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arxiv: 2604.09889 · v1 · submitted 2026-04-10 · 💻 cs.AI

Recognition: unknown

In-situ process monitoring for defect detection in wire-arc additive manufacturing: an agentic AI approach

Pallock Halder , Satyajit Mojumder

Authors on Pith no claims yet

Pith reviewed 2026-05-10 16:47 UTC · model grok-4.3

classification 💻 cs.AI
keywords additive manufacturingdefect detectionmulti-agent AIin-situ monitoringporosityacoustic signalsprocess monitoringwire arc additive manufacturing
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The pith

A multi-agent AI framework using welder signals and acoustic data detects porosity defects in wire-arc additive manufacturing with 91.6 percent accuracy.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper develops an agentic AI approach for monitoring defects during wire-arc additive manufacturing. Separate agents analyze welder process signals such as current and voltage, and acoustic emissions, each trained against X-ray computed tomography data to identify porosity. These agents are then coordinated by a large language model in a multi-agent setup that makes joint decisions. The combined system achieves better results than any agent working alone, with 91.6 percent decision accuracy and an F1 score of 0.821 across multiple runs. This could support real-time adjustments to produce better quality parts without waiting for post-process inspection.

Core claim

The paper claims that an LLM-orchestrated multi-agent system, consisting of a processing agent from welder current and voltage signals and a monitoring agent from acoustic data, both classified against XCT ground truth for porosity, outperforms individual agents by reaching 91.6% decision accuracy and 0.821 F1 score on decided runs over 15 independent trials, with average reasoning quality of 3.74 out of 5.

What carries the argument

The LLM-based orchestration of parallel processing and monitoring agents that fuses decisions from welder signals and acoustic data for in-situ porosity defect classification.

If this is right

  • The multi-agent configuration delivers higher accuracy and F1 scores than any single-agent setup.
  • Evaluation metrics show consistent performance across 15 independent runs for the coordinated system.
  • Both signal-based and acoustic agents can be trained effectively using XCT as ground truth for defect labeling.
  • The framework supports autonomous real-time monitoring toward qualified part production in WAAM and similar processes.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Deploying this in production lines might allow immediate correction of process parameters to avoid defects.
  • Extending the agents to predict other defect types like cracks or lack of fusion could broaden its utility.
  • Replacing the LLM orchestrator with a lighter model might enable faster on-machine deployment.

Load-bearing premise

Welder process signals and acoustic data hold sufficient information for reliable porosity classification based on XCT labels, and the LLM orchestration remains consistent beyond the current experimental dataset.

What would settle it

Apply the trained multi-agent system to a fresh set of WAAM builds with known porosity levels from XCT and measure if the accuracy stays above 85 percent or drops significantly.

Figures

Figures reproduced from arXiv: 2604.09889 by Pallock Halder, Satyajit Mojumder.

Figure 1
Figure 1. Figure 1: System overview of the proposed agentic AI framework for in-situ WAAM process monitoring. The architecture comprises three functional layers: (a) a signal acquisition layer capturing processing signals (welding current and voltage) and monitoring signals (acoustic data), (b) a machine learning tool layer with a 1D-CNN for processing signal classification and a 2D-CNN for monitoring signal (audio spectrogra… view at source ↗
Figure 2
Figure 2. Figure 2: LangGraph workflow graphs for the four agentic orchestration configurations. (a) Processing￾agent architecture: a single processing agent invokes the signal tool and performs reasoning on process signals, followed by extraction, reflection-based review, and report generation. (b) Monitoring-agent architecture: a single monitoring agent invokes the audio tool to analyze acoustic data, followed by extraction… view at source ↗
Figure 4
Figure 4. Figure 4: Class-wise monitoring score (MS) across different agent configurations. MS reflects the practical usefulness of monitoring recommendations. 3.3 Monitoring utility The practical value of a process monitoring system depends on two complementary properties: its ability to flag every defective track for human review, and its ability to leave normal tracks undisturbed. A system that indiscriminately flags all i… view at source ↗
read the original abstract

