Week 10 - Challenge 3 - Door Trim Lower with Engineering Features

DESIGN OF HEAT STAKES AND LOCATORS

1. Introduction

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 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 [reference 1].

There are 12 degrees of freedom for any part in fixture design. 4-Way Locators are designed to arrest 4 degrees of freedom in X+,X-,Y+ and Y- directions. 2-Way Locators arrest only 2 DOF in either X+ and X- or Y+ and Y-. Generally, 3-2-1 rule is applied to completey constrain a part with 2 4-Way and 1 2-Way Locators.

2. Tooling Axis and Draft Analysis

The Tooling Axis was created by the following steps:

• Two lines are created to match the length and breadth of the part.
• Midpoint of the two lines are created.
• Bisecting lines are drawn from the two midpoints normal to the ZY-plane and XY-plane respectively until they intersect each other.
• A Vertical line is drawn through this point, creating the tooling axis.
  
  Tooling axis passed the drafting analysis as shown. The whole class A component is green (>3deg).

3. Draft Analysis of PartBody

Draft analysis showed that the part body cleared the 3 deg draft angle same as the class A surface. The Locators and heat stakes cleared a draft angle of 0.5 deg, they are marked green for positive draft 0.5deg or blue for negative 0.5deg. The negative 0.5 degrees can be ignored because it is a lateral measurement difference rather than a vertical one. Meaning, The heat stakes and locators will clear draft angles with their own vertical axis parallel to the draft axis. The dog houses also clear all drafts. The only Red area is the ribs which will be compensated by cores and supports.

4. Multi View of PartBody

5. Heat Stakes, Locators and Dog House

Heat stakes have a height of 15mm, diameters of 5.2 and 8.2 mm and draft of 0.5 deg. The Locators have a height of 30mm as they will be in contact with the mating part first. They also have 0.5deg draft.

The Dog houses are also drafted for all surfaces.