In mechanical design, geometrical specifications and dimensional tolerances are commonly used to avoid final product malfunction and to allow for assembly integration. Geometric specification usage, in particular, has many manufacturing and durability implications, the feasibility of their measurement and verification, however, is often neglected and the influence of measurement uncertainty in their evaluation underestimated. Often geometrical specifications are defined without considering measurement uncertainties, or measurability at all: it is not uncommon to find approved specifications prescribing unverifiable geometry, or dimension tolerances that exceed state-of-art measurements. This article explores the case study of orthogonality between a circular hole and the plane on which it is drilled, evaluated using a Coordinate Measuring Machine. Such specification is defined, according to ISO 14253, as the angle between the plane normal and cylinder axis. Uncertainty of points coordinates obtained can, however small, play a key role in the final evaluation of orthogonality: if the specified tolerance is thigh enough it is also possible to have misalignment uncertainty higher than the tolerance itself. The authors propose the results of a mathematical and numerical model, meant to help the designer to define specification to assess the relationship between cylinder-plane misalignment measurability, CMM uncertainty and features dimensions.

This paper proposes a bootstrap approach to determine the measurement uncertainty of measurement devices with unknown measurement equation (in this work, a structured light projection system is applied for the measurement of pull broaches) by use of workpieces that are calibrated by a coordinate measuring machine (CMM). The obtained uncertainty is used to perform a conformance assessment of the initial measurement process according to ISO 14253-1 and VDA 5.

According to the increasing interest in metrological systems for the dimensionalmeasurements of large-size objects in a wide range of industrial sectors, severalsolutions based on different technologies, working principles, architectures, andfunctionalities have recently been developed. Among all, the most flexible and easilytransportable solutions are those that have aroused most interest and have found greatersuccess. In order to address the needs of Large-Scale Metrology (LSM) applications, adistributed flexible system based on a network of low-cost InfraRed (IR) sensors – theMobile Spatial coordinate Measuring System II (MScMS-II) – has been developed at theIndustrial Quality and Metrology Laboratory of Politecnico di Torino. This paper presentsa preliminary uncertainty assessment of the system referring to the measured pointcoordinates in the 3D space, focusing on the sources of measurement uncertainty and therelated propagation laws. A preliminary metrological characterization of MScMS-IIarchitecture, experimentally evaluated through a system prototype, is also presented anddiscussed.

The international standard, ISO/IEC 17025 was developed to determine technical competenceand to evaluate laboratories throughout the world. Accreditation bodies playing a vitalrole are increasingly using proficiency testing methodology as a tool to ensure thecredibility of their accreditation programs. The successful completion of a well-designedproficiency test can validate the measurement method and uncertainty budgets of a testinglaboratory. Additionally, proficiency tests can provide a good indication about thequality of the test results. An important part of inter-laboratory comparisons andproficiency testing is the determination of the associated error analyses which arefocused on uncertainty values. This paper presents the implementation of proficiency testsusing inter-laboratory methodology among five different acoustic laboratories. These testswere carried out on 5.27 KWCooling standard unitary air conditioner, A/C, suchas through-wall or split room standard A/C units, for the assessment of Housing &Building National Centre acoustic laboratory. Analyses of results show a good agreementfor En-Value among the selected laboratorieswhen compared with the lowest uncertainty as stated by proficiency tests standards.

This paper presents a joint use of the T2 chart and total inertial tolerancingfor process control. Here, we will show an application of these approaches in the case ofthe machining of mechanical workpieces using a cutting tool. When a cutting tool inmachining impacts different manufactured dimensions of the workpiece, there is acorrelation between these parameters when the cutting tool has maladjustment due to badsettings. Thanks to total inertial steering, the correlation structure is known. Thispaper shows how T2 charts allow one to take thiscorrelation into account when detecting the maladjustment of the cutting tool. Then thetotal inertial steering approach allows one to calculate the value of tool offsets inorder to correct this maladjustment. We will present this approach using a simpletheoretical example for ease of explanation.