AI agents are being increasingly deployed across a wide range of real-world applications. In this paper, we propose an agentic AI framework for in-situ process monitoring for defect detection in wire-arc additive manufacturing (WAAM). The autonomous agent leverages a WAAM process monitoring dataset and a trained classification tool to build AI agents and uses a large language model (LLM) for in-situ process monitoring decision-making for defect detection. A processing agent is developed based on welder process signals, such as current and voltage, and a monitoring agent is developed based on acoustic data collected during the process. Both agents are tasked with identifying porosity defects from processing and monitoring signals, respectively. Ground truth X-ray computed tomography (XCT) data are used to develop classification tools for both the processing and monitoring agents. Furthermore, a multi-agent framework is demonstrated in which the processing and monitoring agents are orchestrated together for parallel decision-making on the given task of defect classification. Evaluation metrics are proposed to determine the efficacy of both individual agents, the combined single-agent, and the coordinated multi-agent system. The multi-agent configuration outperforms all individual-agent counterparts, achieving a decision accuracy of 91.6% and an F1 score of 0.821 on decided runs, across 15 independent runs, and a reasoning quality score of 3.74 out of 5. These in-situ process monitoring agents hold significant potential for autonomous real-time process monitoring and control toward building qualified parts for WAAM and other additive manufacturing processes.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

4 major / 2 minor

Summary. The manuscript proposes an agentic AI framework for in-situ process monitoring and defect detection in wire-arc additive manufacturing (WAAM). It develops a processing agent from welder current/voltage signals and a monitoring agent from acoustic data, each using classification tools trained against XCT ground truth for porosity identification. An LLM-orchestrated multi-agent system is introduced for parallel decision-making; this configuration is reported to outperform single-agent baselines, reaching 91.6% decision accuracy and 0.821 F1 on decided runs across 15 independent runs together with a reasoning quality score of 3.74/5.

Significance. If the empirical results are reproducible, the work offers a concrete demonstration of multi-agent orchestration for combining complementary in-situ signals in additive manufacturing. The use of independent XCT labels for both training and evaluation is a clear strength that avoids circularity. The reported lift from multi-agent coordination and the explicit reasoning-quality metric are also positive features. However, the overall significance is limited by the absence of core methodological details needed to judge whether the signals truly support reliable XCT-aligned classification or whether the gains generalize beyond the specific dataset and prompt set.

major comments (4)
  1. The methods description provides no information on dataset size, number of WAAM builds, train/test split ratios, or cross-validation procedure used to develop the classification tools for the processing and monitoring agents. These details are load-bearing for the central claim that the multi-agent system achieves 91.6% accuracy and 0.821 F1, because without them it is impossible to rule out overfitting or label noise as the source of the reported performance.
  2. No description is given of the feature engineering steps or the specific model architecture/type (e.g., random forest, neural net, or other) employed by the processing agent on current/voltage time series and by the monitoring agent on acoustic signals. This omission directly affects the weakest assumption that the in-situ signals contain sufficient information to classify XCT-labeled porosity.
  3. The temporal alignment procedure between the in-situ process signals (current, voltage, acoustic) and the XCT-detected pores is not specified. Without an explicit alignment method, the ground-truth mapping used to train and evaluate both agents cannot be verified, undermining the validity of the multi-agent decision accuracy numbers.
  4. The criteria used to designate “decided runs” in the multi-agent orchestration and the exact protocol for computing the reasoning quality score (3.74/5) are not stated, nor is any test of stability under prompt variation or across independent builds. These elements are central to the claim that the LLM layer adds reliable value beyond the individual agents.
minor comments (2)
  1. The abstract and evaluation section would benefit from a concise table summarizing the 15 runs (e.g., number of samples per run, decided vs. undecided counts) to make the performance numbers immediately interpretable.
  2. Notation for the two agents is occasionally inconsistent (processing agent vs. welder agent); a single, clearly defined terminology would improve readability.

Simulated Author's Rebuttal

4 responses · 0 unresolved

We thank the referee for their thorough review and constructive comments. We agree that several methodological details were insufficiently described in the original submission and will revise the manuscript to address these points. Our responses to each major comment are provided below.

read point-by-point responses
  1. Referee: The methods description provides no information on dataset size, number of WAAM builds, train/test split ratios, or cross-validation procedure used to develop the classification tools for the processing and monitoring agents. These details are load-bearing for the central claim that the multi-agent system achieves 91.6% accuracy and 0.821 F1, because without them it is impossible to rule out overfitting or label noise as the source of the reported performance.

    Authors: We acknowledge this omission. In the revised manuscript, we will add a comprehensive description of the dataset, including the total number of samples collected from multiple WAAM builds, the train/test split ratios employed, and the cross-validation strategy used to train and validate the classification tools for both agents. This will enable readers to better evaluate the reliability of the reported performance metrics. revision: yes

  2. Referee: No description is given of the feature engineering steps or the specific model architecture/type (e.g., random forest, neural net, or other) employed by the processing agent on current/voltage time series and by the monitoring agent on acoustic signals. This omission directly affects the weakest assumption that the in-situ signals contain sufficient information to classify XCT-labeled porosity.

    Authors: We agree that these details are important. We will expand the Methods section to detail the feature engineering process for both the current/voltage signals and the acoustic signals, as well as the specific machine learning models and architectures used for each agent. This will clarify how the in-situ signals are processed to align with the XCT ground truth. revision: yes

  3. Referee: The temporal alignment procedure between the in-situ process signals (current, voltage, acoustic) and the XCT-detected pores is not specified. Without an explicit alignment method, the ground-truth mapping used to train and evaluate both agents cannot be verified, undermining the validity of the multi-agent decision accuracy numbers.

    Authors: We will include a detailed explanation of the temporal alignment procedure in the revised paper. This will describe how the process signals are synchronized with the XCT data to establish the ground truth labels for porosity defects. revision: yes

  4. Referee: The criteria used to designate “decided runs” in the multi-agent orchestration and the exact protocol for computing the reasoning quality score (3.74/5) are not stated, nor is any test of stability under prompt variation or across independent builds. These elements are central to the claim that the LLM layer adds reliable value beyond the individual agents.

    Authors: We will clarify the criteria for designating 'decided runs' (such as agreement between agents or confidence thresholds) and provide the exact protocol for the reasoning quality score, which is based on expert evaluation. Additionally, we will include results on stability under prompt variations and across the 15 independent runs to support the robustness of the multi-agent approach. revision: yes

Circularity Check

0 steps flagged

No significant circularity; empirical metrics rely on independent XCT ground truth

full rationale

The paper describes an empirical agentic framework where processing and monitoring agents are trained on in-situ signals (current/voltage, acoustics) with classification tools developed from separate XCT ground-truth labels. Reported performance (91.6% accuracy, 0.821 F1 on decided runs across 15 runs) is measured directly against these external labels rather than derived by construction from fitted parameters, self-definitions, or self-citation chains. No equations appear, no uniqueness theorems are invoked, and the multi-agent orchestration lift is presented as an observed outcome, not a mathematical reduction to inputs. The evaluation is therefore self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The central claim depends on the existence of trained classification tools that map signals to XCT labels and on the LLM's ability to integrate agent outputs; no explicit free parameters, axioms, or new physical entities are stated in the abstract.

pith-pipeline@v0.9.0 · 5575 in / 1168 out tokens · 59534 ms · 2026-05-10T16:47:28.975392+00:00 · methodology

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Reference graph

Works this paper leans on

115 extracted references · 104 canonical work pages · 13 internal anchors

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    Results This section presents the quantitative and qualitative performance of individual processing and monitoring agents, a combined single -agent and multi-agent system for i n-situ monitoring of WAAM. Performance is evaluated across classification tool performance, decision accuracy, monitoring utility, reasoning quality, and agentic behavior, includin...

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    This difference likely reflects what each sensor physically measures

    Discussion 4.1 Relative performance of signal modalities The monitoring agent substantially outperformed the processing agent under the conditions of this study, suggesting that a udio signals carry richer porosity- relevant information than processing signals. This difference likely reflects what each sensor physically measures . Monitoring signals captu...

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