Week 9 - Attachment Feature Creation - Challenge 2

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

INTRODUCTION

The B-side of the mold will often have more complicated and protruding features. These features allow the plastic to cool onto that side and away from the A-side. At the same time, allowing the plastic to stick and shrink too hard will make the part eject forcefully or get stuck in the mold.

BOSS: Boss features are commonly found in injection molding designs. They are used to aid in the assembly of molded parts by providing a channel for a screw. Designing plastic screw bosses is fairly straightforward but there are a few considerations to ensure a strong connection between parts and mitigate cosmetic defects.

DOG HOUSE: Dog house is an engineering feature used in plastic trim design. Dog houses are used as supporting feature. Sometimes other engineering features like snaps; locators etc. are mounded on them to increase their strength.

Dog houses are subjected to draft analysis to prevent breakage of the component during ejection from mould cavity. Dog house and other engineering components are built on B-surface.

Design guidelines for screw boss design

1. Draft: 5 deg on each wall.
2. Wall thickness: 40% of the nominal wall thickness
3. Diameter: 3:1 steel but 2:1 used
4. Radius of fillet: minimum 0.25mm

Design guidelines for dog house design

1. Draft: 1.5 deg on each wall.
2. Wall thickness: 40% of the nominal wall thickness
3. Width: 3:1 steel but 2:1 used
4. Radius of fillet: minimum 0.25mm
5. Sink saver: height = 40% of nominal thickness.

Width =3 mm to 6 mm

Steps followed

creating toolig axis

For screw boss

DRAFT ANALYSIS

To perform the draft analysis on the dog house , first set the view parameters to material mode.

Then go to menu bar select insert analysis feature draft analysis

To give the draft direction, use compass and align Z axis of it with the final tooling axis for the dog house model. Once it is properly aligned, lock the draft direction. Select the dog house and it will show us the current draft angle of the model, set the draft value 3 degree under the color scale variant and press ok.

ISO VIEWS

Conclusion

The boss and Dog House for the Centre console coin holder considering the design rules created and draft analysis performed successfully.