Three dimensional coordinate metrology is a firmly established technique in industry.Scanning technology is now widely used in coordinate metrology and is increasingly usedfor the measurement of small features. This paper presents a new real shape approach toclosest point inspection involutes curve of gear tooth by coordinate measuring machinery(CMM). This method aims to select the most likely contact point for each successive arc byapplying geometrical criteria and a fuzzy logic estimator. This method is particularly,but not exclusively, suitable for the metrology of features with small radii as well asmetrological discontinuities. It does not require obtaining the normal vectortraditionally used for probe tip correction. Elapsed time is 144.09 s. Tests have beendone on limps of machine tool speed (pinion type cutter), which is highly applied in ourcountry.

A Proficiency Test Scheme (PTS) for histamine analysis in fishery products using the Lerke and Bell (1976) fluorometric method was conducted in 26 different Moroccan laboratories. The goal of this PTS was to assess the abilities of a network of seven government laboratories and 19 laboratories performing auto-controls on fish processing units in Morocco. The samples used in the PTS were prepared from canned ground mackerel flesh, to which was added two significant concentrations (levels 1 and 2) of histamine. The homogeneity of the PTS samples was verified by a repeatability test and their stability by an intermediate fidelity test. The Cochran test was used to eradicate anomalous scattering and the Grubbs test to eradicate the anomalous averages observed in the results of the participating laboratories. The average and the usual deviations determined for levels 1 and 2 were used to calculate the Z-scores. For level 1 therefore, 23 out of 26 laboratories had satisfactory PTS results, and for level 2, 21 out of 26 laboratories had satisfactory PTS results. An analysis of the PTS samples using the HPLC reference method gave similar results for levels 1 and 2.

This research work describes a novel approach for comparing different technologies forfree form surface metrology: computerized tomography (CT), photogrammetry and coordinatemeasuring machines (CMM). The comparison has the aim of providing relevant information forthe selection of metrology equipment when measuring free form components. Resultsdemonstrate that there is the imperative need to assess the uncertainty andreproducibility of CT and photogrammetry measurements by applying some calibrationprocedures taking into account some recommendations for work piece alignment. This articlealso deals with costs issues, required standards, and necessary additional informationwhen selecting inspection equipment.

In order to achieve nanometer accuracy, metrologists need to identify the sources oferror and develop solutions to eradicate or minimize their effects. A stabilized low powerdual-frequency laser heterodyne interferometer (ZMI-1000A) designed to measure linear andangular displacement with nominal measurement resolution 1.24 nm and 0.0025 arcsec,respectively, is used to achieve measurement of displacements over different travellingaxes by comparison with the electronically reference measurements of the stage over widerange 500 mm. The repeatability and reversal error of linear stage over the workingdistance have agreed opto-electronically and the positioning uncertainty been reduced. Amultivariable framework was implemented for the x-axis due to the crosscoupling between the forward and backward course of the linear stage. Thermal errorreduction is achieved using environmental temperature control (20 ± 0.2 °C)to help reduce thermal errors.

Illumination using artificial light sources is common in these days. Many manufacturesare paying for the design of lamps depending on high efficacy and low UV hazards. Thisresearch is focusing on the most useable lamps in the Egyptian markets; high pressuremercury (HPM), metal Halide (MH), and high pressure sodium (HPS). A set up for relativespectral power distribution based on single monochromator and UVA silicon detector forabsolute irradiance measurements are used. The absolute irradiance in (W/m2) in UVA region of the lamps andtheir accompanied standard uncertainty are evaluated.

Capable measurement of the size and shape of components is a prerequisite for precisionmanufacturers. However, the design community may not fully consider measurement issuesthat could arise when components are manufactured, and the manufacturing community may notwholly appreciate the value that measurement data can bring to design. This paperinvestigates measurement knowledge in this relationship to find out if there are specificknowledge types that could be developed to improve the likelihood of fulfilling designintent. A proven systems-based approach was applied to an illustrative case to develop amodel of knowledge flows and identify key knowledge types. For this case study, it wasfound that knowledge about measurement is dispersed and managed through a variety ofpractices which are relatively isolated from design. Furthermore, conflict was uncoveredbetween the knowledge types, reinforcing the view that a more inclusive and integratedapproach is required. In the course of the research, a novel methodology was developed inwhich group modelling was used to generate questions, rather than the more typicalapproach of grounding a systems model on interview data.

The grazing incidence X-ray reflectivity is used to determine the multilayer thickness ofGaAs/AlAs supperlattice. The measurement process includes the fitting model and themeasurement conditions (different powers of 45 kV × 40 mA, 40 kV × 40 mA and 35 kV × 40mA, different step sizes of 0.005°, 0.008° and 0.010°,and different times per step of 1 s, 2 s, 3 s). In order to obtain the valid measurementprocess, the combined standard deviation is used as the normal of the fitting resultsselection. As a result, the measurement condition of 0.008° step size and 2 stime per step with the power 40 kV × 40 mA is selectable with the operation stability offacilities and smaller error.

The analyses of the performance of a complete photovoltaic system require precisemeasuring equipment in order to obtain reliable comparative results. This paper presents acomputer-based instrumentation system suitable for a characterization of photovoltaicconversion chains. Consisting in a data acquisition stage, a data processor, photovoltaicgenerators and power conditioners, the system evaluates the respective efficiency ofmaximum power point tracker (MPPT) and power conditioner. The efficiency of unknown MPPTfunctions is estimated with great accuracy by means of an extremum control-based MPPT usedas a reference. Efficiency evaluations of two photovoltaic battery chargers during 4 daysillustrate the estimation procedure and the system test facilities.

This work presents the results of a survey carried out among Brazilian calibrationlaboratories accredited under ISO/IEC 17025:2005 with the objective to identify how theselaboratories investigate the root causes of unsatisfactory results in proficiency testing.The survey was coordinated by the Brazilian accreditation body, the General Coordinationfor Accreditation (Cgcre), of the Institute of Metrology, Quality and Technology(Inmetro).

Microscopy is used in most technology processes where two-dimensional distributions, thatare digital images of the shape and appearance of integrated circuit (IC) features, revealimportant information. Optical microscopy and diffraction gratings can be used to measurethe placement of IC features with a precision of less than 1 nm (1σ) witha new technique of separately viewing multiple levels. However, the microscope’s opticaland video camera distortion may cause significant errors in the IC feature measurementunder some circumstances. In this paper, the optical and video camera distortions of anoptical microscope used in IC feature measurement were studied by analyzing digital imagesof a precision grating. MATLAB programs were used to extract the value of intensity ofeach pixel in the grating image. By matching a position dependent, phase-varied idealsinusoidal wave to the processed grating digital image, the phase of the best-fit sinewave was observed to vary by the equivalent of many nanometers at different locationswithin the digital image of the grating. This variation was similar, but significantlydifferent, for different microscope objectives. It is believed to arise from opticaldistortion within the microscope, and possibly also from distortion within the camera.Impact of optic chromatic aberration and microscope stability on the measurement of ICfeatures was also studied. The method described here is inexpensive and easy to implementsince it does not require any sophisticated equipment or controlled environment. Thistechnique provides an attractive option for small companies, university labs andinstrument manufacturers.

Since 2006, the wood preservation laboratory of Cirad is accredited by COFRAC (French accreditation committee – accreditation No. 1-1686) for tests on the durability of wood and wood-based products and on protective efficacy of wood preservatives and termite control products. The metrological approach adopted by the wood preservation laboratory is a key factor on the continuous improvement of practices. Tests to determine the resistance against wood-destroying biological agents are the most difficult of all wood analysis tests. They are aimed at assessing and quantifying the impact of living organism, such as fungi and termites, on a lignocellulosic material. The extent of variability of this impact, which in turn is linked with the diversity of these organisms and of the material, can be readily determined. The validity and reliability of the findings therefore depend directly on the quality of the metrological process, including the choice of measurement devices, their management and compliance with international standards.

The quality of fixtures plays an important role in product quality during manufacturing,measuring or assembly. Finding methods for evaluating a fixture’s quality, which maydepend on workpiece errors, fixture errors, influences of clamping force, friction, etc.,is necessary to improve the product quality. This paper proposes the indicators that areused for estimating the quality of a fixture based on workpiece localizationrepeatability. Here, the workpiece localization will be considered in the followingdifferent cases: (1) considering only the influence of different geometric parameters(types) of the fixture, (2) taking into account the clamping force in the different typesof the fixture, (3) the influence of friction on the contacts of the workpiece-fixture. Afixture model is presented and analysed with some examples. An experimental fixture andworkpiece are then used to analyse and compare with the theoretical results.

At NMISA the SI unit for length is realised by an iodine stabilised He-Ne laser, anoptical measurement. In industry most measurements are performed by mechanical probing.Gauge blocks are the link between the optical measurements and the mechanicalmeasurements, and are therefore critical in disseminating traceability. The gauge blocklength is currently determined by wringing the gauge block onto a platen. This islaborious, requires skill and causes contact errors. Since around 1943, there have beenefforts to build a double ended interferometer where gauge block length can be determinedwithout wringing it onto a platen. While there has been a lot of progress in buildingDEIs, to date, there is still no commercially available DEI. We present a collaborationproject between the National Metrology Institute of South Africa (NMISA), the NationalInstitute of Standards (NIS Egypt) and Stellenbosch University (SUN) in South Africa tobuild a double ended interferometer for use at the respective National MetrologyInstitutes. We investigate improvements to the interferometric calibration of gauge blocksand recent developments. The different systems currently in use in the national metrologylaboratories are described and various designs are investigated. Lastly the expectedoutcome of the project will be discussed.

The wood preservation laboratory of Cirad is accredited by COFRAC (French accreditationcommittee – accreditation No. 1-1686) for tests on (1) durability of wood and wood-basedproducts; (2) protective efficacy of wood preservatives; (3) efficacy of termite controlproducts. In order to test the efficacy of wood preservatives, non-durable wood blocks aretreated using different product doses and exposed to the attack of xylophageous organisms(fungi, insects). To reproduce the ageing of treated wood blocks, some laboratoryprocedures are available. Amongst them, there is an evaporation procedure, reproducing theaction of a warm air flow onto treated wood. This ageing step is very discriminant, asonly the formulations fixing effectively the active ingredients will pass the biologicaltest afterwards. This ageing by evaporation is described in the EN73 standard.Nevertheless, many points remain difficult to overcome. The tunnels used for theevaporation are all prototypes; as such equipment is not available currently on themarket. So each laboratory has got its own tunnel device. Moreover the way to measure thetemperature and speed of the air flow is very difficult to achieve considering theprescriptions of the EN73 standard. The EN73 standard is being revised by the Europeanstandardization group (CEN TC38) and despite the metrological aspects were crucial andinadequate in former version, they were not considered as they should. The woodpreservation laboratory has forwarded remarks in order to supersede some points of therevision document in order to consider the metrological aspects. This is of mainimportance as the ageing procedure is commonly used prior to most of the biological test,and such tested products are put on the market based on the efficacy results.

One of the main calibration services of African NMIs (National Metrology Institutes) isthe measurement of tapes and rules. This is mainly regulated by legal metrology and OIML(International Organisation of Legal Metrology) specifications are therefore referenced.Specifically, OIML R-35 is the standard to which rules or line scales must conform. Theaccuracy of most African NMIs systems however, cannot prove conformance to thisspecification. This article will detail the development of a new, cost effective, linescale calibration system, which will have accuracy better than the specificationprescribed. The system was locally developed and its design is based onoff-the-shelf components and open source software. It is alsoready-for-upgrade to an absolute system. The system and details of theline detection algorithm will be presented.