39 Replies Latest reply on Sep 19, 2017 9:26 AM by Matt Peneguy

    Fabricated parts made from cut plates

    Matt Regan

      I'm looking for advice on methods for modeling a part that will be fabricated from cut (laser, water jet, plasma, etc) plates of steel and then welded together.

       

      I have been using solidworks for many years to make parts for CNC machining and assembles of such parts, but I'm having trouble figuring out a good workflow for these kinds of models. I recently did some front suspension components for a truck:Right front no lift.JPG

      For each of the three major components I started with a solid body made from extrusions, I would then use various combinations of split, shell, and extrude/cut to separate each plate into it's own body within the part. I then saved each body to it's own part, and created a drawing to be cut. It worked, and allowed for some adjustment to the base geometry, but it was very tedious...

       

      I've been experimenting with a couple other methods, but haven't really found one that clicks.

       

      Building the with sheet metal features seems to be more geared towards parts with bends rather than cut seams that will be welded. If I try to take a shelled solid and just rip every edge, the program complains that the pattern is too complicated and won't let me finish the feature.

       

      That lead me to try making a weldment part with custom made library profiles for flat plate, and then cut the profile of each plate sketching it on the outside surface and cut extruding it. Saving out each plate and then arranging them for drawings for the cutter is still a pain though.

       

      This worked fairly well but also seemed like a bit of a hacked way to do it. Is there a better workflow that I haven't stumbled upon? Does anyone who works with these kind of parts have advice? Even a file that I could open and look at the steps to make it would be a great help! I'm looking for a clean solution that I can tweak the overall geometry without having each plate break and need 100 little errors to be fixed on each feature when I change an angle from 10 to 15 degrees!

       

      Thanks!

        • Re: Fabricated parts made from cut plates
          J. Mather

          I am thinking surface modeling and multi-body Thicken each plate.

          • Re: Fabricated parts made from cut plates
            John Stoltzfus

            Now I'm in the furniture industry after spending many years in fabrication and equipment design.  Over the years I have tried many different approaches as well, some good and a lot bad so to speak.  I have come to the conclusion that for me there is only one way to design, if your product needs parametric adjustments and or you have the probability to have more then one size.  Another factor is your companies workflow.

             

            I know there are different approaches that work, but how well do they work if you need to make changes, how well do they work if you need to completely change out a part, like delete and replace with another, then what happens.  Do you want easy to change designs?

             

            This link is called out for large assemblies, however I use the same process with only a handful of components as well

             

            Skeleton Sketch Part Method for Large Assemblies 

             

            Ask if you need more info..

              • Re: Fabricated parts made from cut plates
                Matt Regan

                Thanks John, I will look into that!

                 

                Mostly as far as adjustments go, I'm not too worried about radical redesigns, its more of like tweaking the bend angle on the lower control arm in the picture above, then I would also have to tweak the vertical tower on the spindle to match. I spent a lot of time making small tweaks and then going back into the assembly and checking the range of motion of all the parts and making sure that they moved right. Of course that is something that would be specific to suspension like my example, but the general idea still would work for say chassis design. With the method I used I was still able to do pretty significant changes to the base geometry but occasionally it would break the part and I would have to go through numerous features correcting problems.

                  • Re: Fabricated parts made from cut plates
                    John Stoltzfus

                    Matt Regan - All my Designs are set to where I can stay in any assembly and make my changes right there> Did you know that if you name your sketches and any dimensions in the sketches that you can change them by going to the equations dialog box and filtering dimensions? Then all the dimensions are shown and all you need to do is change the value and rebuild and everything moves accordingly. 

                • Re: Fabricated parts made from cut plates
                  David Matula

                  wow  plasma cut parts....your really getting into that with some complex design and fabrication. Have you considered 3d printing of some of the components...depending on use there is plastic and carbon fiber printers out there that can make the parts.  As far as modeling the parts for a flat 2d cutter all you really need is the flat profile that your planning on cutting....Sheet metal would be the way to go to get there just make sure that your settings are proper for the parts that need the bends and curves that you need to add to the parts once they are cut or your parts may end up to short, leading to redesign or a little long which means cutting and grinding....

                  The work flow...and features that you would use for this come from what you know how to do with the program...one feature may be better than another but  if you don't have the time to invest in learning how to use it then it is best to go with what you know..

