Week 9 - Attachment Feature Creation - Challenge 1

FEATURE CREATION - RIBS

RULES

• Ribs are provided to a plastic part to provide strength and stiffness without increasing the overall thickness of the component
• They help in alignment of the component in an assembly
• They act as guides and stops in a component
• They also help in locating and arresting components in an assembly
• Problems associated with creation of ribs are sink walls and wall thinning, so to avoid these problems, set of rules are followed in creation of Ribs.
• Rib wall thickness should be 0.4T (T=thickness of component)
• Rib wall thicness at tip should be ≥0.75mm
• Rib draft should be ≥0.5°
• Rib depth should be ≤5T
• Rib fillet radius is optional (0.25mm max)
• Rib root thickness should be slightly thicker than the component thickness

STEPS FOR CREATING RIBS

• The surface where the ribs should be placed is extracted
• On the extracted surface, a positioned sketch is created and a line in drawn
• The line is then extruded and given a thickness following the above rules, in this case 0.4*2.5= 1mm
• The height of the Rib is 5*2.5=12.5mm
• Draft angle for the ribs are given next, 0.5° on each side of the rib
• Fillet of 0.25mm is added, but this is optional
• Now, to check for rib root thickness, an intersection is taken and a circle with tritangent is drawn root of the rib
• The same steps are repeated for the n no. of ribs added