39 Replies Latest reply on Jan 17, 2009 3:30 AM by Paul Lemke

    Manufacturing/ Machining to model - Capable?

    Paul Lemke
      There has been some question over the past couple of years at my company about machining parts to model and I wanted to survey at least people in the SolidWorks forum about whether or not they do and what industry do you work for. I am not talking about doing away with drawings completely. Obviously functional faces that are datums and GD&T must go somewhere and I absolutely do not think that the dimxpert is advanced to the point we can put all tolerances in the model. But I was wondering with the capability of cnc mills/lathes, cast to model, rapid prototyping and CMMs is the complexity of parts grown to the point where it is prohibitive to do FULLY defined drawings?

      So copy the following and answer yes or no (sometimes=yes):

      Machine to model:
      Manufacture to model:
      Inspect to model:
      GD&T:
      Fully detailed drawings:

        • Manufacturing/ Machining to model - Capable?
          Anna Wood
          We do Minimum Content or Reduced Dimension drawings all the time. Have operated this way for several years.

          We have software in place for our CNC mills, Wire and Sinker EDM's, Laser and Water Jet and our CMM's, etc to allow us to operate this way. Works very well and keeps us competitive in today's manufacturing world.

          I have several posts on my blog on the subject.

          Cheers,
          • Manufacturing/ Machining to model - Capable?
            Charles Culp
            All our cast parts are to model (with some dimensions on the drawing). Most are "swoopy shapes", driven either my spline based surface models or imported parts. 10 years ago it would have been done to a physical pattern, now it is just to a "virtual" pattern.
            • Manufacturing/ Machining to model - Capable?
              Michael Closson
              Our toolmakers do the square up of details and do the mounting holes and simple machining. Our CNC dept. does the 3D machining per model. Our prints usually just have a note stating "Machine per CAD data" pointing to the 3D areas. I will include dims. like an overall height or some other ref. checks the toolmaker can do at his bench after CNC.
                • Manufacturing/ Machining to model - Capable?
                  David Anderson
                  for in house machining that works to shop "standards" i think that programming a part from a model and supplying a drawing that has critical feature dims can work. yet if any inspection is done other than linear dimensions e.g GD&T, then i still think you need a fully dimmensioned drawing for quailty control purposes.

                  if one has to send a part out for quote or outside fab, a fully dimensioned drawing is necessary to protect both the engineer and manufacturer. there are so many CAD and CAM platforms that to expect all the tolerances etc to be properly ported and displayed using only the 3d model is pretty lofty. Also, considering that SW cannot even follow published standards andthat dimxpert an oxy, leads me to believe that this is not a path SW intend to follow.
                • Manufacturing/ Machining to model - Capable?
                  Paul Lemke
                  Minimum Content or Reduced Dimension drawings: Awesome tech lingo!
                  • Manufacturing/ Machining to model - Capable?
                    Paul Lemke
                    Yeah I took a look at that a while ago and it wasn't too convincing. Do you use it?
                      • Manufacturing/ Machining to model - Capable?
                        Anna Wood
                        Yes, we use the concepts of the ASME standard for our models.

                        Search Google on some of the terms I have thrown out and you will find a number of good bits of info on the subject.

                        Cheers,

                          • Manufacturing/ Machining to model - Capable?
                            Boy Have I come a long way... Here you go.

                            As a former machinist, I've used both paper and software to produce parts. Models are great to machine from although there is no known CAD/CAM software that I know of to generate the tolerances for common machining practices. Putting tolerances and GD&T in the model Do Not generate to CAM software. A good machinist would still need a detailed drawing to communicate such tolerances and GD&T. There is no lazy way about it. Now in my current position being from my machining background I detail drawings for that interpretation, and yes we use ASME, ASTM, MIL-SPEC standards etc. Standards are in place so when one orders an apple one gets an apple. As we used to say while machining 'Part to print - Print to part'. Meaning to put it on the drawing. You WILL get what you ask for. What's your cost...right.
                              • Manufacturing/ Machining to model - Capable?
                                Anna Wood
                                Michael,

                                I will dis-agree with you to a point. We do reduced dimension drawings. Nominals are drawn from the math data. We do provide a dwg with gdt, tolerances, critical dimension/notes, etc.

