Inventor In-Depth: Taming Wire, Cable and Harness Designs

11 Apr, 2006 By: Kevin Schneider

Autodesk Inventor Professional works like a charm on wires snaking through your designs.

Wire, cable and harness design can bring out the Indiana Jones in all of us. Even as we boldly engineer solutions to tough design problems, those serpentine wire paths can practically stop us in our tracks like the snakes in Raiders of the Lost Ark.

Fortunately, Autodesk Inventor Professional features powerful cable and harness design tools that make it easier to design wire harnesses. In addition to an accurate 3D representation of the harness, these tools provide important functional information in the harness properties and reporting. Autodesk Inventor Professional also automatically checks that your design won't pinch wires and creates nailboard drawings so that the manufacturing team can produce the harness quickly.

Here are tips for using some of these powerful design tools.

Check Wire Paths
Complex harnesses can have many wires that weave through your design. Autodesk Inventor Professional shows you the wire path in 3D so that you can visualize a wire's connection to specific components, as well as its path to them.

From the browser window, right-click on a wire you have created. Select View Path from the Context menu that appears (figure 1).

Figure 1. Choose View Path for a 3D view of the wire path you've designed.

The wire's path through the harness appears highlighted by dashed lines. This makes it easy to see how the wire passes through your design and the components to which it connects (figure 2).

Figure 2. Dashed lines mark the individual wire path.

Check Bend Radius
Wires often have a recommended minimum bend radius that's intended to ensure component design won't pinch or bend those wires enough to damage them or impair product function. Use Autodesk Inventor Professional's capabilities to validate your design.

First, set the bend radius recommended by the wire manufacturer, or use the wire diameter x5 preset in Autodesk Inventor Professional.

  1. To set the minimum bend radius, select Harness in the browser and then click Harness Settings from the Context menu (figure 3).

Figure 3. Choose Harness Settings to establish minimum bend radius.

  1. Click on the Segments tab. In the Bend Radius specifications section, check the box for Calculate Size from Wires (figure 4). As an alternative, you can enter a value defined by your wire manufacturer.

Figure 4. To set Bend Radius, choose Calculate from Wires.

Now you're ready to check your design. Return to the browser menu, choose Segments and select Bend Radius from the Context menu and then click on Check All Bend Radii (figure 5). This action will validate all the segments and display a warning icon next to any that violate the minimum bend radius rule.

Figure 5. Choose Check All Bend Radii to find any segments that may pinch wires.

  1. To see any nonconforming elements, choose the segment with the warning icon and select Bend Radius and then Show Violations from the Context menu (figure 6).

Figure 6. Click on the segment with the warning icon and drill down to see problem areas.

  1. The violation is displayed in 3D with a symbol that identifies the specific location where the bend radius is too small (figure 7).

Figure 7. A red marker and approximate work point identify bend radius violations.

Use this information to move points or reroute wire segments and make sure your design conforms to minimum bend radius requirements. After you have a design that meets your needs and passes this error-checking process, you're ready to create the documentation for its manufacture.

Create Nailboard Drawings
Nailboard drawings unwrap the harness and produce straight sections that represent the physical length of the wires needed to create the harness. But creating this documentation by hand in 2D is a time-consuming and error-prone process that also often requires construction of a prototype harness--or at a minimum, running a string through a design to approximate the length of wire required.

You can bypass this painstaking work with the click of a button in Autodesk Inventor Professional. To create a nailboard, simply press the Nailboard button on the panel bar. The nailboard drawing is generated automatically, along with a one-to-one scale view that includes the harness sections unwrapped to their appropriate length (figure 8).

Figure 8. Click the Nailboard button for automatic manufacturing documentation.

A complete set of table and reporting tools helps you annotate the nailboard drawing so that you can identify wire length, diameter and many other important properties easily.

Imagine the time and cost saved by catching errors in wire, cable and harness design early in the development process--without even building a physical prototype. Try these tips and tricks to get started on more efficient and cost-effective harness design.

About the Author: Kevin Schneider

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