Quality and Customer Service 175

5 why analysis

A problem solving method in which a person repeatedly asks "Why?" until the root cause of a problem is identified.

80-20 rule

A principle stating that, in general, 80% of problems or effects arise from 20% of causes or factors. Pareto charts are often used to demonstrate the 80-20 rule.

8D

A team based approach to troubleshooting that seeks to define the problem, employs temporary actions to mitigate the problem until a permanent solution can be identified, and once a permanent fix is validated, changes the process to avoid repeat problems.

acceptable quality limit

AQL. The maximum percentage of nonconforming units of incoming material that remains acceptable for the process average.

acceptance sampling

Inspection of a batch of material from a lot to determine whether to accept that lot. Acceptance sampling assumes a company will accept some level of defects.

accuracy

The exactness of a measurement produced compared to the desired result.

attribute inspection

A determination of whether or not a measurement falls within the acceptable tolerance range. Attribute inspection produces a go or no go result.

calibration

The act of adjusting a measuring instrument against a standard to ensure its accuracy.

capability ratio

A mathematical method used to determine whether or not a process is capable. The ratio is expressed as the difference between the specified limits divided by the estimated process standard deviation.

cause and effect diagram

Also known as a fishbone diagram. A fishbone-shaped diagram used to identify the cause of a specific problem.

centered

A distribution within an acceptable distance from the center of a specified tolerance. The C_pk ratio accounts for process centering.

condition error

A measurement error caused by the environment or conditions in which a device is used. For example, changes in ambient temperature can cause materials to expand and contract.

consumer's risk

The probability that a bad lot will be accepted and introduced into the consumer market. The consumer's risk is an inherent problem with acceptance sampling.

continuous improvement

Replacing ineffective practices, machines, or other manufacturing components with effective ones to attain ongoing, measurable gains. Continuous improvement is a lean principle that says no matter how well a company is doing, there is always room to get better.

control chart

A chart used to show trends in data over a period of time. Points are plotted on the chart and connected by a line to show an upward or downward trend.

correlation

A mutual relationship or connection between two or more things. Correlation occurs when data points on a scatter diagram are close enough to form a line.

correlation matrix

A DOE chart that shows statistically significant relationships between process variables.

customer service

Any activity that is designed to enhance customer experience with a product and provide the real feeling that a company cares about meeting customer needs.

data

Any type of information gathered about a product or process. Data is often in the form of values or numbers.

destructive testing

A form of testing that by its nature places parts under harsh conditions that could lead to product failure. Acceptance sampling is desirable when destructive testing is required.

DOE

A statistically based method of factor analysis designed to reveal how each system input affects process outputs. DOE typically changes one process variable at a time and measures the results against the previous conditions.

factor analysis

A collection of methods used to examine how existing conditions influence the responses on a number of measured variables. DOE is a form of factor analysis.

factorial design

A type of DOE experiment that is symmetrical and places factors orthogonal to each other. The use of the proper symmetry gives the maximum amount of information for the least number of experiments.

failure mode

Any potential means by which a product or process may fail. Failure modes must be identified and accounted for in product and process design.

field service

Any company activity that occurs at a customer location. Field service employees are typically technicians who manage the installation of a new product, or repair existing equipment that is beyond the expertise of maintenance workers or individual customers.

fishbone diagram

A troubleshooting tool that can be used to visually diagram the causes and effects of a problem. Additional possible causes are added as extra lines that branch out from the center, much like the bone structure of a fish.

gage block

A hardened steel block that is manufactured with highly accurate dimensions. Gage blocks are available in a set of standardized lengths.

grand average

The average of sample averages. The grand average is the centerline on an X bar chart.

inspection

The examination of a part to determine if it conforms to specifications. Inspection traditionally follows the completion of a part or the components that compose a part.

ISO

The International Organization for Standardization. ISO establishes documented standards, rules, and guidelines to ensure that products, processes, and services are fit for their purpose.

ISO 9000

A standard published by the International Organization for Standardization that lists requirements for the creation and implementation of an effective quality management system.

ISO 9001

The section of the ISO 9000 standard containing the list of requirements for a company's quality system.

ISO/TS 16949

A standards document containing the quality system requirements specifically for producers of automotive parts and component systems.

just-in-time

JIT. An inventory strategy in which products are delivered at the time they are needed rather than on a set delivery schedule. A JIT system helps to ensure flexible responsiveness.

kaizen

A Japanese word that means "change for the better." Kaizen is a combination of maintenance, problem solving, and innovation that is generally performed by a team.

kaizen event

An improvement tool that brings together employees from various departments to examine a problem, propose solutions, and implement changes. Kaizen events usually take place over one or two days.

lean manufacturing

An approach to manufacturing that seeks to reduce the cycle time of processes, increase flexibility, and improve quality. Lean approaches help to eliminate waste in all its forms.

liability

A manufacturer’s or seller’s legal responsibility for any damages or injuries suffered by a buyer, user, or bystander as a result of a defective product.

linear regression

A technique in which a straight line is fitted to a set of data points to measure the effect of a single independent variable. The slope of the line is the measured impact of that variable.

lot tolerance percentage defective

LTPD. The quality level with respect to a percentage defective at a given risk of being accepted by the customer.

lower control limit

A control limit indicating the boundary for the minimum permissible values.

