Genichi Taguchi- Quality Redefined[/b]
By Pratik Nayak
Genichi Taguchi was Born in Japan, 1924, was an electrical Engineer and worked during 1950’s to improve Japan’s post-WWII telephone communication system. He is known as the Father of the “Taguchi Method” and “Robust Engineering”.
Quality Redefined[/b]
“Any engineered system reaches its ‘ideal function’ when all of its applied energy (input) is transformed efficiently into creating desired output energy.”
? Employee energy = input
? Customer satisfied = output
In the next century, the capability of developing robust technology will be essential to the competitiveness of any manufacturing enterprise. To compete successfully in the global marketplace, organizations must have the ability to produce a variety of high-quality, low-cost products that fully satisfy customers’ needs.
Basic Ideas[/b]
? CUSTOMER SATISFACTION
? Design to the highest standards early in the process to eliminate all non-random errors
? Quality Loss = Loss to Society quantified through “Quality Loss Function”
? Variation (+/-) from optimal measure results in a loss.
Taguchi Design of Experiments[/b]
? Many factors/inputs/variables must be taken into consideration when making a product especially a brand new one
Ex. Baking a new cake without a recipe
The Taguchi method is a structured approach for determining the ”best” combination of inputs to produce a product or service
Based on a Design of Experiments (DOE) methodology for determining parameter levels
DOE is an important tool for designing processes and products
A method for quantitatively identifying the right inputs and parameter levels for making a high quality product or service
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· Taguchi approaches design from a robust design perspective
Robust Design- The Taguchi way ![/b]
? ”Products and services should be designed to be inherently defect free and of high quality”
o Meet customers’ expectations also under non-ideal conditions
§ Disturbances are events that cause the design performance to deviate from its target values
§ Taguchi divide disturbances into three categories
o External disturbances: variations in the environment where the product is used
o Internal disturbances: ware and tare inside a specific unit
o Disturbances in the production process: deviation from target values
§ A three step method for achieving robust design (Taguchi)
o Concept design
o Parameter design
o Tolerance design
The focus of Taguchi is on Parameter design
Concept Design
· The process of examining competing technologies for producing a product - Includes choices of technology and process design
· A prototype design that can be produced and meets customers’ needs under ideal conditions without disturbances
Parameter Design
o The selection of control factors (parameters) and their “optimal” levels
§ The objective is to make the design Robust!
o Control factors are those process variables management can influence.
§ Ex. the procedures used and the type and amount of training
§ Often a complex (non-linear) relationship between the control factors and product/design performance
o The ”optimal” parameter levels can be determined through experimentation
Tolerance Design
o Development of specification limits
§ Necessary because there will always be some variation in the production process
§ Taguchi fiercely advocates aiming for the target value not just settle for “inside the specification limits”!
o Occurs after the parameter design
o Often results in increased production costs
§ More expensive input material might have to be used to meet specifications.
The Taguchi definition of quality
o Ideal quality refers to a target value for determining the quality level
o Ideal quality is delivered if a product or service tangible performs its intended function throughout its projected life under reasonable operating conditions without harmful side effects
o Ideal quality is a function of customer perception and satisfaction
o Service quality is measured in terms of loss to society
Understanding the Math[/b]
L(y) = k(y-m)2
L(y) = Loss
k = constant = cost to correct
tolerance2
y = reported value
m = mean value (average)
Example: Company C received an average of 10 complaints per month last year. In November they received 15 complaints
. Management sets an acceptable level at 2 (tolerance).? It costs the company $50 directly per complaint to correct the problems. They determined the cost in lost sales to be $100.
Total cost per complaint: $150
k = $150/22 = $37.50
L
= 37.50 (15-10)2