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Chapter 32: Using Plastic Features and Mold Tools 1017 However, its biggest limitation is that you can’t draft a face if it has a fillet on one of its edges that runs perpendicular to the direction of pull. To get around this, you usually have to tinker with the feature order. On imported parts you might have to use FeatureWorks to remove the fillet or Delete Face to re-introduce the sharp corner. What to do when draft fails Draft is certainly one of those functions that require you to understand a little bit about the actual capabilities of CAD. Part of the key to success with the Draft feature is that you have your expecta- tions aligned with the actual capabilities of the software. If you recognize a situation where the draft can not work, you may be able to correct the situation by changing feature order, combining draft features into a single feature, breaking the draft into multiple features, or changing the geom- etry to be more “draft friendly.” Sometimes the Allow Reduced Angle option can be used for Parting Line draft. If you use this, fol- low it up with a draft analysis to make sure that you have sufficient draft in all areas of the model. This option enables the software to cheat somewhat in order to make the draft feature work. The SolidWorks Help documentation actually has a more detailed explanation of when to use this option. I tend to just select it if a draft fails, particularly if the parting line used becomes parallel or nearly parallel to the direction of pull. Draft can fail for a number of reasons, including tangent faces, small sliver faces, complex adjacent faces that cannot be extended, or faces with geometry errors. When modeling, it is best to mini- mize the number of breaks between faces. This is especially true if the faces will be drafted later. Generally, the faces you apply draft to are either flat faces or faces with single direction curvature. You can’t just expect SolidWorks to draft any old junk you throw at it; you have to at least give it a fighting chance by making good clean geometry. When draft does fail for a reason that doesn’t seem obvious to you, you should use the Check util- ity under the Tools menu and also try a forced rebuild (Ctrl+Q) with Verification on Rebuild turned on. DraftXpert DraftXpert is a tool used to create multiple Neutral Plane draft features quickly. You can also use it to edit multiple drafted faces without regard for which features go to which faces. Using Plastic Evaluation Tools The plastic evaluation tools in SolidWorks enable you to automatically check the model for manu- facturability issues such as draft, undercuts, thickness, and curvature. The tools used to do this are the Draft Analysis, Thickness Analysis, Undercut Checker, and Curvature tools. Part VII: Working with Specialized Functionality 1018 Draft Analysis The SolidWorks Draft Analysis tool is a must when you are working with plastic parts. The part shown in Figure 32.13 has many of the situations that you are going to encounter in analyzing plastic parts. The Draft Analysis tool has four major modes of display: l Basic l Gradual Transition l Face Classification l Find Steep Faces Draft Analysis is found in the View ➪ Display menu (instead of in the Tools menu), and is either selected or unselected, like the Section View tool. This is a benefit because it updates face colors dynamically as you model. It also has some drawbacks. The display method for the tool leaves the colors looking very flat, without highlights on curved faces, which makes parts — especially curved parts — very difficult to visualize. Basic The Basic draft analysis (with no options selected) simply colors faces red, green, or yellow. Colors may display transitioning if the draft shifts between two classifications. This transition type is shown in Figure 32.13 in the image to the right. For a clearer view of this method, look at the Chapter 32 Draft Analysis.sldprt part on the CD-ROM. FIGURE 32.13 Basic draft analysis results You can perform all types of draft analysis in SolidWorks by selecting a reference flat face or plane, and setting a minimum allowable angle. In Figure 32.13, all walls have at least a one-degree draft, except for the rounded edge shown in the image to the right and the dome. Both of these shapes transition from an angle less than one degree to an angle greater than one degree. Chapter 32: Using Plastic Features and Mold Tools 1019 This basic analysis is good for visualizing changes in draft angle, but it also has some less desirable properties, which will become apparent as you study the other types of draft. Gradual Transition Although the Basic draft analysis is able to show a transitioning draft, the Gradual Transition draft analysis takes it a step further. With the Gradual Transition, you can specify the colors. It is also useful because it can distinguish drafts of different amounts by color. It may be difficult to tell in the grayscale image in Figure 32.14, but the ribs, which were created at one degree, have a slightly different color than the floor of the part, and the walls also have a different color. Notice that cavity and core directions have different colors, as well. You may want to open this part in SolidWorks, re-create the settings, and run the analysis so that you can see the actual colors. FIGURE 32.14 The Gradual Transition draft analysis Some problems arise when you use this display mode, the first being the flat, non-OpenGL face shading that is used to achieve the transitioning colors. This often makes it difficult to distinguish curved faces, and faces that face different directions. The second problem is that you cannot tell that the boss on top of the dome has absolutely no draft. In fact, there is no way to distinguish between faces that lean slightly toward the cavity and faces that lean slightly toward the core. The third