holy sheet metal.pdf

Inventor 2010 Sheet Metal Features Thom Tremblay – Autodesk, Inc.
MA218-1
Class Description
In this class we will cover the basics and the advanced Sheet Metal features of Inventor 2010. Inventor 2010 has expanded Sheet Metal capabilities that will surely delight anyone who needs to create complex folded Sheet Metal components.
Key Learning
Sheet Metal Styles Sheet Metal Design Tools Flat Patterns Detailing of Parts Special Formed Features
NOTE: Included in the body of this handout will be excerpts from a book that I have authored;
‘Autodesk Inventor 2010 – No Experience Required’ ISBN 978-0-470-48169-1 from Sybex
Publishing in which I cover a number of the Inventor Sheet Metal tools. I hope you don’t feel
slighted that I didn’t retype the way that I would normally describe certain features for the sake
of appearing to have new insights.
About the Speaker: After working with the Autodesk Manufacturing Solution sales for seven years, Thom now works for the Autodesk Strategic Universities team. In this role, he consults with engineering programs on how they can move the education of their students forward using Autodesk Mechanical Engineering products. Thom is also the author of ‘Introducing Autodesk Inventor 2009 and Autodesk Inventor LT 2009’ and ‘Autodesk Inventor 2010 – No Experience Required’ available from Sybex publishing
[email protected]

Holy Sheet Metal! Making the Most of Autodesk Inventor 2010 Sheet Metal Features
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Why Sheet Metal tools?
The Sheet Metal design, development, and detailing tools inside of Inventor are simply fantastic. The productivity gains can be astonishing if you’ve been using more traditional Solid Modeling tools to develop Sheet metal components. These tools are stored in a special tab that is only visible in the Ribbon interface when a Sheet Metal component is being edited. The Model tab will remain present because Inventor is flexible in creating Sheet Metal components and will allow you to edit and create with traditional methods as well.
The Inventor Sheet Metal tab
For this hand out I will not cover every tool but I would like to cover some of the more commonly used or innovative tools.
Let’s review the tools of the Sheet Metal Tab with one of the least commonly used but most important tools. Sheet Metal Defaults. It is located in the Setup Panel on the Sheet Metal tab.
Excerpted from: ‘Autodesk Inventor 2010 – No Experience Required’ ’
Sheet Metal Defaults
Sheet metal defaults are essentially styles in the vein of the layer styles or
dimension styles you’ll learn about later in this book. They’re meant to be
established within the templates and standards used in the part. A sheet metal rule
is a name given to a set of properties for the sheet metal that will be used for a
part. It consists of three elements: a thickness, a material, and an unfolding
method. You define a style through the Sheet Metal Defaults and Style and
Standard Editor dialog boxes. After a sheet metal default is defined, it can be
shared through the style libraries.

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The Sheet Metal Defaults Dialog Box
The Sheet Metal Defaults dialog box (Figure 2.21) works a little differently
than most dialog boxes in Inventor. Instead of being the source of the feature that
will be created, or the place where edits are performed, it’s a front-end for either
selecting what rules will be applied to your new component or overriding the
Thickness, Material, or Unfold value of the rules you’ve already created. It lets
you define a new set of conditions unique to the current Part file.
Figure 2.21: The Sheet Metal Defaults dialog box
You don’t establish the rules of your sheet metal components here (you do
that in the Style and Standard Editor); you select which rule will be used and, if
you like, choose to override portions of the rule. Here’s an overview:
Sheet Metal Rule This fly-out lets you select which existing sheet metal rule you want to use.
Use Thickness from Rule Deselect this check box, and you’ll be able to override the default thickness of the
selected sheet metal rule.
Material Style This pull-down shows a list of the materials available in the standard and allows
you to select one that is different from the material specified in the sheet metal
rule.

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Unfold Rule As with the Material Style pull-down, Unfolding Rule is an override option to the
active rule and lets you switch the unfold method from the default.
The Style and Standard Editor
On the right side of the Style and Standard Editor dialog (Figure 2.22) are
three tabs, which establish the conditions for the active rule and let you create the
rule’s properties.
Figure 2.22: Style and Standard Editor showing sheet metal rules
The Sheet Tab
The Sheet tab (Figure 2.22) controls the properties of the raw material and
how it deforms when you begin to bend it.
Sheet
The Sheet group is used to establish the material that is used in the part:
Material Use this pull-down list to select the default material for the rule.
Thickness Enter the value of the material for the rule here. For production use, I suggest checking with your suppliers and perhaps your Manufacturing department to

