Week 9 - Attachment Feature Creation - Challenge 2

Aim:

To Design Boss and Doghouse acoording to the engineering principles on the coin holder part.

Theory:

Boss:
Bosses are used to facilitate the registration of mating parts, for attaching fasteners such as screws, or for accepting threaded inserts.Wall thicknesses for bosses should be less than 60 percent of the nominal wall to minimize sinking. However, if the boss is not in a visible area, then the wall thickness can be increased to allow for increased stresses imposed by self-tapping screws.

The base radius should be a minimum of 0.25 X thickness. Bosses can be strengthened by attaching gussets. At the base or by using connecting ribs attaching to nearby walls.

Dog House:
Dog house is an engineering feature used in plastic trim design. Dog houses are used as supporting features.
Sometimes other engineering features like snaps; locators etc. are mounted 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 a B-surface. Dog houses are used as supporting feature. 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 a B-surface. Dog houses keeps hold of Push pin clips that are mounted on them to snap the mating parts.

DESIGN:

Dog house and Screw Boss are designed wrt the above mentioned Design rules on a Coin holder part as shown.

Result:

The Dog house and Screw boss were designed wrt the design principles.