Screw compressor: restoring a critical rotor pair without original drawings
The task was not simply to measure two components. It was to reconstruct the coupled geometry, manufacturing requirements and inspection basis needed to reproduce a critical industrial screw pair.
Problem
The original production documentation and manufacturing technology were unavailable. The available inputs included physical components, overall assembly data and technical literature on screw machines.
Engineering work
More than 20 specialized Soviet engineering books, reference sources and methodologies were studied. Pavel Samuta reconstructed a 4/6 rotor pair with a transmission ratio of 1.5 and prepared two production drawings, D309.001 and D309.002.
Technical facts
The screw-section outside diameter is 309 mm and the working profile length is 513 mm. The two rotors have a combined mass of approximately 414 kg. The documentation specifies Steel 45 according to GOST 1050-88, a 315 mm blank diameter, HB 174-217 hardness, critical dimensional requirements in the 0.01-0.05 mm range, fits including k6, h7 and f7, and journal roughness down to Ra 1.25.
Result
The design-documentation package for the two rotors was prepared in 15 working days. The company received an engineering basis for local manufacturing, inspection and future reproduction without restarting the reconstruction from zero.
Economic scenario
The published economic model uses assumed downtime of RUB 350,000 per day and compares local manufacture with a longer OEM waiting scenario. The resulting figure of approximately RUB 57 million is a scenario estimate, not an independently audited realized saving.
The lost technology became a reproducible production asset again.