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Unfold Rule
One of the most important things to discuss with Manufacturing is the
method they use to calculate the flat pattern. Based on that method, you may need
to modify the formulas for calculating a K Factor unfold or establish some
different bend tables for your material. Working with Manufacturing may get you
access to existing data that they use, which will make things go more smoothly
when it’s time to get the parts produced.
After you’ve established the range of options for calculating the flat pattern,
you can use the Unfold Rule pull-down to set the default method for this rule.
Flat Pattern Punch Representation
This is another area where it’s beneficial to work with Manufacturing if you
haven’t been previously responsible for generating flat patterns.
Depending on your organization, you may have to include detailed
representations of features that will be punched into your part, or only a simple
center mark for where the punch should strike, or something in between.
Inventor offers four methods, and selecting the appropriate one is very
important:
Formed Punch Feature Even though the part will be flat, the punched features continue to display in 3D
with this option, and a center mark is displayed at the placement origin for the
punch feature.
2D Sketch Representation When you define a punch tool (as discussed later in this chapter), Inventor lets you specify a 2D sketch to use as a representation. This sketch may be the
perimeter of the feature, or it can be a symbol that an automated programming
system uses for tool selection.
2D Sketch Rep and Center Mark This displays the 2D sketch and a center mark for where the strike is programmed
to occur.
Center Mark Only If you plan to use a table to list what punches are used, you can show where the
punches need to be placed on the flat part.

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The Bend Tab
The Bend tab (Figure 2.23) controls the default radius of bends that are
applied and specifies how to treat bends that are less than the full width of another
face.
Figure 2.23: The Bend tab of the Style and Standard Editor
Bend Relief
Before you create a bend, it’s sometimes necessary to cut a notch into the
metal to limit the distortion of the unbent portion. This is called a bend relief .
Relief Shape
This pull-down list lets you select the default relief shape for the rule. The
standard shapes are as follows:
Straight Straight creates a rectangular shape.
Round With this option enabled, the interior edge of the relief is rounded.
Tear With this option enabled, there is no predefined relief, and the metal is allowed to
shear during the bending process.
Along with the shape selection is a preview of the bend shape; you can

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Bend Radius
The default radius can be an absolute value or a factor such as the thickness
of the material divided by 2.
Bend Transition
When a bend occurs that doesn’t require a relief, but the edges don’t align,
you can use this pull-down list to establish the shape of the material at the edge of
the bend. The differences between the options are easiest to see in the flat pattern.
The Corner Tab
The Corner tab (Figure 2.24) tells Inventor how you want the edges of
bends to relate when they’re next to one another in a corner.
Figure 2.24: The Corner tab of the Style and Standard Editor
2 Bend Intersection
There are six methods for defining how a two-bend intersection is
calculated. Two of them (Round and Square) also offer a size for the intersection.
The others calculate the intersection based on the size of the bends included in the
corner and the process that is used in manufacturing.

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3 Bend Intersection
A corner where three bends meet is extraordinarily difficult to calculate. In
reality, as long as the faces and major bends are correct, the geometry of the
corner is relevant only in the flat pattern from which the part is formed.
For this reason, the value you select for the 3 Bend Intersection option only
modifies the way the corner is calculated in the flat pattern. If you look at the
folded part, it shows a notch in the corner and displays the gaps between the
edges. The corner will construct properly when the physical part is made from the
accurate flat pattern—and that is far more important.
Creation Tools
The tools in the Create Panel of the Sheet Metal tab are similar in nature to Sketched Features in Solid Modeling. With the Exception of the Flange tool all of them require that you use a sketch to define some portion of the feature. In addition to the initial shape of the feature they will also do automated blending between features to enable creation of the feature and still keep the flat pattern legitimate for production.
Excerpted from: ‘Autodesk Inventor 2010 – No Experience Required’
The Face Tool
The Face tool is like an Extrude tool, but you don’t have to set a distance.
The distance is determined by the thickness of the material. The only other rule is
that you have to have at least one closed loop in the sketch. Figure 3.10 shows the
dialog box; it’s extremely useful if you need to add a flange to a part but the flange
will have an irregular shape. Very often, the Face tool is used to define the base
feature of a sheet metal part.

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Figure 3.10: The Face dialog box
In addition to having the usual option tabs and sketch-selection tools, the
Face tool can select edges to blend the face to. After an edge is selected, a preview
of how the bend will occur between the new face and the existing body appears.
The Flange Tool
After you create a base feature in sheet metal, chances are you’ll use the
Flange tool next. Figure 2.28 shows its dialog box.
Figure 2.28: The Flange dialog box

