i n t e r n a t i o n a l n e w s

Computer upgrade for surface tester

The computer module of the Hommel T20S programmable surface tester has been upgraded by the addition of another 16-bit microprocessor. In its new form, with expanded software, the instrument enables the user to compile complete measuring programs, including multiple traverses with intermittent parameter print-out, statistical evaluations, recalculations and title print-out.

Much of the expertise necessary for measuring the texture of a surface is now incorporated in the system, making the system more amenable to use by lower skilled operators. All that is required of the operator is to position the stylus of the instrument, call up the appropriate program and to press a button labelled 'run'.

Mounted in a pick-up with an inductive transducer, the diamond stylus traverses across the surface under test. Horizontal sampling rate has been increased to 8,000 digits per traverse, enhancing definition of profile.

Signals from the transducer are stored and evaluated by the computer. The operator can select readings of the different parameters used in the engineering industry to describe surface texture.

All stored information, including measurements and statistical evaluations, can be displayed on the new video unit. Another display is a graphical representation of the surface profile. The operator is able to scan the length of a recorded profile and to obtain a magnified view of any section along the length.

Access to the system is by light pen and displayed menu. Without the video unit, the means of presenting lists of information and profiles would be print-out, so the new facility saves considerable time when there is no need for a permanent record.

Up to nine independent measuring programs can be held in the computer system and are freely selectable. Memory is allocated to each program to store a chosen title and data for statistical analysis. Hahn & Kolb.

Fatigue monitoring adopts handheld computer SES, a division of Welwyn Electronics, is monitoring the fatigue on structures such as pipelines, bridges and roads using an instrument called the Dynamonitor. The multi- channel instrument uses a technique known as 'rain-flow counting', an internationally recognised method of reducing a signal into its constituent cycles, defined in terms of range and means levels. By use ofa handheld computer, the Husky Hunter, these are counted and stored in memory. Data are

collected over a period which may be longer than a month.

The method allows data to be comprehensively analysed, whereas the alternative tape recorder only allows data to be stored. The results of two months' testing can be displayed on site within two minutes and displayed as histograms, cumulative damage calculations and fatigue life predictions.

The analysis program for the combination of instrument and computer is written in a dialect of BASIC and guides the user to set up initial test parameters such as calibration units, gauge identifiers, materials information and weld class. The testing is then carded out in real time, but at any period during the test a 'snapshot' of the data acquired can be taken by using a 'preview data' facility on the computer. A battery- operated printer peripheral is also available.

De-burring by water jet, without abrasive addltwes CERA has developed a combined washing and de-burdng process for a leading European motor manufacturer. Use of a high pressure jet of water with only a detergent additive, has overcome a particularly difficult de-burring problem on an aluminium housing. The process requires no abrasive additive in the fluid. Component washing can be effected at the same time, using the same !iquid medium.

The problem involved the removal of burrs from the edge of a shallow-shaped boss at the bottom of a die-cast housing some 50mm deep. The burrs are created during a face milling operation and not only is it essential that they be effectively removed, but also the finish of the machined surface must not be impaired by the de-burring process.

CERA's approach to this problem was to use high pressure water, delivered through a Flexi-Jet at needle point setting. Flexi-Jet is a microprocessor-controlled wash jet which can

200 MATERIALS & DESIGN Vol. 6 No. 5 OCTOBER/NOVEMBER 1985