Week 9 - Attachment Feature Creation - Challenge 2

Aim: To create a screw boss and dog house for the centre console coin holder by considering design rules.

General Guidelines for the creation of Bosses:

•   Draft  - 0.5 degrees on walls of boss
  
  
•   Thickness -  Typically 40%* of the nominal wall at the base.
  
  
•   Height to Diameter Ratio -  3:1
  
  
•   Radii - 0.25mm maximum radii.  

"C" is where the doghouse contacts the backside of the surface

General Guidelines for the creation of Dog houses:

• Doghouse wall thickness at the intersection of the part wall (C) should be 40% or less than the main wall stock ( T ). 

• The height of (B) should be between 3 – 6 mm.

Creation of screw boss:

• These are supporting attachments for the plastic components in which the screws are mounted to attach the component to another component.
  
  
• To create a screw boss extract the base from the class A surface.
  
  
• For an M6 screw, the diameter should be 5.2 to create a circle.
  
  
• The thickness of the wall should be 0.6 times the thickness of the component i.e., 0.6*2.5*2 for either side is 8.2 mm.
  
  
• Extrude the circles up to 12 mm and make sure that the other side is penetrating into class A.
  
  
• Draft faces with 0.5 degrees with respect to the tooling axis.
  
  
• Add ribs to add strength to the boss.
  
  
• The thickness of the rib should be 0.4 times the base component thickness.
  
  
• Draft all the faces.
  
  
• Assemble and union trim the ribs and screw boss.
  
  
• Assemble the complete screw boss to the main component.
  
  
• To duplicate the screw boss copy the assembly of the screw boss.
  
  
• Use the 'paste special' option and paste it into the main tree of the coin holder
  
  
• Use translate and give coordinates.
  
  
• Give fillets to the sharp edges.

Creation of dog house:

• Check conditions to create a dog house
  
  
• Doghouse wall thickness at the intersection should be 40% or less than the main wall thickness.
  
  
• The height of that thickness should be 3-6 mm.
  
  
• Dog houses are used to mount the supporting features on them when attaching distance is more for snaps locators etc.
  
  
• These reduce the sink marks on class A.
  
  
• To create a dog house create a rectangle and make one side as a construction element.
  
  
• While draft analysis the inside part can’t be cleared with the main tooling axis.
  
  
• A side core axis should be created to make the doghouse.
  
  
• Extract the surface and create a point and line in that direction of the dog house.
  
  
• Sweep the sketch with respect to the draft direction.
  
  
• Don’t use a pad because again draft should be given to the padded surface.
  
  
• Sweep the sketch with a 1.5 degrees draft and the minimum height should be 6mm and width should be 12 mm.
  
  
• Take the extract from class A and offset the dog house height and trim it.
  
  
• Switch to the part workbench and add 2 mm thickness to the part.
  
  
• Extend and extrapolate the rear surface of the doghouse and offset it to the front side of the dog house and split it in the part workbench to get rid of the irregular surfaces.
  
  
• Draft the inside walls of the dog house to 0.5 degrees.
  
  
• Now to create the intersection thickness extract the inside surface of the dog house and offset it to 1 mm.
  
  
• Extract the class A of the base and offset it to a height ranging from 3 to 6 mm.
  
  
• Trim the extract and the offset.
  
  
• Split the output with doghouse towards doghouse on the part workbench
  
  
• Draft the undercut to 0.5 degrees.
  
  
• Give fillets make sure that outside fillet should be the sum of wall thickens and fillet value.
  
  
• Assemble dog house to the main body.
  
  
• Perform draft analysis as the inside part will turn red make the angle to 1.45 as we gave the sweeping draft to be 1.5 degrees.