Sheet metal fabrication – CAD / CAM to manufactured Part
I have listed out below the main design steps that we take when developing your sheet metal fabrications with our Radan software.
1. 3D model in Radan
The information we receive from our customers may be in the form of a 3D SAT or STEP file, a 2D DXF, DWG or PDF file or paper drawings. Sometimes we will be given a sample to copy or adapt to the specific needs of our customer for their own project. The majority of the time if the sheet metal fabrication has any bends we will generate a 3D model as the starting point for the project. This enables us to check out the fit of several sheet metal fabricated parts that might have to fit together such as the box shown here with its surround and flat plate. Often we are called upon to supply this assembly data back to our customers for their checking before we start production and this can be very helpful in checking our customers own drawing dimensions.
2. Developed 2D flat sheet metal blank
The 3D software model of the sheet metal fabrication is then used to ‘unfold’ the parts into developed blanks. This process takes care of any sheet metal gauge bend allowances that will have to be applied to the specific part thickness and material type. If done correctly this will enable the CNC bent part to fold back up to the correct sizes to match the original 3D model. This also has the advantage of removing the need to try out sample parts first for simple sheet metal fabrications as the trial work can be carried out within the software.
3. Developed sheet metal blank cleaned with inspection information
The next stage is to clean up any corner notches that will not suit the CNC tooling, ensure all the details on each face of the box are correct to the 3D model and add any inspection information that might be important to the manufacturing processes for the sheet metal fabrication.
4. Sheet metal part CNC punch press tooled
The Radan software can use the standard CNC tool library that we have to try and match features in the sheet metal fabrications with the correct CNC tool. The library of parts can be seen on the website under the tooling section. This is the stage where the skill of the CNC programmer is also needed to ensure the correct tools are selected and the least number of hits as used to produce the most efficient CNC punched part. This is also where we have to decide how the sheet metal component will be removed from the sheet. It may be tagged at its corners, CNC punched completely out of the sheet to be removed by hand or CNC punched out and allowed to drop through a chute in the Trumpf punch presses into a collecting bin below. This method is usually used on small sheet metal fabrications that may not have an important cosmetic surface finish. There is a video link below of our Trumpf 3000R CNC punching some mild steel bracket through the machine chute straight into a bin below.
5. Sheet metal parts are CNC nested for best sheet layout
The Radan software nester utility is then used to find the best fit of the components to a given sheet of metal. Odd shaped parts can be fitted together and smaller parts CNC punched from the gaps between larger sheet metal parts or even from within window features. The better the fit that we can achieve the higher the sheet metal material yield the cheaper the final part price will be. This becomes all the more important with more expensive materials such as stainless steel, aluminium alloys and brass or thicker sheet materials. With the Trumpf CNC punch presses we can program to produce sheet metal parts from between the machine clamps enabling still more sheet material usage.
6. CNC punch press tool clearances within the sheet nest
The software is also used to check that all the CNC tooling and individual sheet metal fabrications are not overlapping each other. It is also important that the CNC nested sheet is strong enough in production to hold together whilst being CNC punched on our Trumpf punch press machines.
7. Order text is generated to guide the CNC punch press production order
The exact order that the individual CNC tools are punched into the sheet metal can be controlled which is important if you have forms in the sheet metal fabrication such as louvres, dimples, tapped plunged etc as they need to be CNC punched after any other holes or they will be damaged by the head of the Trumpf machine.
8. Production verification is carried out
This stage of the CNC programming allows us to see on the screen within the software what the Trumpf CNC punch presses will do when the sheet metal is being CNC punched. At this stage any strange movements of the sheet metal can be corrected to give the best punching path is production.
9. CNC punch press code blocks
The ‘blocks’ are automatically written as the code needed to talk with the Trumpf punch presses to instruct them when to punch, which CNC tools to use and where to punch on the sheet. This code should need no alteration by us as Radan automatically writes this code based on the order text written in step 7.
10. Final manufactured sheet metal fabrication
The final part after CNC punching, de-burring, CNC bending, welding, cleaning up and powder coating. The sheet metal fabrication is now finished.
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