Week 9 - Project - Master Section Development

Master Section Development

AIM: To Create the Closed part body of B PILLAR from given Class-A and develop attachment features.

OBJECTIVE: The objective of this challenge is to develop Closed Surface Model using Master Sections and develop attachment features for fixation of parts by following OEM Design standards and procedures in CATIA SURFACE and PART WORKBENCH.

INPUT CLASS-A SURFACE:

ABSTRACT:

The report details about Design Life Cycle in AUTOMOTIVE INDUSTRY with working model of B PILLAR Cover of car interior. Report also explains procedure followed to create Tooling Axis by bisecting method. The attachment features are also explained following design guidelines and finally Draft Analysis to prevent failure and improve feasibility of manufacturing parts in Injection Molding Process.

CLOSED PART BODY:

DESCRIPTION:

Four stages of design life cycle are as follows:

• Concept sketch: These are the imaginative and innovative sketches. Concept sketches can be defined as collection of visual cues sufficient to suggest the design to an informed observer. These are the basic sketches which provides general idea about design of the product. These sketches are provided to system either in 2D or isometric form. Example, concept sketch of an automobile.
• Class A Creation: Class A surface refers to those surfaces which are VISIBLE and abide to the physical meaning, in a product. For styling-class A surfaces of automobile ALIAS software is used. These class-A surfaces are used as an input for an Automotive Plastic Designers
• CLAY MODELING: In clay modeling class-A surfaces are provided to clay modeler who design actual model of automobile using industrial clay. Class-A surfaces and clay models are co-related. Using clay modeling physical representation of design is possible which helps in further modifications in the design of the vehicle. Clay modeling of an automobile is most common example of a clay modeling.
• NPD CAD: New Product Development (NPD) Computer Aided Drafting (CAD). This process involves forming strategy, organizing requirements, generating concepts, creating product &

TOOLING AXIS CREATION:

Class-A surface is first analyzed to create tooling axis or tooling direction that molds pull apart in injection molding. Tooling direction is vital for plastic product design as it decides direction for mold separation.

Steps followed for creation of tooling axis:

1. Reference point is first created on extracted surface.
2. New axis system is deployed to plot clearance lines.
3. The X direction and Y direction along the class A were used to create tooling axis
4. Two clearing lines were bisected to form Tooling axis.
5. Graphic properties of tooling axis were change before publishing.

ATTACHMENT FEATURES:

• DOGHOUSE WITH 4 WAY LOCATOR
• RIBS

Using the Master Section Doghouse is created and then part modelled using thickness option. The 4-way locator is formed above the doghouse which locates B-Pillar towards the Mating Surfaces.

Doghouse Design rules are as follows:

• The thickness of connecting surface towards B side should be 40% off the main thickness.
• The walls are drafted with minimum 0.5 degrees along Main Tooling Axis
• Attachment feature created needs separate tooling axis called lifter axis.

RIBS: Rib provides stiffness to the parts and can be to impart toughness without increasing part thickness. Main design in Ribs creation is wall thickness should be 0.4 times of Thickness of part. Rib wall should be drafted with o.5 thickness.

DRAFT ANALYSIS:

Draft Angle: The draft angle is the amount of taper for molded or cast parts perpendicular to the parting line. It can be measured in degrees or mm/mm (in/in). As plastic cools, it shrinks and therefore shrinks onto molding surfaces. Because of this and a few other reasons, we draft (angle) the walls of the plastic part, so as the part is removed it breaks free from the molding surfaces easier and without dragging. 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. What’s also important is to overcome the vacuum forces by letting air in between the metal and the plastic for the part to release properly. Adding an adequate draft angle ensures that warpage upon ejection is prevented while maintaining a decent cosmetic finish.

• Draft angles are generally a requirement of injection molding design (though there are a select few soft materials, like nylon, that can get away with draft angles of zero).
• Draft should be a part of design for manufacture, and Plastic Product Designer should be aware of its need at the outset of the design process. This allows considerations for design requirements to be taken into account.

Importance of DRAFT in Injection Molding:

• Reduces the chance of damage to the part due to friction during release
• Reduces wear and tear and chances of damage to the mold
• Ensures a uniform, smooth, unscratched finish when required
• Ensures the integrity and uniformity of other surface finishes and textures
• Reduces overall cooling time by lessening or eliminating the need for unconventional ejection setups
• Most, if not all, of these benefits offer either direct or indirect overall production cost reductions.

Steps followed for Draft Analysis:

• The part created has to be changed to material mode in display frame.
• Compass is enabled. Align compass along with tooling direction.
• Lock command is then applied to fix compass along with tooling axis
• Color codes are classified and Draft angle is applied.
• Running point analysis is used to display permissible draft angle.

DRAFT ANALYSIS ON CLASS-A SURFACE:

DRAFT ANALYSIS ON SWITCH BEZEL (FINAL CLOSED BODY):

NOTE: All 2D sketches created in this operation are iso-constrained.