Challenge

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

AAshish Kshirsagar22 Aug 2021

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

Objectives-

1. To understand requirements & functions of HEAT STAKES

2. To understand design guidelines for plastic products

3. To create class A, B & C surfaces

4. To create 4- & 2-way locator & Heat stakes

3-2-1 Principle (Arresting Degrees of Freedom)

Degrees of freedom in space

A work-piece free in space can move in an infinite number of direction. For analysis, this motion can be broken down into 12 directional movements or "degrees of freedom". All 12 degrees of freedom must be restricted to ensure proper referencing of a work-piece.

As shown in Fig 1, the 12 degrees of freedom all relate to the central axis of the work-piece. Notice the 6 axial degrees and 6 radial degrees of freedom. The axial degrees of freedom permit straight-line movement in both directions along the 3 principle axis shown as X, Y & Z. The radial degrees of freedom permit rotational movement, in both clockwise & counterclockwise radial directions around the same three axis.

Fig 1: The twelve degrees of freedom

Degrees of freedom of rigid body-

Consider the rigid body shown below which is situated in space. It can have 12 degrees of freedom.

Fig 2: A rigid body on a space

For a rigid body in plane has 6 degrees of freedom (i.e.) The motion of a ship at sea has the 6 degrees of freedom.

_Fig 3: A rigid body on a plane

(1) X+

(2) X-

(3) Y+

(4) Y-

(5) ZCW

(6) ZCCW

Now try to understand 3-2-1 principle of fixturing. The purpose of Fixturing is

Resting - Stability
Locating - W.r.t datum
Orienting - W.r.t secondary datum
Clamping - Ensuring above not disturbed.

Primary Locators

First the three locators or supports are placed under the work-piece. It will be positioned on the primary locating surface also known as datum. It will restrict 5 degrees of freedom.

Axial Movement downward along Z- axis (No.6 in Fig 2)
Rotation about the X & Y axis (No. 7, 8, 9 & 10 in Fig 2)

Primary Locators

Secondary Locators

The next two locators are normally placed on the secondary surface, restricting an additional 3 degrees of freedom.

Axial movement along the Y+ axis (No.3 in Fig 2)
Rotation about the Z axis (No. 11 & 12 in Fig 2)

Secondary Locators

Tertiary Locator

This locator is positioned at the end of the part. It restricts 1 degrees of freedom

Axial movement along the X axis (No.2 in Fig 2)

Tertiary Locator

All these 6 locators will restrict a total of 9 degrees of freedom. The remaining 3 degrees of freedom (1, 4 & 5) will be restricted by the clamps.

4- & 2-Way Locator-

In plastic parts locators are used to locate the part for assembly purpose. These parts All the components are having 12 DOFs in space. Using 321- principle necessary DOFs are restricted using 4- & 2-way locators while remaining DOFs can be restricted using heat stakes in automobile plastic components.

With these locators part will be placed in its orientations with good accuracy so the assembly of components are easy.

4-way locators will be restricting 9 DOFs. With the combination of 4- & 2- way locators along with heat stakes all DOFs of component are restricted.

Heat Stakes-

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.

Applications range from staking plastic bosses for assembly of car door panels to joining PCBs 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.

Tooling axis creation-

In this challenge we are going to create engineering features for the door applique component which do not having any complex geometry. So, we will create tooling axis along the direction which is normal to the component surface (Y- direction).

We have followed our standard process & created Main Tooling Axis as shown below-

Creating CAS (class A surface), CBS (class B surface) & CCS (class C surface)-

As input, we have CAS. Using this input surface, we have created CBS & CCS with our standard process

Close surface body-

As we have obtained CAS, CBS & CCS, next we will create closed body with these surfaces using trim commands.

Using this closed surface body solid part body will be created

Creation of 4- way locator-

Make sure locator height will be higher enough that they will protrude above the locating hole.

Apply suitable edge fillets.

We will be creating 2 nos 4-way locators & 1 nos 2-way locator. All these three are will be placed in triangular shape.

2nd 4-way locator can be made by translating already made locator.

Creating 2-way locator-

Using union trim common join all the locutors with main component. After combining all locators give suitable edge fillets.

Creating Heat Stakes-

Make sure the height of the heat stake will be such that the will protrudes out of fixing surface but smaller than the locator. This is because at the time of locating, first locator should go inside the locating hole.