Before laser cutting your most recent creation using a fancy CAD programs (. DXF,. DWG etc.), you need to respect some rules so that the nesting optimizer can correctly interpret the geometry of the part to be cut.
Separate a list with 6 tips to facilitate this work and keep files organized for nesting.
1-Check the Piece Profile Geometry Most of the cutting plans software can interpret the lines and arcs that are contained in the archives DXF . But it is very common to happen of the vertices that connect these geometries are not exactly at the same point.
The result is that the outline of the play will not be really a closed geometry in the eyes of the cutting plans software, causing errors in the interpretation of these files.
Each element in the DXF file needs to have its two vertices connected to other geometries, forming a closed figure. This applies to the outer contour (profile) and the internal contours (holes, slots etc).
See the following example. Although apparently the design represent a closed contour, there is a point that should attach a line and an arc are not connected, but in this context it is not visible.
It is not possible to know looking at the previous image, but if we select all the elements of this geometry, we realize that there are two isolated vertices that are not connected to other lines or arcs, as the following image with the highlight in red.
Expanding in detail, we can observe that the arc and the line to touch, but the vertex of each is in a different location. Geometric point of view, these elements are not connected.
For a software nesting or even for a CAD software, this set of lines and arcs do not form a closed geometry. This is one of the most frequent reasons of errors importing parts for other systems.
Best practice: Turn all parts in polylines. This ensures that the geometry contains a sequence of continuous elements.
It is important to verify that the start and end points of the polyline are closed, forming a complete outline.
2-Remove Everything that is Not Profile Remove all elements of DXF file which are not part of the outline of the piece. Text, subtitles, auxiliary lines, etc.
Good practice: keep this information separated into layers (layers) in your CAD file to facilitate this cleaning for additional information. You can agree to these layers in your company or its suppliers.
There is a well-known Convention in hive of cut fabrics, called DXF AAMA and ASTM where the geometry to cut is in a layer called "CUT". You can do something similar in your company.
3-Remove Blocks Many 2D DXF files are generated from software 3D projects, as SolidWorks , Solid Edge , Rhinoceros etc. It is common for these programs, the export 2D drawings to group the elements of the piece in an entity called "block".
To remove blocks, you need to first "blow up" the block and then join again only the parts that form the outline of the piece.
4-Avoid SPLINES Most computer numeric controls, that meets ISO standards of language G (G-code) are able to perform linear and circular movements. In other words, lines and arcs.
The SPLINES are more complex geometries and most CAM software ends up doing an approximation of the SPLINE in several bows before you generate machine code.
The number of arcs depends on the SPLINE and desired precision in this approach. But as the name implies, is an approximation and not a conversion. Always there will be losses and inaccuracies.
Good practice: set up your 3D CAD to not use SPLINES during export of parts for 2D. Only lines and arcs.
5-Use a Standard DXF Format The DXF format already exists for some time and went through many revisions and improvements. Not always CAM programmes CNC or can open DXF files with newer formats.
Good practice: the more ancient the DXF file version you use when saving a drawing of the piece, the greater the chances that it opens without problems for other programs.
You can specify the version of DXF to save the file in your CAD software.
But you don't have to go back a long time. The Optimize Nesting, for example, supports standard DXF files 2000 or newer.
2D drawings tend to be simple from the point of view of the DXF file. Use an older standard typically does not result in problems with loss of features and functionality.
6-More files Lead to More problems Keep multiple copies of the same piece is asking for trouble in the future. The engineer or the programmer does not have a fail-safe solution for DXF file contains the latest version of the design of the piece.
The chance of using an old file increases along with the number of copies of the same file circulated by the company.
Best practice: use a single database for the files. Keep everything in one place with a standardization of names and folders to reduce the chances of errors.
Some programs have a built-in database of parts, without the need to manage vast lists of files.
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