Week 9 - Project 1 - Door Applique Design with Engineering Features

AIM

1. Create the Base Bracket Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class-A Surface should be created meeting the requirements of the draft angle and at the end perform the Draft analysis on the model.
2. Create the Heat Stakes and the locators considering the design rules mentioned in the video for the door applique.

OBJECTIVE

Design of an Automotive Plastic Component – Driver Side RH Door Applique Design with 4-Way, 2-Way Locators and Heat Stakes using industry principles and Design Rules. Concepts such as Rib design rules, Draft angles, Draft Analysis, Determining the Tooling Axis, Class A, Class B and Class C surfaces. The component is designed to manufacture maintaining a wall thickness of 2.5mm for Applique using Surface Design and Solid Design techniques in CAD package CATIA V5.

INTRODUCTION

Heat Staking:

• Heat staking also known as thermoplastic staking is the process of joining two dissimilar materials together.
• In heat staking we use local heating and cooling to raise the temperature of plastic components and allow plastic reforming to be carried out.
• This reforming can be used in a wide variety of applications.
• The Plastic Stud protrudes through a hole in the component to be locked in place.
• Heated thermal tips are used to melt the top of the studs which fills up the volume of the cavity to produce a head locking the component in place.
• The progressive melting of plastic under continuous pressure forms the head.
• When staking, the right combination of heat and pressure is critical.
• Applications range from staking plastic boss’s for assembly of car door panels to joining PCB’s to plastic housings.
• Benefits of this technique include; no vibration damage, no particulates, the ability to stake metalized coated applications and the capability to stake in difficult to access or restricted areas.

• In short the Locators locate the component and lock 12 degrees of freedom whereas the Heat Stake is a Fixation which locks the Final DOF.

Advantages of Heat Stakes:

• Similar and dissimilar materials may be joined: metal to metal, plastic to plastic, metal to plastic.
• Accurate control operating within a small process window.
• Local heating resulting in no damage to surrounding materials.
• Processing of glass-filled materials.
• No mechanical vibration.
• Many heat-stake shapes possible through custom designed tools.

2 and 4 way locators:

• Locators are used to locate a job or a component to arrest its degrees of freedom using the 3-2-1 Principle which is arresting of 3 DOF's first, then 2 DOF's and last DOF in a sequence.
• A 4 way locator will look like a '+' and a 2 way locator will look like a '-' .
• Both these locators use the same Rib Design Rules and principles.
• These Locators are placed on the B side of the component and must have same height with respect to the B surface.

Guidelines For Rib Design:

Rib Specification	No-Show Surfaces	Show Surfaces
Draft Angle	Min 0.5º per side, Recommended 1.5º per side	0.5º per side
Rib Thickness at Base (w)	0.5 * t	0.4 * t
Rib Thickness at top	Min 0.75mm	Min 0.75mm
Rib Height (y)	Max 5*t	Max 5*t
Spacing Between 2 Ribs (x)	2*t	2*t
Fillet Radius (r)	0.125*t	Max 0.25mm
Rib Root Dia	± 30 % of t	± 30 % of t
y/x ratio for multiple ribs	3:1 2:1 preferred	3:1 2:1 preferred

Fixture Design Rules:

• For a fixture designer, the major portion of design time is spent deciding how to locate the workpiece in the fixture.

  You know that any free body has a total of twelve degrees of freedom as below:

  6 translational degrees of freedom**: +X, -X, +Y, -Y, +Z, -Z**

  And 6 rotational degrees of freedom:

  - Clockwise around X-axis (CROT-X)

  - Anticlockwise around X-axis (ACROT-X)

  - Clockwise around Y axis (CROT-Y)

  - Anticlockwise around Y axis (ACROT-Y)

  - Clockwise around Z-axis (CROT-Z)

  - Anticlockwise around Z-axis (ACROT-Z)

  You must fix all the 12 degrees of freedom except the three transitional degrees of freedom (-X, -Y, and -Z) in order to locate the workpiece in the fixture. So, 9 degrees of freedom of the workpiece need to be fixed By using the 3-2-1 method as shown below:

• Rest the workpiece on three non-collinear points of the bottom surface (XY), and you will be able to fix the +Z, CROT-X, ACROT-X, CROT-Y and ACROT-Y degrees of freedom**.**

  Now, rest the workpiece at two points of the side surface (XZ), and you will be able to fix the +Y and ACROT-Z degrees of freedom.

  Now, rest the workpiece at one point of the adjacent surface (YZ), and you will be able to fix the +X and CROT-Z degrees of freedom.

  So, you can successfully fixate 9 required degrees of freedom by using the 3-2-1 principle of fixture design.

• The jig and fixture are tools used for holding the workpiece in a correct location for mass production. Various types of fixtures are used in the industry. The 3-2-1 method is the fundamental principle for all types of fixture design.

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CONCLUSION

The Design of Automotive Plastic Component –Driver Side RH Door Applique Design with 4-Way, 2-Way Locators and Heat Stakes has been completed by using industry principles such as Rib design Rules, Draft Angles, Draft Analysis for Class A and Final enclosed surface, Tooling Axis creation and implementation, Class B and Class C creation and conversion to a solid part