You have a requirement to find out if the factory violates Chinese labor rights. It is obvious that factory management will not willingly disclose the information to you. You need to find out yourself or with the help of an interpreter that can directly ask questions of the workers.
Some of the workers may appear very young to you but there may not be anything wrong. If you suspect they are too young just have your interpreter ask them their age. Surprisingly most workers usually do not lie. They will tell you that they are only 15 years old, which is below the PRC minimum working age of 16.
Other things that you or the interpreter should ask the workers is how much overtime they have to work and whether they are being paid for it.
A less known requirement is that the factory usually has to pay or reimburse workers the cost of their journey home during the Chinese New Year Holidays. This is an expense many factories attempt to avoid.
Of course, the length of your visit is limited so you will not be able to go into detail about labor rights. But a few questions will give you insight about management’s attitude towards the workers.
A personal reason you are concerned about workers rights is because dissatisfied workers can cause havoc for a factory when they leave for better paying jobs. It takes time and money for management to train new workers and get them up to speed so they perform satisfactorily.