Week 9 - Attachment Feature Creation - Challenge 1
DESIGNING RIB FEATURE BASED ON DESIGN RULE
Aim:
To design ribs on the coin holder considering every design rule coinsidered in industry.
Rib design:
Ribs provide a means to economical stiffness and strength in molded parts without increasing the wall thickness.They also facilitate,
- Locating and arresting components of an assembly
- Providing alignment in mating parts
- Acting as stops or guides for mechanism
Rib design involves five main issue
- Thickness
- Height
- Location
- Quantity
- Manufacturability
Thickness:
Rib thickness,W=0.4*t=0.4*2.5=1
t-Thickness of the base
The larger the area at the base of the rib the more hear retained.The retained heat causes more shrinkage,which causes sink.
Height:
Rib height <5*nominal wall thickness
5*2.5=12.5
It is limited by draft and thickness requirement
Rib thickness at tip:
Minimum thickness at rib tip should be 0.75mm.
Rib fillet radius:
Optional rib fillet radius is 0.25mm maximum.Do not want to significantly increase rib thickness.It must not violet 40% thickness requirement.
Rib root thickness:
Rib root thickness should not be more than 30% wall thickness to avoid sink marks.
Root thickness ≤ Wall thickness + 30% of wall thickness
Spacing between two ribs:
Rib should be spaced so that sheel between the ribs is at a height/width ratio 3:1.Whereas 2:1 is preferred.Prevents thin steel conditions which leas to crack
Isometric view:
Front view:
Top view:
Side view:
Tooling axis:
Y axis is selected for tooling direction
Since the part is given as input,it's faces are taken as multiple extract and using this the tooling direction is created.
Now a sketch is drawn in XY axis and the intersect 3D element is taken between product and the axis.Now from the side walls of the intersect a bisecting line is drawn and this line is used as tooling axis.
Draft analysis:
Here the dreft angle is 0.5
The green colour indicates the draft angle 0.5 and above
The blue colour indicates draft angle between 0-0.5,
The red colour indicates negative draft(below 0 deg).
Inorder to create the ribs with the given draft angle side core should be used.
