just in case we already have existing suppliers, can we still initiate vendor evaluation for them? or we can only do the evaluation for new candidates/ suppliers?
Yes, of course you can do it for new and old (existing). Again: focus on
How do we ensure (as far as we can) that when we buy stuff, we get 'good stuff'?
If we can evaluate existing suppliers and they fail the evaluation, how are we suppose to handle it?
Think about it, talk to people what handle this, and if there isn't already an existing process in place, create one!
Usually you link supplier problems in to your Nonconformity/Corrective Action process - ie, if you received a delivery of 20 widgets, and 2 are faulty, do you just ignore it? Or if you see that of 20 deliveries from that supplier in the last 3 months, say, that 7 were late (and thus) delayed your delivery and 5 were unacceptable quality, what
do you do?
Say oh well, sh*&^t happens? Or do you
do something about it? Like going back to them & saying 'these 2 are no good, pls replace... and don't send me any more like that!'. Or 'we notice a pattern of lateness, please correct your own internal system to ensure that we get our deliveries on time'.
And if they do it again, what do you do then? Strike them off?
If it's a customer-nominated one, surely you'd be communicating this to your customer, explaining the impact, and seeking their permission to use a different supplier?
As always,
apply common sense.
And of course make sure you have some degree of records (paper trail) to show that you a/recognised the problem and b/did something about it and c/what you did was effective.