                                We do this everyday with a lot of success with our manufacturing people, both in house and out-sourced. There is very little that we are not capable of manufacturing in house for the products we sell and contract manufacture/design.

                                Totally math model based with all of the PMI (Product Manufactuing Information) info embedded in the model is a bit tougher. The main reason we do not do that is we would have to invest in more computers to have on the shop floor.

                                We are not a company that scrimps on computer resources either. We have better IT resources then most very big companies. There is a point though that we do not have the added gain by going 100% Model Definition Based. So we have come up with best practices for our company that gives our manufacturing personal what they need and keeps engineering from spending non-value added time 100% dimensioning drawings.

                                Cheers,
                                  • Manufacturing/ Machining to model - Capable?
                                    Dwight Livingston

                                    Anna Wood wrote:

                                     

                                    . . . We do reduced dimension drawings. Nominals are drawn from the math data. We do provide a dwg with gdt, tolerances, critical dimension/notes, etc. . . .

                                    Anna

                                    That describes our approach. Our drawings also provide revision control for the model file, by specifying the model file in the drawing note.

                                    Our system lacks the use of models for inspection. Any dimension we want measured, ever, has to be on the drawing. Our metrology people are not going to open models and measure the solids. I would like to see the time where we scan parts and compare the scan to a nominal model. I've seen the instruments amd programs that do that, but they do not yet have the precision we need. We'd need around a tenth of mil, and I have not seen close to that yet.

                                    I do wish, also, that our company had the same attitude as yours about our computer gear.
                            • Manufacturing/ Machining to model - Capable?
                              Paul Lemke
                              I have had some problems trying to convince people that the model is often more important than the drawing if people use it to machine to and inspect to of course. There are a few parts I have seen on several occasions where the model had no draft but then a note was added that said draft this surface one degree. Can you guess what the actual part looked like? That's right NO draft. Certainly drawings can be useful for specifying tolerances, datums and areas of concern but models are much better to communicate shape. It is this fact that is the root cause that autoCAD (2d) lost and solidworks and other 3d companies won.
                                • Manufacturing/ Machining to model - Capable?

                                   

                                  Certainly drawings can be useful for specifying tolerances, datums and areas of concern but models are much better to communicate shape.

                                  Let us not pat you on the back so soon Paul. Most of us are in the business of precision. The MODEL obviously didn't communicate a draft. As you stated...

                                   

                                  models are much better to communicate shape

                                  . What is your cost? Doing it right the first time or find out you have a problem later? Designers CANNOT get lazy. Machinist are not mind readers.
                                  • Manufacturing/ Machining to model - Capable?
                                    David Anderson
                                    hi paul,

                                    i would argue that the reason autocad lost was not because it was 2d, for it was 3d wireframe and had 3d solid modeling long before SW was on the scene. It lost cuz it was a low rent 3d package. i know cuz i used its 3d wireframe for machine design and 3d solids for designing instruments for the hubble space telecscope (no, not the primary mirror). it was tailored to architects and by the time acad decided to get into parametrics it was too late as SW was had a jump start from the ProE folks who alread knew parametrics.

                                    w/o a print, you will end up with something other than what you want. perhaps there will be another another medium to take the place of drawings, but in the forseeable future i cannot rely solely on the cad model for the end product. on the bright side, there is a great benefit to creating drawings and that is i find all my errors when i detail a print like wrong tapped hole size etc. so i find it to be a valuable check process as well.

                                    just my 2 cents...

                                    dave
                                  • Manufacturing/ Machining to model - Capable?
                                    Paul Lemke
                                    I have been trying to convince people at my company that Anna's way is the best way. and I can't describe it better than to use her definitions. Minimum content or Reduced dimension drawings can cut design time up to 60% and provide manufacturing with the least amount of re-input errors with highly accurate information. Drawings are needed. BUT don't assume you don't have the 3d model at all. This would be ignoring an important aspect of our increasingly "digital" world.

