WHICH IS THE BETTER SOLUTION TO PROVIDEHIGHLYACCURATEINTERMITTENT TRANSFER-MOTIONS: A MECHANICAL CAM OR AN ELECTRONIC SERVO? NIGEL TAYLOR OF PRECISION MOTION (COFIL) ARGUES THAT, IF YOUR REQUIREMENTS CAN BE SATISFIED, THERE ARE SOME BIG ADVANTAGES IN FAVOUR OF A CAM DRIVEN SYSTEM. In these times of versatile digital control of motors, there is a danger of automatically assuming that a servomotor system must be the best solution for all motion control applications, This assumption is not true, There are a whole host of positioning applications where the servomotor is far from the best solution, certainly not the most reliable, and not even the lowest cost, Why settle, then, for a second class solution when, for a significant proportion of intermittent motion applications which include positioning, is available for lower cost? The question to ask is whether the transfer motion output stroke has to be exactly repetitive each cycle, If the answer is no, then some sort of feedback/control system is going to be required, and that is going to point you towards an electronic solution, But if the answer is yes, then a mechanical cam may well be a far better solution, Compared with a typical servomotor system for the same task, a cam device will provide inherently less jerk and shock, usually higher positional accuracy, and will offer the possibility of higher speeds, It will be automatically locked in station position without any brake, will deliver zero backlash in the system, will offer much higher repeatability, and will cost less to buy and to run.
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