Week 9 - Attachment Feature Creation - Challenge 1

AIM : To Create the rib for the Centre console coin holder considering the design rules.

THEORY :

RIBS :

Ribs provide a means to economically augment stiffnessand strength in molded parts without increasing overall wall thickness. Other uses for ribs include:
• Locating and captivating components of an assembly;
• Providing alignment in mating parts; and
• Acting as stops or guides for mechanisms.

Ribs usually project from the main wall in themold-opening direction and are formed in blind holes in the mold steel. To facilitate part ejection from the mold, ribs generally require at least one-half degree of draft per side .More than one degree of draft per side can lead to excessive rib thickness reduction and filling problems in tall ribs.

generally, taller ribs provide greater support. To avoid mold filling, venting, and ejection problems, standard rules of thumb limit rib height to approximately three times the rib-base thickness. Because of the required draft for ejection, the tops of tall ribs may become too thin to fill easily. Additionally,very tall ribs are prone to buckling under load. If you encounter one of these conditions, consider designing two or more shorter, thinner ribs to provide the same support with improved moldability.Maintain enough space between ribs for adequate mold
cooling: for short ribs allow at least two times the wall thickness.

PROCEDURE :

since we already have created coin holder before, now we will add ribs for the purpose of providing strength to the component.

here we have created two lines of length to our choice and make it iso-constrained.

now we will extrude those lines with height between 3T and <5T so it will be 2.5*5=12.5.since here we are creating two ribs so we will extrude both lines with 12.5mm and then we will define some thickness to it.

here we define thickness to the extruded surfaces which has a value of 0.4*T = 0.4*2.5 = 1

after giving thickness now its time to add draft angle to the rib with value of 0.5deg by giving top face as a neutral plane to take draft direction from to all 4 sides of the rib.

now its time to add those two ribs attached to the coin holder body with boolean operation in part workbench.

after performing boolean add of ribs to the main body we will add edgefillets of 0.25 to all corners including the base corners

finally we will insert draft analysis and define the tooling direction by moving it around until we find that the total body of the rib is green i.e., it is satisfying the 0.5 degree draft condition.

RESULT :

Hence we have finally added ribs to the coin holder and performed draft analysis on it considering the design rules mentioned in the video.