Moygr1
I have been supporting the cost traget developments for large welded & machined steel frames or structures. Typically we start with a bottoms up approach since there exists a sound production intent design. If there were no design, we would probably use an analysis of a competitors face-of product or design.
The bottoms up cost development process is to simply develop a cost for labor and materials specific to each component in the bill of materials or BOM. then add additional labor and materials to complete the frame or structure, such as welding, finishing, assembly, inspection etc. Then roll it all together to come up with the starting cost or direct material cost. This is not what we recommend as the selling price to another department but only it's starting cost. To be added are things like depreciation and corporrate allocations. etc. That is sepcific to the company your are working at. That becomes the transfer price your might be after
For processing or manufacturings element costs, lately I have seen machining costs of around $50 to $100 per hour depending on many things. One of the largest influences is the current work load in some of the CNC machining job shops. Its has been low so there are very low fire sale costs per hour. Besides this, typically I would use close to $100/hour for large CNC non-depreciated assets. Your should locate a machine hour rate model or develope one yourself. There are a lot of references on the libraries. The elements in the model with the largest impact on the final horly rate usually will be the cost of the machine tool 1st, if its not depreciated already, floor space per square foot, energy and direct labor.
Good Luck