Autodesk Inventor and Sheet Metal Manufacturing: From Drawing to Fabrication

Transcription

1 Autodesk Inventor and Sheet Metal Manufacturing: From Drawing to Fabrication Andrew Warren Striker Systems, Striker Technology Solutions, Engineer Support Service MA219-3 Learn how to draw sheet metal parts or assemblies in Autodesk Inventor that manufacturing can fabricate. If you ve been told something can t be made, or been given a model that is impossible to make with their current manufacturing capabilities, join this class to learn how you CAN make it. If you are a designer who works directly with a manufacturing facility, or a manufacturer having problems producing what has been designed, then this class is for you. If you know how to make a part and know how to draw in Inventor, this class will put the two together. About the Speaker: Andy is an applications engineer for Striker Systems in Nashville, Tennessee, with over 15 years of experience with Autodesk products. He worked in the retail-store fixtures industry for several years before joining the Striker Systems team, where he works extensively with CNC machine tools, specifically Lasers, Plasmas, Waterjet, and Turret Punches. Andy was recently promoted to ATC manager for Striker Technology Solutions, the only Autodesk ATC in Tennessee. His primary expertise is in 3D design flow to the manufacturing floor. His certifications include Manufacturing Certified Implementation Expert, Inventor Certified Expert, Machine Programming from Murata Machinery, and Lean Manufacturing. [email protected]

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3 Conceptual Issues to ask yourself What is the Most Important part of Sheet Metal Design? Know your Part! What is it for? Where does it go? What is it exposed to? What kind of loads? How long should it last? How important is cost? Is it a one of a kind or a production run? Are their Time issuess for the customer, is this a test, should we go the extra mile to make this a marketing drawing? Know your People! Who is designing it? Who is making it? Who is assembling it? Who is installing / setting it up? How much lead time do we / they have? Is design separate from engineering separatee from manufacturing? Do the designers follow a company standard, and is it your company s standard? Does the design team use FEA? Do the designers / engineers have hands on experience with the methods used to make part they are designing? Do the designers and MFG work for the same company? Are they in the same; Building / City / State / Country? Do they speak the same language? Page 2 of 2

4 Corners / Bend Reliefs Do we use bend reliefs? What happens when we just tear them? What if it is somewhere in the middle? Does MFG adjust bends? Did they figure out with 2D they had to add here, or subtract there, add tool over there? - MFG may have to Re-Zero their thinking because of this. - Does this information travel back to engineering or stay on the floor Bend Tables? What are bend tables How does the K-Factor help me? Can you rely on the k-factor without doing test bends Do we mark bends? Are you marking bend locations for the Press Break? Quality Control, Flat to 3D model Are you following through to make sure the finished product is correct? Flat Reps When should I make a change to the flat versus the 3D model? Which environment should I use? Inventor vs. AutoCAD vs. CAM systems Which finish am I using? Stainless, Powder coat, Paint, Bare steal, laminate, anodized, galvanized, chrome plated? How do I plan for this in my design? Does Temp affect the parts? You are adding heat when making these (laser, plasma, Punching) will this affect the design? Etching? Are you etching with a laser or marking tool? Post Finishing / Welding? Do we need to oversize the blank to account for post finishing? Add so much weld need to reduce part size to allow room for it? Assembly design vs. Part by Part design When you go from designing each part independent to designing them as a whole what happens? Do you still make them one by one, or nest the entire thing? Page 3 of 3