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A flange is a placed feature with a lot of options. The Flange tool and the
Face tool have the same tabs that allow individual override, so we’ll focus on the
Shape tab.
The Shape Tab
You place a flange by selecting an edge to which you want to add a bend
and adjacent face. The upper-left portion of the Shape tab (Figure 2.28) is where
you select those edges. The Edges list displays the number of edges that have been
selected.
You can select edges in two ways:
Edge Select Mode This option lets you select individual edges to place flanges on. You can select
multiple edges, but you have to select them with individual clicks of the mouse.
Loop Select Mode This option lets you select all the perimeter edges of a face with a single click.
These selection options also work with the Contour Flange tool when it’s
placed after the initial feature is placed.
Additional options on the Shape tab are as follows:
Flange Angle This option establishes the angle at which the flange will be developed once you’ve located it by selecting the edge.
Height Extents You can set the height of a flange by value using Distance or until it meets a face using the To option. You select these options from a pull-down list.
You can also flip the direction of the flange by clicking the Flip Direction button.
Height Datum The three buttons illustrate the options that you can use to define whether the
height of a flange is measured aligned to the length of the flange or orthogonal to
the face plane.
Bend Position Four modes are available to define how the bend is started from the selected edge.
The icons illustrate clearly how the bend is developed.

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More (>>) Expanding the dialog box exposes an option to create flanges that are narrower
than the selected edge using different types of selections. There is also an option
for using an older definition methodology limited to the Height Datum and Bend Position options.
Many of the dialog boxes have Unfold Options, Bend, and Corner tabs.
These tabs provide access to override tools for the individual feature. The tabs
contain the same properties as the sheet metal rule definition tabs, but changes
affect only the current feature, not the active rule. This gives you the ability to take
one feature and give it a special bend radius or change the bend relief. You can
even go back and change a feature after it has been placed, using Edit Feature.
The Contour Flange Tool
Sometimes, you need to create a part with a lot of bends that are all the
same width. Think of a drainage gutter: It’s cut to consistent length, but it has
bends that flip from one side to the other. If you were to sketch the basic shape,
thicken it, and have it extend to a length, the part would be done. That is the
inspiration for the Contour Flange tool; its dialog box is shown in Figure 2.26.
Figure 2.26: The Contour Flange dialog box

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The Lofted Flange Tool
If you’ve ever seen the way a duct transitions from a round shape to a
rectangular shape, you’ve seen the inspiration for this tool. Although the tool has a
few different uses, creating ducts is its primary function.
The Lofted Flange dialog box (Figure 3.4) displays many of the same
characteristics as other dialog boxes, but it also includes some unique features that
we need to review and some that you’ve already seen but that we haven’t
discussed yet.
Figure 3.4: The Lofted Flange dialog
When you created a contour flange and a regular flange, you
may have notice three icons with arrows in the dialog boxes. Selecting one of
these icons will define which side of the sketch or selected edge your material is
added to or whether the material’s thickness is divided equally on each side.
You’ll also see these options on many of the tools on the Model tab. It’s important
to verify that your material is being added to the side that you want, or your
overall component size may be affected.

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Output Options
The Output group in the dialog contains two primary options. You need to
know how this part will be manufactured, to select the option properly:
Die Formed Selecting this option creates a transition where the bent portions are created as a single bend. This requires a more specialized manufacturing process, but the
result is a smoother part. Selecting this option also disables the Facet Control
options.
Press Break If the part will be manufactured using a press break, and if having the transition
formed in steps or facets is acceptable, then you should use this option. Picking
the Converge check box lets Inventor blend the facet edges together at the end where they meet.
Facet Control Three options define how large and how many facets make up the bent portions of
a transition. They’re called out by a letter and name. The dialog also displays an
illustration that offers a graphical description of the selected option:
A - Chord Tolerance This option calculates the number and size of facets based on a tolerance
for how far the flat face can deviate from the ideal curve.
B - Facet Angle This is a limit on how much the facet can deviate from the adjacent facet,
measured in degrees.
C - Facet Distance Use this option if you want to limit the maximum width of the facets.
Bend Radius Instead of having a Bend tab in the dialog, the opportunity to override the default

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There are additional tools in the Create Panel that were not covered in the book so here are some quick definitions of the remaining tools:
Contour Roll: This tool is essentially similar to the Contour Flange tool but can bend a bent feature about an axis. In all reality this tool deserves a book of its own. It is able to generate a flat pattern of something that was previously incredibly difficult to calculate.
Hem: A simple looking tool. The options such as Single and Double are fairly straight forward creating features where the material is simply folded over itself along an edge. Teardrop and Rolled options offer far more interesting geometry but all options are difficult to properly construct without a purpose built tool.
Bend: The bend tool can mend gaps between faces (or flanges) with a bend. Inventor’s ability to create disjointed parts carries over into Sheet Metal and the ability to generate a bend between faces in space opens a great deal of flexibility in constructing your parts.
Fold: So, you have 20 years of AutoCAD drawings? Don’t you wish you could just fold them into the Sheet Metal parts that you make from them? With this tool it’s possible. Simply define a face from the perimeter of the flat pattern then use the existing bend lines to “Fold” the part into the 3D shape.
Modification Tools
Continuing the tradition of obvious tool Panel names is the Modify Panel. These tools also closely resemble the conceptual workflows founding Solid Modeling by behaving like Placed Features. Only one purely Sheet Metal modifying tool; Rip requires the use of a sketch. Let’s take a look at the Modify tools.

