Forgings process size design and process selection are carried out at the same time, therefore, the following points should be paid attention to when designing process size:
(1) Follow the law of constant volume, the size of the design process must conform to the key points of each process; After a process, the volume before the process is equal to the total volume after the process. The total volume refers to the sum of the volume of semi-finished products obtained by the process and the volume of material loss occurring in the process.
(2) Must be estimated in the process of deformation of the billet some changes, leaving enough shrinkage and insurance, to avoid the size of out of tolerance, such as punching will reduce the bad height, the height of the billet will increase when the reaming.
(3) The size of semi-finished products obtained from one process should enable the next process to proceed smoothly. For example, when first pulling long and then upsetting, you can't pull too long, otherwise upsetting will be destabilized and bent.
(4) When forming parts, it is necessary to ensure that each part has enough volume.

(5) When multi-fire forging, the possibility of intermediate heating of the middle fire should be considered, such as the size of the forging process, the middle fire, the semi-finished product can be placed in the furnace heating and so on.
(6) Must leave enough final forgings correction, in order to make the surface of the forgings smooth and appropriate length and size.
(7) For long shaft forgings required length direction size is very accurate, it must be estimated that the length size will be slightly extended when dressing.
The cutting head amount of shaft forgings should meet the requirements.