Product Design Ch 15 - Robust Design
What qualities make a product "Robust"
It performs properly even in the presence of noise.
What are "performance metrics"
Product specifications of interest in the experiment Ex: Seatbelt System Safety Test (Slip of buttocks, forward knee motion)
What type of experimental plan provides the most efficient method for exploring the main effects of each factor chosen for the experiment?
The ORTHOGONAL array experimental plan
What are "control factors"?
The design variables to be varied in a controlled manner Ex: Seatbelt System Safety Test (webbing stiffness, anchorage location)
Define "Robust Design"
The product development activity of.. - Improving desired performance while.. - Minimizing the effects of noise
What is the primary goal of Design of Experiments (DOE)
To determine multi-factor interaction effects
What are "noise factors"?
Variables that cannot be explicitly controlled during the manufacturing and operation of the product Ex: Seatbelt System Safety Test (Passenger positioning and webbing wear)
Identify which is the Control Factor, Noise Factor, and Performance Metric For a Handheld Surgical Tool 1. Ease of Use 2. Tool Diameter 3. Patient's BMI
1. Ease of Use (Performance Metric) 2. Tool Diameter (Control Factor) 3. Patient's BMI (Noise Factor)
Identify which is the Control Factor, Noise Factor, and Performance Metric For a Surgical Implant 1. Implant Material 2. Procedure Time 3. Surgeon's Strength
1. Implant Material (Control Factor) 2. Procedure Time (Performance Metric) 3. Surgeon's Strength (Noise Factor)
What are "robust setpoints"?
A combination of design parameter values for which the product performance is as desired under a range of operating conditions and manufacturing variations
What mathematical phenomenon is generally used to analyze robustness? Why?
*The Objective Function* Because it captures... - Mean performance due to each control factor - Variance of performance due to noise factors
Name some general examples of noise common to all products (3 items)
- Manufacturing variations - Operating conditions - Product deterioration
List the Robust Design Process (7 Steps)
1. *Identify* control factors, noise factors, and performance metrics 2. Formulate an *objective function* 3. *Develop* the experimental plan 4. *Run* the experiment 5. Conduct the *analysis* 6. Select and *confirm* factor setpoints 7. *Reflect* and repeat
