Firstly, the main specification of the machining center should be in line with the overall size of the workpiece. So choose small machining center for workpiece of small size, big machining center for big workpiece, that is to use the machine rationally; 

Secondly, the structure of the machine is depend on the machine size and the weight of the workpiece. So you should study the main specification and the capability of the machine;

 Thirdly, Choose the machine according to the precision requirements of the workpiece, this is also the rational use of the machine; 

Fourthly, the power, rigidity and working range should be in line with the quality of the procedure and cutting parameter. For example, in the rough machining work for a workblank, if the allowance is quite big, so the cutting allowance should also be big, and these require the machine should be with high power and good rigidity.

Fifthly, simple tool clamping structure and conveninent operation should also be considered. Vertical machining center or horizontal machining center, which will determine the clamping tools and frame of axes, and then in turn will also inflence the level of difficulty of programm editing and reliability of the CNC machining. In a word, you should take full advantage of CNC function, to optimize the function of the machine. And then based on the machine, design the best processing programm and production lines, adjust the procedure when needed.