NDTnet - February 1996, Vol.1 No.02

| German |

A tool for cost management
Digital ultrasonic testing technology

Wolf Dietrich Kleinert, Johannes Büchler
Contact to authors

Abstract:

In the field of quality assurance in the production process, ultrasonic testing has achieved a high degree of importance. It is also being applied more frequently for monitoring machines or installations, resp. damage prediction of components. In this way, repairs can be carried out before any damage occurs and high investments can be planned a great deal better.

It goes without saying that optimum ultrasonic characteristics are also necessary conditions for digital ultrasonic flaw detectors. In addition to this, digital testing technology offers considerable advantages. These are especially apparent in the ability to store data on an electronic data carrier for documentation and filing. On the one hand, the filed data is proof that the test has been correctly made in cases of doubt as well as enabling the test results to be documented, and on the other hand, due to stored data, the instrument can be exactly reset to the settings made at the time of storage in order to carry out repetitive tests.

  • The RS 232 interface

     An RS 232 serial interface is sufficient for transfer of individual data or for direct documentation on a printer. The following data can be transferred via this interface Fig. 1 Data Interface via serial interface RS232.): An ultrasonic flaw detector can also be completely remote controlled via the RS 232, this means that each setting can be recalled as well as changed.

  • Application software

    • The data transferred from the instrument are, according to purpose, further processed with corresponding software. If the data are to be transferred for documentation then such a program as UltraDOC can be used which does not only transfer the data but also stores it in standard formats. Data which are stored in these formats can be compiled into test reports using any normal word processing program.
    Fig. 2 Application software for documentation of test data.


    If the main purpose is to file instrument settings and test results the user software ParDAT can be used. This package does not only enable data transfer but also filing into a database. In this database, the adjustment data and the A Scans are filed together with an individual definable mask containing addition information (operator, order no. etc). Using an integrated search function, the data can be sorted according to any search criteria and displayed on a PC. By overlaying various A Scans, time behaviours of individual flaw indications can be displayed and monitored.
    Fig. 3 Application software for test data management

  • Real time outputs and LINK interface according to RS422

    In many cases, the documentation of individual test positions is not sufficient. Here, complete documentation of a test sequence is required. The data from the ultrasonic flaw detector must be linked with the probe position. For this, the ultrasonic flaw detector makes data available for each test cycle in various forms and limits the data flow, as far as possible, which is already precompressed. The following data in each test shot are fed to the outputs: Times of flight (16 bit) as well as the amplitudes (8 bit), for the event of each gate, are transferred at a transfer speed of 10 MBit/s via a serial LINK interface according to RS422. Due to the high data transfer rate, it is possible to transfer these values shot by shot even at the high pulse repetition frequency. In addition to this, the precompressed A Scan information, as displayed on the ultrasonic flaw detector, is transferred via this interface. The transfer is made at the same speed as the A Scan refresh rate on the instrument. Inputs are also additionally available which enable external control of the ultrasonic flaw detector. For example, the trigger input via which one or a number of test shots can be externally triggered. In order to transfer all data, there is a PC interface board which accepts all data in real time. This board also contains three analog inputs which can be used for acceptance of probe positions. Alternatively, there are two counting inputs for processing the position information also from incremental position generators. The interface also contains a buffer so that no data for the PC are lost. The interface board can either be used in a polling or interrupt mode. The following maskable events can trigger an interrupt: Beyond this, there are additional control inputs and outputs for the ultrasonic flaw detector and for further peripherale.
    Fig. 4 The USD 15 - digital ultrasonic testing technology.

  • Application of this testing technique with manual scanners

    • Together with a mechanical position generator, the ultrasonic flaw detector records test sequences which have been made manually. Apart from storing the time of flight and/or amplitude for each position, the whole test range is monitored for complete scanning and good coupling. The test results processed by the corresponding software package can be presented in various forms, from C Scan to 3 D presentation. The data of the same test piece recorded with this system at different times can be compared with each other and the deviations between the result recordings graphically displayed. The time behaviour is estimated using this comparison. In doing this, decisions can be made in good time regarding repair, procument of spares or the sorting of critical parts. The time for ordering is very cost critical especially where the procurement of expensive components is concerned. Premature ordering ties down capital unnecessarily and ordering too late means that a stoppage can cause considerable costs. Comparable evaluations are made with corresponding stationary test systems by which the test object is scanned on programmable tracks, e.g. water jet coupling. Due to the fact that with stationary operation there is less importance attached to weight, size and current consumption, early data compression can be relinquished. Therefore it is not only the time of flight and amplitude which is stored for each measurement point but also the complete A Scan. After completion of the test the corresponding A Scan for each point can be viewed and analyzed in the C Scan displayed on a PC.

  • Ultrasonic testing and cost management

    • It is sufficient to record individual flaw positions depending on how critical a component is. The documentation of individual indications can be carried out after termination of the test due to the data stored in the instrument. With critical components it is necessary to make a complete recording of the test sequence in real time during the test. The condition for this is that the ultrasonic flaw detector produces corresponding data in real time. To carry out such a costly test economically, the applied test instrument must operate with a high pulse repetition frequency in order to enable correspondingly high scanning speeds. The test data recorded by such a system enable, by comparing test results recorded at different times, information to be obtained about the time behaviour of flaw positions. This results in a basis for decisions concerning repair, procurement of spares or the sorting, resp. shutdown, of critical components. Therefore this makes the ultrasonic test a tool for cost management.
    The authors:
    Wolf-Dietrich Kleinert works as Marketing Manager and
    Mr. Johannes Büchler, Manager of the Hardeware Development Department,
    both from Krautkrämer GmbH D-Hürth.
    E-Mail:     100656.65@compuserve.com

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    Rolf Diederichs 01.Febr.1996, info@ndt.net
    /DB:Article /AU:Kleinert_W_D /AU:Buechler_J_ /IN:Krautkramer /CN:DE /CT:UT /CT:instrument /ED:1996-02