5 3D means better designs 3D allows for; less scrap, less rework, more accountability - No longer can mistakes be blamed on the design. Shipping Parts Autodesk Inventor and Sheet Metal Manufacturing: Do we need to make it smaller to be easier to ship, what about packaging, will it be bent in shipping? Physical Issues Press Breaks / Forming Tools (RAS folders, Rollers, Benders) What do we own, what can we form, Does Size Matter? A lot of manufactures use the same dies for different materials because of the time it takes to change them. Press Breaks tools generally describe the size of the die opening not the radius it is going to form. So if your MFG floor tells you they have a ¼ L-1 with a UP-1 on top, this means it can bend a 1/32 radius* in the part you are bending. Because it had a 1/32r top punch with a ¼ wide opening in the bottom die. Tooling is actually less than 90 to allow for spring back and air bending, reducing tonnage required to bend the part. *Depending on metal thickness and type. From Drawing to Fabrication Bend tables / K Factor Does our part use a funky bend calculation? Some Manufactures make bends that cannot be modeled. For example, some bend a hem with a RAS folder, then run it back through without the die and crush it to create a very tight hem to make an inter-lockinbend tables to make INV flats match what the floor uses. Make part. Before you start creating special sure the Operators on the press break are not using an unfolder in the controller of the break, or have pre-programmed fudge factors added in because of AutoCAD designs. Some machines you type in the folder part distances and then let the break figure the flat, Inventor can make a much more accurate flat; make them go back to the flat dims. Some of the new Breaks can automatically add additional bend distances to account for wrong flats (i.e. you tell them to bend it at 2, the machine takes the 2 bend and adds 1/32 automatically). Page 4 of 4

6 What is the K Factor or Bend Allowances When sheet metal is bent, the inside surface of the bend is compressed and the outer surface of the bend is stretched. Within the thickness of the metal, lies its Neutral Axis, which is a line in the metal that is neither compressed nor stretched. If you have a piece with a 90 degree bend in which one leg measures A, and the other measures B, then the total length of the flat piece is NOT A + B. To work out what the length of the flat piece of metal needs to be, we need to calculate the Bend Allowance or Bend Deduction. This will tell us how much we need to add or subtract to our leg lengths (A & B) to get exactly what we want. The location of the neutral line can be different depending on the material itself, the radius of the bend, the ambient temperature, direction of material grain, and the method by which it is being bent, etc. The location of this line is what is referred to as the Kfactor. K-factor is a ratio that represents the location of the neutral sheet with respect to the thickness of the sheet metal part. To find if your manufacturing process works best with Inventor s Bend allowance is to reverse engineer a sheet metal part. Measure strip of material, bending it, and measuring it will give you the correct bend allowance. These bend allowance can be measured for many materials and scenarios and then be used in an Inventor bend table Reverse Engineering the K Factor First, cut a strip of material and measure its length and thickness as accurately as possible. The width of the strip is not that critical but generally somewhere around 4 inches or so will work. Then, bend the strip to 90 degrees, and measure its Length X and Length Y as shown in the diagram below. Page 5 of 5

7 The correct K-factor to use in Autodesk Inventor can now be calculated as follows: BendDeduction = Total Flat Length X Length Y K-Factor = (-BendRadius (BendDeduction / (π * BendAngle / 180))) / thickness The other option Inventor has is a Bend Table option to control flat patterns. The bend table file is an ASCII format.txt file. You can edit a bend table file with a text editor or you can create one with a spreadsheet. A sample bend table file and a spreadsheet are included in the \Autodesk\Inventor [version]\ Design Data\Bend Tables directory. Tooling Limits (Punch) Can our punches rotate (Auto-Indexing Stations, A.I.), Do we have keyed punches, what about the station it is in? Unless you own a machine with 90+ stationss all A.I., you will more than likely not have more than a couple AI stations. If possible only have special tools in one direction. Machine Tonnage; do we have specials that are made to do this? If you are punching with a standard turret in an AI station, tonnage may be less than you think. On a 50 ton machine the AI stations are typically rated at 20 to 25 tons becausee of the AI station, you will get an error if you use to large of a punch in too thick of material in a AI station.. Tooling Limits (Break) Can it go to that degree of bend; do we have special tools that can fit into the part? Just because it can be drawn or modeled does not mean it can be made in a signal part, with standard shop tooling. Tooling Limits (Profile) How thick can we burn, is the hole smaller than kerf, should we pre-pierce the part? Laser limits usually do not affect the design as much as tooling, unless you are making really small holes or tight bends. Also keep in mind if you add any formed object to you part (extrusions, single punches) you need to remove those items from the blank so they are not burned by the laser / Plasma. Forming / Special tools Do we use: louvers in both directions, Keys, extrusions, Custom made tools? Here is a good way to use the punch reposition to make communication easier from design intent to actual CNC/ /CAM and Manufacturing. You can also make forms that do not unfold correctly show up as a special shape for the CAM program to recognize it is a forming tool. Page 6 of 6

