Week 9 - Attachment Feature Creation - Challenge 2

AIM:

Create the Screw boss and Dog house for the centre console coin holder,

General rules for the Screw Bosses.

• Draft of 0.5 degree on walls of boss.
• Thickness is 40% of the nominal wall at the base.
• Height to diameter ration-3:1
• Fillet radious of max 0.25mm

Boss features used to aid in the assembly of molded parts by providing a channel for a srew.. 

C is where the doghouse contacts the back side of the surface.

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 betwen 3-6 mm

Doghouse is an engineering feature used in plastic trim design Dog house are used as supporting feature. Dog house are subjected to draft analysis to prevent breakage of the component during ejection from mould cavity. Dog house and other enginnering components are built on B surface.

 CREATION OF SCREW BOSS:

• First step is to create sketch for the screw boss slot and  strenghten it with iso constrained.

• Then Pad the sketches for 12mm height as shown in the below images.

• Next Drafting the Screw bosses with minimum of 0.5 degree.
• also .25mm fillet also.

After this define the Coin Holder main body 

Then Assemble the srew bosses to the main body.

• Now create sketch for the supporting Rib for the Screw Bosses and  strenghten it with iso constrained.

• Then Pad the sketch for minimum height which is not cross the height of the screw boss.

• Next Drafting the Rib with minimum of 0.5 degree.
• Then also add 0.25 mm fillet also.

• Now Define the Screw boss.
• Apply the Boolean trim operation between the screw boss and Rib.
• Select the removable portion of the rib which is inside the screw boss.

• Then assemble with the main part.
• After that use translate to move the Screw boss to where you want.

CREATION OF DOG HOUSE: 

• Extract the base of Class A Surface and offset it with part Thickness as 2.5 mm.
• Draw sketch of rectangle and that should be open at one side.

• Sweep the sketch along with the Tooling Axis at 1.5 degree.
• Increase the 1mm extra on both side during Sweep it will ensure the enough intersection during the trim operation.

• Now offset the base of the sketch at 20mm height,
• Then trim between sweep and offset base.

• Add thickness in outward direction with 2mm thickness.

• Add Draft of 0.5mm to the inner wall of the Dog house.

• Give radious to the inside wall=0.4t=0.4*2.5=1mm

• Then give radious to the outer edges=Inner tradious+Thickness=1+2=3mm

• Now offset the inner sweep profile of the dog house outward direction at 1mm
• Then also offset the Base of the sketch at 4 mm and trim it.

• Now Split it in outward direction.

• Add draft to the undercut surface.

• At last Define the main body.
• Assemble the Doghouse to the main body 
• Finally position the Screw boss on the Dog House.

DRAFT ANALYSIS:

FOR MAIN TOOLING AXIS:

FOR SIDE CORE TOOLING AXIS:

The Green colour surface will not create any issue during the ejection process but Blue surface needs to be correct regarding the draft angle,

RESULT:

CONCLUSION:

The Screw and Doghouse are created for given Coin Holder According to the design rules.