ARNITEL® TPE-E DAMPENS NOISE, VIBRATION IN DELICATE CONSUMER PRODUCTS

Arnitel® thermoplastic copolyester elastomers (TPE-Es or COPE) from DSM Engineering Plastics, well known for applications that exploit its heat resistance, flexibility and strength in automotive and other demanding applications, has another side: noise management.

With the strength and ability to resist environmental attack to serve as heavy rail sound deadening between track and ties, Arnitel has also found use in comparatively miniaturized and delicate consumer products as well. Applications include tiny gears for camera autofocusing mechanism and a disk-player ejector system.

Arnitel is a family of TPE-Es manufactured and marketed by DSM. These copolyesters combine the strength and processing characteristics of engineering plastics with the performance of thermoset elastomers, providing benefits in processing and productivity. As thermoplastics, they do not require vulcanization to obtain their optimal properties, which often leads to substantial reductions in part cost. Relative to other elastomers, polyester-based materials offer the most consistent performance over their entire operating temperature range, as their properties vary little from low to high temperatures. Arnitel grades are used for automotive CV-joint boots, airbag covers, wire & cable connectors and insulation, seals, gears and even (in film grades) medical drape, house-wrap and roofing membrane.

Kyocera T-Zoom 35mm camera

Kyocera, a leader in high-end cameras, optical imaging devices, and electronic components, uses Arnitel in its T-Zoom 35mm film camera’s autofocusing mechanism. While television news and motion pictures have given a certain cachet to the whir and click of motor-drive film transport, noisy autofocusing soon becomes an irritant. If heard, the continuous operation of the mechanism would significantly reduce the camera’s appeal.

The T-Zoom incorporates a high-precision five-point passive autofocus system, ensuring accurate focus from 50 cm (20 in.) to infinity, with 240 autofocus steps in telephoto mode. Measuring distances in five separate areas, the camera focuses the subject when it is positioned off-center, typically when photographing a person. It is also switchable to a spot autofocus useful for focusing on a specific position.

In the autofocus system, a subminiature motor provides torque to turn the lens barrel for focusing, via a speed-reducing set of seven gears, two of which are noise-reducing Arnitel, one of PL406 and one of EL740. The Arnitel low-noise gears develop a noise level inaudible during operation—far lower than other materials tested. In addition, Arnitel easily accommodates the camera’s temperature range, sub-zero to that of a hot car in summer, 49C (120F) or more.

Beyond its performance benefits, Arnitel provided the lowest system cost. Fast production cycle time, low reject rate, excellent surface finish and absence of flash made it the lowest-cost option versus other thermoplastic elastomers tested for the application.