Glossary of Quality, Inspection and Welding Terms

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8D Quality management: Eight disciplines problem solving: a team based method from problem description through containment, root cause, corrective action and prevention to closure. 8D Problem Solving →

A

A-scan NDT: Ultrasonic display of echo amplitude against time or distance. Ultrasonic Testing →
Acceptance criteria Quality management: The measurable limits a product or result must meet to be accepted, taken from the drawing, specification or standard.
Acceptance number (Ac) Inspection and sampling: Maximum number of nonconforming items in a sample for which the lot is accepted. AQL sampling calculator →
Action priority (AP) Automotive and core tools: AIAG VDA FMEA rating (high, medium, low) replacing RPN for prioritising actions.
Adhesion test Coatings and corrosion: Cross cut or pull-off test of coating attachment to the substrate.
Alloy Materials and metallurgy: Metal made by combining a base metal with other elements to obtain properties.
Annealing Materials and metallurgy: Heat treatment to soften material, relieve stress or refine structure.
Anodizing Coatings and corrosion: Electrochemical oxide layer on aluminium. Anodizing →
AOI Manufacturing processes: Automated optical inspection of PCB assemblies.
APQP Automotive and core tools: Advanced product quality planning in five phases up to production launch. APQP →
AQL Inspection and sampling: Acceptance quality limit: the worst tolerable process average for continuing sampling under ISO 2859-1. AQL Sampling Explained →
Arc energy Welding: Energy per unit length of weld from arc voltage, current and travel speed; multiplied by efficiency it gives heat input.
As-built documentation Projects, expediting and contracts: Drawings and records updated to reflect the delivered product.
Attribute inspection Inspection and sampling: Inspection that classifies items as conforming or nonconforming, or counts defects, without measuring values.
Audit Quality management: Systematic, independent and documented process for obtaining evidence and evaluating it objectively against audit criteria.
Audit criteria Quality management: The set of requirements used as a reference during an audit, such as a standard, a contract or a procedure.
Audit finding Quality management: Result of evaluating audit evidence against criteria: a conformity, a nonconformity or an opportunity for improvement.
Audit programme Quality management: Arrangements for a set of audits planned for a specific time frame and purpose. ISO 19011 →

B

Back gouging Welding: Removal of weld metal from the reverse side of a joint before welding that side.
Ballooned drawing Dimensions and GD&T: Drawing with numbered characteristics used for FAI reports.
Basic dimension Dimensions and GD&T: Theoretically exact dimension, shown boxed, from which tolerances are applied.
Blast profile Coatings and corrosion: Surface roughness created by abrasive blasting, measured in µm. Abrasive blasting and surface preparation →
Burr Manufacturing processes: Raised edge left after cutting, punching or machining.
Butt weld Welding: Weld joining two parts lying in approximately the same plane.

C

Calibration Quality management: Comparison of a measuring instrument with a reference of known accuracy, traceable to national standards, with the result documented.
Calibration block NDT: Reference block of defined material and geometry used to set up NDT equipment.
CAPA Quality management: Corrective and preventive action: actions to eliminate the cause of a detected nonconformity and to prevent potential ones. Nonconformity, Root Cause and CAPA Management →
Carbon equivalent (CE) Materials and metallurgy: Value estimating weldability of steel from its chemical composition.
Carburising Manufacturing processes: Diffusing carbon into steel surfaces before hardening. Case hardening (carburising, nitriding) →
Case depth Materials and metallurgy: Depth of the hardened layer after case hardening, often to 550 HV. Case hardening (carburising, nitriding) →
Casting Manufacturing processes: Shaping by pouring molten metal into a mould. Sand casting →
CE marking Projects, expediting and contracts: Manufacturer's declaration that a product meets applicable EU requirements. CE Marking and Technical File Support →
Certification body Quality management: An accredited organisation that audits and certifies management systems, products or persons. QUALITAS TR is not a certification body.
Charpy impact test Materials and metallurgy: Pendulum test measuring energy absorbed by a notched specimen; indicates toughness. Mechanical Testing →
CMM Dimensions and GD&T: Coordinate measuring machine measuring points in three dimensions. CMM and 3D Measurement →
CNC Manufacturing processes: Computer numerical control of machine tools. CNC milling and machining centres →
Concentricity and coaxiality Dimensions and GD&T: Tolerances controlling how well axes or centres coincide.
Concession Quality management: Permission to use or release a product that does not conform to specified requirements, usually limited in quantity or time.
Consumable Welding: Filler metal, electrode, wire, flux or gas used in welding.
Container loading check Inspection and sampling: Supervision of loading: container condition, quantities, stowage, sealing and photos. Packaging, Preservation and Loading Supervision →
Containment Quality management: Immediate action to stop nonconforming product reaching the customer, such as quarantine, sorting or extra inspection. Sorting, Containment and Rework Supervision →
Continual improvement Quality management: Recurring activity to enhance performance, central to ISO 9001 and the PDCA cycle.
Control chart Automotive and core tools: Chart plotting process data against statistically derived control limits. SPC →
Control plan Quality management: Document describing the characteristics, methods, frequencies and reaction plans used to control a process. Control Plans and Process Flow →
Controlled shipping (CS1, CS2) Inspection and sampling: Containment levels in automotive: CS1 by the supplier, CS2 with a third party at the supplier's cost. Sorting, Containment and Rework Supervision →
Corrective action Quality management: Action to eliminate the cause of a nonconformity and to prevent recurrence.
Corrosivity category Coatings and corrosion: ISO 12944 classes C1 to CX describing environmental corrosivity. ISO 12944 →
Cost of quality Quality management: Total cost of prevention, appraisal and internal and external failure. Most of it is hidden. Cost of Quality →
Coverage NDT: Area or volume of the part examined by an NDT method; must be stated in reports.
Cp Statistics: Process potential: tolerance width divided by six standard deviations. Cp and Cpk calculator →
Cpk Statistics: Process capability including centring. Process Capability: Cp and Cpk →
Crater crack Welding: Crack in the crater at the end of a weld bead.
Crimp height Manufacturing processes: Key dimension of a crimped terminal. Cable and wire harness manufacturing →
Critical defect Inspection and sampling: Defect likely to result in hazardous or unsafe conditions; usually zero acceptance.
Critical path Projects, expediting and contracts: Sequence of activities determining the earliest completion date.
Customer specific requirements Quality management: Additional requirements a particular customer imposes on top of a standard, common in automotive.

D

DAC NDT: Distance amplitude correction curve used to evaluate ultrasonic indications.
Data book Projects, expediting and contracts: Compiled quality records of a project delivered with the equipment. Quality Documentation Review →
Datum Dimensions and GD&T: Theoretically exact reference from which features are located, established by datum features.
Decarburisation Materials and metallurgy: Loss of carbon from the steel surface during heating, reducing surface hardness.
Deep drawing Manufacturing processes: Forming sheet into cups or shells by drawing it into a die. Metal stamping and deep drawing →
Developer NDT: Fine powder layer in penetrant testing that draws penetrant out of defects.
Deviation permit Quality management: Written permission before production to depart from the original requirements for a limited quantity or time.
Dew point Coatings and corrosion: Temperature at which moisture condenses; steel must be at least 3 °C above it during painting.
DFT Coatings and corrosion: Dry film thickness of a coating. Coating Thickness and Coating Inspection →
Die casting Manufacturing processes: Injection of molten metal into steel dies. High pressure die casting →
Digital radiography NDT: Radiography using digital detectors instead of film (CR or DR).
Distortion Welding: Change of shape caused by welding shrinkage.
Document control Quality management: Managing the creation, approval, distribution and revision of documents so that only current versions are used.
DPMO Statistics: Defects per million opportunities. PPM and DPMO calculator →
Dross Manufacturing processes: Resolidified metal adhering to the bottom edge of a thermal cut.
Ductile iron Materials and metallurgy: Cast iron with spheroidal graphite, giving strength and ductility (EN 1563).
Duplex stainless steel Materials and metallurgy: Stainless steel with roughly equal austenite and ferrite, strong and corrosion resistant.
DUPRO Inspection and sampling: During production inspection, typically at 20 to 60 percent of production. Factory Inspection: PPI, DUPRO and FRI →
Dwell time NDT: Time the penetrant remains on the surface before removal.

E

Eddy current testing (ET) NDT: Electromagnetic method detecting surface defects and measuring conductivity or coating thickness.
Electroplating Manufacturing processes: Depositing metal coatings by electrolysis. Electroplating (zinc, nickel, chrome) →
Elongation (A%) Materials and metallurgy: Permanent extension of a tensile specimen at fracture, as a percentage.
EN 10204 2.2, 3.1, 3.2 Materials and metallurgy: Inspection document types; 3.1 is validated by the manufacturer's independent inspection department. EN 10204 →
Engineering change notice (ECN) Projects, expediting and contracts: Document recording an approved change to design or documentation. Engineering Change and Technical Query Management →
Excess weld metal Welding: Weld metal above the plate surface in a butt weld, limited by ISO 5817.
Execution class (EXC) Welding: EN 1090 classes EXC1 to EXC4 defining requirements for steel structure execution. EN 1090 →
Expediting Projects, expediting and contracts: Monitoring and promoting supplier progress to secure delivery dates. Expediting →
Extrusion Manufacturing processes: Pushing material through a die to form a constant profile. Aluminium extrusion →

F

Factory acceptance test (FAT) Inspection and sampling: Test at the manufacturer's works, often witnessed, to confirm equipment meets requirements before shipment. Factory Acceptance Testing (FAT) →
FAI Inspection and sampling: First article inspection: complete verification of the first part from a new process, tool or revision. First Article Inspection →
False indication NDT: Indication not caused by a discontinuity, such as from geometry or surface conditions.
Feature control frame Dimensions and GD&T: Rectangular box stating a geometric tolerance, its value and datum references.
Feeder (riser) Manufacturing processes: Reservoir of molten metal that compensates shrinkage during solidification.
Ferrite content Materials and metallurgy: Amount of ferrite in austenitic or duplex stainless steel welds, measured in FN. Thickness, Ferrite and Surface Roughness →
Fillet weld Welding: Weld of approximately triangular cross section joining surfaces at an angle.
Final random inspection (FRI) Inspection and sampling: Sampling inspection of finished, mostly packed goods before shipment. Factory Inspection: PPI, DUPRO and FRI →
First party audit Quality management: Internal audit performed by or on behalf of the organisation itself.
Fit Dimensions and GD&T: Relation between hole and shaft sizes: clearance, transition or interference (ISO 286).
Fit-up Welding: Alignment and gap of parts before welding, inspected before the root pass.
Flash Manufacturing processes: Excess material at the parting line of forgings, castings or mouldings.
Flatness Dimensions and GD&T: Form tolerance limiting how much a surface may deviate from a plane.
FMEA Automotive and core tools: Failure mode and effects analysis of design or process risks. FMEA →
Forging Manufacturing processes: Shaping metal by compressive force, usually hot. Closed die forging →
FQC Inspection and sampling: Final quality control at the end of production. Independent Quality Control →

G

Gating system Manufacturing processes: Channels that deliver molten metal into the mould cavity.
Gauge R&R Dimensions and GD&T: Study of repeatability and reproducibility of a measurement system. MSA →
GD&T Dimensions and GD&T: Geometric dimensioning and tolerancing to ASME Y14.5 or ISO GPS. ISO 1101 →
General inspection level Inspection and sampling: ISO 2859-1 levels I, II and III that set the relation between lot size and sample size; level II is normal.
General tolerances Dimensions and GD&T: Tolerances for dimensions without individual tolerance, such as ISO 2768-m. ISO 2768 →
Go / no-go gauge Dimensions and GD&T: Fixed gauge checking whether a feature is within limits without measuring a value.
Grain size Materials and metallurgy: Average size of crystals in a metal, influencing strength and toughness.
Grinding burn Manufacturing processes: Thermal damage to a ground surface, detected by nital etch. Grinding →

H

Hardness Materials and metallurgy: Resistance to indentation, measured by Brinell, Vickers or Rockwell methods. Hardness Testing →
HAZ Welding: Heat affected zone: base metal whose microstructure was changed by welding heat.
Heat input Welding: Arc energy multiplied by the process efficiency factor, in kJ/mm; controls toughness and hardness.
Heat number Materials and metallurgy: Identification of a melt of steel, linking material to its certificate.
HIP Manufacturing processes: Hot isostatic pressing to close internal porosity in castings and printed parts.
Histogram Statistics: Bar chart of the frequency distribution of measured values.
Hold point Inspection and sampling: ITP point beyond which work may not proceed without the inspector's attendance or written waiver. Inspection and Test Plans (ITP) and Quality Control Plans →
Holiday Coatings and corrosion: Pinhole or discontinuity in a coating, found with a holiday detector.
Hot dip galvanizing Coatings and corrosion: Zinc coating by immersion in molten zinc. Hot dip galvanizing →
Hydrogen embrittlement Materials and metallurgy: Loss of ductility caused by absorbed hydrogen, a risk for high strength fasteners and welds.

I

IATF 16949 Automotive and core tools: Quality management requirements for automotive production and service parts. IATF 16949 →
Impartiality Quality management: Presence of objectivity: no conflicts of interest influencing the inspection or audit result. Our independence →
Inclusion Materials and metallurgy: Non-metallic particle in metal such as oxides or sulphides.
Incomplete penetration Welding: Root of the joint not fully fused through the thickness.
Incoterms Projects, expediting and contracts: International rules defining delivery responsibilities between buyer and seller, such as EXW or FCA.
Indication NDT: Response or evidence from an NDT examination that requires interpretation.
Induction hardening Manufacturing processes: Local surface hardening by induction heating and quenching. Induction hardening →
Injection moulding Manufacturing processes: Injecting molten plastic into a closed mould. Plastic injection moulding →
Inspection and test plan (ITP) Inspection and sampling: Document listing inspection and test activities, references, acceptance criteria and the involvement of each party. Inspection and Test Plans (ITP) and Quality Control Plans →
Inspection body Inspection and sampling: Organisation performing inspection, assessed for competence and impartiality to ISO/IEC 17020. ISO/IEC 17020 →
Inspection release note (IRN) Inspection and sampling: Document authorising shipment after successful inspection. Pre-Shipment Inspection →
Internal audit Quality management: Audit of an organisation's own processes and system, required by ISO 9001.
Interpass temperature Welding: Temperature of the weld area just before the next pass; often limited by the WPS.
Investment casting Manufacturing processes: Lost wax casting with ceramic shells. Investment casting →
IPC-A-610 Manufacturing processes: Acceptability standard for electronic assemblies.
IPQC Inspection and sampling: In-process quality control during manufacturing. Independent Quality Control →
IQC Inspection and sampling: Incoming quality control of purchased materials and parts. Independent Quality Control →
IQI NDT: Image quality indicator used to confirm radiographic sensitivity. Radiographic Testing →
ISO 5817 quality levels Welding: Levels B, C and D for limits of imperfections in steel welds; B is most stringent. ISO 5817 →
ISO 9001 Quality management: The international standard for quality management systems. ISO 9001 →

K

Kerf Manufacturing processes: Width of material removed by a cutting process.
Kick-off meeting Projects, expediting and contracts: First meeting after order placement to align scope, schedule and quality requirements.
KPI Quality management: Key performance indicator: a measured value used to track performance, such as PPM, on time delivery or audit score.

