Cost-effective encoders satisfy demanding roles

Citation

(2003), "Cost-effective encoders satisfy demanding roles", Anti-Corrosion Methods and Materials, Vol. 50 No. 6. https://doi.org/10.1108/acmm.2003.12850fab.001

Cost-effective encoders satisfy demanding roles

Cost-effective encoders satisfy demanding roles

Keywords: Encoders, Optics, Microtechnology

Cost-effective customised optical encoders for virtually any measurement, control or positioning system are being manufactured to the highest levels of accuracy and performance by micro-engineering metal part specialist, Tecan.

Various in-house manufacturing techniques are employed by the company, to produce the most appropriate encoder for a given requirement. Photo-chemical machining (PCM), for example, will produce excellent results for a wide range of applications, typically with accuracies of ±10 per cent the thickness of the metal used – from 1.5 down to 0.01 mm. In cases requiring even greater accuracy, electroforming manufacturing techniques are utilised, a typical tolerance here being ±8 microns, in some cases ultra-high tolerances of ±2 microns or less can be achieved. Single-thickness and bi-level discs can also be produced readily, to suit varying optical and mechanical performance needs.

A recently cited by-level encoder case study looks at Banbury, Oxfordshire-based, TymeSync Controls Limited, a company which designs and manufactures highly specialised torque transducer systems. Liaising with Tecan engineers the company realised that a demanding encoder requirement, for a torque transducer in a sophisticated aerospace project, could be cost-effectively satisfied, while ensuring optimum opto-mechanical performance.

Two side-by-side encoder discs are used in the torque transducer application which is part of a development and analysis system used to measure torque in aircraft flap actuators and other applications where torque measurement is required. Critical elements in the design and production of the encoder disc were the need to maintain mechanical strength under varying torque, speed and temperature conditions while ensuring fine optical resolution through high-accuracy apertures. The result is a single rigid electroformed part, with localised thickness variations to suit both optical and mechanical requirements. As opposed to traditional photo film techniques, Tecan employed specialised high-resolution chrome-on-glass tooling to achieve optical aperture tolerances of ±1.6 micron.

Encoder specifiers require cost-effective accuracy, says Tecan, which is increasingly winning business from traditional manufacturers due to its fast response capability and high-accuracy manufacturing techniques. In addition to higher resolution optical bars and slots, the inside diameter accuracy of the prop shaft hole can be significantly improved. The company offers a bespoke service for the supply of burr- and stress-free discs and similar components – including simple or complex designs for low, medium or high-volume requirements.

Subject to acceptance, a bespoke rapid prototype service guarantees despatch of first samples within five working days. In addition to rapid delivery of the first low-volume parts, the service has other benefits. For example, once a part is adopted, down-the-line production speeds and costs are reduced because the tooling is already in place. Modifications can be cost-effectively incorporated within the company's powerful CAD system, ensuring that any "knock-on" tooling costs are also minimised.