A quote from "The Soviet economy and the Red Army, 1930-1945" by Walter S Dunn:
On June 24, 1941, the Council for Evacuation was appointed. On July 4, 1941, the Council ordered Voznesenskii, director of five-year planning, to organise the movement of industry and workers to the east. Local committees used the five-year plan structure with 3,000 agents controlling the movement. Evacuation of industrial plants began in August 1941 and continued until the end of the year. But evidence shows evacuation began much earlier, or at least the transfer of machine tools and skilled workers to "shadow factories" in the east. The US military attache reported significant transfers of machines and men from the Moscow area to the east in late 1940 and early 1941. The rapid growth in production in early 1942 suggested that the evacuation had started in 1940. The tempo increased in August 1941.
Evacuation began with a recommendation from a local agency to the commissariat of the appropriate industry. After investigation, the recommendation was approved by the Evacuation Council and placed on a schedule giving the date, method of transport, and relocation site. In addition, unapproved evacuations took place on the initiative of local authorities.
Evacuation was well under way in the first week of August 1941. Sacrificing immediate production, many factories closed in August, packed up, and moved to the Ural Mountains. But because their products were needed, some plants remained in production until too late to be moved. Only 17 of the 64 iron and steel plants in the Donbas were evacuated between October and December 1941. The Kharkov tank factory was being dismantled when the Germans arrived.
The railroad made evacuation possible. As the railroads moved 2.5 million men to the front in June, July and August, they moved industrial machinery on their return. For example, on 7 August 1941, 3,000 rail cars per day evacuated iron and steel manufacturing equipment from the Dnieper area - 1,000 cars per day for the electrical industry, 400 cars per day for the chemical industry, and others. From August 8 to August 15, 1941, 26,000 rail cars evacuated industries in the Ukraine. In Moscow, 80,000 cars transported 498 factories, including 75,000 lathes, leaving only 21,000. Production by many factories resumed by December.......The operation was not always orderly. Other indications that planning was not complete and that turnaround time was longer than average were anecdotes of equipment having been dumped beside the tracks to empty the cars for a return journey. Of the 700 plants evacuated in the first months, only 270 arrived at planned destinations fully equipped, and 110 arrived with only part of their equipment....At times, inadequate planning resulted in trains having been loaded with materials and despatched with no destination to prevent capture by the Germans. These orphan trains moved around the country for long periods because there were no plans to use the equipment and no one knew what to do with them.....The evacuation of the factories was an immense undertaking. In the last three months of 1941, GOSPLAN moved 1,360 factories: 455 to the Urals, 210 to Western Siberia, and 250 to Central Asia and Kazahkstan. By the end of 1941, 1,523 large factories were moved. A few went to the Far East. The total was only a small proportion of the 32,000 factories captured by the Germans, but arms-related factories, representing 12% of the industrial potential in the occupied zone, were evacuated.
The relocation of soviet factories 1941 - Axis History Forum