This is an acronym for average outgoing quality. This refers to the maximum percent of defective products that can go to a customer after inspection is performed by an acceptance-sampling plan. AOQ requires 100 percent inspection if defectives in a batch or lot of products exceed some minimum standard. This helps reassure customers that suppliers will deliver products that will not include more defectives than expected.
This refers to the measurement and decision of whether or not the quality and performance of a product or service are acceptable. These criteria can be technical specifications (such as level of size tolerances allowed in parts), contract terms and conditions, or performance of a process or service. Implied in the term is the idea that all processes, products, and actions should have an assigned level of acceptable performance that one can measure. Consistent with the understanding that criteria grow out of process capabilities, technicians should periodically measure for acceptability to find out how well a process or item is meeting specifications.
AQL is the limit of a satisfactory process average at a particular quality level when a continuing series of lots is considered.
Sample testing techniques use acceptance numbers as a quantifiable standard to determine if a batch of product meets basic quality control standards. As long as the number of defective items is less than the acceptance number, the entire product lot is accepted as within quality standards.
A specific plan that indicates the sampling sizes and associated acceptance or nonacceptance criteria to be used. In attributes sampling, for example, there are single, double, multiple, sequential, chain, and skip-lot sampling plans. In variables sampling, there are single, double, and sequential sampling plans.
Accreditation is granted by governmental or internationally recognized organizations. It validates the ability of a third-party quality control company to perform inspection services with integrity, objectivity, and expertise.
One of the most common tests for consumer goods inspections. It verifies the resistance of the logo and other labels/marks to daily use by applying 3M tape onto them and then removing the tape. If the logo peels off, there is a high risk that the printed information will disappear quickly.
This is a set of flexible manufacturing processes that leads to the rapid design and manufacture of products that provides customers with what they want, when and where they want it. Using agile manufacturing rather than traditional manufacturing methods, firms can offer more customized products at competitive prices with no compromise in quality or damage to the environment.
This is a statistical technique used when running experiments to identify problems and/or capabilities of an industrial process to deliver an end product with the desirable characteristics.
This is a method for breaking down and analyzing the total variation in the outputs of any process, understanding the causes of this variation, and then assessing their significance. The goal is to come up with a process in which variation in outputs will be minimized.
An audit is the inspection of a manufacturer by a third-party organization to verify compliance with your standards and/or international standards such as ISO 9001, SA8000, ISO 14000.
The expected average quality level of an outgoing product for a given value of incoming product quality.
The maximum average outgoing quality over all possible levels of incoming quality for a given acceptance sampling plan and disposal specification.
On a control chart, the number of subgroups expected to be inspected before a shift in magnitude takes place.
The average number of sample units inspected per lot when reaching decisions to accept or reject.
The average number of units inspected per lot, including all units in rejected lots (applicable when the procedure calls for 100% inspection of rejected lots).
The beginning point, based on an evaluation of output over a period of time, used to determine the process parameters prior to any improvement effort; the basis against which change is measured.
A definite quantity of some product or material produced under conditions that are considered uniform.
This is a distribution with two modes in the frequency of occurrence of whatever the population is being measured. It is usually displayed using a histogram. The bimodal distribution documents a relationship between two factors in a process, such as time of day and level of traffic.
The process of testing and adjustment of an instrument, kit, or test system, to provide a known relationship between the measurement response and the value of the substance being measured by the test procedure.
This technique concentrates on identifying specific failures or defects, discovering the root causes of those failures, and concluding with recommendations on how to eliminate those defects by implementing solutions that address the appropriate cause.
Fulfillment by a product, process, system, or service of a specified set of requirements.
This inspection is performed at the manufacturer's warehouse or the forwarder's premises. The aim of this inspection is to verify your products, the quantity of goods, and the loading process. This inspection includes: 1) an inspection of the container before the loading, 2) an inspection of your products, 3) an inspection of the loading process.
This is an approach to sampling that is most appropriate for the output of processes that deliver a continuous flow of a product. In this plan, a company begins by inspecting 100 percent of the units coming from the process. After a certain number of items that have been inspected with no defects, the plan goes to inspecting only a fraction of items. This continues until the company finds a nonconforming unit. At that point, the plan reverts back to 100 percent inspection following the same pattern.
A graphical method for evaluating whether a process is or is not in a 'state of statistical control.' The determinations are made through comparison of the values of some statistical measure(s) for an ordered series of samples, or subgroups, with control limits.
This is a factor based on the mathematical probability that facilitates the calculation of control limits on X-bar and range charts.
