17 Replies Latest reply on Sep 25, 2017 11:49 AM by Eric Eubanks

    Is it ok to not dimension the molds?

    Eric Eubanks

      I wouldn't think you need to dimension the molds because the people at the shop can just look at the drawings for the parts. I would think you only need an assembly drawing to see how all the molds fit together. Also if this is true what do I do if it's a one piece mold. Can you have a one piece assembly?

        • Re: Is it ok to not dimension the molds?
          Dave Dinius

          I would really like to see this "one piece" mold!

          Think hard about that question of one piece being an assembly.

          Make some drawings, you could use the practice.....

            • Re: Is it ok to not dimension the molds?
              Eric Eubanks

              The top of the flag is just flat so there's no reason to have two pieces.

               

              Well of course it seems silly to have a one piece assembly, but I've asked questions like that before and got an answer I didn't expect.

                • Re: Is it ok to not dimension the molds?
                  Dave Dinius

                  That is an (incomplete) insert. This is a (rather small) mold:

                   

                  I have a few mold makers that I work with and don't need to do full dimension drawings for them. This id due to myself working with them for over 10 years now, they know me, I know them I do give them a drawing for the parts that the mold is going to make. If I don't work with these shops, I do have to make my drawings with much more detail. I guess this practice doesn't make me a "good" designer, just an ashhole.

                    • Re: Is it ok to not dimension the molds?
                      Anna Wood

                      Dave Dinius wrote:

                       

                      That is an (incomplete) insert. This is a (rather small) mold:

                       

                      I guess this practice doesn't make me a "good" designer, just an ashhole.

                       

                      No, you are a smart designer....  Efficiently utilizing your cad data and your time.  Reduced Dimension Drawings and Model Based Definition concepts have been around for quite a while now.  They work very well in the right environment.

                        • Re: Is it ok to not dimension the molds?
                          Dennis Dohogne

                          Anna Wood wrote:

                           

                          Dave Dinius wrote:

                           

                          That is an (incomplete) insert. This is a (rather small) mold:

                           

                          I guess this practice doesn't make me a "good" designer, just an ashhole.

                           

                          No, you are a smart designer.... Efficiently utilizing your cad data and your time. Reduced Dimension Drawings and Model Based Definition concepts have been around for quite a while now. They work very well in the right environment.

                          You point out the value of developing a great relationship with your vendors.  Boy does that really simplify things!  They never taught us in school that Great Relationships = Efficiency, but they should have.

                        • Re: Is it ok to not dimension the molds?
                          Newell Voss

                          Not trying to knock down anyone's technique here (as I am guilty of this too), just stating based my own experience. At my last job we had master bases and drawing packs laid out in our library so 90% of the work is already done when after you do a pack&go and completed the design. It is acceptable to minimally dimension the plates, inserts, etc. if you work directly at the shop which the tool is being made, but a lot of tool shops don't staff designers in house or outsource to random vendors based on capacity. Also yes, many class A toolmakers will (should) posses the knowledge to complete a build without the designer telling them what goes where and how but that is not always the case. I would imagine it took a little bit of time before you got familiar with your current setup and what the guys out on the floor expect to receive before you started handing out non-dimensioned prints. This is why I would recommend making it a habit before finding the socially acceptable "easy route" within your company.

                        • Re: Is it ok to not dimension the molds?
                          Deepak Gupta

                          I think you would still need a two piece mold as you can not keep it open

                           

                          In addition, have you added drafts? If not then you would need them.

                           

                          Further are you looking to have rounded corners? If yes then you might have to split the cavity into two plates.

                      • Re: Is it ok to not dimension the molds?
                        J. Mather

                        The mold makers will want dimensions for the mold (at least critical the critical dimensions, as these days they are likely to g-code from the part).

                         

                        Have you included part shrinkage if appropriate for the mold design?

                        • Re: Is it ok to not dimension the molds?
                          Chris Saller

                          Wouldn't the mold part drawings have dimensions on them?

                          Molds should have dimensions on them and be checked/inspected before the parts are made. Molds are expensive, and are more expensive if not checked and you have to redo.

                          • Re: Is it ok to not dimension the molds?
                            Newell Voss

                            Despite all the CAM being done according to the CAD model(s), you still should be generating a full series of prints for every tool.

                            Why? because it is common practice amongst *GOOD* disigner/drafters and you are leaving too much open to interpretation when you don't. Most CNCs are pretty damn accurate but still issues can occur in setup and run so usually mold makers will run a couple quick checks against the print to make sure everything came out clean (PL height, width, length, etc.)

                            Every tool I have ever designed (yes even "one piece" molds..) get a full print pack. assembly with section views, fully detailed plate prints (not including part geometry as this is a QC after the fact and customers will update their prints to reflect your TVs (tool verification dims) including runner size, water line location, etc. You will also generate a BOM for the tool so the toolmakers know what components to use and layouts to show where they go. Not to mention adequate documentation when the tool is damaged and the original CAD model is nowhere to be found.

                            If you are designing molds I would hope you have enough understanding that even in the case of "on piece" molds where all your geometry is biased to one side, you still need an A plate to shutoff on. you cant just throw whatever size/shape "mold" you want into a press and expect it to work. Even without geometry present, you will still make a print indicating there is no actual detail to me machined and include the overall size and height of the plate.

                            • Re: Is it ok to not dimension the molds?
                              Matt Peneguy

                              Eric Eubanks,

                              I think you are getting a much better education about this on these forums than you did in school...I know I am.  I really know very little about injection molding.

                              So, please tell us what material you chose for the flag.  Is it fiberglass, like I think you had selected in another thread for another piece of your assembly?  Or have you chosen another material?  If you answer that question I'm sure you will get more targeted advice. 

                              And as some people have stated, regardless of what your material is, you will need a little draft so that the part releases from the mold. (probably not the 5 degrees I show, but I'm trying to show the point):

                              • Re: Is it ok to not dimension the molds?
                                Doug Seibel

                                No Eric Eubanks, you cannot have a one piece injection mold assembly.

                                 

                                Go to your library and bring yourself up to speed on the manufacturing processes you are designing for.  While you are there, you can also check out "The Solidworks Bible" by Matt Lombard.  It is an invaluable resource for anyone learning/using Solidworks and it is available at your library.

                                 

                                http://catalog.slcpl.org/search/searchresults.aspx?ctx=1.1033.0.0.6&type=Keyword&term=solidworks&by=KW&sort=MP&limit=TOM…

                                 

                                http://catalog.slcpl.org/search/searchresults.aspx?ctx=1.1033.0.0.6&type=Keyword&term=injection%20molding%20of%20plastic…

                                 

                                You've got a massive public library at your disposal, with a wealth of information covering everything you're struggling with.  Why are you not making use of it?

                                • Re: Is it ok to not dimension the molds?
                                  John Kreutzberger

                                  I have been designing and detailing injection molds since 1977. I have learned to simply give the mold-maker what he says he needs and charge accordingly. For many this means supplying an assembly drawing with a bill of materials along with the 3d model. There are a few that don't want any drawings at all-just the model. Other shops want fully detailed drawings of each insert that 'touches plastic' and don't require drawings for the mold base plates. Then I have shops that want details of every mold plate as well. One thing you don't need to do is try to tell a mold-maker what you think he needs. You're likely to learn some new vocabulary if you do that very often.