Adaptive CNC Milling Speed Control for Variable Material Hardness

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Solution Overview

Problem

CNC milling systems face challenges in efficiently processing non-uniform materials like stone, as they require careful control of track speed and tool rotation to avoid chipping, limiting production rates due to the need to set speeds based on the hardest material volume encountered.

Innovation Solution

A method and system that determine multiple indications of material hardness along a workpiece surface, programmatically controlling the cutting tool's speed and rotation rate to adjust accordingly, reducing speed and rotation where material is harder and increasing where it is softer than a nominal hardness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If track speed is reduced to avoid chipping harder material, then material damage is prevented, but production rate decreases

Engineering Contradiction:

Improvematerial integrityVSAvoidproduction rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts track speed and tool rotation rate based on real-time material hardness feedback. Instead of using a fixed conservative speed for the entire workpiece, the control system modifies parameters on-the-fly according to actual material conditions encountered during milling, allowing optimal speed for each local region.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system incorporates feedback mechanisms that monitor material hardness during the milling process. This feedback information is used by the control system to adjust track speed and rotation rate, creating a closed-loop control that prevents material damage while maximizing productivity through adaptive parameter modification.

Inventive Principle:

Principle #23Feedback

2Reliability

If tool rotation rate is reduced to accommodate hardest material, then chipping is avoided, but material removal efficiency decreases

Engineering Contradiction:

Improvecutting qualityVSAvoidmaterial removal rate

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts tool rotation rate based on real-time material hardness feedback. Instead of using a fixed conservative rotation rate for the entire workpiece, the control system modifies rotation speed on-the-fly according to actual material conditions encountered during milling, allowing optimal rotation for each local region.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system incorporates feedback mechanisms that monitor material hardness during the milling process. This feedback information is used by the control system to adjust rotation rate, creating a closed-loop control that prevents material damage while maximizing productivity through adaptive parameter modification.

Inventive Principle:

Principle #23Feedback

3Reliability

If track speed is set to minimum for hardest material volume, then uniform material processing is safe, but speed cannot be increased for softer regions

Engineering Contradiction:

Improveprocessing safetyVSAvoidtrack speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The system applies different track speeds to different regions of the workpiece based on local material hardness characteristics. Softer regions receive higher track speeds while harder regions receive lower speeds, optimizing both safety and efficiency for each local area rather than using a uniform conservative speed throughout.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts track speed based on real-time material hardness feedback. Instead of using a fixed conservative speed for the entire workpiece, the control system modifies parameters on-the-fly according to actual material conditions encountered during milling, allowing optimal speed for each local region.

Inventive Principle:

Principle #15Dynamics

4Reliability

If tool rotation rate is reduced for hardest material volume, then tool damage is prevented, but rotation rate cannot be optimized for softer material

Engineering Contradiction:

Improvetool protectionVSAvoidrotation rate

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The system applies different rotation rates to different regions of the workpiece based on local material hardness characteristics. Softer regions receive higher rotation rates while harder regions receive lower rotation rates, optimizing both tool protection and material removal efficiency for each local area rather than using a uniform conservative rotation rate throughout.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11980986B1Material hardness compensation in an automated milling system

Publication Date: 2024.05.14 MURUGANANTHAM RATHAN P

AI summary

A method and system for milling or engraving a workpiece provides improved throughput by varying one or both of a track speed or a rotational rate of a rotary cutting tool as the cutting tool cuts along a track. Multiple indications of material hardness are determined at a surface of the workpiece, movement of the cutting tool along a tool track is programmatically controlled to remove material from the workpiece, and one or both of a rotational rate of the tool or a track speed of the tool is adjusted along the tool track in conformity with the indications of material hardness, so that the rotational rate of the tool and/or the track speed is reduced at locations with harder material and increased at locations with softer material along the tool track.