Week 8 - Challenge 4 - Coin Holder Design

COIN HOLDER DESIGN

Introduction

Class A surface

This is the styling surface which provides the aesthetic features of a component. A designer starts the component design from a class A surface.

Class B surface

Class B surface is obtained by offsetting the class A surface by the component thickness value. This B surface contains all the engineering features of the component.

Class C surface

Class C surface is created along the tooling direction of the component and connects the class A and class B surfaces.

Tooling Axis

Tooling axis is the direction in which the 2 halves of a mould (core and cavity) opens or closes, or the direction in which the part is released from the mould.

Draft Analysis

Draft analysis measures the draft angle on multiple surfaces of a part along the tooling axis to check if the surfaces have the minimum required draft angle for it to be moulded properly.

Process

1. Creating Tooling axis

The tooling axis for the coin holder is made perpendicular to the base surface along the Y axis since the faces of the coin holder are not at a draft angle

2. Creating B surface

• The faces of the coin holder are extraced individually from the class A surface
• The extracted surfaces are untrimmed and extrapolated
• They are then offset by a distance of 2.5mm in the required direction
• The offset surfaces are then trimmed with each other
• Finall the fillets are applied and the B surface is created

Final B Surface

3. Creating C surface

• For this model the C surface is not created along the tooling axis but perpendicular to the A surface
• The outer edge of the A surface is extraced along with the faces adjacent to the boundary
• The extracted outer edge is then swept perpendicular to the adjacent faces
• This is the C surface for this model
• The surface is then trimmed with the B surface and then joined with the A surface to cerate the surface body
• This is then converted to a closed plastic body

C surface (in orange color)

C surface trimmed with B Surface

Final surface body

Plastic Body

4. Draft analysis

Draft Analysis of class A surface

Draft analysis of closed plastic body

Report

• From the draft anaysis, the faces in green have a draft angle of 3degree or greater
• The faces in blue have a draft angle between 0 to 2 degrees
• While the faces in red have negative draft angles
• From the draft analysis it is clear that the coin holder need to designed such that the faces in red have a draft angle of minimum 3 degrees