Automation equipment drawings design, material 45 steel, standard size 20, 15 thickness, buy material is to buy what kind of specification thick?

Look at the processing requirements, if the requirements are not high can directly buy 15mm thick steel plate. Thickness δ <30mm steel plate, nominal thickness by 0.5mm multiples of any size, thickness δ ≥ 30mm steel plate by 1mm multiples of any size, GB/T709-2006 inside the regulations. The market is generally dominated by steel plates in integer multiples of 1mm, and even numbers account for the vast majority.