Edwards has been struggling with a tendon problem in his shoulder for a number of weeks which has recently deteriorated and the decision has now been made to put the ex-Shrewsbury gloveman under the knife.
Williams moves to the Shakers on a one-month deal, with no view to a permanent transfer. Carlisle also have a 24 hour recall clause on the Welshman incase of injury or supsension to regular Blues keeper Keiren Westwood.
The month not only gives Williams the chance of some first-team football but it also allows United's youth team goalie Adam Bradley to take the place of Williams between the sticks in the reserves and perform his substitute keeper role for the first-team.