1. KEY CHARACTERISTICS ARE QUICKLY BECOMING A BEST COMMERCIAL PRACTICE
A COMMUNICATIONS TOOL
FOCUSES RESOURCES IN DESIGN & MFG –BY APPLYING DOE & SPC
LEADS YOU TO KEY MFG CHARACTERICS
NOT THE SAME AS A KPP
Subject matter experts determine what features and processes are key
World Class Companies are using Key Characteristics as a commercial best practice to help them achieve quality and productivity while reducing cost.
Key Characteristics are a communications tool used by all functions up and down the supply chain to identify user requirements, and then to translate those requirements into design criteria. It allows manufacturing and quality to focus scarce resources on the few “key” characteristics that drive performance.
Key characteristics are determined and controlled through the use of statistical tools like Design of Experiments (DOE) and Statistical Process Control (SPC). These tools lead you to manufacturing processes and controls that determine if a product will meet or exceed standards.
Key Characteristics are not the same as Key Performance Parameters. KPPs are derived by the user and identify the important performance parameters and sets minimum thresholds.
Users determine the KPPs, while design and manufacturing experts determine the Key Characteristics.
NOTE: Additional information is provided on the notes pages. Either view or
print the notes pages for this information, or run as a slide show to hear the presentation.

2. KEY CHARACTERISTICS
Different organizations have different definitions:
A PRODUCT FEATURE THAT HAS THE GREATEST AFFECT ON SAFETY, COST, RELIABILITY OR CUSTOMER SATISFACTION
FEATURES OR CHARACTERISTICS WHOSE VARIABILITY HAS THE GREATEST IMPACT ON FIT, PERFORMANCE, OR SERVICE LIFE OF A FINISHED PART
Vilfredo Pareto ( ) was an Italian economist who, in 1906,observed that twenty percent of the Italian people owned eighty percent of their country's wealth. Over time this analytic has come to be called Pareto's Principle, the Rule or the "Vital Few and Trivial Many Rule."
What it means to us is that in a product design that contains thousands of dimensional characteristics and their tolerances, only a few of those characteristics are vital. Those few are called “Key Characteristics.” However, different companies and organizations have put their own spin to the definition of “Key Characteristics” to include these definitions:
“A product feature that has the greatest effect on safety, cost, reliability or customer satisfaction.” Note the four distinct elements and consider how the many characteristics of say a brake pad could impact these four elements.
“Features or Characteristics whose variability has the greatest impact on fit, performance, or service life of a finished part.” Note that this definition introduces the concept of variability and how variability from the target value might impact the three elements noted in this definition.
The ability to achieve or control “Key Characteristics” is largely dependent on a firm or organizations production and design capabilities, and experience with identifying and controlling “Key Characteristics.”
Other than safety, key characteristics depend on a firm’s
particular capabilities and experience.

3. SAE AS9100 Section 3; Terms and Definitions
“Key characteristics: The features of a material, process or part whose variation has a significant influence on product fit, performance, service life or manufacturability.”
Section Design and development outputs
e) “shall identify key characteristics, when applicable, in accordance with design or contract requirements.”
Section Monitoring and measurement of product
“ When key characteristics have been identified, they shall be monitored and controlled.”
The Society for Automotive Engineering’s (SAE) Aerospace Standard (AS9100) covers Quality Assurance in Design, Development, Production, Installation, and Servicing. AS9100 defines Key Characteristics as “The features of a material, process or part whose variation has a significant influence on product fit, performance, service life or manufacturability.”
In addition, Section e) states that you “shall identify key characteristics, when applicable, in accordance with design or contract requirements.”
Finally, Section notes that “when key characteristics have been identified, they shall be monitored and controlled.”

4. WHY USE KEY CHARACTERISTICS?
PERFORMANCE AND QUALITY COME FROM REDUCING VARIABILITY OF KCs
WHERE DO I APPLY KCs?
- On everything? - NO
- Which features or functions are most important?
- How do you identify the most vital features/functions?
safety, reliability, mission essential, cost
Everyone knows that you can improve quality by reducing variability, but how can reducing variability improve performance? Consider the simple ball bearing. It is embedded in many products like bicycle wheels. You really do not think much about ball bearings until they wear down.
So what happens if during manufacturing you produced ball bearings that are slightly out of round, while your competition is producing perfectly round bearings? Whose bearings would fail first? Which would have a higher reliability cost?
The question now becomes, where do you apply variability reduction? On all characteristics? Even a simple bicycle has hundreds of characteristics, an automobile engine thousands, and an aircraft could have millions. Do you need to apply management attention to all characteristics or can “Key Characteristics” provide you with a tool for identifying the features that are the most important.
We are going to show you how you can identify “Key Characteristics” and how you might use KCs as a communications tool in production and with your supply base.
KCs are a communications tool and a resource allocation tool

5. Key Flowdowns KPPs TPMs Product Key Characteristics
Manufacturing Key Characteristics
Key Performance Parameters or KPPs are driven by the user or in the case of the DoD, the warfighter. KPPs are what the user determines are the key performance parameters their system will need in order to meet their needs. These KPPs then become Technical Performance Measures or TPMs.
For example, the Army may have an airlift requirement to haul a Stryker vehicle and it’s compliment of men and equipment, 3000 nautical miles in six hours.
Since the Air Force is responsible for long-haul, it is their responsibility to come up with a solution to this need. The Air Force might provide these requirements to an aircraft contractor which would take these requirements and then translate the requirements into product characteristics, manufacturing features and assembly directions. But lets take a look at a more specific example.
Assembly Key Characteristics

