Re-designing when time is money . . . .
Reverse Engineering & DFX - LED Lantern
The project discusses the reverse engineering of the Coleman 600 LED lantern which includes an assessment of the product, an analysis of the initial design, potential design changes, and finally another assessment of the redesigned product.
Beginning with a full decomposition of the product i.e. fully dismantling the lantern and breaking up the parts into separate subassemblies, the team modeled each of the removed parts and began running a design for assembly analysis. The intended purpose of this analysis is to determine the difficulty of assembling this product as well as the efficiency with which it was designed. In addition to the DFA analysis, the team ran manufacturing, material, and cost analyses on the individual parts of the assembly.
Based on the results of these analyses, as well as user feedback, the team began to discuss potential design changes. These design changes are meant to retain the product’s functionality while reducing manufacturing difficulties, assembly complexity, and overall costs. Once decided upon, these design changes were modeled and used to create an improved assembly of this lantern. With these design changes in mind, the team ran DFA and cost analyses again to show the benefits of improved assembly compared to the original design.
Design for Assembly (DfA)
The purpose of DFA is to make the assembly process more efficient.
Reduced the Complexity Factor, Error Proofing, Handling, Insertion, and Secondary Operations.
Increased the Theoretical Minimum Part Efficiency and Practical Minimum Part Efficiency.
Risk & Root Cause Analysis of System-Level Failures - Fault Tree Analysis (FTA)
To improve the product design and quality, FTA is a method widely used to study system problems in reliability engineering.
Here, we used FTA to identify the internal causes of failure. This method provides both qualitative and quantitative results.
Probability of Occurrence of:
1. Battery Failure (0.0445)>Component Failure (0.009975)
2. Battery Failure (0.0445)>Wiring Failure (0.0347)
Selection of Material
Based on Ashby's Chart calculations and FEA structural analysis, few materials with high strength and low density were determined. These materials include PMMA, PC, PA, PEEK, and PET. Of these materials, PMMA appeared to be the least expensive and suitable for engineering purposes.
Selection of Manufacturing Process
Considering the time for each manufacturing process and the amount of units/day that needs to be manufactured, Injection Molding and Compression Molding were found to be best suited.
Design for Manufacturability (DfM)
Incorporated Press Fit feature - Eliminate Use of Fasteners
Changing Materials based on the usability - Added extra flanges and reduced stress from 1322 PSI to 576 PSI
Provided Additional Slots for Ease in Aligning Clear Glass
Eliminating unnecessary parts - Knob Indicator
Avoid Variety of Fasteners - Only Use 3 different fasteners instead of 6.
Design for Inspection (DfI)
Selected proper datum and tolerances to ensure that the manufacturing process is producing components that meet the specification requirements and to allow finished products to be easily inspected.
Design for Cost (DfC)
Order of Magnitude cost estimation technique to find the rough estimate of each component based on Material Cost and Manufacturing Cost.
Summary of Results
Design Analysis :
Cost Analysis :
