Week 9 - Attachment Feature Creation - Challenge 2

SCREW BOSS

In plastic parts, bosses are typically used to assist in assembly, as a receptacle for a screw or threaded insert or as the locator for a mating pin on another part. Because of its function, a boss must have sufficient strength to do its job. This dictates a minimum size for the feature.

Design rles for the Screw boss

So the design rule for the screw boss is.

The hight of the boss should be 5 times of thickness of the component.

the thickness of the wall is 40 % to 60% eache side of thickness of component.

Radius should be 25 percentage of the thickness.

The depth of the bass is 30% or less than that inside of the component thickness.

angle should be 0.5 min.

DOGHOUSE

Dog house is a 4 sided box attached to a flat surface which usually requires a riser/slide to mold. In other words, it has 3 sides and a “roof”, where the roof usually has a hole for attachment purposes. The molded part will then be more close to intended design due to shrinkage and internal stresses at the corners.

properties of doughouse'

To avoide sink marks.

To overcome the lenght issue og the screw boss.

To create perpendicullar screw bosses.

Design Rules for the DOGHOUSE

Draft - 0.5 degrees on walls of boss

Thickness - 40 percent of the nominal thickness

hight to Diameter ratio - 3:1

Radius - 0.25mm maximum

rest of the imformation in the image.

Creation Of the SCREW BOSS

to create screw boss we used the coin holder componet.

to create the screw boss extract the base surface from the component.

sketch ot the extracted surface usong position sketch.

we designed the screw boss for M6 screw so the inner diameter is 5.2mm and the outer diameter is 8.2mm.

then extrude the sktch in uside so the hight is 5 times of thickness of component.

then apply draft to the extrude using draft with direction and angle.give 1.5 degree draft angle use tooling AXIS as draft direction.

then to provide strength to the screw we design the ribs for the boss in support of the boss, with the design guidlines of the rib.

Copy the sketch of the screw boss edit the sketch then converth both the circles in to the construction geometry. draw two line coicident to center of the ciccle and intersecting perpendicular to each other.

then extrude them in upward give appropriat hight and thickness of 1mm w.r.t to the thickness of the component.

draft with dirction of the tooling axis.

then use boolean operation to screw boss and ribe, use union trim and trim inner part of the ribes.

then add the screw boss with the main component using Boolean operation.

apply fillets to the every face of the screw bass.

DOGHOUSE DESIGN

to create the doghouse use the componet surface or if you want to modify it seperatly use indipendent sketch support for the doghouse.

Here we used the same component surface as the sketch support surface.

slketch on the extracted surface using position sketch.

draw rectangle with one open end.

then use sweep command to extrued the sketch of the doghouse so it will get the drafted surface before thickining it.

use draft with directon, draft angle should be 1.5deg as per the gudlines of the doghose design. drafting direction is tooling axis

then with part workbench thicken the surface outside by 2 mm.

then cut the doghouse from the nottom as per the design rules to get an proper shape of the doghouse.

now create an side core tooling axis for the doghouse so it will be cleared by the side core while manufacturing.

use the line command and then select point and direction option select the point of the main tooling axis and extend the line in Z direction so this line should be peroendicular with the main tooling.

then use the draft analysis to check the clearence from the side core direction for the doghouse and the overaal component.

TREE STRUCTURE