6. Key Characteristic - Top Down Approach for a Digital Clock
CUSTOMER REQ’MTS
RELIABILITY
WEIGHT
PERFORMANCE
COST
Courtesy Boeing Corp.
SYSTEM DESIGN
PERFORMANCE
KEY
KEY
SUBSYSTEM DESIGN
CLOCK READABILITY
ACCURACY
KEY
MANUFACTURING
KEY
PROCESS PARAMETERS
SOLDER JOINTS:
TEMP
TIME
SPEED
WAVE HEIGHT
SOLDER TYPE
The SIOP or Single Integrated Operations Plan, requires very strict timing so that bombers and missiles do not get in each others way. This requires bombers and missile combat crews have to have clocks that are not only synchronized but are very accurate.
A key performance parameter “be on time” gets translated into an “accurate clock.” Keeping with this need for accuracy and timeliness, the clock must be easily read, so having good illumination becomes a key characteristic, and this is controlled by the quality of a “photo diode” and the current that drives it. The manufacturing of the photo diode in turn must be tightly controlled. In this case the important or key manufacturing process is soldering and what you have found through process studies that you need to control the belt speed of the wave solder machine and the pre-heat temperature. These manufacturing processes are then put under statistical process control.
This is how a Key Performance Parameter (be on-time) gets translated into “Key Characteristics” and then flowed down to manufacturing processes and quality controls.
HARDWARE REQ’MTS
VOLTAGE:
CAPACITANCE
CONFORMAL COATING
RESISTANCE
POWER
SUPPLY
DISPLAY
ASSEMBLY
ILLUMINATION
VOLTAGE
KEY
KEY
KEY
KEY
KEY
PHOTO
DIODE
LCD
PANEL
LAMP
CURRENT
KEY

7. So Which Car Would You Rather Own?
They look the same….
Here are two identical 1990 Ford Escorts…or are they identical? While they may look alike, one performs significantly better than the other one. One is more reliable while the other has higher maintenance and repair costs. And it all has to do with “Key Characteristics.” And now for the rest of the story.
But, are they?

8. Same TDP – Different Results
Ford Batavia Plant:
Ford Escorts were selling so well that Ford had to subcontract the production of transaxles.
Ford owned 60% of Mazda; they sent them the TDP and had them drop-ship the product to the Ford assembly plant.
Ford buyers began asking for the Escort with the Mazda transmission. When asked why, customers noted that the Mazda transmission had a reputation for reliability.
Ford was surprised and began an investigation.
Mazda (Korean) Plant:
Received the drawings and specifications and accomplished an analysis of the “Key Characteristics.”
There are over 10,000 dimensional and other characteristics on a typical transaxle.
Mazda found that only four (4) of these characteristics were “key or critical.”
Mazda used Statistical Process Control to manage those four characteristics.
When Ford first introduced the Escort, the public loved it and sales soared. Sales were so impressive and unexpected that Ford had a hard time producing enough automobiles to meet demand. Ford had built a brand new, state-of-the-art plant in Batavia, Ohio to build the transaxles, but this new facility could not keep up with production. So Ford took the design and gave it to Mazda (Ford owns 60% of Mazda) and told them to build-to-print and ship to Ford’s Escort assembly facility. And Ford began assembling Escorts, some with Mazda built transaxles and some with Batavia transaxles. Soon Ford customers started showing up in the showrooms asking for the Escort, but wanting the Mazda transaxle instead of the Batavia, which surprised Ford executives. For some reason, no one at Ford seemed to know that there was a difference, but word on the street was that the Mazda transaxles worked better and lasted longer.
So Ford investigated this phenomenon by tearing down ten Mazda and ten Batavia transaxles. They measured and compared thousands of characteristics. They talked to Mazda and found that Mazda was using “Key Characteristics” to identify the dimensional features that most impacted form, fit and function. Mazda identified four characteristics out of the ten thousand that needed controlling and they put these under statistical process control. The end result was that Mazda with an older factory, and less capable machinery, was able to produce a better transaxle. Of course, once Ford understood what Mazda was doing it was relatively easy and inexpensive to apply those same techniques at the Batavia facility and achieve the same outstanding results.

9. Summary Key Characteristics provide a focus for product improvement
One measure of quality is conformance to nominal on all key characteristics
Reduce variation on key characteristics by using statistical
process control
The number of key characteristics must be controlled or
they lose their value
Advanced Quality Systems or AQS uses key characteristics as the 1st step in product improvement. The purpose of identifying a characteristic as key is to focus improvement efforts on those features that yields the greatest return on investment.
The new quality philosophy is on reducing deviations from nominal, as opposed to being content with meeting specification.
Deviations from the nominal or target value on key characteristics create cost and performance problems.
Deviations from the nominal on non-key characteristics cause very little impact to cost or performance and are thus considered “robust.”
Because deviation from nominal on key characteristics has a much bigger impact, this is where you want to put your management attention. For every Key Characteristic there are hundreds of non-key characteristics.
Although the focus has been on key characteristic at the top level, improvement occurs at the process level. Thus it is important to control these characteristics through the use of Statistical Process Control (SPC).