Rollers are the defining component of all web machines. If you buy a roller bigger than necessary, you cost your company money. If you buy a roller smaller than needed, you really cost your company money. It is, in short, a defective design that risks waste, delay, and customer complaint. An entire book has been written on getting roller details right. Here we start with the most basic. Width and diameter. Yet, even with these most basic sizing parameters it is not unusual to get it wrong. If you do, your company will pay for the error at least once (purchase price) if not for the life of the machine (under sizing etc). The link below will help you know whether the designer got it right.
Web201.50c YouTube clip link: https://www.youtube.com/watch?v=zM-kkrUBif4