12 Replies Latest reply on Jun 29, 2016 9:57 AM by Mark Greenwell

    Assembley or Multi Part

    Mark Greenwell

      Hi,

       

      Can someone offer the benefits of using Multi body part over an assembly

       

      Just need a bit of a option on what you think is the better / preferred method.

       

      I have always used the Assembly function to build the models, either top down or bottom up.

       

      In the main I already have the parts made and just add / constrain in the assembly, however occasionally I make the parts in the context of the assembly.

       

      I haven't had to do any multi body parts and want to know if their is any advantage in using this method over using the assembly.

       

      Will I be able to get a BOM like in an assembly from a multi bodied part, our parts are all unique and made here so no stock items.

       

      This is a screen shot of something I have just done.

       

       

      Thanks

       

      Mark

        • Re: Assembley or Multi Part
          Mark Dougall

          I usually use multi-body parts when I know the sub-assembly is an integral part that is usually just seen as one whole on the shop floor or if it's a bought in component that we have no hand in making. Just go with what would make the BOM easier to deal with really. Multi-body is best for weldments when you need beams to align with each other so you can restrain features to other bodies and allow the whole part to change when you make only one.

           

          Most of the time I'll use Assemblies just because I know I can make configurations if I need to later on. An example of both below is an assembly I made like I usually would because I can suppress individual parts for different configurations but the headboard is a multi-body part because that's a fairly standard item that has some complexity to it.

           

          Untitled.png

            • Re: Assembley or Multi Part
              Mark Greenwell

              Hi Mark,

               

              Thanks for the input, I did read up on it on the internet where it did mention the advantages for weldments or bought in parts, similar to what you have described.

               

              My example was vey basic only half a dozen parts, other assemblies could be more complex and have a lot more parts.

               

              Thanks for taking the time to reply. I will also award you the correct answer, as you were the first to reply.

               

              Mark

            • Re: Assembley or Multi Part
              Thomas Voetmann

              Just as an example.

              I have some VERY complicated plastic parts that comes in pairs. They interact in many places ranging from overall shape to mounting bosses as well as common interaction with other parts.

              I modeled such a pair as multi-body part because it would be next to impossible to control this in a top-down fashion in an assembly

              The feature tree starts with surface modeling to define the overall outer shape (~100 features). These are then thickened or otherwise converted to basically two solid bodies (~40 features). Interaction elements (e.g.. bosses and screw holes) are added and merged to each body (~200 features). At this point I created two configurations - one for each body. Final touch (fillets, draft, stamps etc.) are added in folders to each body in each configuration (~300 features each). The feature tree ends with some clean up so I don't accidently shows the wrong solid. Finally I made an assembly containing the part two times - one for each configuration and fasteners. Using this as a sub-assembly I can control the BOM.

                • Re: Assembley or Multi Part
                  Mark Greenwell

                  Thanks Thomas.

                   

                  Your parts sound a lot more complicated than anything I would ever need to do.

                   

                  So would the amount of features / parts determine if you would make as a multi bodied part or an assembly?

                   

                  Thanks

                   

                  Mark

                    • Re: Assembley or Multi Part
                      Thomas Voetmann

                      In assemblies I don't want part "A" have references to part "B" at the same time as part "B" references part "A". In the assembly it is not easy to control in what order the references are processed but in the multi-body environment it is strictly controlled by the feature order.

                      It is not the number of features in total but the numbers of features that would have external references if modeled in an assembly environment. They might give a performance and maintaining hit. Also the information flowing in both directions calls for a multi-body.

                      • Re: Assembley or Multi Part
                        Glenn Schroeder

                        Mark Greenwell wrote:

                         

                        So would the amount of features / parts determine if you would make as a multi bodied part or an assembly?

                         

                         

                        I work  mostly with steel.  My usual practice is:  If it's welded together, it's a multi-body Part, and gets a cut list in the drawing.  If it gets bolted together it's an assembly.  And assemblies often contain one or more multi-body Parts.

                          • Re: Assembley or Multi Part
                            Mark Greenwell

                            Hi Glenn,

                             

                            Like you I also work in the steel industry, (Heavy Fabrication, bridges towers, football stadiums etc), to be fair 99% of our drawings are done using X-Steel.

                             

                            Not an expert in it but I think that they model the whole job then select any thing that is welded to the main item and make that into an assembly, anything that is bolted gets a unique assembly drawing.

                             

                            So this ties in with what you are saying, welded Multi bodied, bolted single bodied.

                             

                             

                            Thanks

                             

                            Mark

                            • Re: Assembley or Multi Part
                              Mark Greenwell

                              Glenn,

                               

                              Just to be sure on what you were talking about, attached is an assembly drawing (from X-Steel) where we would build this as one part as all pieces are welded. Would you make this as a multi bodied part? or design in an assembly.

                               

                              Thanks

                               

                              Mark

                                • Re: Assembley or Multi Part
                                  Glenn Schroeder

                                  Mark Greenwell wrote:

                                   

                                   

                                  Would you make this as a multi bodied part? or design in an assembly.

                                   

                                  It's hard to say since I've never needed to work with more than maybe a couple dozen bodies, but I'm a big believer in cut list properties, so as long as it didn't bog down my machine I believe I'd stick with multi-body Part.  I'd be interested in other opinions from people that also work with that many bodies.

                                    • Re: Assembley or Multi Part
                                      Mark Greenwell

                                      Thanks Glenn,

                                       

                                      This is quiet a small assembly from what we usually do, we have done some assemblies made of a 100 + individual parts up to around weighing around 60 - 70t an assembly. I wouldn't have to try and model this in SolidWorks as our drawing office do these for us.

                                       

                                      Just trying to get a feel of whens best to use a multi part or an assembly, suppose just carry on doing what I have always done Top or bottom up modelling, might give multi parts a go next time and see if it has any benefits.

                                       

                                      On another issue if you notice on the Left side of the drawing is a weld table, the welds all have a unique number i.e. 001, 002, 003 etc.

                                      Do you know if their is a macro that would look through a SolidWorks drawing for weld and add a sequential number to each weld.

                                       

                                      Thanks

                                       

                                      Mark