                                    Can I come and work there? )
                                      • Manufacturing/ Machining to model - Capable?
                                        Dear Anna and Paul,

                                        The need for keeping a digital base system is great. I'll give you both that much.

                                        Like you (Anna) our company has a great IT backbone, with computer stations at all CNC machines. We do give the machinist the model so they may produce their tool paths. I ask you this... how often does your shop floor (machinist) come to you to explain a feature? Talk about time management. You now have two highly paid employees discussing what should have been. Who knows maybe a third or fourth party has to join in. While this is going on the machine is sitting idol and not making money. The answer is given and back to the machine. Now has to reprogram the machine to make the changes. What's your cost?

                                        My point to both of you is it just takes a little time to produce a drawing to communicate your needs. Simple drawings I would agree to have 'General Requirements 9900000' take care of it. It does save cost, but opens up wide range of guess work for tight tolerance work.

                                        A man walks into a Mexican restaurant orders beans, ground beef, lettuce, tomatoes, and cheese with a tortilla. Does he want a Taco, Burrito, Tostada, Enchilada etc.? Good thing the restaurant took the time to draw up a menu to avoid such complications.

                                        Sometimes the simplest things need a drawing.
                                      • Manufacturing/ Machining to model - Capable?
                                        Paul Lemke
                                        Michael,

                                        I have seen, much more often, where our machinists come up when the drawings are fully detailed because loose tolerances and mid tolerances cloud part function and design intent. I like putting the extremely functional and tight tolerances on the drawing and then it is very clear as to what is tight and what is "fit to wind." Especially on legacy hand drawn stuff. (We have been open for 40+ years)

                                        It is obvious that some here have not tried reduced dimension style drawings. They are much clearer with intent and as for your Mexican friend. Imagine that they listed every chemical compund that was in that burrito in alphabetical order instead of puttting "#5 burrito" you listed Garlic, NaCl, nitric acid, pinto beans, and the like. We have the menus with combination style recipes. These are the important parts. This is tapped locate to model. It is clear and concise.

                                        Dwight, Our system is all on one drive and drawing numbers match model numbers and revs are on both latest rev rules. I also see your using Adept. I couldn't quite convince management to make the plunge on that. It is way better than PDM eh?

                                          • Manufacturing/ Machining to model - Capable?
                                            Dwight Livingston

                                             

                                            Originally posted by: Paul LemkeOur system is all on one drive and drawing numbers match model numbers and revs are on both latest rev rules.

                                            I don't think that would get by an FDA audit. Our design history and approvals have to be very clear and documented.

                                             

                                            Originally posted by: Paul LemkeI also see your using Adept. I couldn't quite convince management to make the plunge on that. It is way better than PDM eh?

                                            I find some thing about Adept inconvenient. It is more difficult to open a component model if the higher assembly is already open. You cannot save items to the library without closing them in SW and checking them in. Should you want to check in a copy and continue working, you still must close, check in, check out, reopen. It is easy to do the wrong thing and lose a relationship. Some things are handy, but overall I wish we were using PDM Enterprise.
                                          • Manufacturing/ Machining to model - Capable?
                                            Paul Lemke
                                            Let's face it. Drawings involve a lot of interpretation and they also assume your audience knows how to read what you put down per the ANSI/ASME standard. I have seen mill/lathe operators misinterpret the drawing and mirror machine a parts bolt circle or other features. So drawings are not perfect they involve a measure of intelligence in themselves and whenever you have to rely on intelligence you are taking an extra chance that that intelligence makes the correct decision. This is what machine to model does for you. It makes sure that the machine operator is working off of a nominal, machine interpreted geometry set.
                                              • Manufacturing/ Machining to model - Capable?

                                                 

                                                assume your audience knows how to read what you put down per the ANSI/ASME standard. I have seen mill/lathe operators misinterpret the drawing and mirror machine a parts bolt circle or other features.

                                                You need to get better machinist. Send your parts to us.

