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Outlined here are suggested practices for using the SolidWorks CAD software´s sheet metal functionality for SolidWorks. This information is supplied for training and may be redistributed and reused for training and instructional purposes, including posting on a company intranet and training (including paid) for reference usage.
1.Model A Formed Part For Most Parts.
Always model a completely formed part and unfold to get the flat blank.Don’t make a flat and then try to bend it.This is absolutely impractical in 99% of all applications.
2.Define Sheet Metal Early In The Modeling Process.
Always define “sheet metal” immediately so that the “extrude to thickness” function is available.By doing this you will be able to “rollback” to the flat state periodically to confirm that you are making features that can be unfolded.Add all your new features in the “no bends” state (rolled back).Don’t wait until the end to “insert bends” only to find out that your geometry is “unsuitable for unfolding”.When inserting the sheet metal definition on a model with only a single panel, you will get the “No Bends Found” message.This is normal, as all your subsequent features will be placed directly after the sheet metal definition with the model rolled-back.
3.Name Your Panels.
When creating panel sketches, define them with descriptive names (example —– BottomPanel —-, —– RightSidePanel —–, —– FrontFlanges —–, etc).Always roll-back and add new features to the panel sketch if they are not needed as a pattern feature.For items that need a pattern in the future, add hole wizard holes that are sequentially after the panel in which they appear.Essentially, make good use of roll back to group all your features for a given panel together.
4.Let SolidWorks Create Your “Form Radii”.
Let the modeler create the “form radius” fillets between panels.Model your panels and features with sharp corners and let the system create the inner and outer radii for the model when you insert your sheet metal definition (or “roll forward’ you sheet metal definition).
5.Use “Complex” Panels To Keep Your Tree Short.
When using panel sketches, be aware that you can extrude multiple closed contours to define many co-planar formed tabs that are not contiguous.Use a single extrude feature to define many panels that are coplanar.
6.Add detail to your edge flanges by using “edit flange”.
When using “edge flange” functionality, if more detail is needed in the flange, always “edit flange profile” to add detail instead of cutting away.Also, if the flange is already created, edit the sketch that created the flange to add more detail.
7.Control Your Bend Relief By Modeling Them.
Always model your own relief clearances, as this gives you maximum control over the form, size and location.If you decide to let the system generate your relief features, be prepared to compromise a little on the form, size and location.
8.How to “Globally” Redefine Your Material Thickness.
When needing to re-define the thickness of a part, double-click the sheet metal definition, revealing two model dimensions on screen (thickness & default radius).Edit the thickness and rebuild the model to update to the new thickness.Note: If your attempt to redefine your material thickness and the model “errors-out”, the panels defined may not have been extruded using “link to thickness”.To clear the error, re-edit your features using “link to thickness”.
9.Design With Small Gaps When Needed.
Design with small gaps (.001) between panels that will touch in reality.Doing so will allow the software to unfold the model. Don’t design one flange exactly coincident into another when it is in the folded up state, as the program will not be able to unfold the model.Of course this does not apply to any flange being taken off of its supporting base – these will always touch.
10.Minimize Your Reference To Bend Lines.
Don’t references bend lines or the endpoints of bend radii when dimensioning any new feature, as this lends to possible instability of location when unfolded.Form Tools are particularly susceptible to this problem.
11.Use “Split Line” To Allow Two-Stage Unfolding.
For formed profiles that need to be bent in multiple tooling stages, split the form radius into two segments and constrain the break point, yielding two concentric bends that can be independently formed to simulate your tooling steps.This is helpful with multi hit bends, like for an acute bend that requires two hits or a curl operation that is hit in multiple hits.If you are on an older version of SolidWorks, use small “micro” lines between the arcs.
12.Use Unfold To Make “Non-Oblique” Cuts.
Always add an “unfold” feature when adding a cutout to a flat blank, but only when the cut required cannot be put in any other way.I.e. when a cut needs to traverse bend lines at an angle in the flat, or a shaped cut needs to be put into a large radius.
13.Add A Fold After An Unfold.
Always add a “fold” feature after adding an “unfold” if a cut was made, or other feature added to return the model to its “finished” state.
14.Understand The Limitation Of “Edge-Breaks”.