8 Buying new tools Autodesk Inventor and Sheet Metal Manufacturing: From Drawing to Fabrication Are we limited to what tools we already own, if we do buy a new one what is the turn around on getting it? If you are designing something that you will need a new special tool for, you should notify manufacturing as soon as you can. You can get tools in as little as a few days for standard shapes, but it can take weeks for special shapes, and longer for form tools. Tonnage If we own an older 50 Ton Machine can it really hit with all 50 Tons? If you are working with tough or thick materials you need to know what the limits of your machine are and if it is up to those limits. You can work with you machine dealer you use for maintenance to have the tonnage tested. You may also want to design your parts with thinner material to keep from over tonnage your machine and or tools. Material Availability Do we use standard sheets, do we have to order, what if we run out, what other sizes can we use? If you are designing something on material that cost $1,000 sqft, then you need to make sure manufacturing knows to handle parts with care. If one gets damaged it could be a week or more to get replacements depending on where in the world it comes from. You may design a flat 60 x 190, but they may come back and say we have the extra stock 60 x 120 sheet can we use them and redesign the parts to fit them. The cost and time savings may be worth doing a little redesign. Grain consideration What happens if part needs to have gain in the Y axis and it is over the table limits? Stainless and titanium manufactures have to watch material grain direction. This must be taken into account of the design. If you design a part with grain running east west, yet taller in the Y, this can be a problem if the Y dim is taller than the y on machinery you own. Part Size Will it fit in our machines, will it fit out the door of the shop, and will it fit on a truck? As above, will it fit on the table of a punch press or laser? Then you have to think can it fit out the door of the shop, on a truck, or can your forklift pick it up. You may have to design it to be broken down into smaller pieces. Page 7 of 7

9 Assembly Autodesk Inventor and Sheet Metal Manufacturing: From Drawing to Fabrication Do we make and assemble it? Does it need to be partially assembled and then shipped and finished onsite? Do we buy parts already made? Remember final assembly is not the end game of the design. It may have to be broken down into pieces for shipping. It would be good to break thesee parts into actual sub-assemblies in Inventor, the same way they are manufactured. If you use purchase or outsourced parts be careful not to send purchased parts to Manufacturing. With much of the CNC Fabrication software they can pull all Sheet metal parts. They will pull all parts, but allow you to omit parts that are purchased or made in another MFG area. Part comes first! Part at the end is all that really matters!!!! It doesn t matter how good or how bad a model is, what the idw or dwg looks like, or how much FEA and analysis you do. The physical part is all the customer cares about. Weldments Should I use them or should I NOT? A lot of manufacturers use weldements to make subassemblies into single entities. If manufacturing has to do any treatments to prepare for this then you should use them in your model. If you are welding two pieces of thin sheet metal together and no need for grinding or removal of material for the weld, then I would not use them. You can still add them for special projects and marketing type models, but day to day you have to ask do they addd value? Also test your CAM or CNC software to make sure they can separate out the parts to make the base blanks. Templates Design / Modeling Issues Multiples, Horizontal, Vertical, Long, Short. One thing that takes a lot of time to set up are iproperties, and supporting information to be entered into a model. You can save some time by entering everything that is generic and then having different groups of templates. Here I have a.prt template for Horz, Vert, Short, and Tall parts. Find the common threads in your parts and then pre-populate your templates. Page 8 of 8