                   

                  The best thing I can think of if your really wanting some info is to hit up the local user group and do a presentation on what you make.  Go over the steps and show some of the tools that you use...Someone has bound to come up with a few questions....or suggestions.  You may teach someone how to use the program better and also learn something yourself. 

                    • Re: Fabricated parts made from cut plates
                      J. Mather

                      David Matula wrote:

                      .......your really getting into that with some complex design and fabrication. Have you considered 3d printing of some of the components.......

                      This is simple planar plate geometry.

                      Are you using 3D printed components for the suspension on your truck?

                        • Re: Fabricated parts made from cut plates
                          David Matula

                          as the tech improves I can see printing parts for the truck...not sure about the suspension....think I would go to the parts store for that...and let the mechanic take care of it...not sure if he only works with suspension or what but some of the complex welding and fusing of metal could be taken out by 3D printing if the strength of the materials available will work for the application...

                            • Re: Fabricated parts made from cut plates
                              Matt Regan

                              I do love 3D printing, it's so much fun to design a part and then just print in rather than all the complexities of machining. As a matter of fact, we have a desk top machine that is currently giving me headaches I'm writing this as I wait for it at the moment! ... Unfortunately that method of production isn't really applicable to these kind of parts and there's no way they would hold up a 3/4 ton diesel truck! Hopefully someday the tech will advance to that point though. For now, CNC plasma cutting and or laser/water jet is easy enough to have a local shop cut for me, the turn around time and cost is pretty low. Hopefully soon we will have an in house plasma table that will further reduce this!

                                • Re: Fabricated parts made from cut plates
                                  David Matula

                                  Plasma cam makes a little table 4x4...with indexing.  I was looking at one of these for an exciting business opportunity till I ran the numbers on it and decided that the return would not be worth it.  People think that metal art is cool and all till you quote the a price.  Nothing like spending a week drawing up and programing something for someone then they think that the time is worth $25 instead of $100.  The plate to cut it out of would cost more than that...Then again if I was a salesman I would not be drawing things up.

                                  When looking for the table standard plate size is important.  The next thing to worry about is the type of plasma cutter that you are going to use with it.  Thickness of materials to cut speed and details come in here.  Then the quality of the air that the plasm would need.

                          • Re: Fabricated parts made from cut plates
                            Elmar Klammer

                            Hi Matt,

                             

                            Just from a manufacturing point of view i would combine many of your single plate and replace them with formed sheetmetal.

                            You will save a lot of welding & fit-up time not to mention heat distortion due to all these unnecessary welds. Besides that I would suggest to model it the same way you build it. That would require sub weldments or sub assemblies. Since you will have a left and a right version I would suggest you model the components with symmetry in mind.

                            Go to Tab and Slot - YouTube and you will get some good ideas on how to position plate for easy fit up. Great tutorials.

                            Might not fully apply in your case but some would for sure.

                             

                            Elmar

                              • Re: Fabricated parts made from cut plates
                                Matt Regan

                                Thanks Elmar.

                                 

                                I'm not too concerned with manufacturing as most of my jobs are custom applications, otherwise I would agree about the bends. As it is, the flat plate method works very well for me because I'm a welder so I can stitch them together pretty quickly. I can also make a single flat pattern and then just assemble it "upside down" to make the other side in a case like the suspension example rather than having a mirrored bent part. For a lot of these parts the TIG weld stack of times look is more desirable than a bend from a cosmetic standpoint too.

                                 

                                For tab and slot I have used a couple interlocking features, you can kind of see them in the back of the lower control arm in my picture. there is a "spine" inside for extra strength with tabs to locate it. For me, usually I will add slots to a design if I end up refining it for something I have to make a lot of.

                              • Re: Fabricated parts made from cut plates
                                Glenn Schroeder

                                I think I can simplify your process a little bit.  You said you separate the bodies of your original multi-body part into separate Parts for Drawings.  Maybe you have one, but I've never seen a need to do that.  The "Select Bodies..." button (see #15 at Frequently Asked Forum Questions) works wonderfully.

                                • Re: Fabricated parts made from cut plates
                                  Matt Peneguy

                                  Matt,

                                  You have received some pretty good suggestions, already.  You may also look into weldments.  You could create that part as a single weldment.  Then show the bodies separately in your drawings.  This would keep your bodies linked to your model. (The below method may work with your existing model, if you didn't use "merge solids" to create it.)

