Critical situation

As industry and R&D sectors demand ever-higher accuracy, so measurement and inspection
equipment developers strive to meet the challenge. Matthew Peach reports.

Measuring and inspection technologies have undergone steady development throughout the history of engineering.

Traditional physical inspection techniques, which initially performed at the micrometer level, have been joined in recent years by sophisticated optical methods, such as scanning tunnelling microscopy, to assess developments in semiconductors, pharmaceuticals and in the booming nanotechnology sector.

Banner Engineering of Minneapolis has some of the most advanced manufacturing capabilities in the measurement, sensing and safety sectors. The company produces more than 15,000 different products at its six automated manufacturing facilities worldwide. The company typically employs surface mounting systems and rapid pick-and-place methods on its device boards at up to 30,000 components an hour.

Head of engineering, Dr Neal Schumacher, said: ‘Our customers are demanding ever higher accuracy over a wider range of environmental operating conditions. A typical request, for example, is for greater device stability over a wider temperature range.

‘The market is also pushing for lowercost solutions that still provide the best performance. Lasers and ultrasonic technologies are good examples of the trend for the hi-tech solution that will quickly become standard technology.’

Typical of the company’s range of systems is its chemically-resistant U-Gage ultrasonic sensor, which is protected by a Teflon flange and filmcoating bonded over the transducer. This seals it against gases that would quickly destroy standard models. The sensor, which has a sensing range between 200mm and 8m is designed for level control applications in corrosive or caustic environments.

A combination of the proliferation of standards that impact on manufacturing, customer demands for 99.999 per cent accuracy, reliability of finished products and producers’ own internal productions and safety standards mean that across industry, measurement and inspection technologies are a strong growth area.

This is particularly significant in pharmaceuticals, biotech and genetics R&D and production, where the slightest misalignment or contamination renders all work and investment invalid.

German co-ordinate measuring machine (CMM) manufacturing group Wenzel-CMM, of Wiesthal, near Frankfurt, is also addressing the  demands for higher accuracy. Andy Woodward, managing director of Wenzel UK, in Bristol, said: ‘As the market — especially in countries such as the UK — is specialising in high-end R&D and manufacturing, demands for higher accuracy CMMs, such as our new Mythos measuring system, are on the increase.’

Mythos was launched at last month’s EMO 2005 machine tool show in Hanover. It employs continuous scanning probes and works with high accuracy. Although the Mythos is relatively new, Wenzel already has installations at Gibbs Gears, Frenco International and Hewland Engineering, which represent a new market diversification for the group into gear testing.

Woodward said there is another key trend in this market: ‘There is a growing need for measurement on the shop floor — close to the action as opposed to offline in the laboratory.

This means more demand for quick and tough measurement solutions that can operate in big temperature ranges in harsh factory conditions.’ Wenzel has responded to this need with another measurement product development, the SmartCMM system.

Engineers are on a mission to develop more sophisticated metrology devices that are both rugged and economical. For the hardware this often means extensive use of insert-protected electronics or external overmoulding to allow these small products to cope better with challenging environmental conditions.

The combination of device sophistication, economy and resistance to harsh conditions means that producers are focusing closely on their own components, production techniques and tolerances.

Schumacher said: ‘Producing low-cost, high performance laser-based and ultrasonic sensors requires careful integration of all components, housings, and electronics. And when designing a new product, we have to integrate all facets of engineering disciplines. A good example of this is in the new QS18 range: the Diffuse Laser; Laser Adjustable Field and the Ultrasonic Sensor.’

He said other product trends he observes in this wide marketplace include the expansion of sensors with discrete outputs and those with both analogue and digital outputs. Such devices are allowing for cost-effective means to use temperature as a control parameter in areas where the operator does not know the absolute temperature of an object.

Schumacher believes that vision products are also becoming a key need for many customers, as they increasingly need to make ‘full field’ evaluations in complex assemblies. ‘Banner’s Presence Plus Pro, GEO, and Edge are intended to satisfy this demand,’ he said .

‘We have also found that most customers need complementary products, such as ultrasonic sensors, lasers, temperatures or vision systems. For others again, measuring light curtains may be needed. There is often a great deal of overlap in these technologies’ potential to solve a given application problem.’

One of the biggest names in the sector is Japan’s Mitutoyo, based in Kanagawa. It recently won a contract with NAVSEA (the US Navy’s Systems Command) to replace an old CMM to improve its metrology R&D department.

NAVSEA engineers, builds and supports the US fleet and its combat systems, accounting for nearly one-fifth of the navy’s budget — around $20bn. The department manages more than 130 acquisition programmes, representing customers such as almost all US defence and civilian government departments,NASA and the National Institute of Standards and Technology (NIST).

After market tests of machine accuracy, NAVSEA opted for Mitutoyo’s Legex 12128; the company says the Legex accuracy ISO-10360-2 specification (0.6+1.5L/1000 µm) was the deciding factor.

Another key player in the field is Carl Zeiss. In 1973 the company developed the first numericallycontrolled 3D co-ordinate measuring machine, UMM 500. With this system it was possible to measure with accuracy of 0.5µm in 3D, which was big news in the early 1970s.

Carl Zeiss has diversified and expanded since then, but is still at the forefront of metrology and inspection. Aubrey Lambert is head of instrument marketing at CZ’s microscopy division, which deals with some of the newest markets for inspection, the biotechnology and pharmaceutical sectors.

A key technology in this sector is the automated microscope, where precise and repeatable movements and functions are critical. ‘In the biopharma sector one must be able to measure activity on a single cell scale, and research projects usually require multiple repeats necessitating predictable movements,’ said Lambert.

While the optical side of the equipment is already relatively developed, the R&D action here is in motorised support stands and translation stages that move the subject rather than the scope. Thus Carl Zeiss has been releasing new generations of motorised microscopes — such as its Activa 200 MOT and the latest model, the Axio Imager, which features a built-in computer to control its movements.

Relatively new technologies for internal inspection of materials and finished manufactured devices include various established X-ray techniques, but another technology that is taking off, especially in the vehicle engine development area, uses a combination of acoustic and optical technologies.

Renault is known to be experimenting with ultrasound excited thermography (UET), in which acoustic waves heat up, say, an engine block before an infrared sensor detects changes in the consequent thermal emissions to determine if the inside of the block has been correctly finished.

So whatever your field, and whatever the product, you will need to measure and inspect. It is a massive field of engineering — but a critical one.