Interview with Traian Onaciu, Director of the Department of metrology in the Ascamm Foundation

Traian Onaciu Was cream in Transilvania in 1952, although his look límpida does not remember in at all the hálitos that attribute to any of his paisanos. It conserves the citizenship rumana since, in 1992, moved to Spain, where validate and expanded to a large extent his studies of Mechanical Engineering, realising the doctorate on MMC.

Seems very very calibrated and encourages in expressesing always of exact form. It is married and has two children. In this interview gives us account of the evolutions of the dimensional metrology since it did charge of the department in Ascamm twelve years ago, and the tendencies that aim in this science and in the industry related.

MetalUnivers: How they have evolved the systems of measurement in these twelve years of activity of the service metrológico of Ascamm?

Traian Onaciu: From the beginning the laboratory was instrumented with the basic means to give answer to the diversity of problems of metrology. Along this time our means have diversified, have relocated in some appropriate surroundings and have followed the improvements of the programs of application with the help of the it. These programs have migrated cheese cheese to the surroundings “Windows”, giving ease in the use and improvement in the productivity.

MU: But the equipment also have evolved in these years...

TO: The manufacturers have concerned to build machines with structures more balanced, instrumented with a diversity of systems of acquisition of data that complement one to another to give solutions improved to the demand metrológica of increasing complexity.

Have developed the systems of acquisition without contact, based in the principle of the “triangularización optical”. Emisores Laser of low power or sources of white light project on the mesurando in analysis patterns known. The projection registers by means of receptors of imgn. In the triangle formed by the emisor, the object explored and the receptor there is sufficient elements known to be able to calculate the space coordinates of points situated on the zones explored. These systems have the purpose to reduce the time employed in the process of acquisition of data. They show very useful in works of dgitalizado and over time improved the uncertainty specifies.

Regarding the machines to measure, the method of analysis of structures, using finite elements has determined important structural changes to improve the requirements of rigidity and speed in movement. Can have of impressesive speeds of positioning and/or exploration to a level of acceptable uncertainty. This is very important in lines of manufacture, where realises an inspection in series of products and no so much in our case, since we inspect mostly singular pieces or developing prototypes.

MU: In that been of development finds the measurement on line of production?

Those that require inspection on line already are instrumented with machines incorporated like a cell more in the process of development of the product. These machines find in a microentorno of work to keep in appropriate parameters of cleaning and temperature and if it is precise include in his structure sensors of temperature that are able to correct derives it thermal sensors. It is necessary to have present that the fluctuation of the temperature is the main factor of error in the dimensional metrology. If it derives it it is constant can correct but if there is fluctuation of temperature the correction is practically unfeasible . A recently mechanised piece can not go in like such in the cell of measurement.

MU: In that field have specialised ?

TO: In the world of the dimensional measurement think that in Ascamm have done important steps in the inspection advanced of forms by comparison with the model CAD and also in the implementation of the service of calibración.

MU: Which needs covers this system of inspection advanced?

TO:  It treats of a service with an increasing demand that derives of the style and the current capacities of design. Today in surroundings CAD modelan with relative ease form complex based in geometries SPLINE, NURBS etc and effects a chequeo visual of style. If it proceeds it realises the prototyping fast. The systems FALLS can improve the design of the product and recommend the important parameters for the matrix or the mould generator of the product. The systems CAM generate the programs of mechanised for these complex forms. Like this they design and they develop technologies in Ascamm for pieces of plastic and in the short term find you with first samples like frontal of car, carcasas of mobile phones etc that it is necessary to inspect to validate his technology. This type of pieces can not inspect only with the help of the traditional means.

MU:It could deepen more?

TO: They imagine the rear-view mirror of a car. In addition to aesthetic criteria will have to fulfil specifications of aerodynamic type. Of here it derives the need of the compliance with the model CAD that can not value with a “foot of king”. In this case it proceeds to an analytical inspection, point by point. In exploration by palpado discreet, the correct form of acquisition of points realises in movement 3D along the normal venue, identified and mattered from the model CAD.

MU: Which sectors sue this type of analysis?

TO: The sector of the car and the aeronautical sector component manufacturing sector component manufacturing are the main beneficiarios. Of the most demanding are the specifications to inspect reflective surfaces in optics, profiles of levy or profiles and surfaces with application in hídro or aerodynamic.

MU: In that situation finds the integration of the CAD with the systems of measure?

TO: We find us with improvements regarding transfer of information respect to previous years, although we suffer a lot the fault of compatibility between distinct systems. The translators work but almost all ocasionan loss of information. Every time it is more complicated to dare to give services of metrology without having good knowledges of CAD. The information CAD arrives us sometimes desorganizada, with excess elements (curves, flat auxiliaries, surfaces no recortadas etc), with zones that do not have the appropriate continuity or simply are missing in the model. Before beginning to measure it is necessary to prepare the model so that it was appropriate for the purpose metrológica.

