Creating Plastic Features in Inventor – Ribs

Posted on July 17, 2013 by Jim Swain, Project Manager, Manufacturing Solutions:

Inventor’s plastic part design tools simplify the creation of many types of features common to plastic parts.  This tip will look at the Rib tool.

The Rib tool allows the easy creation of free-standing or connected thin walls.  It uses a single sketch to define the various segments of the rib.  If center points are included in the sketch it can also create holes or pegs.*

  *New since release 2012.

For this first example, a simple curved cover needs to have some stiffening ribs added.

A sketch is placed on a work plane slightly recessed into the part.

This sketch includes points added to the six intersections.

These were added, then constrained to be coincidental to the sketch lines.  This allows them to be used for bosses.  These bosses are different from the dedicated Boss feature in that there aren’t any center holes in these bosses.

Once these points are  constrained they are very difficult to see in the sketch.

pr5  

Finish the sketch, start the Rib command, and select all the sketch objects.

The choice for ‘Normal to Sketch Plane’ is only the choice that gives a solution preview.  If the sketch lines were parallel, the ‘Parallel to Sketch Plane’ option would ‘give’ shelves in the work plane.

The Extend Profile option is also turned on, which extends the sketch lines to existing part faces.

Other settings on the Shape tab control: how thick the rib will be, in which direction(s) the wall will be offset and if the wall extends all the way to the bottom of the part or is only a thin beam.

The Draft tab controls where the wall thickness is held to the specified value and how much draft is applied.

The Boss tab allows points to be picked for centers of bosses.  The Offset value is the height that the boss extends above the rib.

Note: Ifpr11 the points aren’t constrained to be coincidental to the rib’s sketch lines they aren’t available for creating rib bosses.

I hope this helps you design more efficiently.  Any other features or design workflow giving you problems?  Let us know or search this blog for what you need.

Until next time,

Jim

Jim is Synergis’ Project Manager for Manufacturing Solutions and has been with Synergis since 1997.  Prior to joining Synergis he worked in the consumer electronics and automotive industries as a design engineer, a test engineer, and as a CAD administrator. He has also taught design classes at the college level. Jim’s broad knowledge base helps him to understand customers’ problems and offer appropriate solutions. Jim earned BS and MS degrees in Mechanical Engineering from Lehigh University. Jim is a certified Inventor Expert, having been in the first group of people to take and pass the Autodesk Inventor Certified Expert Exam at Autodesk University in 2003. He has also presented classes at Autodesk University since 2003. Email Jim with a question or request.

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