A laser cutting torch generates a sudden and forceful concentration of energy initiating the cutting sequence. Each pierce point takes a toll on the torch until it eventually requires replacement. Reducing the number of pierces used when laser cutting will extend tool life. An effective way to extend torch life is to pierce once and cut as many parts on a sheet as possible. Here are some techniques to reduce pierce points for laser cutting.
Common-line Nesting and Cutting
Common-line nesting is the practice of arranging parts so that neighboring parts have a shared edge whenever possible. This allows the laser to cut along a common-line to make a single cut where two may otherwise be needed and move uninterrupted from one part to the next. Pairs of parts may be common line nested and be cut using a single pierce point.
Reducing the number of pierces used when laser cutting will extend tool life. “Soft Piercing” is a technique used to reduce pierce points for laser cutting.
Programmers may consider using a soft pierce to extend torch life. The laser makes a series of pulsations rather than a sudden burst. This sometimes allows the machine to initiate the cutting path on an actual cut line, eliminating the need for a lead-in. On the downside, however, soft piercing can add more time to the job.
Common-line nesting for laser cutting requires experience. Most parts require space for lead-ins and optional lead-outs. The programmer must leave ample space around parts so that the laser can move from one part to another. The amount of space around parts depends on several factors including material type and thickness, the cutting process, and the shape of the parts.
Merge Pierce Points
Like common-line cutting, the merge approach to initiating a series of cuts begins with a single pierce point. In this case the pierce point serves as a hub allowing the laser to move out to cut a part before returning to the place of origin. From there, the torch can proceed to cut a new part utilizing the existing pierce point.
Laser Cutting – Bridge Cutting and Chain Cutting
- Bridge cutting moves from one part to the next cutting through the skeleton and continuing on to the next part without lifting the head.
- Chain cutting is similar in that it provides a continuous cut. The difference is that chain cutting will lead out of a part, cut through the skeleton and lead in to the next part, again, without lifting the head and piercing into the next part.
Experienced programmers can have a significant impact on all aspects of laser cutting. Manual pierce point and lead-in manipulation can be set by the programmer to reduce laser pierce points. In addition, knowing when to use each of the previously mentioned methods (Bridge Cutting, Chain Cutting, Common Line Cutting, Soft Pierce) and where to place leadins and lead-outs, for example, are key.
SigmaNEST automatically reduces laser cutting pierce points by creating a “step-out eyelet” cutting approach to dramatically reduce the number of pierces in a nest. The program improves on the limitations of bridge cutting and chain cutting by cutting each part completely while optimizing the lead-in placement for the next part automatically. The software creates an eyelet into the skeleton as it cuts the part, and then places the next lead-in in the eyelet area, eliminating the need for a pierce.