Avoid the edge-break command as it only does external edges, and not internal ones.Use the fillet or chamfer feature instead as you can control both inner & outer edges.As another alternative, add the fillets to the panel sketches if possible as this keeps the feature tree “tidy”.
15.Shallow “S-bends” – Avoid Thin Extrude Features Here.
When modeling shallow “S-bends” that conform to the pattern line-arc-arc-line, always model the profile as a closed loop to assure more robust unfolding.Don’t use a thin extrude when there is an arc to arc condition with a shallow form, as bend deduction in less robust in this situation.
16.Choose “Common” Form Radii For Your Defaults.
Use (inner) bend radii that are compatible with common manufacturing practices. Always specify inner radius as the outside radius in not easy to control. Keep the bend radius common throughout the part, as this allows you to keep all your relief clearances common. This also helps the manufacturer minimize tooling requirements.These sizes are suggested as commonly available:
|Common Imperial Sizes||Radius Size|
|Often what is used for
17.Add Configurations To Help Your Manufacturing Process.
When adding features such as extrusions that require a pre-hole, add the pre hole in a configuration and then model your extrusion “over” the pre-hole in a subsequent configuration.Doing this allows you to show both configurations for tooling.
18. Use Numbered Configs For Progressive Ops.
When laying out a progressive stamping operation, create the model with numbered configurations (1 – flat blank, 2 – first form, 3 – second form, 4 – cam-pierce, etc.) that show the work to be performed at each station (whether in progressive die or hand fed).If the operations are performed in one tool, make an assembly with a component pattern.The component pattern’s “repeat” would match the advance of the tool.Adjust each instance of the pattern to the configuration showing the work done at each station.Thus this can serve as a guide for your strip development activities.
19. Understand The Limitation Of “Form Tools”.
Avoid the use of form tools as the geometry created by them is not entirely editable.In cases when you decide to use form tools, be aware that SolidWorks will let you model impossible features. I.e.Single sided louvers without any material “pull back” from the ideal shear line, lances tabs will have same size punch and die openings, which are actually different based on the punch/die clearance.Essentially form tools will not account for cutting clearance in many cases without some “extra” work. If form tools are used, be aware of the editing limitation.
20. Use Your Model To Create A Draw Tool.
When a draw tool is needed for a multifaceted part for which you have geometry whether imported or native to SolidWorks, the cavity function can be used to pattern an upper & lower punch & die, the same way a mold cavity is created.
21. Reduce or minimize “normal cuts”.
Limit the use of normal cuts.While normal cuts are set as the default once a part becomes sheet metal, realize that this type of cut is not commonly needed for most sheet features.
22. Miter Flanges May Also Contain Arcs.
When using miter flanges, realize that the profile need not be a single line and that the miter need not be perpendicular to the panel that is taken off of.That is miter flanges may be complex profiles and need not always be 90 degree bends.Miters may only contain lines in 2001+.
23. Set Your Relief Ratio To A Reasonable Number.
When using the SolidWorks automatic relief ratio, use a factor of at least 1.0 instead of the default .500, as the default number is not manufacturing friendly in any way.If possible, set this as high as 2.If you are comfortable with the registry, set these default values there.
24. Consider your “K-factor”.
When taking the default bend “k-factor”, if you intend to use your models for any manufacturing, set this to less than the (sometimes) default .500, as this will not unfold accurately for most bending scenarios.Manually override this setting in SW or if possible, set the registry to .42 or .33 based on your most likely tooling method.The table below shows some common k-factors, but always develop and test your particular material and forming conditions if you are unsure:
|Bend Type||Common “K” factors|
|Large Radius Bend
(radius 4x+ larger than stock)
|Rotary Bender (like “Ready bender”)||.43|
|90 Deg. Wipe – No Set Radius||.38|
|90 Deg. Wipe Plus Set Radius||.33|
25. Legacy Installs Have Limitations.
Understand the limitations in 2000/2001+ when inserting base flanges.Parts created with this method cannot unfold swept profiles (i.e. miter profiles cannot contain arcs, nor will “wall” flanges unfold because they are inserted “post” bends).Individual bend parameters (k factor) are not configurable per bend, but inherited globally.2003 remedies all these issues.
