Is SINOMACH a central enterprise?

It is a central enterprise.

According to (Aiqicha), SINOMACH is a subsidiary of China Machinery Industry Group Co., Ltd., and China Machinery Industry Group Co., Ltd. (SINOMACH) is an important state-owned backbone enterprise directly managed by the central government. It originated from the First Ministry of Machinery Industry and evolved from more than 70 research and design institutes, equipment manufacturing and industry and trade enterprises of the former Ministry of Machinery Industry.