Week 9 - Attachment Feature Creation - Challenge 1

Q) Create the rib for the Centre console coin holder considering the design rules mentioned in the video.

Rib: One of the ways to strengthen a part is by adding one or more “ribs” to the design. Ribs are thin protrusions that extend perpendicular from a wall or plane to provide added stiffness and strength. Designers commonly try to increase the strength of a part by making its walls thicker.

Rib provides a means to economical stiffness and strength in molded parts without increasing overall wall thickness.

They also facilitate:

• Locating and arresting component of an assembly
• Providing alignment in mating parts
• Acting as stops or guides for mechanisms.

Proper rib design involves five main issues:

• Thickness
• Height
• Location
• Quantity
• Manufacturability

Earlier challenge we have done creation of Class B and Class C and joint together & with final part draft analysis.

AIM: Create the rib for the coin holder with considering design rule.

Design Consideration:

• Nominal wall thickness of a plastic component 3mm
• A deviation of +/- 30% from the wall thickness is accepted

Ex: 3mm thickness of the wall

2.1 mm is minimum

3.9mm maximum accepted

• Ideal draft for a component Is 3 deg
• Minimum 0.5 deg accepted in ribs

Rib Creation:

• Draw a line on the base surface of the coin holder with using portion sketch and construct the line with using axis.

• Use extrude comment and extended this line as a surface at tooling direction.
• Height of the extrude surface 12.5mm

Design Consideration:

• Height of the rib is 5mm * thickness.
• Thickness is 2.5mm, so Height of the rib 5*2.5=12.5.

• Use thickness comment and given thickness as 1mm

As per design consider thickness should be:

Thickness of the rib =0.4*t (t= Thickness of the coin holder).

=0.4*2.5=1mm

• Give the draft angle 0.5 degree.

Design consideration for draft angle ≤0.5°.

• Fillet thickness given as 0.25mm.

Design consideration rib fillet radius r optional -0.25mm Max.

• Same way created one more rib on the coin holder surface.
• Add and assemble two surfaces with coin holder.

• Ribs should be spaced so that the steel between the rib is at a

Height /Width Ratio

• 3:1 steel
• 2:1 is preferred.

Gap between Two ribs 3:1 ratio

• Height of the rib is =12.5mm
• Using formula Y/X=3
• Y=12.5mm, X=12.5/3=4.16mm is minimum.

• Rib root thickness is R=1.34mm

Tree Structure: