mtec 2010

07/07/2010

UK trade show disappoints!

mtec 2010

The annual mtec exhibition, a constituent of the much larger Advanced Manufacturing UK seems to be moving further and further into the year. Originally a stalwart as first major event on this side of the Atlantic in February, last year it was in March and this year it was a week later than the mammoth Hannover Messe.

As usual the whole show was a eclectic mix of engineering capabilities from the precise medical area through mechanical, to building services, manufacturing and measurement capabilities.

The show itself was a bit disappointing and seemed smaller than last year though visitor numbers seemed busy enough. This was particularly noticeable in the Medtec, medical appliance site of the show. Most exhibitors were happy enough with their own performance commenting however on the apparent shrinkage. The fact that the emphasis appeared to be on the Medtec part of the show was also commented upon and indeed all the signs to the hall in which the exhibits were housed emphasised this show with the other six constituent shows getting less emphasis.

The only really new item that we saw at the show was a new micro-flowmeter from Titan Enterprises. “The Atrato” is set to create a breakthrough change in small bore flow metering, it uses patented technology which enables the direct through meter to handle flows from laminar to turbulent according to company founder Trevor Foster. His enthusiasm for his new product was infectious and I think unique in the show this year.

There were also a number of seminars organised to coincide with the exhibition. Those dealing with industrial communications were entirely to do with wireless and were organised by the England Section of the International Society of Instrumentation.

The wireless semnars, which were held on the first morning, progressively attracted more attendees. Starting off was Russel Hobbs of ISA England and Yokogawa who outlined the ISA100.11a, which, as reported last October, was approved and published last year. Industrial wireless communication opens up new resources for highly flexible and efficient automation solutions.

Ian Ramage of Techni Measure and the British Society of Strain Measurement, gave lots of practical examples of wireless transmission particularly in the areas of stress, strain and vibration. He discussed the harvesting of energy in these applications where vibration can be converted into power to power the transmitters. Applications included bridges, moving of delecate or sensitive pieces of equipment. He quoted for instance the used of these transmitters (from MicroStrain Inc.) in the moving of one of America’s most treasured monuments, the Liberty Bell in Philadelphia. He also mentioned possible interference to watch out for in wireless applications caused by micro-wave ovens in the canteen and sometimes with Bluetooth enabled systems in the vacinity.

Ian Bell of National Instruments at mtec

National Instruments’ Ian Bell gave a run down on their applications using their Labview product. “Instruction and research involving RF and wireless communications systems require a flexible platform for software design, hardware prototyping, and implementation. National Instruments RF tools deliver a high-performance platform for hands-on learning and pioneering research.”

Mark McCormick of Siemens, referred to  WirelessHart, accepted in March 2010 as an IEC standard (IEC 62591Ed. 1.0). Whether GSM/GPRS, IWLAN or WirelessHART, industrial wireless communication products have to be reliable, rugged and secured to meet hard conditions indoor and outdoor. Nowadays numerous industrial WLAN applications such as cranes and AGV are proving outstanding reliability even in safety applications.

Completing this series of talks Gary Wedge of Honeywell, who, while like the other speakers did not hide the advantages of his own company’s products, or choice of protocol emphasised also the necessity of the openess whatever platform is used. “This is not a conflict between Honeywell and Emerson as the media sometimes make out,” he said.

There are a number of points that the independent ARC Advisory group published on wireless which indicated ten or eleven requirements for industrial wireless applications. The most requested points were that the units must be “multifunctional” and also the ought to be “multiprotocol.” In other words users do not want to tied down to one supplier or one type of protocol. Most o the applications to date are for monitoring and measurement but there is a demand for control applications and indeed one of the points made out in the ARC report is a request that industrial wireless be “control ready!”

All in all it was an interesting show though whether it was worth a long journey to attend is debatable.

Advanced Manufacturing UK 2011 is scheduled to be held next year at the same venue on the sixth and seventh April 2011.


Non contact measurement in concrete plant

24/02/2010

Following a request from a manufacturer of concrete products,  Applied Measurements has developed a user-friendly, low-cost device to rapidly and accurately measure tension in pre-stressed wire and cable.

Applied Measurements Limited offers a comprehensive selection of transducers based on strain gauge technology.  Our product range includes sensors to measure load, pressure, torque and displacement.  In addition, a custom transducer design service and strain gauge bonding facilities are also available.

