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

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.

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

Pad the drawn sketch to create the dog house and draft the pad body 0.5 degree.

shell the doghouse for the thickness fo 2.5mm

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

Again, provide draft to the inside surface as shown.Give radius/fillet to inside as 0.4*T=0.4*2.5=1mm and for outer edges give fillet as inside radius + part thickness.

After created Dog house,have to place screw boss on top. Usign translate point to point option to place top of the dog house and assemble with body.

DRAFT ANALYSIS.

Analysing draft angle with respect to tooling axis.

Analysing draft angle with respect to slider axis.

Isometric view of component with draft analysis

isometric view of Coin holder design with attachment features.

Tree Structures.

CONCLUSION

The attachment features such as Screw boss and Dog house created in the center console coin holder component as mentioned design rules and preformed analysis draft angle.