Week 9 - Attachment Feature Creation - Challenge 2

AIM:

To Create attachement features such as the screw boss and Dog House for the Centre console coin holder with respect to the design rules.

INTRODUCTION:

SCREW 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.

Design rules:

lets consider Nominal wall thickness is T

Height of rib H- 3:1 ratio

Draft Angle for inside and outside - 0.5 degree

Fillet radius- 0.25 mm

Inner diameter of rib - depends on metric size screws. IF we take M6 Screw is inner dia is 5 mm.

Thicknes of boss W- 0.6*T

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.

DESIGN RULES:

Doghouse wall thickness at the intersection of the part wall ( C ) should be 40% or less than the main wall stock ( T ).

Height of ( B ) should be between 3.0 – 6.0 mm.

Design attachment features Screw Boss and Dog House :

Draw circular sketch inside circle of dia 5mm and for outer circle wall should be 0.6*T on one side so outside dia = 2*(0.6*2.5)+5(inside dia)=8mm and Pad it with main tooling direction considering height to dia ratio of 3:1

DRAFT :

Give draft of 0.5 degree with tooling axis.

Now have to a support for the screw boss and draw sketch ribs with respect to the below rules

Pad the sketch with thick option for thcikness value of 1 mm

Draft to ribs of 0.5 degree.

Do union trim with screw boss and assemble with coin holder body and give fillets to the edges.

Translate the screw boss with using paste special with link and translat point to point option

Design Dog House:

Draw sketch of rectangle with respect to axis system which created in the point.

sweep the drawn sketch to create the dog house and extrude the upper to create upper surface and thicken it in for 2.5mm and draft the body 0.5 degree

Draw a sketch and sweet to trim split the front face properly

Now to create coaring cut section as shown in design rules of B and C section,

Extract inner surface of Dog house and coin holder surface ,offset the base surface in between 3 to 6 mm.

Trimmed all surfaces to create coring section.

Switch to part workbench and split the C and B Section with solid part.

DRAFT ANALYSIS:

Analysing draft angle with respect to tooling axis.

isometric view of Coin holder design with attachment features.