These are the extra expenses caused by delivering poor-quality goods or services to customers. These expenses have two sources: (1) internal failure costs (from defects before customers get the product) and (2) external failure costs (costs after a customer receives the poor product or service). Rework, repairs, damage to a brand’s reputation, and loss of client confidence are just a few examples of costs associated with poor quality.
The cost of quality refers to all expenditure involved in the prevention of quality issues and defects, including assessments of process performance, and the costs of internal and external failure. The cost of quality provides justification for the amount of resources required by quality efforts and should be seen as an investment rather than an expense.
This is a defect that, based on experience, is considered hazardous to employees or has the potential to harm or injure end-users of a product or process.
A long-term relationship between a buyer and supplier characterized by teamwork and mutual confidence. The supplier is considered an extension of the buyer’s organization. The partnership is based on several commitments. The buyer provides long-term contracts and uses fewer suppliers. The supplier implements quality assurance processes so incoming inspections can be minimized. The supplier also helps the buyer reduce costs and improve product and process designs.
A data-driven quality strategy for designing products and processes, it is an integral part of a Six Sigma quality initiative. It consists of five interconnected phases: define, measure, analyze, design, and verify.
This is (a) any nonconformance from a customer’s requirement (b) any attribute of a product or service that fails to meet specifications (c) any state of unfitness for use. Defects are usually cataloged into three types critical, major and minor.
A defective unit is a unit of product that contains one or more defects with respect to the quality characteristic(s) under consideration.
This is a tool for tracking defects, or various types in process outputs. This type of chart is a way to measure the quality of outputs from a process. Demerits are usually broken down into the four categories of defects: critical, serious, major and minor. These are given weights, and each type is then tracked for a specified number of demerits by the total number of products. Using this as a baseline, the companies can then track additional lots or batches of outputs to measure improvement.
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.
Refers to the spread and shape of a frequency curve of some variable. A histogram is one way to graphically display the distribution of test results by showing the frequency of observations on the y-axis versus the magnitude on the x-axis. The normal or Gaussian curve is one form of distribution.
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.
This inspection takes place when about 20% to 50% of the production has been completed. DUPRO is especially good for products that are in continuous production and have strict requirements for on-time shipments. In other cases, it can be conducted as a follow-up when quality issues were found prior to manufacturing during a pre-production inspection.
A European quality management system standard for the medical device industry. Technically equivalent to ISO 13485:1996, an international medical device standard.
A European quality management standard for the aerospace industry. Considered the technical equivalent of AS9100.
A problem-solving approach to identify, correct and eliminate recurring problems.
Someone who purchases products or services for their own use.
1)Deviation from the truth or from an accepted, expected true or reference value; between the estimated value of a quantity and its true value. 2) Measurement error. The result of a measurement minus a true value of a measurand.”
A hybrid form of error proofing. It means a bad part can be made but will be caught immediately, and corrective action will be taken to prevent another bad part from being produced. A device is used to detect and stop the process when a bad part is made. This is used when error proofing is too expensive or not easily implemented.
The inability of an item, product, or service to perform required functions on demand due to one or more defects.
This is a method for designing with reliability and minimizing the causes of failure in a product. It focuses on analyzing the 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.
Communication of information from customers or users related to a process or performance. Feedback is used to make decisions directed toward improving or adjusting a process or performance as necessary.
A term sometimes used to define the term “quality” to indicate the degree to which a product or service meets the requirements for its intended use.
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 and ISO 9003.
which covers all the processes of a company from design and development to procurement, production, testing, installation and service.
which covers everything except design and development
which covers only inspection and testing.
A quality characteristic’s departure from its intended level or state without any association to conformance to specification, requirements or to the usability of a product or service.
A verification activity. For example, measuring, examining, testing and gauging one or more characteristics of a product or service and comparing the results with specified requirements to determine whether conformity is achieved for each characteristic.
Inspection of all the units in the lot or batch.
A statistical measure of how well an organization is doing in a particular area. A KPI could measure an organization’s financial performance or how it is holding up against customer requirements.
A product characteristic that can affect safety or compliance with regulations, fit, function, performance, or subsequent processing of the product.
A record containing the specific tests, evaluations, and calibrations a laboratory has the ability and competency to perform, the list of equipment it uses, and a list of the methods and standards to which it adheres to each of these.
An initiative focused on eliminating all waste in manufacturing processes. Principles of lean manufacturing include zero waiting time, zero inventory, scheduling (internal customer pull instead of push system), batch to flow (cut batch sizes), line balancing and cutting actual process times. The production systems are characterized by optimum automation, just-in-time supplier delivery disciplines, quick changeover times, high levels of quality and continuous improvement.
