Week 9 - Attachment Feature Creation - Challenge 2

ANSEWER:

AIM: Create the boss and Dog House for the Centre console coin holder considering the design rules

General Guidelines for Bosses:

• Draft - 0.5 degrees on the 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

• 

• 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 3.0 – 6.0 mm

Creation of tooling axis:
Since the model is a coin holder, which is like a bin, we can always take the tooling axis direction w.r.t the bottom surface as shown in the figure.
First, we need to check in all directions for the tooling axis for the core and cavity direction.
The draft angle needs to check for all surfaces so that no interference occurs while ejecting the core and cavity.
First, extract the bottom surface and create a point. With help of a point creates a line in the perpendicular direction of the surface.

class A surface

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 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 the outside fillet should be the sum of wall thickness 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

iso-constrained sketches:

iso-metric views ina all directions:

DRAFT ANALYSIS FOR A SOLID BODY:

when we change the degree from 3 -0.45 the draft analysis changes on screw boss and dog house

TREE STRUCTURE:

CONCLUSION:

Screw boss and dog house are created by considering the design rules. and performed the draft analysis