Circuit Board Ejector Mechanism

The goal of this project is to improve ergonomics for installation and removal of circuit boards in Schweitzer Engineering Laboratories (SEL) products.

=Problem Definition=

Background
SEL designs, manufactures, and supports products and services ranging from generator and transmission protection to distribution automation and control systems. In most of their products, circuit boards are connected by spring clips at the back of the case. These clips cause a large frictional force on the board, making it difficult to install and remove the boards. With the current clips the force required to remove and insert a board is around 40lbs (total).

Deliverables
The scope of this project is to design a mechanism or system that reduces the necessary force to install and remove circuit boards from SEL products.

Specifically:
 * Research on existing mechanisms
 * Any ejection system (not restrictive to tray ejectors)
 * Decision Matrix
 * Material selection and cost analysis
 * Functional concepts, made using a variety of materials and methods
 * Longevity analysis for chosen production material
 * Fatigue testing
 * Working prototype using production material
 * Design validation testing results with various materials
 * Insertion force
 * Insertion cycles
 * Thermal and Vibration
 * Production implementation plan - proposed tooling method and supporting business case
 * 3D prototype if feasible
 * Mold and factor for plastic parts
 * Final report containing full information listed above with detailed design info, analysis and test results

Value Proposition
Project Value Proposition

Specifications
=Project Learning=
 * Must pass SEL vibration testing
 * Must reduce user force to <5 lbs
 * Must be contained inside the chassis
 * Must not contact the circuit board

Refined Designs
=Selected Design=

The Rails idea was decided on for the final design, it showed the most benefits, namely, ease of use, simple individual parts, and is available for multiple manufacturing processes. The next step of the design process is to select the manufacturing process for the parts, while keeping in mind the clients needs. The processes available to us are sheet metal fabrication, injection molding, and die casting.

Injection Molding
Our clients at SEL are proponents of injection molding, because of their ability to make these parts on-site, which lowers the overall cost of manufacturing. Modification to the parts will be made to factor in limitations with the process, particularly, draft angle and wall thickness.

Die Casting
Die casting is a similar option to injection molding, but with a stronger material. The process has similar design considerations as injection molding, so the basic design will also need modified for it. SEL does not have on-site facilities for this, so cost will be higher than the previous method.

Sheet Metal Fabrication
The arms and hinge piece are easily modified for fabrication with sheet metal, while the rails themselves will be machined.

=Validation=

Design Validation Plan

=Team Members=

=Additional Documentation=

Project Schedule

Gantt Chart

Meeting Minutes

Meeting Minutes Presentations

Informal Design Review Formal Design Review Detailed Design Review

Client Interview