L

Lack of fusion Welding: Lack of union between weld metal and parent metal or between passes.
Lap (forging) Manufacturing processes: Fold of metal forged into the surface without fusion.
Layered process audit Automotive and core tools: Short, frequent audits of the same process by different management layers.
Leak testing (LT) NDT: Methods such as pressure decay, bubble or helium tests that locate or quantify leaks. Pressure and Leak Testing →
Leg length (z) Welding: Distance from the root of a fillet weld to the toe; related to throat a by z = 1.41 a.
Level 1, 2, 3 NDT: NDT personnel certification levels under ISO 9712 with increasing responsibility. ISO 9712 →
Lift-off NDT: Distance between probe and surface affecting eddy current and coating thickness readings.
Limit sample Inspection and sampling: Physical sample showing the boundary between acceptable and unacceptable appearance.
Lot Inspection and sampling: Collection of units produced under essentially the same conditions, inspected as a whole.

M

Major defect Inspection and sampling: Defect likely to cause failure or materially reduce usability.
Management review Quality management: Periodic review by top management of the quality system's suitability, adequacy and effectiveness.
Measurement uncertainty Dimensions and GD&T: Range within which the true value lies with a stated probability.
Microstructure Materials and metallurgy: Structure of a metal visible under a microscope after polishing and etching.
Milestone Projects, expediting and contracts: Significant event in a schedule, such as material arrival or FAT.
Minor defect Inspection and sampling: Defect unlikely to reduce usability materially; a departure from standards with little effect.
MMC / LMC Dimensions and GD&T: Maximum and least material conditions, used to modify geometric tolerances.
MSA Automotive and core tools: Measurement system analysis. MSA →
MT NDT: Magnetic particle testing for surface and near surface defects in ferromagnetic materials. Magnetic Particle Testing →
MTC Materials and metallurgy: Material test certificate documenting chemical and mechanical properties of a heat. Material Verification and Certificate Review →

N

NCR Quality management: Nonconformity report: the record of a nonconformity, its disposition and follow up. Nonconformity, Root Cause and CAPA Management →
Nitriding Manufacturing processes: Diffusing nitrogen into steel surfaces at low temperature.
Nodularity Materials and metallurgy: Percentage of graphite in spheroidal form in ductile iron.
Nonconformity Quality management: Non fulfilment of a requirement. Graded as major or minor in audits.
Normal distribution Statistics: Bell shaped distribution described by mean and standard deviation.
Normal, tightened, reduced inspection Inspection and sampling: ISO 2859-1 switching states that adjust sampling severity according to recent results.
Normalising Materials and metallurgy: Heating above the transformation range and cooling in air to refine grain.
Notified body Projects, expediting and contracts: Organisation designated by an EU member state to assess conformity under directives. QUALITAS TR is not one.

O

OC curve Statistics: Operating characteristic curve showing probability of acceptance against lot quality.
Opportunity for improvement Quality management: Audit observation that is not a nonconformity but where performance could be improved.
Overcoating interval Coatings and corrosion: Minimum and maximum time before the next coat may be applied.

