Russian to English Tech/Engineering Metallurgy / Casting

Of four more abbreviations in this list of duties of metal workers, I think I know twо, but can't find this and one other, which I've posted as a separate question

This is from the duties of the head of shift.

Координирует в смене работу всех участков ЦТМ, ЦПиО, ЦОМ, ЦПМ-1 и ЦПМ-2 при возникновении противоречий или несогласованности с целью выполнения производственного графика прокатки холодного листа и отгрузки готовой продукции

ЦТМ - цех травления металла

ЦПиО - цех прокатки и отжига

ЦПМ - See prеvious question.

So I think Ц is цех and М is металла, but what is O? I thought it might be обработки, but couldn't prove it.