                                  I'll show you how it works, because somebody on these forums showed me.  Take this bridge, here (yes that's a single weldment part):

                                  I drop the part into a drawing, and use "Select Bodies" to show just the body I want to detail.  For instance I can select one of those W shapes to detail:

                                  Now I can detail that part only:

                                  I hope this helps.

                                  • Re: Fabricated parts made from cut plates
                                    Paul Risley

                                    Multi body part without saving each file is how we handle it. We run laser cut/ machined parts frequently. Welded structures with post op machining. I mocked up a quick visual of what you have there for an example. Nothing trick and not exactly how I would approach a project. But a quick and dirty part tutorial so to speak.

                                     

                                    Hope it helps.

                                    • Re: Fabricated parts made from cut plates
                                      Jerry Myer

                                      I'm gonna also say, look into 'Weldments'.   It is not what it sounds like.  It is great for inserting orthogonal shapes. 

                                       

                                      ----

                                       

                                      p.s. - if you are like me, your time and attention are being wasted by the snap-to-midpoint feature.

                                      • Re: Fabricated parts made from cut plates
                                        Paul Risley

                                        Sorry for the late response. Attached are some Parasolids and the screen shot of my model I mocked up.

                                         

                                        Hope it helps.

                                        • Re: Fabricated parts made from cut plates
                                          Ryan Navarro

                                          I would recommend checking out the "Convert to Sheet Metal" feature (see attached PDF)

                                           

                                          convert.PNG

                                           

                                          With this workflow you would want to model a solid body to represent the volume you want to enclose (using solid Extrude or Loft features, etc). Then use the Convert to Sheet Metal feature to pull off a plate for each side (one plate per feature). Make sure to have the "Keep Body" option enabled until the final feature so the base body stays there for selection.

                                           

                                          You can also use Convert to Sheet Metal feature to capture press brake bends as well if desired by selecting edges for bends. But using it to just pull off plates for individual sides is very useful for fabricated parts.

                                           

                                          You could also model these base volumes in-context of an assembly which can be a good way to break up larger structures.

                                          • Re: Fabricated parts made from cut plates
                                            Matt Regan

                                            Lots of good advice for making the drawings, I've definitely learned some good methods here!

                                             

                                            Now I'm just looking for a good way to create the model itself. Ryan posted what looks like a pretty good method if I go the route of starting with a solid, thanks for that! It is basically what I did before but a little bit more refined by using the sheet metal tool set instead of just cutting, slicing, shelling, and extruding.

                                             

                                            Are there other ways? In my head using weldments to create plates from 3D sketches and then trimming those to shape seems like it would be a really powerful way to go about it, but it is a very new way of generating geometry for me. Most of my experience modeling and machining parts is with just 3 axis cnc machining and turning so the geometry is 2D sketches that are normal or perpendicular to a primary axis. Learning these new techniques to model parts with lots of off angles, but everything is made out of standard thickness plate (with some "normal" machined parts is both exciting to learn something new but also takes some head scratching. I know lots of guys do this kind of stuff in the offroad fabrication business but they have better things to do than to sit down and teach me! I appreciate all the help from this forum though, I have already learned a lot!

                                              • Re: Fabricated parts made from cut plates
                                                Jerry Myer

                                                the way that I build cardboard boats is I design the hull - the whole boat, as a solid.  Then I shell it so that it is hollow.  Then I put cross section planes throughout the boat like a wine carton.   Now imagine putting a cross section in there and making a weldment that extrudes both directions to the inside of the boat.  There are other variations of this idea, but I think that is how I do it.

                                                 

                                                DSC00291.JPG

                                              • Re: Fabricated parts made from cut plates
                                                Joseph Dunfee

                                                > Building the with sheet metal features seems to be more geared towards parts with bends

                                                > rather than cut seams that will be welded. If I try to take a shelled solid and just rip every

                                                > edge, the program complains that the pattern is too complicated and won't let me finish the feature.

                                                 

                                                Just to throw out a half-baked idea, I wonder if adding a dummy tab, that you know to ignore, might be a way to trick the program into letting you use sheet metal.  You would later have to manually edit out that extra tab from the flat pattern. This would probably have to be done in such a way that the association between the 3D model, and the flat pattern were broken.

                                                 

                                                -Joe