P

Packing list Inspection and sampling: Shipping document listing contents of each package, checked during pre-shipment inspection.
Pareto analysis Statistics: Ranking causes by frequency to focus on the vital few. Pareto Analysis →
Parison Manufacturing processes: Tube of molten plastic inflated in blow moulding. Blow moulding →
Passivation Coatings and corrosion: Conversion treatment that improves corrosion resistance, for example of zinc plating or stainless steel.
PAUT NDT: Phased array ultrasonic testing using multi-element probes to steer and focus beams.
PDCA Quality management: Plan, Do, Check, Act: the improvement cycle underlying ISO management system standards. Third-Party Quality Assurance →
Perpendicularity Dimensions and GD&T: Orientation tolerance controlling 90 degree relationships to a datum.
PMI Materials and metallurgy: Positive material identification by XRF or OES to confirm alloy grade. Positive Material Identification →
Poka-yoke Automotive and core tools: Error proofing device or method that prevents or detects mistakes.
Porosity Welding: Gas pores trapped in weld metal. Weld Imperfections Guide →
Position tolerance Dimensions and GD&T: Zone within which the axis or centre of a feature must lie relative to datums.
Powder bed fusion Manufacturing processes: Additive process melting powder layers with a laser or electron beam. Metal additive manufacturing →
Powder coating Coatings and corrosion: Electrostatically applied powder cured by heat. Powder coating →
Pp / Ppk Statistics: Performance indices using overall rather than within subgroup variation.
PPAP Automotive and core tools: Production part approval process with up to 18 elements and a part submission warrant. PPAP →
PPI Inspection and sampling: Pre-production inspection of materials, components and preparations before mass production. Factory Inspection: PPI, DUPRO and FRI →
PPM Statistics: Parts per million defective. PPM and DPMO calculator →
PQR / WPQR Welding: Procedure qualification record (ASME) or welding procedure qualification record (ISO): the test record supporting a WPS. ISO 15614 →
Pre-inspection meeting (PIM) Projects, expediting and contracts: Meeting before manufacturing to agree ITP, procedures and inspection logistics.
Preheat Welding: Heating of the base metal before welding to reduce hydrogen cracking risk and cooling rate.
Preload Manufacturing processes: Clamp force in a tightened bolt. Bolted joints and torque control →
Prepreg Manufacturing processes: Fibre reinforcement pre-impregnated with resin. Composite manufacturing (FRP, GRP, CFRP) →
Preventive action Quality management: Action to eliminate the cause of a potential nonconformity before it occurs.
Primer Coatings and corrosion: First coat applied to the prepared substrate for adhesion and corrosion protection.
Process approach Quality management: Managing activities as interrelated processes with inputs, outputs, resources and measures.
Profile tolerance Dimensions and GD&T: Tolerance zone along a true profile of a line or surface.
Progress report Projects, expediting and contracts: Periodic report on actual progress against plan with forecasts and risks. Project Monitoring and Reporting →
Progressive die Manufacturing processes: Press tool performing several operations as the strip advances.
Proof strength (Rp0.2) Materials and metallurgy: Stress at which 0.2 percent plastic strain occurs; used as yield for many materials.
PSI Inspection and sampling: Pre-shipment inspection of finished goods before dispatch. Pre-Shipment Inspection →
PSW Automotive and core tools: Part submission warrant, the summary document of a PPAP.
PT NDT: Liquid penetrant testing for surface breaking defects in non-porous materials. Liquid Penetrant Testing →
Punch list Inspection and sampling: List of open items to be completed or corrected before acceptance or handover.
Purchase order (PO) Projects, expediting and contracts: Contract document defining what is bought, the requirements and delivery terms.
PWHT Welding: Post weld heat treatment, usually stress relieving, to reduce residual stress and hardness.

Q

Quality assurance Quality management: Part of quality management focused on providing confidence that requirements will be fulfilled. Third-Party Quality Assurance →
Quality control Quality management: Part of quality management focused on fulfilling requirements through inspection and testing. Independent Quality Control →
Quality manual Quality management: Document describing an organisation's quality management system; no longer mandatory in ISO 9001:2015.
Quality plan Quality management: Document specifying the procedures and resources applied to a specific product, project or contract. ISO 10005 →
Quench and temper Materials and metallurgy: Hardening by rapid cooling followed by tempering to the required strength and toughness. Heat treatment (quench and temper, normalise, anneal) →

