In this context, advanced punching machines are evolving and specializing their technology to finish complex parts with different types of operations such as drilling, bending, drawing, tapping, marking, sheaving, etc. with the shortest possible programming and cutting time as well as applying processes that facilitate flexible manufacturing, which can be done automatically, manually or semi-automatically. What’s more, the use of 3D allows the cutting sequence to be simulated, which helps to avoid undesired behavior in the actual operation.
In this transformation it is necessary to have a system that clearly defines the desired characteristics and programs taking into account if the operations affect the lower or upper side of the sheet, with the objective of giving a correct order on the use of each tool. Likewise, the system must divide the punching of the sheet in several stages, so that no collisions occur in the machine.
In those cases where the tools allow small folds in the pieces, the programming is obliged to detail the height of the deformations and to treat the radius of the stripper so as not to damage it with subsequent blows, often applying malleable plastic elements that reduce the impact near the drawing. At the same time, the pieces used have changed their typology adopting different shapes (even and uneven), favoring a more efficient use of the space in each sheet taking into account different optimization criteria, both by paths and by angles. To this end, it is essential that nesting automatically selects the required tool according to the type of contour and part thickness and shows the overlap in punching machining.
Under this premise, manufacturers focus their investment on methodologies to remove the skeleton and remnant between the claws. An example of this are those that allow the piece or remnant to be re-trimmed and removed automatically by means of a trapdoor, even applying a rotation to the piece, remnant or skeleton just before removal, in such a way that any nesting can be programmed in the same way as a cutting one. In this evolution, tools such as EasySnap and ShearButton also stand out, whose usefulness resides in improving the finishing quality of the piece, once the nesting is totally punched. Both are complementary depending on the work being done.
The ShearButton allows minimizing problems when working with thicknesses greater than 2 mm and the machine does not have trapdoors. This is the reason why in this case we are obliged to generate micro cuts, running the risk that they will not hold out before completing the nesting if they are made too thin. The workpieces may come loose during machining. In addition, filing these micro cuts with such large thicknesses is laborious and the exterior finish is not very satisfactory. Thanks to the ShearButton, this type of inconvenience is minimized.
When the machine punches the whole nesting, this punch moves the micro cut up or down, in such a way that when extracting the pieces manually it is easy to separate them and the finish of the pieces, whilst not perfect, is much better than when not working with this punch. For thin thicknesses (up to 2mm in hardened steel and 1.5mm in stainless steel), the appropriate tool is EasySnap, a punch that hits the sheet metal in such a way that it tears the top and bottom of the sheet metal (about a third of the sheet thickness on each side). In this way, the nesting remains attached until the end, thereby reducing vibrations. Once the nesting leaves the machine, the operator only has to break the joints between pieces, bending the sides a little. Its great advantage is when nesting, where the pieces can be placed without leaving gaps between them or micro cuts.
