Fillet (mechanics)

Applications

• Stress concentration is a problem of load-bearing mechanical parts which is reduced by employing fillets on points and lines of expected high stress. The fillets distribute the stress over a broader area and effectively make the parts more durable and capable of bearing larger loads.
• For considerations in aerodynamics, fillets are employed to reduce interference drag where aircraft components such as wings, struts, and other surfaces meet one another.
• For manufacturing, concave corners are sometimes filleted to allow the use of round-tipped end mills to cut out an area of a material. This has a cycle time benefit if the round mill is simultaneously being used to mill complex curved surfaces.
• Radii are used to eliminate sharp edges that can be easily damaged or that can cause injury when the part is handled.

  Design process

Terminology

• Autodesk Inventor, AutoCAD, CATIA, FreeCAD, Solidworks and Vectorworks refer to both concave and convex rounded edges as fillets, while referring to angled cuts of edges and concave corners as chamfers.
• CADKEY and Unigraphics refer to concave and convex rounded edges as blends.
• PTC Creo Elements/Pro refers to rounded edges simply as rounds.