You can freely build on How Early Numerical Control Systems Automated Industrial Milling Machines
This patent expired in 1975. Every claim — 0 independent, 0 dependent — is now unenforceable. Anyone can use, reproduce, manufacture, sell, or offer for sale this technology without a license.
Original assignee
Parsons Corp
Patent granted
1958
Expired
1975
Forward citations
44
What this patent covers
The system uses a motor-driven apparatus to control the position of a machine tool based on pre-recorded data. By reading instructions from a medium like punched cards, the system translates numerical coordinates into physical movements of the machine's cutting head. This allows for the precise, automated shaping of complex parts that would be difficult or impossible to produce manually. It essentially replaces the human operator's manual adjustments with a repeatable, machine-readable control loop.
What is now free to use
All 0 claims of US 2820187 are in the public domain. Specifically:
The 0 dependent claims add narrowing limitations and are also free.
What is NOT covered
Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.
Does not cover software-based CAD/CAM systems that design the parts themselves
Does not cover modern CNC systems that use real-time sensor feedback for error correction
Does not cover machines that operate without a motor-driven positioning mechanism
Does not cover manual machine tools where the operator directly guides the cutting path
Who is building on this today
Major industrial automation firms like Fanuc, Siemens, and Haas Automation continue to evolve the principles of numerical control established here. These companies have transitioned the technology from mechanical punched cards to sophisticated digital control systems.
Products built on expired version of this technology
Modern CNC milling machines
Automated industrial lathes
Early aircraft wing component manufacturing
How to cite this patent in your documentation
Parsons Corp. US Patent 2820187. Motor controlled apparatus for positioning machine tool. Granted 1958, expired 1975. Now in the public domain.
Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.
PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.