R

Recast layer Manufacturing processes: Resolidified surface layer left by EDM. EDM, wire and sinker →
Recordable indication NDT: Indication above the recording level that must be reported.
Recovery plan Projects, expediting and contracts: Plan to bring a late project back on schedule. Project Recovery Support →
Reflow Manufacturing processes: Melting solder paste in a controlled temperature profile.
Regrind Manufacturing processes: Reground runners and rejects reused in moulding, usually limited by specification.
Rejection number (Re) Inspection and sampling: Minimum number of nonconforming items in a sample for which the lot is rejected.
Resident engineer Projects, expediting and contracts: Engineer stationed at a supplier for continuous surveillance. Resident Quality Engineering →
Review point Inspection and sampling: ITP point where documents are reviewed by the inspector without physical attendance.
Risk based thinking Quality management: ISO 9001 concept of considering risks and opportunities when planning and operating processes.
Root cause Quality management: The fundamental reason a problem occurred; removing it prevents recurrence. Root Cause Analysis: 5 Why and Ishikawa →
Root pass Welding: First pass deposited in the root of a joint.
Roughness (Ra, Rz) Dimensions and GD&T: Parameters describing fine surface irregularities. Thickness, Ferrite and Surface Roughness →
RPN Automotive and core tools: Risk priority number: severity × occurrence × detection. FMEA RPN calculator →
RT NDT: Radiographic testing with X or gamma rays to detect volumetric defects. Radiographic Testing →
Run at rate Automotive and core tools: Trial run at planned production rate to confirm capacity and quality.
Run test Manufacturing processes: Operation of an assembled machine to verify function, noise and vibration. Mechanical assembly and end of line testing →
Runout Dimensions and GD&T: Variation of a surface as a part rotates about a datum axis.

S

S-curve Projects, expediting and contracts: Cumulative progress curve plotted against time.
Sa 2½ Coatings and corrosion: Very thorough blast cleaning grade to ISO 8501-1. ISO 8501-1 →
Safe launch Automotive and core tools: Period of increased inspection after start of production.
Salt spray test Coatings and corrosion: Accelerated corrosion test in neutral salt fog (ISO 9227).
Sample size code letter Inspection and sampling: Letter in ISO 2859-1 derived from lot size and inspection level that selects the sample size. ISO 2859-1 →
Sandelin effect Coatings and corrosion: Excessive galvanizing thickness on steels with certain silicon contents.
Second party audit Quality management: Audit of a supplier by or on behalf of the customer. Supplier Qualification and Capability Audits →
Segregation Materials and metallurgy: Uneven distribution of alloying elements within a casting or ingot.
Shore hardness Manufacturing processes: Durometer hardness of rubber and plastics, such as Shore A.
Short shot Manufacturing processes: Moulded part not completely filled.
Sink mark Manufacturing processes: Depression on a moulded surface over a thick section.
Sintering Manufacturing processes: Bonding powder particles by heating below melting point. Powder metallurgy and sintering →
Site acceptance test (SAT) Inspection and sampling: Tests after installation at site to confirm correct function in the final environment. SAT, Installation and Commissioning Support →
Six Sigma Statistics: Improvement methodology targeting very low defect rates using DMAIC.
Slag inclusion Welding: Non-metallic solid trapped in weld metal, typical of MMA, FCAW and SAW.
SMT Manufacturing processes: Surface mount technology for PCB assembly. PCB assembly (SMT and THT) →
Soluble salts Coatings and corrosion: Contamination on steel that causes osmotic blistering under coatings.
SOP Automotive and core tools: Start of production.
Sorting Inspection and sampling: 100 percent inspection to separate conforming from nonconforming parts. Sorting, Containment and Rework Supervision →
Source inspection Inspection and sampling: Inspection at the supplier's premises before goods are shipped. Supplier Inspection and Production Surveillance →
Spatter Welding: Droplets of metal expelled during welding that adhere to surfaces.
Special characteristic Automotive and core tools: Product or process characteristic affecting safety, regulations or fit and function, marked on drawings.
Special process Quality management: A process whose result cannot be fully verified by later inspection, such as welding, heat treatment or coating. Special Process Control →
Springback Manufacturing processes: Elastic recovery of sheet after bending.
Standard deviation Statistics: Measure of spread of values around the mean.
Straightness Dimensions and GD&T: Form tolerance for lines or axes.
Stress relieving Materials and metallurgy: Heat treatment reducing residual stresses without changing structure significantly.
Subgroup Statistics: Small set of consecutive measurements used for control charts.

