Week 10 - Challenge 2- Attachment Feature Creation (Dog House)
AIM
Create the Dog House for the Door Trim consdiring the design rules.
INTRODUCtion
DOG HOUSE
Dog house is an engineering feature used in plastic design. Dog house 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
OBJECTIVE
. Create a Tooling axis for the given Class-A surface.
. Create the CLASS-B and C surfaces of door trim using the given CLASS-A surface.
. Create to final surface model and convert it into a solid body using the close surface
command in the part design workbench.
. Create side core axis for the dog house.
. Create Doog house on the B surface by considering the design rules.
. Perform draft analysis for both Class-A Final part body.
Design Methodology
Class -A surface means visible surface. It gives the aesthetic of the component which is
created by the styling team and givesto the part design engineer to create the part with all
engineering aspects.
Given CLASS-A surface
Check for continuity af the given surface using join or Boundary commands.
If there are no gaps on the A surface, create tooiling axis.
Procedure for Tooling axis creation
. Check the best possible tooling direction by manually the compass.
. By analysing it is found that the y axis as tooling direction would clear most of the faces
without any difficulties.
. Now axtract 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 of CLASS-A surface
CLASS-B surface creation
Class-B surface means the thickness of a part it is not visible and is inside part in other
words, the Class-B surface is a surface below a certain thickness from the clas-A surface.
This is the surface that contains engineering aspects of a model.
. Create offset surface in Class-A about 2.5 mm inward direction.
. Check for discontinuity and rework on the offset surface using extract, multi-extract, multi
section surfaces.
. Join the surfaces and ensure the final Class-B surface create has no gaps.
CLASS-C surface creation
The surface that joins class-A and class-b surfaces class-C surface. Class C is often
specified for interior surfaces not reddily visible, surfaces that will be covered by another
part when assembled.
. Create the sweep concerningerence to the surface and tooling axis multi-extracting the
Class-A boundry
. Join the sweep surfaces by using commands like extrapolate, multi-section surface.
. Finally join all the sweep surfaces and ensure the continuity of the CLASS-C surface.
Creating the Final surface
. For creating the Finals door trim surface, join the CLASS-A and CLASS-C surface together.
. Then extrapolate the B surface little bit outward direction to make sure that there would
not be any gap when trimming with the joined surface.
. Then trim the extrapolated CLASS-B surface with join surface (CLASS-A and CLASS-C)
Make a solid part body using the close surface command in the part design workbench
DOG HOUSE Creation
. Dog houses are designd to avoid SINK MARK created on the CLASS-A surface by screw bosses
and to solve the length issues when giving screw bosses which need to be
assembled to other components.
. It is also useful when perpendicular screw bosses are required on the part to the tooling direction.
. C thickness should be 40% of the main wall thickness T
. Minimum width of the dog house is 12mm.
. Height of B should be 3.0-6.0 mm
. Minimum draft for the dog house degree 5 degreeto die draw.
Precedure for creating the DOG HOUSE
. The first step is to create a side core axis .
. I have chosen the normal to the point method for creating the side core tooling axis
. Create the Dog house by creating a positioned sketch on the z-x plane. Using extrude or
sweep method create dog house outer walls.
. Now close the top wall using the multi-section surface command.
. Using thicken command in the part workbench, create a solid part of the dog house,
. Give proper draft angles and fillets by considering the design rules.
Using Boolean operation, union trim the dog house body part with the door trim component
3D Part model in various orientations (isometric, Front, Side, and Top View)
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
on the analysed element where the deviation from the draft direction at any point,
corresponds to specified values.
Draft analysis is done after determining the tooling axis, draft analysis is used to check
whether the minimum draft (3 degree) is maintained or not.
. Procedure for performing the draft analysisare as follows
. Change the view mode of the component to be in customized parameter mode and then
select the shading mode as materials.
. Then open the featured draft analysis tool from the insert menu.
. Then the click on the use the compass to define the current drafting direction and then drag
and align the compass on the Tooling axis.
. Then lock the draft direction and perform draft analysis by clicking on the component.
Colour Range representation
Green Colour - Positive Draft
Red colour - Zero Draft
Blue colour - Negative Draft
Draft analysisof DOG HOUSE using the Side Core Axis
Draft analysis of final Door trim component
Conclusion
I have successfully created CLASS B and C surfaces using the given CLASS A surface of the
door trim created main and side core tooling axis, Performed draft analysis the final
component and the Dog House.