Metal and casting
The blank cost depends on the material grade, part weight and batch size. СЧ20 and ВЧ50 cast iron, steel 20 and 09Г2С differ in melt price and cooling practice, so the same pattern with a different grade yields a different unit cost. Mill certificate requirements are priced in as well: chemical composition and mechanical property checks are part of the batch cost. Larger batches reduce the share of tooling and set-up overhead.
Machining
Machining of mating dimensions, holes and sealing face is the second cost component. The sealing face type (raised face, recess or connecting face) affects the number of machining set-ups. Drawing complexity directly drives labour time: non-standard hole diameters, special chamfers and extra drilling add machine hours.
Documents and packing
Batch reports, certificates, marking and export packing are part of the FOB calculation. Marking each item speeds up receiving at the buyer's warehouse and helps installation crews. Flange face protection matters most for mixed loading: separators and wrapping add to packing cost but reduce transport damage risk.
Inland logistics to port
Delivery to Qinhuangdao and Tianjin is calculated by cargo volume and weight, and by the container loading plan. One mixed container is usually cheaper than several small consignments. The port delivery date is agreed in advance: transport booking and the shipping window depend on the batch ready date.