10 Standards K.I.S.S. and write them down, then make sure to keep it consistent Standards do not have to be elaborate books on how to drawn a line in a sketch. Start a little at a time and just puts some notes in a word document laying out what has to be done and why. Add a couple of screan shots and picture is worth a thousand words. Ex. shows the part and the information for edge banding, along with descriptions of the abbreviations. Don t forget to add the actual location in the iproperties where it should be added. If you change these do not forget to tell everyone where, how, and when they changed, ncluding contractors and MFG personnel. Revision tracking What kind of Data Management do you use? If you don t use Vault or other 3 rd party data management, do so now. Designerss can get away without tracking revisions to an extent. It is easy to overwrite or delete files you need. Also if you copy a design from one part to another, IV is stubborn enough to be linked to the original without you realizing it. Tracking design revisions and design status is helpful for many reasons. If you have a DM solution, it will automatically track and keep revisions up to date. This allows you to roll back to a previous version with the flip of a switch. Custom iproperties Do you need them are you going overboard, can you pull them from you MRP? With a MRP / ERP system, you can link them to your models via Productstream and automatically populate them. However if you do not use a MRP / ERP you can use Custom iprops for things like Work in Progress fields, Assembly notes, finish notes, and CAM / CNC information. Most of your CAM programs can take a custom iprop and use it to populate their fields is looks for the word wood to send it to the router not the laser, populate the machine name field, or what library to use. Page 9 of 9

11 The Custom Properties shown are for material part numbers so the operators on the floor know what stock to pull to manufacture this part. iparts and iassemblies Are there any considerations with my CAM software and using iparts? Some CAM software can pull all the parts from the assembly model. Verify they can pick up and distinguish the difference in the same ipart in different configurations. Try this, make a small ipart with two configurations, then add each version to a assembly. Next add that assembly to your manufacturing software. Did it get two parts? Are they actually different or did it pull two copies of one of them? Make sure the iproperties are correct for each one, along with the part number and name. Sheet Metal All Parts need to be called Sheet Metal if they are SM parts even Plate A lot of manufactures may outsource or have separate fab shops from the rest of manufacturing. If you send all Sheet Metal parts to a Fab Shop via automated system or manual passing of parts, make sure you identify the Plate parts as SM too. Most peoplee don t consider a 1 thick part as SM, but if you are burning it on a laser or plasma it is the same thing. Holes vs Extrude If you have a hole to add to a part which do you use? Always try to use the hole tool when drawing simple or even complex holes, yes some times when importing dwg sketches you can use extrude. If you use the hole command it will make it easier to find later for editing. NO Extrude to add material!!! You can use Face, Flange, Couture Flange, but no straight extruded features; this will bite you some day This can also make the flat unable to unfold because adding material in a area it cannot come from. Face works just like extrude but ensures the flat will work correctly when made. Features Page 10 of 10

12 Bananafananafofo Feature Can you remember what feature does what? If you use a part drawing a lot over and over again, can you remember what flange is what in six months from now? If you have a lot of flanges or holes or features in general, try to give them names. This makes editing them down the road much easier, or if someone elsee has to pull it up it will let them know what is what. Do you know which dimension is d487? What if d12 =d47? Renaming dimensions in the parameters window is also good for conveying information and makes linking them easier as well because you can then select them from the list parameters inside the dimension command. Bending Tools are hard to change and expensive to buy, bend features are easy to change If you use sheet metal styles correctly you can make changes on the fly to keep changes on the floor away. Check with the floor manager to seee how often they change Break tooling. If they prefer to use the same tools for multiple gauges look at your design and ask does it have to have that big/ small of a corner radius? If your design is a little flexible you can save a lot of man hours using the same tooling. Set all the bends in the range they use on the floor to an actual radius instead of a formula. The Radius on the left is set to thickness; the one on the right is set to ¼, will this really change the design? Part vs. Assembly Do you punch or burn flat blanks with holes, then in assembly drill additional holes? Try adding the holes during assembly to the top level assembly. They will not show up on the flat blank but will be in the model. Model it the way it is going to be built in your production / manufacturing process. Page 11 of 11

