Week 9 - Attachment Feature Creation - Challenge 2

Screw Boss and Dog House attachment on Coin Holder

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. Designing plastic screw bosses is fairly straightforward but there are a few considerations to ensure a strong connection between parts and mitigate cosmetic defects.

Guidelines:

First we make inner circle (smaller radius) as per the screw we will be using then as per the guidelines we will calculate the thickness required for screw boss that is 0.4T, T is thickness of coin holder.

After creating this we Pad sketch and keeping the ratio of 3:1 between height and diameter

Now we draft both inner and outer faces of the pad.

After creating tis we need to provide support for cylinder projection which will make screw boss complete for functioning

We create these ribs as per rib guidelines so thickness will be 0.4T that is 1mm

After that we will give the fillet that is 0.25 max

Draft analysis

Dog House Creation:

Doghouse: They are used for supporting screwbose. When the mating are at large distance then we cant increase screwbose height at it will create buckling in it so we need to provie support for screw boss so we use the Doghouse feature for this.

Guidelines:

We sweep this sketch with draft direction taking draft 0.5 degree

At the intersection of doghouse some material is removed to avoid sink marks

Now we need to make side core axis for doghouse to be cleared from side

Now we give draft to side surfaces as per the side core tooling direction.

Draft Analysis

Now we can translate the screwbose over this doghouse

Final Part:

ISO View

Front View:

Side View:

TOP View: