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Adaptive Machining – Dimensional Metrology’s Critical Role

In today’s precision manufacturing landscape, achieving optimal CNC machining outcomes is not just about cutting metal; it’s about orchestrating a symphony of variables to create parts with the required accuracy. One of the key players in this machining symphony is dimensional metrology. In this article, we delve into how dimensional metrology contributes to adaptive control of machining processes.

Understanding Adaptive Control

Adaptive control refers to the dynamic adjustment of machine parameters during the machining process. Unlike traditional fixed parameters, adaptive control responds to real-time data, making adjustments based on changing conditions. It’s like having an intelligent assistant that fine-tunes the machine’s behaviour as it encounters variations in material properties, tool wear, or environmental factors.

The control implies decision making based on a data and feedback to control how this data is affected. In this case, data is the dimensional measurement or metrology data gathered on the machine. Decision making is analysing this data per the design specifications and relating to the contributing machining factors. Feedback is the automatic updating of these factors to adapt the process to finally finish a part in acceptable dimensional criteria despite all the factors affecting this process.

The Role of Dimensional Metrology

Pre-Machining Setup

Before the first chip flies, dimensional metrology steps onto the stage. Here’s how it plays its part:

Machine Calibration: Dimensional metrology ensures that the machine tool is calibrated accurately, and this calibration is maintained during the operation via easy and automatic checks. Any deviations are detected and corrected, setting the stage for precise machining.

Work and Tool Offsets: By measuring workpiece dimensions and tool geometries, metrology provides critical information for setting up specific work and tool offsets. These offsets compensate for variations and ensure that the machining process starts from an optimal position.

In-Process Adaptive Manufacturing

As the CNC machine runs through its cycle, dimensional metrology continues its performance:

Real-Time Feedback: On-machine probing or 3D scanning captures data during the machining process. This real-time feedback allows the system to adapt on the fly. If the part shifts due to thermal effects or fixturing errors, the machine adjusts its path accordingly.

Tool Wear Compensation: Metrology detects tool wear early. Adaptive control responds by adjusting feed rates or tool paths, extending tool life and maintaining consistent quality.

Part Offsets: Variations in part dimensions are inevitable. Metrology identifies these deviations, and the machine adapts by modifying its program at cycle end or mid-cut resulting in precise parts, every time.

Cutting program is created based on a perfect part model creating a cutting tool to model relationship. Part offsets as well as part deflections would change this relationship. Differences are detected and intended tool orientation to part surface can be maintained.

Post-Process Quality Reports

When the part is completed machining, metrology software transitions its role from measuring to reporting:

Detailed Quality Reports: Metrology software generates comprehensive reports with optional statistical process control (SPC) analysis. These reports validate the final product’s dimensions, ensuring compliance with specifications.

Trend Analysis: By analysing historical data, metrology software identifies trends. Are deviations increasing over time? Is a particular tool consistently underperforming? Adaptive control uses these insights to fine-tune future processes.

Real-World Application

Metrology software developer Applied Automation Technologies (AAT3D) announced a significant enterprise software contract with a leading North American aerospace manufacturer for adaptive machining. Their CAPPSNC CAD-based online and offline dimensional measurement software integrates directly with CNC machine controllers. Here’s how it works:

On-Machine Metrology: CAPPSNC provides real-time metrology data during machining. It acts as a virtual coordinate measuring machine (CMM), offering adaptive work offsets and tool offsets.

Closed-Loop Manufacturing: AAT’s system links over 80 different CNC machines across multiple manufacturing facilities. CAPPSNC ensures closed-loop manufacturing by continuously adjusting machining parameters based on dimensional metrology feedback.

Factory 4.0 Smart Manufacturing: By leveraging metrology information throughout the process, CAPPSNC exemplifies Factory 4.0 principles whereby it’s not just about making parts – it’s about making them right.

Ray Karadayi, Applied Automation Technologies (AAT3D) President and CEO emphasizes. “CAPPSNC software is truly Factory 4.0 smart manufacturing technology because it is using metrology information throughout the manufacturing process for adaptive control.”

“The software provides easy & precise part set up and machine axis diagnostics. This pre-process approach allows manufacturers to set specific work and tool offsets before the machining process. In process adaptive manufacturing occurs when the software automatically makes machining program corrections with real-time in-process feedback through on-machine probing based on the metrology results. Finally, in the post-process, detailed quality reports are created for the machine with SPC analysis and metrology data. Overall, CAPPSNC is being used for on-machine probing or on-machine 3D scanning. It supports sensor interfaces including CNC touch probes, scanning contact probes, non-contact laser scanners and non-contact CCD cameras. It provides dynamic feedback for errors due to part offsets, errors due to part fixturing, errors due to tool wear and errors due to thermal effects. For large non-rigid parts and structures, CAPPSNC also can adapt 5 Axis NC cutting programs which are created based on a CAD model by reposting the tool orientation to match the reverse engineered actual part shape and location. Ultimately, it can provide all the necessary advanced CMM reporting.”

AAT3D and machining technology systems supplier DMG-MORI USA operates a partnership offering the innovative on-machine measuring software solution within the DMG MORI Qualified Products (DMQP) program.

Dimensional metrology is an active and critical participant in harmonizing precision manufacturing. As adaptive control becomes more prevalent, metrology’s role will continue to evolve. So, the next time you see a sophisticated CNC machine humming away, remember that behind the scenes, metrology is orchestrating its moves, ensuring that every cut counts.

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