13 #1 important SM issue!!!!! Will Inventor make it into a flat? Is it complete, does the flat designed match the flat going into the press break, if not why? If you designed a part and Inventor will not make a flat, chances are it will be very difficult to manufacture. If you get an error like this you may want to check the flat to see what is wrong. Inventor will unfold it and show you the interference. If you have to have this flat, then you are goingg to have to make it a separate part and fasten it to the original. You want your flat in Inventor to match 110% of what is produced physically on the floor. If it does not find out why You may be correcting or allowing for something that is not even used or understood on the floor. Just because that was the way it has always been done: is not a good reason. Does the floor add bend reliefs? Flat Are they doing something they should not? Are you doing something to look pretty that is not practical? Is something wrong with the finished part that drives this? Definition: Bend reliefs are added to prevent the metal from tearing when it is folded. Tear is really the wrong verbiage, in reality it wrinkles most of the time, or cause another part to bend or bow out. If part size and shape tolerances are pushed beyond the limits manufacturing has to add the reliefs to control this warping of the material. If the final part is OK and within tolerances, and manufacturing is removing them before the blank is formed, remove your Inventor relief as well. If the floor is adding it without you telling them, you may want to add the same one to the Inventor model. On screen Bend relief s tent to look larger than they are in real life, thus designers exaggerate the gaps. If you make 14 gauge stainless steel cabinets and you model a gap with.015 spaces and a tear corner, are you sure? I have seen SS welds be as large as 3/16 to 1/4 thick. The Page 12 of 12

14 same goes for bend reliefs, bigger and smaller. If you have a turret, try to use a common size punch for reliefs to limit tool changes. How many pieces does it need to be? Do you need to break it into smaller pieces to be made then welded together? Too big for Turret, too long for break, bends back into itself? In Inventor you can make a piecee of sheet metal 200 or 2000 long if you want to. You may want to scale that back to smaller pieces that are more manageable. Even if you just design and send it out to be made, you can save money if the shop does not have to order special steel for the job, and it speedss up turnaround time. Next would be does it need to be knocked down in other words does it have to be made smaller for shipping? Sometimes parts are too big for Trucks, Trains, or even Boats, but even small things may have to be reduced to save on shipping charges. Also can the parts fit onto your laser / punch / break? Some manufactures have really large laser beds; some have really small punch tables. Check on this to see how big is too big. You say yes these are good things to think about but why sheet metal. You are more likely to use standard size sheets in sheet metal than regular parts. Sheet metal Fab shops don t like to buy big expensive machines to handle one or two jobs a year. It is cheaper to have it broken down to the max size of existing machines. Sheet metal is harder to weld back together f you have to break it into smaller pieces. Unlike thick plate or billet type parts that have a lot of bulk mass compared to their relative size. With thin gauge metal you need overlap, or tabs of some sort to accommodate welds, rivets or bolts to reassemble. This can cause weak points and unsightly seams in parts. If you find this out in the beginning you can add tabs, or make the brakes at corners that can hid the bolts or rivets. Flat Reps Punch and formed features going to the Flat With Inventor 2008 you can specify what punches look like in the flat representation. In the past any kind of punch or something that stretches metal did not make a pretty flat. This makes it hard for CNC CAM software to automatically pick it up and add tooling correctly. You createe it as a standard ipart and then create a secondary sketch to be the reposition. To createe a Punch tool with alternate flat: 1. Create the punch using standard part modeling features such as cut in the case of this vent cluster punch. Note: Don t forget the center mark in the initial sketch. Page 13 of 13

15 2. Create an alternate flat rep with a simple sketch. 3. Use the Tools>Extract ifeature to make the sheet metal punch out of the feature you created. 4. Select the Simplified Representation arrow and pick your simplified sketch for the alternate rep. 5. Save your ifeature 6. When you insert the ifeature it will look normal, when you activate the flat it will appear as the sketch. This gives you something easier for CNC software to find and reduces the size of your model when you have multiples of these types of punches. For more information: Remember most of the answers you already know or have someonee working with you that does. Ask you operators, welders, and material handlers how the design works for them. They understand the simple things like how to make it go together better, and what is going to save them time. You can also contactt your machine tool dealer or manufacture. They keep A/E s on staff to help make designs that help their machines run smoother. They are more than happy to help answer design questions and get you procedures for your operators to take advantage of your 3D design over the old 2D designs. Not to mention if you have a support contract with a CAM software company call and ask that is what you are paying for me for any further questions I am always more than happy to help someone in need out Trust me I have needed and will need help again with the same issue you are having. I believe in peer support, so don t forget about AUGI and all the peer support groups out their happy to be of service. For discussion forums to get help from other going through the same thing you are: Page 14 of 14