Malcolm Baldrige National Quality Award

An award given to U.S. companies that recognizes highly effective customer-focused quality systems. The MBNQA's main focus is system outcomes.

measurement standard

A recognized true value. Calibration must compare measurement values to a known standard.

measuring system analysis

A mathematical method of determining how much the variation within the measurement process contributes to overall process variability.

metrology

The science of measurement. Metrology strives for accuracy, precision, and repeatability.

National Institute of Standards and Technology

NIST. Part of the Department of Commerce, NIST administers the Baldrige Award.

natural limits

The typical range of variation for a measurement. Natural limits must fall within the range of specified limits for a process to be capable.

natural variation

Variation resulting from sources that are normal and expected. Natural variation is random and can be difficult to detect.

parallax error

A measurement error caused by the position of the operator relative to the instrument. The angle at which you view a reading can skew perspective.

Pareto analysis

The practice of using a bar chart to show the order of the most frequently occurring errors or source of errors. Pareto charts best represent discrete data.

Plan Do Check Act

PDCA. A four-step scientific process used in lean for continuous improvement.

plotting

A graphical technique for representing a data set, usually as a graph showing the relationship between two or more variables.

precision

The dispersion of measurements or fineness of readings. Precise readings show very little variation.

probability

The likelihood that a particular event will happen in the future. Probability can be expressed as a fraction, ratio, or percentage.

process capability

The ability of a process to consistently meet a set of specific limitations.

process capability analysis

A method used to determine how well a process meets a set of specification limits. A process is deemed to be capable if it consistently outputs parts within the specification range.

process variable

Any number of controllable parameters that influence process outcomes. Temperature, feed rate, and material composition are examples of process variables.

producer's risk

The probability that a good lot will be rejected. The producer's risk is an inherent problem with acceptance sampling.

QS 9000

The original automotive quality standard developed by the U.S. auto industry in the 1990s.

quality

An approach to manufacturing that focuses on customer satisfaction. Quality products conform to specifications, are free of defects, and meet the requirements of their anticipated use.

quality assurance

The overall effort by a manufacturer to ensure that all of its products meets stated specifications. Quality assurance sets standards to regulate the quality of materials, assembly processes, products and components.

R chart

The control chart that tracks sample ranges over time. An R chart is used with variable data.

range

The difference between the smallest and the largest values within a numerical set.

reliability

A key characteristic of a quality product that increases the probability that a product will meet a consumer's demands repeatedly during its life cycle.

repeatability

The extent to which a group of measurements taken with the same instrument are in agreement. Repeatability is a test of precision rather than accuracy.

root cause

The origin of the problem. Troubleshooting attempts to identify the root cause of a problem rather than simply addressing the symptoms.

sampling

The practice of selecting at random a predetermined number of representative items from a data set. Sampling provides a more manageable data set.

sensitivity

The minimum input required to produce a noticeable output on a measuring device. Sensitive instruments can provide more accurate readings.

specified limits

The range into which it is acceptable for a measurement to fall. If the natural limits are within the range of the specified limits, a process is capable.

standard deviation

A number representing the degree of variation within a numerical set. The lower the standard deviation, the more reliable the numerical data.

statistical process control

A method of measuring and controlling the processes that yield a product. In SPC, statistics are used to collect sample data and allow predictions of the overall process.

statistics

The science of collecting, summarizing, and analyzing numerical data. Statistics makes it possible to predict the likelihood of events.

technique error

A measurement error caused by the operator using the device incorrectly.

total maintenance

A manufacturing improvement method that increases production and reduces waste through continuous attention to the condition of machines and processes.

total quality management

TQM. Total quality maintenance encourages all employees to actively engage in doing the job right the first time.

traceability

The ability to trace the history, application, or location of an item using documentation.

unnatural variation

Variation resulting from one or more sources that involve a fundamental change in a process. Unnatural variation is undesirable.

upper control limit

A control limit indicating the boundary for the maximum permissible values.

validation

A common quality assurance process that provides clear evidence that a product, service, or system accomplishes its intended purpose and is meeting the needs of the customer.

variable inspection

A form of inspection that reveals the degree of variation from a given standard. Variable inspection is quantitative.

variation

Any change from what is normal and consistent. Variation is undesirable but unavoidable.

X bar

A chart used to track a series of sample averages. X bar charts are common tool for SPC.