problem is the strange effect that appears on the filleted corners. The corners were filleted after you applied the draft and before the shell, and so the filleted corners should have exactly the same draft as the sides; however, from the color plot, it looks to be a few degrees more. Part VII: Working with Specialized Functionality 1020 Caution Software can sometimes interpret things differently from the way that a person does. As a result, any computer analysis must be interpreted with common sense. Due to this and some of the other problems that I mentioned earlier, I recommend using the Gradual Transition draft analysis in conjunction with one of the other tests. Gradual Transition gives an interesting effect, but it is not a reliable tool for determining on its own whether or not a part can be manufactured. n Face Classification Face Classification draft analysis groups the faces into classifications using solid, non-transitioning colors. You will notice a big difference between the coloration of the Face Classification draft analy- sis faces and of the Basic or Gradual Transition faces. Face Classification uses OpenGL face shad- ing, which is the same as that used by SolidWorks by default. This allows for better shading and differentiation between faces that face different directions. The Basic Analysis coloration looks like all the faces are painted the same flat hue, regardless of which direction they are facing, which makes shapes more difficult to identify. The non-Open GL alternate shading method makes it pos- sible to display a transition in color. SolidWorks OpenGL shading cannot do this. Another advantage of using the OpenGL shading is that the face colors can remain on the part after you have closed the Draft Analysis PropertyManager. Face Classification draft analysis also adds a classification that is not used by the Basic draft analy- sis. Straddle faces refer to faces that straddle the parting line, or faces that, due to their curvature, pull from both halves of the mold. These are faces that need to be split. On this part, a straddle face is shown in Figure 32.15. FIGURE 32.15 Face Classification draft analysis and a straddle face Straddle face Chapter 32: Using Plastic Features and Mold Tools 1021 The light bulb icons to the left of the color swatches enable you to hide faces by classification. This is useful when you are trying to isolate certain faces, or visualize a group of faces in a certain way. This can be an extremely useful feature, especially when you have a very complex part with a large number of faces, some of which may be small and easily lost in the mix with other larger faces. The face counts that appear in the color swatches are a very helpful feature that is absent from the Basic draft analysis. Best Practice I prefer Face Classification draft analysis because it is the clearest. If I need additional detail regarding other types of faces, then I may run a Steep Face draft analysis as a supplement. The best practice here is not that you follow my favorite type of draft analysis, but that you understand what you need to know and then use the appropriate tools to find this information. This may include running multiple analyses to collect all the neces- sary information. n Find steep faces A steep face is defined as a face that transitions from less than the minimum angle to more than the minimum angle. Steep faces are different from straddle faces in that straddle faces are actually posi- tive and negative, while steep faces are either entirely positive or entirely negative. On this part, the dome inside the part is classified as a steep face, as shown in Figure 32.16. FIGURE 32.16 A steep face Steep face Part VII: Working with Specialized Functionality 1022 Thickness Analysis Thickness Analysis is part of the SolidWorks Utilities, which are part of SolidWorks Office or higher. After you have activated the Utilities add-in (Tools ➪ Add-ins ➪ SolidWorks Utilities), Thickness Analysis appears under the Tools menu. Note The tools from the Utilities add-in are always listed in the Tools menu, whether or not the add-in is loaded. When any of the tools is selected, the add-in is automatically loaded. SolidWorks has also done away with the Utilities menu, so if you are accustomed to using this functionality from previous versions, some new function- ality awaits you. You can run Thickness Analysis in two modes: Show Thin Regions and Show Thick Regions. Of these, Show Thick Regions is the most versatile. Show Thin Regions The Show Thin Regions option, or the “Thinness” Analysis, requires you to input a minimum acceptable thickness. Every face with a thickness above this value is turned a neutral gray, and every face with a thickness below this value is displayed on a graduated scale. Figure 32.17 shows the PropertyManager for this analysis and its result on the same part used for the draft work in the previous sections. FIGURE 32.17 Results of the Thinness Analysis Chapter 32: Using Plastic Features and Mold Tools 1023 One of the things to watch out for here is that some anomalies occur when you apply this analysis to filleted faces. The faces shown as colored were created by the Shell feature and should be exactly .100 inches thick. However, it does correctly represent the undercut on the end of the part and the thickness of the ribs. A nice addition to this tool would be the identification of minimum thickness faces. Perhaps you can submit an enhancement request. Show Thick Regions The Show Thick Regions option works a little differently from Show Thin Regions. You need to specify an upper thickness limit value, beyond which everything is identified as too thick. In these examples, the nominal wall thickness of the part is shown as .100 inches, and the thick region limit is set to .120 inches. For this type of analysis, the color gradient represents the thicknesses between .100 inches and .120 inches, while