All rolls have some degree of waviness on the surface due to barring, chatter, or just standard grinding. The question is how much waviness is allowed in a particular application. FMT Equipment has developed a measuring instrument with accurate electronics and recording system in order to measure the amplitude and wave length of the waviness of a roll surface. Now there are means to check and record waviness reliably and get data for analysis, and a base to set tolerances.
The waviness measuring instrument consists of a measuring head assembly, photo-electronic gage head, encoder, recording hand-held computer or wiring directly to a PC system, and a computer system with the RollTrack® software.
The following is a sample measurement report graph of barring of a super-calender roll with 4" (100 mm) wave length and .000050" (0,0013 mm) amplitude.
Picture 1. Typical Barring.
Picture 2. FMT RollTrack® Waviness Measuring Head Assembly.