Many existing models of granule coalescence assume that the two granules have successfully coalesced provided that they stick during their initial impact. However, although non-rebound is a necessary condition for coalescence, it is not sufficient. It is also required that the bond formed between the two granules be strong enough to resist being broken by subsequent impacts within the granulator. A theoretical framework is proposed in which both the rate of bond strengthening and the distribution of impact separation forces are included in order to calculate the probability that the collided dumbbell will survive and hence permanently coalesce. This work highlights the need for further research into the mechanisms and the rate at which a granule dumbbell becomes moulded into a single larger granule: and also the distribution of impact forces inside a granulator.