How Early Numerical Control Systems Automated Industrial Milling Machines
A 1952 invention by John Parsons that used punched cards to automatically guide machine tools, effectively launching the era of computer-aided manufacturing.
Original patent title: “Motor controlled apparatus for positioning machine tool”
A 1952 invention by John Parsons that used punched cards to automatically guide machine tools, effectively launching the era of computer-aided manufacturing. Granted to Parsons Corp in 1958 with 44 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
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.
The gap
What does this patent NOT cover?
- 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
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The invention moved the intelligence of the machining process from the operator's hands into a set of instructions, decoupling the design of the part from the physical skill of the machinist.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Modern CNC milling machines
Automated industrial lathes
Early aircraft wing component manufacturing
Why it matters
The bigger picture
This patent is considered the foundation of modern CNC (Computer Numerical Control) machining. It enabled the aerospace and automotive industries to manufacture high-precision, complex components at scale. It fundamentally shifted manufacturing from human-guided craft to automated, data-driven production.
Filed
May 5, 1952
Granted
January 14, 1958
Market context
Who's building on this
Companies in this space
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.
Market impact
This patent triggered a massive shift in global manufacturing, enabling the mass production of complex aerospace parts. It created the entire CNC industry, which is now a multi-billion dollar sector essential to almost every aspect of modern hardware production.
Claim 1 — Plain English
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.
The clever bit
The invention moved the intelligence of the machining process from the operator's hands into a set of instructions, decoupling the design of the part from the physical skill of the machinist.
What it does not cover
- 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
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Early stage
Citation count
33/40
Moderately cited
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$16K – $52K
Midpoint $32K · expired or expiring · industry ×1.5
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Concepts involved
Citations
Patent lineage
Cite this patent
Parsons, J. T., & Stulen, F. L. (1958). How Early Numerical Control Systems Automated Industrial Milling Machines (U.S. Patent No. 2,820,187). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/2820187/numerical-control-machine-tool-parsons
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Early Numerical Control Systems Automated Industrial Milling Machines cover?
A 1952 invention by John Parsons that used punched cards to automatically guide machine tools, effectively launching the era of computer-aided manufacturing.
Who owns patent US 2820187?
Parsons Corp owns this patent, granted in 1958.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 2820187 cited by?
This patent has been cited by 44 later patents that build on its ideas.
What problem does this patent solve?
This patent is considered the foundation of modern CNC (Computer Numerical Control) machining. It enabled the aerospace and automotive industries to manufacture high-precision, complex components at scale. It fundamentally shifted manufacturing from human-guided craft to automated, data-driven production.
What does this patent NOT cover?
Does not cover software-based CAD/CAM systems that design the parts themselves
Patent monitoring