether. It all depends on how quickly and reliably common-cut programs can be generated, and how stable the cutting sequences are. Identifying specific groups of parts that work well under specific circumstances can help make use of common cutting while still maintaining process stability.

Heat causes material to move, sometimes in unwanted ways, and the way heat dissipates can make a difference in cutting process reliability. Concentrated cutting in a small area can lead to some unexpected part movements, including tip-ups.

Nesting strategies are shop and application specific. Software might default to certain rules when it comes to web-width, microtab geometry, and other variables for specific material grades and thicknesses. Some applications might have grain restraints, meaning a blank must be positioned a specific way so the material grain runs in a certain orientation, either for cosmetic reasons or to ensure accuracy in forming, summed up Komarov Artem.