                                                 

                                                So drawings are not perfect they involve a measure of intelligence in themselves and whenever you have to rely on intelligence you are taking an extra chance that that intelligence makes the correct decision.

                                                Let us do your detail work for you too.

                                                 

                                                (We have been open for 40+ years)

                                                How did 40 years go by without you?
                                              • Manufacturing/ Machining to model - Capable?
                                                Paul Lemke
                                                Nice Michael, good arguments. Very logical. I realize that people make mistakes. Maybe I made one just now in thinking I was posting to someone that could respond logically. Thanks for voting me down too.
                                                  • Manufacturing/ Machining to model - Capable?
                                                    I see your awake now Paul.
                                                    Those were you quotes not mine.

                                                    Bottom line is if one can't take the time to do the job right the first time, get outa dodge. This includes proper modeling as well. I have seen models come to us from other sources with no knowledge of machining practices. A machinist may very well say they can't produce a feature. Designers think it looks good on paper or in this case your computer. Guess what, back to the drawing board. So models are not perfect ether.
                                                  • Manufacturing/ Machining to model - Capable?
                                                    Paul Lemke
                                                    I am NOT saying that models are perfect. I did say that they are better for communicating a nominal shape. I also say that "tolerances must be communicated on a drawing" and yes a knowledge of how it is manufactured is always a must.

                                                    What gives you right to insult my companies machinists because I have seen them make a few mistakes? Our machinists are very good. They know how to "machine to model." Is your companies machinists perfect? Do you expect them to interpret everything perfect? Are you perfect at laying things out? I think my approach IS right. It focuses the machinist on the tightest tolerances and features versus relying on him to make the judgment or expecting him to find the few dimensions on a drawing with hundreds of dimensions. Maybe you just do simple stuff and don't have 20 page D size drawings that could be done on 4 pages with machining to model?

                                                    Of course I am trying to appeal logically again.
                                                      • Manufacturing/ Machining to model - Capable?
                                                        Paul calm down,

                                                        Discussion started with your question on the pros and cons. Do you do full detail drawings or do you manufacture to models? This is a clear communication gap.

                                                        As far as your company... I apologize if I came on strong.

                                                        As far as my company... everything has to be perfect. We work on a multimillion dollar program where one mistakes could cost hundreds of thousands. All I's dotted T's crossed. So the devil is in the details.
                                                      • Manufacturing/ Machining to model - Capable?
                                                        Paul Lemke
                                                        Dwight,

                                                        Really? I could have swore the library card approach was much better than the presentation SW VAR gave on PDM. How long have you been on Adept? and What is your experience with PDM enterprise?

                                                        We do not do a whole lot of medical equipment but we do have ISO 9000/9001 cert and it does pas that.
                                                        • Manufacturing/ Machining to model - Capable?
                                                          Paul Lemke
                                                          Designers think it looks good on paper or in this case your computer.<--- This was you not me and I am calm.

                                                          We also work on multi million dollar equipment. We do turbopumps fer Rockets, and turbo driven powerplants that run in the 70,000 to 100,000 rpm. The devil is in the details and I am telling you that the machinist can see those details better if he doesn't have to go searching through long complex unimportant dimensions for the tightest tolerances. He will find the tightest tolerances easy if those are the only ones on the drawings.
                                                          • Manufacturing/ Machining to model - Capable?
                                                            Paul Lemke
                                                            Yeah, Just one more....
                                                            ASME Y14.41-2003, Digital Product Definition Data Practices
                                                            • Manufacturing/ Machining to model - Capable?
                                                              Paul Lemke
                                                              Thanks Dwight. We evaluated it a couple of years ago so maybe pdm works has changed a lot since then. I know SW has changed significantly in that time.
                                                              • Manufacturing/ Machining to model - Capable?
                                                                Kevin Quigley
                                                                Here's my take on this. I work as a product designer for a number of different companies, and I get involved in setting up design systems. I think what you have in place very much depends on how much work you sub contract out and the nature of the sub contract. Let me give you an example.

