In spooling or level-wind applications, material such as cable or flat roll-stock is wound onto a spool. It’s critical to maintain the proper relationship between the speed of the take up spool and the supply spool, since the material on both reels changes diameter as it is winding. Also, most operations require monitoring of the length of material. Finally, in many instances it is necessary to maintain the proper tension on the material to avoid stretching, breaking or winding too tightly or loosely. Rotary encoders can supply the necessary feedback for all these functions.
Mechanically, shaft, thru-bore or measuring wheel encoders can be applied, depending on what design is most readily integrated into the system. The encoders may be applied to drive motors, the reel shaft, pinch rollers or tension rollers. EPC's Model TR1 TruTracTM, an integrated encoder measuring-wheel pivot-arm assembly, is well suited for spooling or level-wind applications.
Electrically, variables such as resolution, output type, channels, voltage, etc., should all be specified to meet the individual application requirements. In the vast majority of installations, incremental encoders are most suitable. With uni-directional travel, a single-channel encoder is adequate; however, quadrature output is recommended in order to avoid edge jitter during stoppage.
Environmentally, proximity of the encoder to potential exposure to liquids, fine particulates and extreme temperatures will dictate specification. In applications with washdown requirements, an IP66 or IP67 seal can offer protection against moisture ingress. However, consider a stainless steel or polymer composite housing to mitigate the effects of harsh cleaning chemicals and solvents.