T

Technical file Projects, expediting and contracts: Documentation supporting a manufacturer's EU declaration of conformity. CE Marking and Technical File Support →
Technical query (TQ) Projects, expediting and contracts: Formal question on technical requirements and its answer. Drawing, Specification and Feasibility Review →
Tensile strength (Rm) Materials and metallurgy: Maximum stress a material withstands in a tensile test.
Third party audit Quality management: Audit by an independent organisation, typically for certification.
Throat thickness (a) Welding: Height of the largest triangle inscribed in a fillet weld section; the design dimension.
TOFD NDT: Time of flight diffraction ultrasonic technique for sizing defects in welds.
Tolerance Dimensions and GD&T: Permitted variation of a dimension or characteristic. Tolerance and deviation calculator →
Tolerance stack-up Dimensions and GD&T: Accumulation of tolerances along a chain of dimensions.
Torque-angle tightening Manufacturing processes: Tightening to a snug torque then a defined angle for consistent preload.
Traceability Quality management: Ability to trace the history, application or location of an item, such as heat number to certificate to part.
Turning Manufacturing processes: Machining a rotating workpiece with a stationary tool. CNC turning →
Turtle diagram Quality management: Process analysis tool showing inputs, outputs, resources, people, methods and measures of a process. Manufacturing and Special Process Audits →

U

UCL / LCL Statistics: Upper and lower control limits on a control chart, not to be confused with specification limits.
Undercut Welding: Groove melted into the base metal at the weld toe and left unfilled.
USL / LSL Statistics: Upper and lower specification limits from the drawing.
UT NDT: Ultrasonic testing for internal defects and thickness. Ultrasonic Testing →

V

Validation Quality management: Confirmation by objective evidence that requirements for a specific intended use have been fulfilled.
Variables inspection Inspection and sampling: Inspection that measures values on a continuous scale and evaluates them statistically (ISO 3951).
VDA 6.3 Automotive and core tools: German process audit standard for automotive suppliers. VDA 6.3 →
VDR Projects, expediting and contracts: Vendor document register listing documents a supplier must submit, with status. Documentation and Shipment Readiness Expediting →
Verification Quality management: Confirmation by objective evidence that specified requirements have been fulfilled.
Void content Manufacturing processes: Volume percentage of voids in a composite laminate.
Volume solids Coatings and corrosion: Percentage of paint volume remaining as dry film. Coating DFT and WFT calculator →
VT NDT: Visual testing, the first and most used NDT method. Visual Testing →
Vulcanisation Manufacturing processes: Curing of rubber by cross-linking under heat. Rubber moulding and vulcanising →

W

Warpage Manufacturing processes: Distortion of a part after moulding or heat treatment.
Weighted progress Projects, expediting and contracts: Overall progress calculated from activity progress weighted by effort or value. Weighted progress calculator →
Weld line (moulding) Manufacturing processes: Line where melt fronts meet in a moulded part, often weaker.
Weld map Welding: Drawing that identifies each weld with its WPS, welder and inspection requirements.
Welder qualification (WPQ) Welding: Test proving a welder can produce sound welds within a range of variables. ISO 9606 →
Welding coordinator Welding: Person responsible for welding related activities under ISO 14731, such as an IWE.
WFT Coatings and corrosion: Wet film thickness, measured during application to predict DFT.
Witness point Inspection and sampling: ITP point notified to the inspector, who may attend; work may proceed if they do not.
Work instruction Quality management: Detailed step by step description of how to perform a task at the workplace.
WPS Welding: Welding procedure specification: the instruction defining how a weld is made. WPS, PQR and Welder Qualification Review →

Y

Yield Statistics: Proportion of good units produced; first pass yield excludes rework.
Yield strength (ReH, Re) Materials and metallurgy: Stress at which a material begins to deform plastically.

Glossary of quality and inspection terms

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