in the Thinness Analysis, the color gradient represents the values between .100 inches and 0 inches. The analysis can produce some anomalous results, especially at the corners, and also in the middle. Again, this is a useful tool, if not completely accurate. You can use it to find problem areas that you may not have considered, but you should certainly examine the results critically. The Treat Corners As Zero Thickness option should always be selected. I have never seen a situa- tion where selecting it improved the results; in fact, I have found that deselecting it has always made corners and fillets behave worse. This feature can generate a report, which to some extent answers questions about how or why it classifies faces in the way it does. To get a complete picture of the situation, it may be useful to look at the report when you are using the results to make design or manufacturing decisions. A sample of the report is shown in Figure 32.18. FIGURE 32.18 A sample of a Thickness Analysis report Part VII: Working with Specialized Functionality 1024 Undercut Detection The Undercut Detection tool is in the View menu (relocated from the Tools menu) or on the Evaluate tab of the CommandManager. It is also an on or off display tool, which changes dynami- cally as you change the model. Undercut Detection is conceptually flawed in that it gives incorrect results every time. However, if you think of the labels as being changed slightly, the results become partially usable. Even if you and your mold builder know that a part has absolutely no undercuts, the Undercut Detection tool will nonetheless always identify all the faces to be undercut. In fact, the only faces that this tool will identify as not undercut are faces that have no draft on them. The only time it correctly identifies an undercut is when it classifies the undercut as Occluded Undercut. Faces that have no draft and are occluded undercut are improperly identified as simply No Undercut. You may want to avoid this tool because too much interpretation of incorrect results is necessary; however, if you still want to use it, here is a translation guide that may help: l Direction 1 Undercut. Should read Pull from Direction 2 l Direction 2 Undercut. Should read Pull from Direction 1 l Straddle Undercut. Should read Straddle faces l No Undercut. Should read No draft in the primary draft direction, but may be occluded undercut faces l Occluded Undercut. Should read Occluded Undercut faces that have draft in the com- pletely irrelevant primary draft directions; does not include occluded undercut faces that have no draft in the primary direction Figure 32.19 shows the PropertyManager for this function and the results. If you would like to test it for yourself, the part is on the CD-ROM with the filename Chapter 32 Draft Analysis. sldpr t. FIGURE 32.19 The results of the Undercut Detection tool Chapter 32: Using Plastic Features and Mold Tools 1025 Working with the Mold Tools Process The SolidWorks Mold Tools are intended to help you create cavity and core blocks for injection molds. They do not provide libraries or functionality for building the entire mold or mold compo- nents. Mold Tools entail a semiautomatic process to follow, with the tools in order on the toolbar. Mold Tools rely heavily on surfacing, and require a fair amount of manual intervention for certain types of parts. The next section deals with the manual intervention techniques. This section deals with the idealized semiautomatic process. In order to fully understand the formalized Mold Tools process, it might be helpful to understand SolidWorks’ capabilities with mold geometry in general. First, understand that to create cavity and core geometry in SolidWorks, you are not required to use the Mold Tools. You can manually model surfaces or solid features to accomplish the same tasks. Surface features are widely used for mold modeling because they allow you far more control than solid features. You can also make mold geometry using an assembly of in-context parts or multi-body techniques. The formal Mold Tools uses the multi-body approach. This has benefits and drawbacks. With the formal SolidWorks process, you start in part file with just the final plastic part in it, and then build both the cavity and core blocks around the plastic part. You also build any side actions or core pins within the part file. Figure 32.20 shows the part of the Mold Tools toolbar that identifies the process. From the left to the right, the icons are: l Split Line l Draft l Move Face l Scale l Insert Mold Folders l Parting Lines l Shut-off surfaces l Parting Surfaces l Tooling Split l Core FIGURE 32.20 The Mold Tools Part VII: Working with Specialized Functionality 1026 Mold Tools are really meant for tooling engineers, but part designers often use the first part of the process to apply draft to parts. Tooling engineers often need to add or correct draft to plastic parts they receive from part designers without draft or that are not designed with any process in mind whatsoever. Cross-Reference The Split Line feature was covered in Chapter 7, and is not covered again here. Draft was covered earlier in this chapter. n The general workflow for using Mold Tools to create cavity and core blocks for an injection mold is as follows: 1. Create split lines to add draft where needed. 2. Create draft as needed (Move Face can be used to angle faces much like the Draft feature). 3. Scale the part up to compensate for shrinkage during molding. 4. Identify the parting lines that separate cavity faces from core faces. 5. Create Shut-off faces, which are surfaces that close any through holes (windows or pass-throughs) in the part and represent places where the steel from the cavity side of the mold directly touches steel from the core side of the mold. These openings in the part are capped by surface features. 