To support the transducer range, a variety of analogue and digital instrumentation is available including high resolution, high speed and RS232/485 equipped signal conditioners and indicators, as well as portable battery powered indicators with integral data-logging, enabling us to offer complete systems with calibration traceable to UKAS standards.

In addition to our comprehensive range of ‘standard’ transducers, we also have the capability to design, develop and manufacture custom devices to meet specific needs.  Our expertise is based on bonded strain gauge technology, which is carried across our complete line of transducers.  Our involvement in your project can be at any stage, from development and design, through prototypes, testing and into full production.

The Challenge:
To rapidly and accurately measure the tension within pre-stressed steel wire or cable using a repeatable process that will serve to increase the confidence of the end product.  To manufacturers of concrete products, the ability to make these measurements using a simple process that removes operator uncertainty from the measurement is paramount.  This was the challenge set to Applied Measurements, by Bison Concrete.

Bison is one of Britain’s leading producers of structural, pre-cast concrete products. Consistent, quality control is vital to maintain the company’s position at the forefront of the sector.  The company is particularly renowned for pre-stressed elements, including hollow-core floors, solid composite floors and beams.

This development was prompted by a customer asking for a non-contact method for determining the tension in reinforcing cables and bars for pre-stressed concrete beams.  Peter Lewis, the managing director of Applied Measurements investigated the dynamics of the measurement and discovered that a vibrating steel wire or bar would have on an externally applied transverse magnetic field.

After significant development the ‘Digiforce’ was born and the patented device has now been supplied to many other concrete manufacturers’ including RMC, Concrete, Tarmac, Spiroll Precast, Coltman Precast, Milbank in Britain, Burns in the USA and Impact in Australia – and other blue chip construction companies all who share the need to make rapid and accurate tension measurements on-site.

The Solution:
The equipment used for this tensioning process must be tested on a regular basis, but current methods are cumbersome and time-consuming and accuracy is in part dependent on the skill of the operator.  The Digiforce developed by Applied Measurements has enabled Bison to achieve rapid, repeatable, non-contact tension measurement using cutting-edge technology.

Integral to the durability and structural performance of these products is the correct tensioning of the pre-stressing steel tendons. There are approximately 30 tendons in the average 1200mm-wide hollow-core floor slab, which may be up to 160m in length.  By striking the wire or cable under tension and observing their fundamental natural frequency of vibration, it has proved possible to develop a battery powered hand held instrument capable of accurately determining the tensile forces applied to them.

Although simple in theory, the low frequencies – Hz to a few tens of Hz and complex sound spectra have up to now, prevented their accurate analysis on-site.  The Digiforce addresses this issue via the integral mathematical software, to process only those frequencies of interest that contributes to the measurement.  This means that the user no longer has to refer to look-up charts or return to the office to run complex calculations pertinent to that piece of equipment or installation.

Operation:
The instrument is first programmed with the length of the wire or cable whose tension is to be measured.  Also inputted is its weight per unit length. The magnetic sensor at the end of the instrument is then placed adjacent to the part to be measured. The measurement process is triggered and the part is struck lightly with the mallet supplied. After a few moments, the tension appears on the LCD display on the instrument.

Tensions in stainless steel or other non-ferromagnetic wires can be measured by attaching clips (also supplied) made of ferromagnetic materials, provided that their masses are insignificant compared to that of the cable to be measured.

The vibrations being analysed are complex and the fundamental frequencies that the method uses are in the range 3Hz to 70Hz and not the metallic note heard by the ear.  The tension is determined from the formula, T = 4 x length2 x Hz2 x weight per unit length.  Because of the very low frequencies, tuned circuit filter methods are not an option. Instead, the device makes an initial 20 measurements of each oscillation and discards these. The next five measurements from 10 oscillations are then used to establish a tolerance band to establish which measurements are reasonable to contribute to the calculation and which should be rejected as spurious. Subsequent measurements are then made and those that fall within the tolerance band are used to calculate the final measurement value.

Because the principal business of Applied Measurements is in designing and manufacturing precision load cells and force sensors, the measurements are traceable back to NPL calibration standards.

The Digiforce boasts an on-board data-logging facility for collecting results and an RS232 port / USB converter for later downloads to a host PC, driver software, aluminium striker, rugged carrying case and full instructions.  Additionally the device is supplied with a 3-year warranty.

Following the success of the Digiforce in pre-stressed concrete, other applications are now being realised.  One such success story is Stage Technologies in London, who use the product to monitor the loading on cables used to support various stage elements.