Week 9 - Project - A pillar Design with Master Section
Aim :To create the A Pillar Design with the master section given as the intersection sketch with the Class A surface and create the tooling axis and perform the Draft analysis for the final solid part.
Objective :
Create the required Tooling axis by using master section and bisecting methode.
Design the Class-B and Class-C surfaces and close all three surfaces.
Design the Dog house and its internal parts as given Drafts and mater section sketch.
Draft analysis for the final solid part and side core Draft analysis.
Tooling Axis :
Class-A surface is first analyzed to create the tooling axis or tooling direction that molds pull apart in injection molding. Tooling direction is important for plastic product design as it decides direction for mold seperation.
Step followed for creation of tooling axis :
Reference point is first created on extracted surface.
New axis system is deployed to plot clearance lines.
The X-direction and Y-direction along the class-A were used to create tooling axis.
Graphic properties of tooling axis were change before publishing.
Draft Analysis :
The Draft angle is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees. A functional part for injection molding has to have Drafts facing both cavity and core sides to reduce the risk of damage to the parts and ensure ejection. And also important is to overcome the vaccume forces by letting air in between the metal to the plastic for the part to relaese properly. Adding maintaining a decent cosmetic finish.
Nominal values for Draft angle :
3 Degrees is the nominal Draft angle.
7 Degrees for textured surface.
At the minimum of 0.5 Degrees can be manufactured by special tools. But it will increase the manufacturing cost.
Tooling Axis Creation :
For this part tooling axis creation is done by using the mater section which is given along the Class A surface. Because in this master section the Dog house is there and the Draft for the wall of the Dog is given by the tooling axis. So can take tooling axis from the master section. This master section and Class A surface is given below.
Draft analysis :
The part created has to be changed to material mode in display frame.
Compass is enabled and align it along with the tooling direction.
Lock command is then classified and Draft angle is applied.
Color codes are classified and Draft angle is applied.
Running point analysis is used to display permissible draft angle.
CLASS B SURFACE
After all the validation has been done, the class B surface is created by offsetting the class B surface to a distance of 2.5 mm
After offsetting a large opening in the surfaces is found which is closed with the help of sweep and multi section commands
The class B surface is then extrapolated in parts to trim it along with the class C surface
CLASS C SURFACE
The class C surface which connects the class A and class B surface is created by sweeping the boundary of the class A and using the class A as a reference.
The sweep is divided into several parts in order to avoid complexity
Surfaces which are parallel to the tooling direction are swept with the tooling axis as reference and with a draft angle of 3degrees
Creation of Dog House :
Sketch for Dog house :
The two main purposes of a dog house are to avoid sink marks and to house various other engineering features like screw boss, locators etc.
The dog house should follow certain design rules which are stated below
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 ON PART:
Draft analysis is done on the final part with the tooling axis as reference
Green surface indicates the areas where the draft is more than 0.5 degrees.
Blue surface indicates the area having negative draft.