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Quality Terms (Part 2)

06/02/02021 | BY ducanh

The first article in the series can be found here.

Here is the next 26 commonly used quality-related jargons that you may see regularly:

  1. Design of experiments (DOE)

This is a formal branch of applied statistics that focuses on planning, conducting, studying and interpreting the results of controlled tests. Genichi Taguchi, a Japanese quality expert, is a pioneer in developing the DOE approach. Common steps in DOE are to (1) define a problem to be solved; (2) list the factors that might affect the way the process operates; (3) conduct experiments that allow for different combinations of these factors to be studied; (4) choose the combination that yields the best result.

  1. Double sampling

This is an inspection technique in which you inspect a first lot of n1 size, which leads you either to accept or reject it. If you reject it, then you inspect a second sample of a larger lot size n2, which in turn leads to a decision to accept or reject the lot.

  1. Failure Mode Effects Analysis (FMEA)

This is a method for designing in reliability and minimizing the causes of failure in a product. It focuses on analyzing origins of product failure by examining raw materials, components, and assembly processes. The goal is to determine the probability of failure in these items and take preventive action based on this analysis.

  1. Inspection

This includes the acts of measuring, testing, examining, or gaging one or more characteristics of the output of a process and then comparing results to specified requirements. The objective is to determine if the output features conform to the specifications of size, function, appearance, and other characteristics that may be relevant to the product or service.

  1. ISO 9000 Standards

This is a set of quality standards developed in 1987 by the International Organization for Standardization. The three major areas of certification are as follows: ISO 9001, ISO 9002 andISO 9003.

  1. ISO 9001

which covers all the processes of a company from design and development to procurement, production, testing, installation and service.

  1. ISO 9002

which covers everything except design and development

  1. ISO 9003

which covers only inspection and testing.

  1. Lot Tolerance Percent Defective (LTPD)

This is a way of quantitatively defining the relationship between the probability of acceptance by a customer of a product lot compared to the possible percent of defectives within that lot. This relationship shows that the higher the percent of defectives, the lower the probability of accepting the lot.

  1. Lower Control Limit (LCL)

This is the line on a control chart indicating the lower limit within which a process is in statistical control. The LCL is positioned on the chart three standard deviations below the average of the measurements of process outputs through time.

  1. Minimum Acceptable Quality

This is the maximum level of defectives or variants in a specified quantity of products, components, or services that, for purposes of quality sampling, can be considered satisfactory as the average for the outputs delivered by a process.

  1. Nondestructive Testing and Evaluation (NDE or NDT)

This refers to testing and evaluation techniques that do not damage or destroy what is being tested, such as products or parts.

  1. Number of Defective Units Chart (np Chart)

This kind of control chart is used to evaluate the stability of a process by looking at the total number of units with particular defects from a series of lots in which the sample size from each lot remains constant.

  1. Pareto Chart

The Pareto Chart is based on the 80/20 rule and illustrates, in descending order, the frequency of occurrence of particular events or process outputs.

  1. Process Quality Audit

This is an analysis, appraisal, and evaluation of process performance against certain standards. The audit includes an evaluation of how operators maintain process quality and make accept/reject decisions about outputs.

  1. Q9000 Series

This is an abbreviation for ANSI/ASQC Q9000-1 series of standards, the U.S. version of ISO 9000 standards, adopted by the American National Standards Institute in 1987. They are quality standards, documentation, and audit procedures for a variety of activities performed primarily by manufacturing organizations./dd>

  1. Quality Control

This term refers to those activities a company and its employees undertake to ensure that organizational processes deliver high-quality products or services.

  1. Quality Engineering

This incorporates the skills and expertise needed to apply statistical quality control techniques in the design and implementation of manufacturing processes to assure they operate efficiently, improve continuously, and deliver products that are free of defects and with minimum variation.

  1. Random Sampling

This is a standard sampling method by which random samples of units are chosen such that all combinations of these units have an equal chance of being chosen as the sample.

  1. Reliability Engineering

This is the branch of engineering devoted to improving product performance. It includes a set of practices that focus on accurately predicting when and under what circumstance products or processes might fail or not deliver acceptable outputs.

  1. Representative Sampling

This is a process by which samples are pulled from batches or lots of units so as to contain minimum bias between the values of the samples characteristics and the batch, or lot, as a whole.

  1. Sample

This refers to a specific number of items of a similar type taken from a population or lot, for the purpose of examination, to determine all members of the population or lot conform to quality requirements or specifications.

  1. Statistical Process Control

This is the body of statistical techniques used to measure and monitor the performance of processes. The reason for applying these is to identify specific areas for improvement in processes and to measure variation in outputs of processes, all leading to actions that will reduce variation in outputs.

  1. Statistical Quality Control

This is a broader term than statistical process control, implying the use of statistical techniques to measure and improve processes and quality.

  1. Taguchi Methods

Named after Genichi Taguchi, a leading Japanese expert on quality improvement, these methods comprise a variety of techniques for evaluating quality and figuring out how to improve it. Taguchi based his methods on the idea that any variation from customer requirements represents a loss to customers and to the company.

  1. Variation

This is an idea that suggests there will always be some difference between any two or more actions within a system and in the outputs of that system.