                                                                I have one customer who does most things in house - family run, niche market, wide range of manufacturing capability (pressing, forming, sheet metal, injection moulding, assembly etc). When I first started working for them the owner would sketch out a design and take it to the toolroom and they would make it - more craft than science. Tools were made like this as well. The products are not that complex but even so that was the process.

                                                                I started to work with them and used 3D modelling (back in 1994) for design and visualisation, and CAD generated 2D production drawings. One product we did was a hook device consisting of a blanked stainless steel hook shape, insert moulded with a couple of rivetted levers. This took 10 A3 sheets to fully define using 2D CAD. The dxfs were used for the wire cutting the tools.

                                                                I put SolidWorks into their company in 1997, along with CNC Mill, Lathe and laser cutter, driven by AlphaCAM. Within 12 months the designers were sending packages out to the toolroom that consisted of fully dimensioned and toleranced drawings, dxf blanks for laser cutting, BOMs linked to models, models with the SolidWorks Viewer. We put in a quality process whereby a designer and toolmaker would sit down and check the issued drawings. It was a disaster. The problem was that the toolroom guys could not interpret the design as they saw fit so there was an endless stream of machinists asking for clarification of details and dimensions and tolerances. The other (bigger) problem was that the designers did not have the manufacturing experience to place critical tolerances or even to fully comprehend the process they were specifying. There was a high staff turnover!

                                                                Going forward to now, the design team consists of a manager (who I employed in 1997), supported by 3 designers, all of whom are time served in the toolroom. The toolroom consists of a manager (the same one) backed up by 4 cell leaders, who in turn control production. A lot of the tools are now out sourced.

                                                                My point is that it has taken this company 10 years to move from the "fag packet" to the 3D model. Detailed drawings are still produced but now they are done primarily for the purposes of out sourcing tools or sub contract components. The company knows what they want and what processes they need to achieve it so they are very clever about out sourcing now.

                                                                The other example is a completely different situation. A new start medical company, where we have gone through clinical trials, and moved into volume manufacture and licensing. Due to the nature of development, there were hardly any drawings done at all up until production tooling tenders stage. The reason being that we worked closely with a toolmaker for prototype tooling and this was chopped and changed with each trial. The process was model, GA assembly drawing for approval, model issue with critical dimensions marked (and I'm talking maybe 2 or 3 a sheet max). The toolmakers knew what needed to be done and they knew what had to fit where so we left the tolerancing up to them - it was the end result that mattered.

                                                                Move onto production tooling (£400k investment) and we issued 3D model data, GA assembly drawings and component drawings with the 2 or 3 critical dimensions, and assembly procedures as pdfs, and, most importantly, the prototype mouldings that worked.My experience is when dealing with China for tooling and sub contract manufacture is don't get too precious with tolerancing and how you think it should be made. 9 times out of 10 it won't be done like that anyway, and to be honest as a designer, provided the function is right, I'll always bow to the experience of a manufacturer who makes parts like these day in day out.
                                                                • Manufacturing/ Machining to model - Capable?
                                                                  Paul Lemke
                                                                  Clearly there has been some improvements to both machining programs(like Mastercam) and machines like 5 axis mills as well as machinists becoming a little more familiar with 3d machining. I have worked out of house with other manufacturers, besides our internal shop, and they have had little problems with my reduced content drawings.

                                                                  So just to get a long story shorter. Sometimes it works and sometimes it doesn't? I have to believe there were some reasons to why it didn't work as well as why your last two worked.

                                                                  What the heck is a "fag packet"? A packet of drawings? Unfamiliar with lingo.

                                                                  Certainly designers who do not have manufacturing experience or tooling experience should try to get some.

                                                                  Michael your comments are really unneeded. They are of little or no value. What is pure poetry? Are you delighting that Kevin had problems and couldn't solve them in the 1990s?
                                                                    • Manufacturing/ Machining to model - Capable?
                                                                      Kevin Quigley

                                                                      Paul Lemke wrote:

                                                                       

                                                                      Clearly there has been some improvements to both machining programs(like Mastercam) and machines like 5 axis mills as well as machinists becoming a little more familiar with 3d machining. I have worked out of house with other manufacturers, besides our internal shop, and they have had little problems with my reduced content drawings.