26. Use Real “PEM” Models.
Do create an assembly with all your parts and PEM nuts in them. Use real PEM models from a library, toolbox or the PEM website http://www.pemnet.com. Don’t use fake PEMs or part features to simulate PEMS.If you use “fake” PEMs then use configs to make the proper hole without the hardware.
27. Define Semi Perfs In The “Attached” Part.
Always define semi-perfs in the parts that they are in and have then drive the size and position of the corresponding in-context “hole” features in the receiving part (typically a hole & slot).
28. Use Patterns For Hardware.
Always use patterns for multiple PEM and fastener features so that you may insert a single PEM into the “primary” hole and use a component pattern in the model.Always name these patterns so you can easily identify the parts.
29. Use Assembly Overlays To Show Part Progression.
For tooling layouts in particular, to show a part in its pre-tooled and post-tooled state, create an assembly of your sheet metal part and superimpose an instance of your part upon itself. Create 1 assembly configuration corresponding to each sequential per part state (see PRT-18, configure instance 1 to “2 – first form” and instance 2 to “3 – second form”).Then create a drawing of the assembly showing instance 1 and use an alternate position view to show instance 2.In this way, you can get a superimposed view of 2 states of the part.This is critical as all tooling receives a part in a given state and outputs it in another state.This is a work around for the fact that alternate positions cannot be made for parts.
30. Use The “System Flat Blank”
When initially inserting your flat blank into a drawing, always take the system generated “flat pattern”, as this flat blank “joins and solidifies” the panels into one panel with continuous profiles.For CNC processes, this eliminates the “line-line-line” condition that may hinder turret programming (in particular).
31. Provide A Reference Flat For Quoters & Fabricators
Always provide a reference flat blank with any design for estimation and manufacturing purposes.Use the “measure” command to chart out the full “perimeter” of the part (simply touch the main surface) and include a note indicting this length.This can be very useful in determining laser time, cutting tonnage and wire-cutting time for hard tooling. Always require your vendor to be responsible for bend development and flat pattern accuracy and note this in the layout.
32. Turn On “Tangent Edges” In ISO Views
When inserting an isometric (or other 3D view) of a sheet metal part, always turn on “Tangent Edges with Font” or “Tangent Edges Visible”.Never leave the view with the tangent edges turned off.
33. Turn Off “Tangent Edges” In Ortho Views
Generally turn off “Tangent Edges With Font” or “Tangent Edges Visible” in an orthogonal view, as this often confuses the eye with the stock thickness.Ignore this rule when you need to show clarity.
Imported Data & Feature Works:
34. Sharpen & “Strip” Radii
When working with an imported sheet metal part, to gain control over the inner form radii, use feature works to “recognize” all the inner and outer (form) radii and then delete them from the model.After this is accomplished, insert the sheet metal definition into the model that now has dead sharp corners and you will be able to define the exact form radius.Use this method to overcome the “locked” state of form radii on imported models.
35. Recognize Panels with Feature Works
For an in depth treatment, see Using Imported Data.
For imported sheet metal parts, to gain control over the panel sketches, use feature works to strip the radii as above and then manually “recognize” each panel starting with the outermost panels and working your way “inward” to the panel that shares the most bend lines with other panels.Once this is done, add sheet metal and edit the sketches as needed.
36. Verify Recognition With “Quick” Unfold
After initial insertion of an imported model, insert a sheet metal definition into the part to verify its unfoldability.If it unfolds without issue, the part will be “receptive” to full feature works recognition.
37. Get Data Closest To Your Kernel
Get data that is closest to you kernel as possible.I.e. get parasolids before IGES if possible.
38. Use A Native To “Dumb” Overlay Assembly To Confirm Your Part
When you are recreating a native SW model (if you are a vendor) from a customer supplied imported model, define an assembly and superimpose your model upon theirs (with mating).This allows you to make a shape comparison of both models.Ideally, you would superimpose your model upon theirs immediately after defining the first main panel.Doing this allows you to check for errors feature-by-feature as you create your model.Additionally, you can now derive edges from their model to develop your panels.Also this may be the only available method to derive geometry from the supplied model in the case of a “hybrid” (i.e. paper print + model control the part geometry).
All suggestions made here are for training purposes only. The author is not liable for any loss relating to the misapplication or usage of this information.You may freely use, reproduce and print this data as long as it remains intact in its original format. The information presented here may be used for “paid” training purposes.