We might need to use lot control to trace the plastic we use into our customer's final product. After we assign what part #'s we want to be under lot control I am a little confused as to what we do next. It seems like when a purchase order is created for a lot control part # it should then ask for the lot # this delivery will be under. Instead it asks for the lot # when the part # is delivered under the purchase order # and allows the receiver to create the lot #.  
 
If anyone uses lot control, please let me know your experience.
 
Thank you

We use lot control on many of our items. Most of the lot numbers are determined by our Vendors and are traceable to their internal manufacturing process through that lot number. If the Vendor does not include a lot number on the shipment to us, we assign a lot (something like the PO number and date received eg 17542-021011).  Once the lots have been identified, obviously they must be segregated in the stockroom and will be issued by lot number when issued. By doing this, even though the Vendor does not provide a lot number, if there is a problem you can go to the Vendor and identify the shipment demonstrating the problem.