We produce a product that requires a 1.5 or 2.5 hour curing time after it has been through one work centre before it can be used in the next stage of the process.  Now Odoo makes the product ready to be used before it is cured.  How can I add a time for each product that does not have any cost associated with it?  I tried setting up a new work centre called curing, but that required the operator to start and stop a new Work Order for the curing.  I want this to happen automatically as soon as the previous step is completed.