New low-cost draw-wire sensor is ideal for OEMs and machine builders

Industrial Robot

ISSN: 0143-991x

Article publication date: 7 March 2008



(2008), "New low-cost draw-wire sensor is ideal for OEMs and machine builders", Industrial Robot, Vol. 35 No. 2.



Emerald Group Publishing Limited

Copyright © 2008, Emerald Group Publishing Limited

New low-cost draw-wire sensor is ideal for OEMs and machine builders

New low-cost draw-wire sensor is ideal for OEMs and machine builders

Sensor manufacturer Micro-Epsilon UK has just launched a new range of OEM draw-wire sensors that offer an unbeatable price-performance ratio, with a measuring range of 2,100mm at a selling price of less than £130. The sensor does not compromise on accuracy either, with a resolution of 0.5mm on the standard unit.

Compact, reliable and cost effective, Micro-Epsilon's MK77 draw-wire sensors (Figure 4) are ideal for integrating into products or measurement equipment produced in high volumes. The MK77 is an extension to the company's existing, well-proven MK Series, developed specifically for high-volume OEM applications. Although the MK77 benefits from using standard sensor technology, it can also be easily customised to suit the individual application. Potentiometric or incremental encoder outputs are available.

Figure 4 The Mk77 draw-wire sensors from Micro-Epsilon UK

One of the distinctive features of the MK77 is that the housing is now engineered plastic (rather than metal), resulting in a more compact, lightweight solution for the customer, enabling OEM production costs to be minimised. Machine builders and designers will benefit from a lower cost and a more compact sensor design that will open up new possibilities in machine design and cost optimisation. This also means that OEM customers can now select whether they require a metal-bodied draw-wire sensor for use in harsh operating environments, or a significantly lower cost plastic-bodied sensor that does not compromise on performance.

By using unique manufacturing methods, Micro-Epsilon has kept manufacturing costs of the MK77 to a minimum. The sensor drum, holder and complete housing are moulded in one piece, which means there is no separate shaft or additional bearings.

The principle of a draw-wire displacement sensor is relatively straightforward, hence its inherent reliability. The sensor works rather like a tape measure, except with a draw-wire sensor; the user does not have to read off the measurement of the extended tape. The rotation of the drum on which the steel wire is wound is measured automatically. The drum itself incorporates a long-life spring drive, which ensures the steel wire is rewound.

Although the MK77 was officially launched in June 2007, the sensor was originally developed for a specific customer in the fast food industry. A US-based fast food restaurant chain is now using the MK77 sensor on its oil frying tanks (for French fries) to measure the level of oil in the fresh oil storage tank. Current order requirements total more than 4,000 sensors per year for this customer.

Thomas Birchinger, Product Manager draw-wire and inductive sensors at Micro-Epsilon comments: “The customer originally had to change the oil manually when the tank (200cm£80cm) was empty. This hot oil was considered unsafe for manual handling and so a safer, more reliable solution was sought. The machine builder of the oil frying system and storage tanks chose to use the MK77 to measure the oil level in the fresh oil feeder tank.”

The frying system consists of two tanks, with fresh cooking oil being pumped slowly but continuously from the fresh oil tank to the frying equipment. “The crucial factor in working with Micro-Epsilon was the MK77's excellent price-performance ratio and its inherent reliability” adds Birchinger.

The MK77 is the latest addition to Micro-Epsilon's plastic-bodied range of draw-wire sensors, which already includes the MK30 and MK46 sensors.

Micro-Epsilon's range of draw-wire sensors is already being used in a diverse range of applications. In the medical industry, for example, where sensor requirements typically include long life, low-protection class, high precision and constant temperature, Micro-Epsilon's draw- wire sensors are being used on dentist chairs, hospital beds, rehabilitation equipment, ambulance stretchers and X-ray systems.

In the aerospace sector, applications include landing gear test systems; measuring simulator position; and testing of wing structures. In the automotive industry, the sensors are being used to measure engine vibration, pedal position and suspension, as well as crash testing.

Lifting technology is another area where draw-wire sensors can be used. Applications include theatre stages; vehicle lifting platforms; lifting systems on garbage trucks; mobile hydraulic lifting platforms; and telescopic materials handling equipment.

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