A letter of credit is a contract that provides a safe payment method protecting buyers and suppliers. It stipulates the conditions under which a payment can be released from the buyer’s bank account to the supplier’s. This contract is prepared by the buyer and the supplier and presented to the bank for validation. A letter of credit usually requires an inspection certificate for the release of payment.
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 percentage of defectives, the lower the probability of accepting the lot.
The number of units in a lot.
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.
The probability that a given maintenance action for an item under given usage conditions can be performed within a stated time interval when the maintenance is performed under stated conditions using stated procedures and resources. Maintainability has two categories: serviceability (the ease of conducting scheduled inspections and servicing) and repairability (the ease of restoring service after a failure).
A major defect is one, that is likely to result in failure, or to materially reduce the usability of the unit of product for its intended purpose. It is less serious than a critical defect. A major defective is a unit of product that contains one or more major defects.
A man-day is the unit of value used by inspection companies to estimate the cost of an inspection. It represents a working day spent by a Quality Controller (or Quality Inspector) to perform an inspection.
A manufacturer is an entity with facilities, workforce, and machinery that allows them to make goods on a large scale.
A document for displaying the relationships among various data sets.
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.
A minor defect is one that is not likely to materially reduce the usability of the unit of product for its intended purpose or is a departure from established standards having little bearing on the effective use or operation of the unit of product. A Minor defective is a unit of product that contains one or more defects.
Nonconformance may be defined as the failure of a unit of product to conform to specified requirements for any stated quality characteristic. The extent of nonconformance of product to the required quality characteristics is expressed in terms of either percent defective or defects per hundred units (DHU).
This refers to testing and evaluation techniques that do not damage or destroy what is being tested, such as products or parts.
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.
Work or steps to transform raw materials into finished products.
A term that indicates a unit does not meet a given requirement or specification.
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.
A control chart for evaluating the stability of a process in terms of the percentage of the total number of units in a sample in which an event of a given classification occurs. Also referred to as a proportion chart.
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.
The overseeing of process instances to ensure their quality and timeliness; can also include proactive and reactive actions to ensure a good result.
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.
A subjective term for which each person or sector has its own definition. In technical usage, quality can have two meanings: 1) the characteristics of a product or service that bear on its ability to satisfy stated or implied needs; 2) a product or service free of deficiencies. According to Joseph Juran, quality means “fitness for use”; according to Philip Crosby, it means “conformance to requirements.”
This term refers to those activities a company and its employees undertake to ensure that organizational processes deliver high-quality products or services.
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.
A systematic, independent process of gathering objective evidence to determine whether audit criteria are being met. Audits are based on a sample and are independent of the system, process or product being audited, unlike verification activities, which are part of a process.
Managing activities and resources of an organization to achieve objectives and prevent nonconformances.
A formal system that documents the structure, processes, roles, responsibilities, and procedures required to achieve effective quality management.
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.
A rule or a directive set by an official authority, government, or trade union that regulates the commercialization of consumer goods within a market and limits the risk of injuries and death that could be caused by the products.
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.
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.
A factor that caused a nonconformance and should be addressed with corrective action.
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.
Sampling inspection in which the inspection of the first sample leads to a decision to accept a lot, reject it, or take a second sample; the inspection of a second sample, when required, then leads to a decision to accept or reject the lot.
Sampling inspection in which, after each sample is inspected, the decision is made to accept a lot, reject it, or take another sample. But there is a prescribed maximum number of samples, after which a decision to accept or reject the lot must be reached.
Sampling inspection in which the decision to accept or reject a lot is based on the inspection of one sample.
A term generally used to indicate process capability in terms of process spread measured by standard deviations in a normally distributed process.
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.
This is a broader term than statistical process control, implying the use of statistical techniques to measure and improve processes and quality.
Confidence a supplier's product or service will fulfill its customers’ needs. This confidence is achieved by creating a relationship between the customer and supplier that ensures the product will be fit for use with minimal corrective action and inspection. According to Joseph M. Juran, nine primary activities are needed: 1) define product and program quality requirements; 2) evaluate alternative suppliers; 3) select suppliers; 4) conduct joint quality planning; 5) cooperate with the supplier during the execution of the contract; 6) obtain proof of conformance to requirements; 7) certify qualified suppliers; 8) conduct quality improvement programs as required; and 9) create and use supplier quality ratings.
A system put in place which aims to deliver a specific product to the end consumers. It involves sourcing, manufacturing, quality control, and transportation activities.