MANUFACTURING GLOSSARY

Automated visual inspection of an object, in order to perform measurements or check for defects.

A term describing equipment that is used to automatically test a UUT. The size of an ATE system can range from a single computer connected to a benchtop measuring instrument, through to large scale multi-rack based equipment.

A burn-in process often involves running a device for a time period prior to it entering its service life. Often electrical, thermal or mechanical stress is used to accelerate the burn-in process. Typically burn-in processes are used to condition a device for service and also detect early failures. Also see: ESS

See Kaizen

A term used to describe non-bespoke components, usually designed for general tasks, but can be integrated into bespoke systems. The use of COTS equipment provides significant benefits such as: reduced costs, spares availability, support and upgrades.

See UUT

A methodology used in Six-Sigma. This process defines the general stages of a Six-Sigma project: Define the project goals, Measure the current process, Analyse the data to determine relationships and causality, Improve the process based on the conclusions drawn during the analysis phase and finally Control the process into the future by maintaining the framework for measuring and correcting defects.

Used to describe the process of applying thermal cycling or vibration to a UUT in order to detect defects. Environmental Stress Screening allows the accelerated detection of weaknesses, which would not usually manifest themselves as faults until a product is partically through its service life. Due to the high cost of ESS it is typically only applied to high value, safety critical components; with a common area being electronics for aerospace and defence applications.

See PAT

Describes a form of testing where the UUT is treated as a 'black box', so that testing only examines the standard inputs and outputs of the unit. Functional testing usually compares the measurements from a manufactured unit against the parameters described in the design specifications. In electronics manufacture Functional Testing is often carried out on completed fully assembled enclosed units, whilst ICT is done on PCBs and sub-assemblies.

A process carried out during product development to identify potential weaknesses, which may cause failure during its service life. For more information see ESS.

A stress screening process carried out during manufacturing. For more information see ESS.

A form of testing where the UUT is treated as a 'white box', so that testing examines the operation of internal interconnects and components. When testing a printed circuit board, in-circuit testing may use a bed-of-nails test fixture to directly access components. Techniques such as boundary scan are superceding in-circuit test.

A strategy for streamlining processes in order to reduce inventory. This is often coupled with "pull" production, or producing output in accordance with customer demand. In essence, Just In Time ensures that wastage is reduced - in terms of warehouse space and employee time, and that risk is reduced by producing to order.

Often referred to as "Continuous Improvement", this is a cycle whereby processes are improved in order to match business or operating requirements. This involves monitoring existing processes, planning required modifications, implementing the new strategy and maintaining the realised benefits. The cycle then repeats to ensure that the process remains at peak performance, and responds to the needs of the business.

A combination of methods and tools used to reduce wastage, and to streamline process flow. Lean works on the principle of ensuring that all steps in a process flow are used to add value, that these steps undergo continuous improvement and that non-value adding steps are identified and reduced to the bare minimum. By measuring and understanding your existing processes, it becomes possible to put these improvements in place improve productivity, stock levels, quality and OEE - whilst reducing costs.

A unit within a larger piece of equipment such as an aircraft that is designed to be field replaceable. Units that are designed with this capability usually allow simple removal/refitting through the use of easily removeable electrical/hydraulic connectors and fixings that require only a small set of standard tools.

A measure of how well a piece of equipment is performing compared to its ideal operating conditions. Expressed as a percentage, this value takes into account downtime (scheduled and unscheduled), production yields, cycle time and disjointed flow (as part of the overall manufacturing process).

A test procedure used to determine whether a UUT has been correctly manufactured. Usually a manufacturer will require a pass result from a PAT prior to shipping a unit to a customer.

Used to describe any mechanism which protects a process against operator errors. A commonly found example of poka-yoke would be the USB connector; where it is impossible to insert it the wrong way round due to the non-symmetric plastic insert.

A statistical measure of how well a process is performing, with respect to its variation and how well it is centred between its specification limits. It can be used to predict the number of defects or errors produced by the process. Process Capability is often expressed as one or more of the following indices: Cp, Cpk, Pp, Ppk - with each one having special significance in different situations.

A method used to monitor processes in order to detect variations which may cause defects. It enables the possibility to predict failures, ensuring that preventative maintenance or modifications can be carried out to reduce rework and scrap.

The state of a manufacturing process where production forms a single flow from input materials to output product - with a significant reduction or total elimination of batch production and inventory.

Provides a framework to deliver significant quality and efficiency improvements. Utilising a number of statistical tools, it is possible to identify potential causes for error, or defects, and apply long-term solutions. The term Six-Sigma is often used to denote 3.4 defects per million opportunities - a statistical figure derived from a normally-distributed process having six standard deviations between its upper and lower specification limits.

A term used to describe a device or assembly that is being tested. UUT is commonly used in the electronics industry to describe a device that is being tested by an ATE system.