                                                                      Absolutely. These days CAM systems are a lot more robust than they used to be. The reality is that a decent CAM system (like say Powermill from Delcam) operated by someone who knows the process and the software can get results that we could only dream about 10 years ago. Everything gets better - the CAD software, the CAM software, the CNC controllers, the cutting tools, the CNC machines themselves, and most importantly the toolmakers now have a breadth of experience in cutting from 3D models as opposed to manual on machine programming.



                                                                       

                                                                      So just to get a long story shorter. Sometimes it works and sometimes it doesn't? I have to believe there were some reasons to why it didn't work as well as why your last two worked.

                                                                      The main reasons why the process didn't work was a combination of human inexperience, immature technologies and too much control. Back in 1997 this was still fairly new for small UK companies. Sure it was established in the big companies but not smaller ones. Nobody in the process really knew what we were doing - we were learning on the job and we tried to put systems in place that we thought would work. In actual fact the processes settled down after a few years, but it was really only when the staffing issues were resolved that it all worked out. That and the acceptance by the company owners that they couldn't compete by doing everything in house.


                                                                       


                                                                      What the heck is a "fag packet"? A packet of drawings? Unfamiliar with lingo.

                                                                      That would be cigarette packet Paul As in sketch on the back of. It is a figure of speech here - but I have actually seen a tool drawing on a napkin


                                                                       


                                                                      Certainly designers who do not have manufacturing experience or tooling experience should try to get some.

                                                                      This is the missing link in design education as far as I'm concerned. It needs to be more integrated into the curriculum. Having said that I learned more in 6 months at that small company than probably in the 10 years before then. Sometimes designing can be a join the dots affair when it comes to manufacturability and you actually need to do things to fully understand the implications of what you are proposing. I think that the wide availability of rapid prototyping by additive machines has actually made this worse in recent years. I know plenty designers who have no experience of moulding yet happily fire off crazy models for prototyping then present these to customers for approval. Use with care!


                                                                       


                                                                      Michael your comments are really unneeded. They are of little or no value. What is pure poetry? Are you delighting that Kevin had problems and couldn't solve them in the 1990s?

                                                                      Paul maybe I'm seeing the light side but I'm taking it that Michael sees some resonance with my recollections about the issues faced in getting from the design to the finished product?

                                                                    • Manufacturing/ Machining to model - Capable?
                                                                      Paul Lemke
                                                                      Thanks for the input Kevin, it lines right up with mine. I agree with your appraisal of what is possible working directly with a manufacturer or more directly with the guy on the floor who is producing the part. Knowing about woodruff cuters, shaped tools, and what is possible with a five axis mill really helps with DFM. However, we recently hired a couple of younger but really talented guys who have sort of created a renaissance in our shop. Things that were previously considered "impossible" are now easy. Both of them have different angles of coming at specific problems but they have really created a competition among the "mill" guys to "manufacture whatever is on the model. I have also seen that even if I ask a set of questions twice to the same machinist he will not answer the same given a short amount of time between.

                                                                      Some of it could be that they are constantly learning new tricks and they have certain tooling around but I think it is more fundamental than that. I think you really have to see how it could be manufactured which is not an easy job and can be quite tough. It means that you have to keep up on even the capabilities in the shop of specific people and processes. But if you do this and then out-source you are stuck with tailoring the design. Do you pander to the most incapable person or to the median or highest skill level? But there are a lot of processes out there as well. The ASME codes tend to focus on function of the part and not manufacture methodology. So I think this becomes a problem while using it. I think it does depend on the job and the mode of manufacture.

                                                                      This is the primary reason I started this thread and I think I received my answer loud and clear. Thanks for the input people.

                                                                      P.S. His resonance does nothing for him, he knows if he does or does not resonate, does it do anything for others to just know he does? I am guessing you wouldn't be asking a question if you knew what he meant directly? Which is why I stated that it doesn't do anything for anyone if he does not state what he thought was poetry it is useless.