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The Punch Tool
The Punch tool is a specialized feature that creates deformations or custom-
shaped holes in the part. The location points of these features can be extracted for
detailing in the drawing or for programming production machinery. Figure 2.48
shows the PunchTool dialog box.
Figure 2.48: The PunchTool dialog box
When you open the tool, you’re shown a list of included sample punch
tools. There is also a dialog box in which you can access special geometry or size
the tool if it has optional sizes.
The Geometry Tab
The Geometry tab (Figure 2.49) lets you select placement points for the
Punch tool and set its placement angle.

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The Size Tab
When an iFeature or Punch tool is defined, its size values can be set to
unlimited, within a range, or with only certain sizes selectable from a list. Use the
Size tab (Figure 2.50) to set those size values by entering a value or selecting it
from the Name pull-down next to Value.
The Rip Tool
In cases where you use a lofted flange or a solid-modeling technique to
create a sheet metal part, and you need an opening to enable proper flat-pattern
creation, the Rip tool gives you three options. Depending on the option you

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Figure 3.15: The Rip tool dialog box
Single Point Creating a sketch on a face allows you to rip the face by selecting only a single
point.
Point to Point This option also relies on a sketch being present but gives you the added control of picking a beginning and an end point to cut between. This option even allows
spiral cuts along a curved surface.
Face Extents Acting as a placed feature, this removes the face you select and the material
normal to it to create the gap.

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The Unfold and Refold Tools
Inventor has the ability to preview the flat pattern in a sketch (as you did in
Chapter 2, “Building the Foundation of the Design”) to establish how that feature
will appear in the flat pattern. Sometimes you need to be able to see a portion of
the part in an unfolded state to add geometry.
A great example is adding a stiffening feature across a bend. You unfold
the bend, add the stiffener to the flattened portion, and refold the model, including
bending the stiffener.
Unfold and Refold are arguably the same tool, but they need to be
calculated independently because you may need to create more than one unfold
and refold all or a different set of unfold features at once. Even the dialog boxes
for the two are the same except the name at the top.
The dialog requires a stationary reference to get started. This can be a flat
face or an edge. Most often it’s be a flat face, unless you have a bent part without a
flat portion. I select the stationary reference as though it were the portion of the

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You can unfold as many bends as you like; there’s even an Add All Bends
option to speed things up. As you select bends to be unfolded, give Inventor a
moment; it will calculate a preview of how the part will look.
If there are 2D sketches on a face or hanging over a bend from a face, you
can include them in the Unfold feature as well.
You’ll use the Unfold tool to see what your cut needs to be. Then, you’ll
refold your part after you make the cut.
Corner Round: A fillet tool that only applies a round to the short edge so that the round can be cut in
the flat pattern
Corner Chamfer: A tool that only applies a chamfer to the short edge so that the edge can be cut in the
flat pattern
Detailing and Annotation Tools
More so than most types of manufactured components; Sheet Metal components are fabricated from 2D drawings or at the very least from having their three dimensional geometry converted to 2D geometry. Therefore the toolset available for the Sheet Metal design must have a broad array of capabilities and flexibility.
Let’s begin with a review of some of the special tools for converting the 3D body to a 2D body and preparing it for manufacturing documentation.
Go to Flat Pattern: A functional Sheet Metal toolset cannot exist without the ability to generate an accurate Flat Pattern. This flat patter will include distortion of the material that happens during the process of bending the part into the calculation of the Flat Pattern. The precise formula is determined by the settings of the Sheet Metal Defaults.
Bend Order Annotation: Once the Flat Pattern Is created the designer can dictate the order that the
features of the part should be created. These overrides can also transfer to the 2D
drawing.

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Flat Pattern with Bends 1 and 2 manually reordered
In addition to the specialized tools you can add many Sheet Metal features and even use regular solid modeling tools to modify the flat pattern. Even though Inventor’s Flat Patterns are excellent, professional have long added material into the corners where features come together so that the material will be “crushed” into the corner as the feature is made thus adding strength to the part. Inventor allows you to continue this practice and make other changes. It is important to note the changes to the Flat Pattern will not be represented in the folded part.

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If you’re creating a 2D drawing of the Flat Pattern you may want to call out the angle, radius and direction of the individual bends if your company does not have automated forming equipment. Inventor even allows you to generate a list of bends with that information in a table form. If you’ve modified the order of the bends your specified order will be accounted for in the Bend table.
Bend callouts can be relocated with leaders
A Bend Table reflects your Bend Order overrides

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