To the mates of design would transmit them this ours wish of improvement regarding the manufacturing of the model for the geometrical inspection. Have to specify with rigurosidad those elements that participate the the alineación, each one with his degrees of freedom. The system has to remain “very restricted ” to be able to find a mathematical solution. It is necessary to define which are the zones to explore, cual is the density and the distribution of points in these zones. In a lot of cases these specifications are missing and have to arrive to agreements with our customers. If these hypotheses do not document by writing loses the trazabilidad metrológica.

MU: What you would ask is a simpler integration between CAD and metrology?

TO: they are doing Advances but no to the speed that we would ask...

MU: Which are the reasons?

TO: I do not want to throw the fault to anybody, but think that the economy of the free market is generadora of this socially useless effort – the incompatibility. The right to the patent rights and all the tentativas to violate it have generated systems that have encerado (armoured) in if same for autoprotegerse. Who fix all this? As between all, understanding us better think that could do the most transparent things , more transportables but at the same time with respect to the copyright.

MU:..And the calibración?

TO: Calibrate supposes to register, process and contrast the information of exit of an instrument, in several points along his scale of capacity, with the value of confidence of a pattern of trazabilidad certified, with the end to evaluate his uncertainty. In summary the systems of aseguramiento of the quality demand that all the instruments metrológicos surpass a periodic test. With instruments of inappropriate uncertainty exists the risk to classify as bad part of the good production, what translates in stray economic. The another risk still greater is the one to classify as good part of the bad production, what drives to stray of prestige.

Are instrumented with means and procedures to calibrate smooth rings, rings of thread, cylindrical or threaded tampons, micrometers, feet of king, blocks pattern etc. Our next aim is to achieve the accreditation ENAC and while this was not like this respect the trazabilidad metrológica and the specifications of the norm ISO 17025.

MU: To improve the precision in the mechanised would be well have a machine to measure in enclosed bow: measure the result with an able system to generate corrections to improve in the following phase. In which state is?

TO: In the development of machines- tool have achieved important progresses regarding design of structures, numerical controls of several axles, systems of communication and control in enclosed loop. In the cambiador automatic of tools one of the places is used to to be occupied by a sensor palapdor with purpose metrológica. There is provable confidence that the machines begin giving good results. Nevertheless, depending on his origin, of the diet of work, of the maintenance etc., after a true time, the machines accumulate errors and when these exceed a threshold criticise pose problems.

To know the state of wear of the machines in Ascamm have thought in giving a new service: it treats of the “geometrical verification of machines-tool”.

That in the market there are technologies like the interferometría laser, able to signal failures of linealidad, rectitud, perpendicularidad of axles or the technology “Ballbar”,able to realise a chequeo fast of the machine, by means of the analysis of the results Of the behaviour in circular interpolations realised with a sensor of length in the main planes of work. In these cases treats of chequeos that realise out of the normal operation of the machine.

Ours proposal supposes a chequeo in real conditions, with real materials, and with the headlines of the machine, operating in similar conditions to the ones of the daily work. The machine will mechanise a model designed by us, we would inspect the result and would be able to provide a three-dimensional information on his behaviour. With this information the user will be able to do a ranquing of his machines, knowing with hygiene cual is the best , to which can program only desbastes etc.

The model test now in study will be a surface, based in curves of geometry known that will put the machine in complex conditions of interpolation.

This model will be property of the user and realising the test annually will be able to create a historial of each machine.

MU: Which are his laboratories of reference?

TO: We consider us situated more next to the base that to the tip of the pyramid of the trazabilida  metrológica, nearer to the productive processes.

To the same level that we are the laboratories metrológicos of ITM, Unimetrik, Tekniker. Above our competitions in our vicinity finds LGAI (Laboratori General d'Assaigs i Investigacions) with means metrológicos of better uncertainty. To national level is the CEM  (Spanish Centre of Metrologia) and to international level would be the famous PTB (Physikalish-Technische Bundesanstalt). It treats of the entity metrológica of reference in Germany that acts like a faro in the European Community, so much by the diffusion of information as by the calibración in the world of the metrology.

MU:In that state finds the investigation metrológica in Spain?

For my is a pegunta delicate. An appropriate answer can come of the Department of Science and Technology

MU: ?!

Personally have information of the efforts of development of basic investigation in metrologia in Trimek – the national manufacturer of machines to measure - in Unimetrik, in the University of Saragossa. It would be for my one grata surprise that signal me that there are more centres and people with worries and results that could share .