Challenge

Week 10 - Challenge 2- Attachment Feature Creation (Dog House)

AIM

Create the Dog House for the Door Trim considering the design rules

INTRODUCTION

DOG HOUSE

Dog house is an engineering feature used in plastic design. Dog houses are used as support feature. Sometimes other engineering features like snaps, locators, and screw bosses are mounted on them to increase their strength.
Dog houses are subjected to draft analysis to prevent breakage of the component during ejection from the mould cavity. Dog house and other engineering components are built on the B-surface.

TOOLING AXIS

Tooling direction Iis created by manually adjusting the compass.
Now extract any surface and create a mid-point on it.
Then create a dummy axis creating a line on the point and direction along the y-axis.
Perform draft analysis to find whether the given axis clears the draft analysis. If not create a new tooling axis.

DRAFT ANALYSIS FOR CLASS A SURFACE

CLASS B SURFACE

Create offset surface of CLASS-A about 2.5mm inward direction.
Check for discontinuity and rework on the offset patch surface using extract, multi-extract.
Join the surfaces and ensure the final CLASS-B surface created has no gaps.

COMPLETE B SURFACE WITHOUT PATCHES

CLASS C SURFACE CREATION

Create the sweep to the surface and tooling axis multi-extracting the CLASS-A boundary.
Join the sweep surfaces by using commands like extrapolate, trmulti-sectiontion surface.
Finally join all the sweep surfaces and ensure the continuity of the CLASS-C surface.

FINAL JOIN

DOG HOUSE CREATION

Dog houses are designed to avoid SINK MARK created on the CLASS-A surface by screw bosses and to solve the length issues when giving screw bosses.
It is also useful when perpendicular screw bosses are required on the part to the tooling direction.

Doghouse wall thickness at the intersection of the part wall ( C ) should be 40% or less than the main wall stock ( T ).
The height of ( B ) should be between 3.0 – 6.0 mm

DRAFT ANALYSIS

The Draft Analysis is a command that enables you to detect if the part you drafted will be easily removed.
This type of analysis is performed based on colour ranges identifying zones.

FINAL DRAFT ANAYLSIS