6. Create Parting surfaces. These are the faces outside the part where the steel from oppo- site sides of the mold touch. 7. Create the Tooling Split. Tooling Split uses the faces of the Shut-offs and Parting Surfaces, and the faces of either the Cavity or the Core side to split a block into two sides. 8. Create any Core features. Core is an unfortunately named feature in SolidWorks. Even in mold lingo, the word has several meanings, and it doesn’t become any clearer when translated into SolidWorks terminology. In this case, the word “core” refers to the mate- rial used to make core pins, side action, slide, lifter, or pull in a mold. If you were to create a mold with manual modeling functions, you might go through roughly the same steps in the same order. The SolidWorks process often breaks down in the automated surface modeling areas, such as shut-offs and parting surfaces. You may need to manually intervene in the process for these steps. Fortunately, the SolidWorks process is flexible enough to allow for manual modeling as needed. Each one of these process steps may have several steps of their own. Cavity and core creation is far from a push-button operation, but when you understand the overall process, the detailed steps become clearer. [...]... you to make animations within SolidWorks and output movie files as *.avi or a series of *.bmp or *.tga still images You can use it with the default (OpenGL) SolidWorks display, RealView display, or in conjunction with PhotoWorks to create more realistic rendered animations Note PhotoWorks will be replaced by PhotoView 360 in SolidWorks 2011 As of this writing, SolidWorks 2 010 SP0 is the current version,... short line from the bottom-right corner of the rectangular notch so that it makes a 100 -degree angle with the horizontal line 10 Use a Split Line to split all the faces that the lines project onto (should be a front, a back, two fillet faces, and a side for five total faces) Figure 32.31 shows the Split Line and the sketch 103 7 Part VII: Working with Specialized Functionality FIGURE 32.31 Setting up a... careful that the Parting Line goes around the Step Draft faces correctly n 103 9 Part VII: Working with Specialized Functionality FIGURE 32.33 Creating a skyline rib 104 0 Chapter 32: Using Plastic Features and Mold Tools FIGURE 32.34 The part as of Step 15 FIGURE 32.35 The Parting Line PropertyManager and the model up to Step 19 104 1 Part VII: Working with Specialized Functionality 20 Click the green... need to finish the feature manually When the parting line and shut-off surfaces are complete, SolidWorks will automatically knit together all the surfaces in each Cavity and Core folder into a single surface body 102 9 Part VII: Working with Specialized Functionality Parting Surface The Parting Surface in SolidWorks works best on planar parting lines that are convex all the way around That is to say... off The Model tab shows the normal SolidWorks interface You can add tabs to create multiple motion studies Figure 33.1 shows the lower-left corner of the SolidWorks window with each of the buttons activated If you cannot see this interface, you may need to turn on the MotionManager To do this, right-click on a toolbar and select MotionManager from the list of toolbars 104 6 Chapter 33: Animating with MotionManager... factor) Also note the Interlock surface option in Figure 32.25 Most if not all of the examples of molds that you see created with SolidWorks mold tools are going to employ parting line interlocks This is not because most molds are built that way, but because it is the main way that SolidWorks gets around the limitations in the Parting Line functionality n Core I will use the Core feature to create a set... centered on each of the screw boss cores in the Cavity body When I exit the sketch using the Confirmation Corner, SolidWorks prompts me for an extrusion depth for the sketch to create the feature The Core PropertyManager and the feature preview are shown in Figure 32.26 FIGURE 32.26 The Core feature 103 2 Chapter 32: Using Plastic Features and Mold Tools Again, you can save out these core pins as individual... method SolidWorks uses to create the Parting Surface is insufficient for most tasks It will work well if you are molding a range of Frisbees or dinner plates, but it will not work well for handheld medical devices Figure 32.28 shows the part on the CD-ROM named Chapter 32 – frame parting surface.sldprt The result is entirely unacceptable for several obvious reasons From this you can learn that the SolidWorks. .. different techniques The goal of the tutorial is to make you familiar with the workflow of the tools rather than to teach every available option 103 6 Chapter 32: Using Plastic Features and Mold Tools 1 To create a simple plastic part, start by opening a new SolidWorks part file 2 Draw a Centerpoint Rectangle on the Top XZ plane centered on the Origin, 4 inches (vertical) by 6 inches (horizontal) 3 Extrude... surface folder l Parting surface folder 102 7 Part VII: Working with Specialized Functionality Parting Lines The Parting Lines feature identifies (automatically or manually) the edges that separate the cavity faces from the core faces Figure 32.22 shows the PropertyManager as well as the preview for this feature The edge selections for this feature were mostly manual SolidWorks intends for you to use the . face Part VII: Working with Specialized Functionality 102 2 Thickness Analysis Thickness Analysis is part of the SolidWorks Utilities, which are part of SolidWorks Office or higher. After you have activated. Undercut Checker, and Curvature tools. Part VII: Working with Specialized Functionality 101 8 Draft Analysis The SolidWorks Draft Analysis tool is a must when you are working with plastic parts. The. the part is shown as .100 inches, and the thick region limit is set to .120 inches. For this type of analysis, the color gradient represents the thicknesses between .100 inches and .120 inches,