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Fast FMCW Terahertz Imaging for In-Process Defect Detection in Press Sleeves for the Paper Industry and Image Evaluation with a Machine Learning Approach
- Source :
- Sensors (Basel, Switzerland), Sensors, Volume 21, Issue 19, Sensors, Vol 21, Iss 6569, p 6569 (2021)
- Publication Year :
- 2021
- Publisher :
- MDPI AG, 2021.
-
Abstract
- We present a rotational terahertz imaging system for inline nondestructive testing (NDT) of press sleeves for the paper industry during fabrication. Press sleeves often consist of polyurethane (PU) which is deposited by rotational molding on metal barrels and its outer surface mechanically processed in several milling steps afterwards. Due to a stabilizing polyester fiber mesh inlay, small defects can form on the sleeveās backside already during the initial molding, however, they cannot be visually inspected until the whole production processes is completed. We have developed a fast-scanning frequenc-modulated continuous wave (FMCW) terahertz imaging system, which can be integrated into the manufacturing process to yield high resolution images of the press sleeves and therefore can help to visualize hidden structural defects at an early stage of fabrication. This can save valuable time and resources during the production process. Our terahertz system can record images at 0.3 and 0.5 THz and we achieve data acquisition rates of at least 20 kHz, exploiting the fast rotational speed of the barrels during production to yield sub-millimeter image resolution. The potential of automated defect recognition by a simple machine learning approach for anomaly detection is also demonstrated and discussed.
- Subjects :
- Fabrication
Terahertz radiation
Computer science
TP1-1185
Molding (process)
Biochemistry
Article
Rotational molding
Analytical Chemistry
Machine Learning
terahertz imaging
frequency-modulated continuous wave
Data acquisition
Nondestructive testing
Electrical and Electronic Engineering
Instrumentation
Image resolution
nondestructive testing
business.industry
Chemical technology
Pulp and paper industry
anomaly detection
Atomic and Molecular Physics, and Optics
paper industry
Anomaly detection
press sleeves
business
Subjects
Details
- ISSN :
- 14248220
- Volume :
- 21
- Database :
- OpenAIRE
- Journal :
- Sensors
- Accession number :
- edsair.doi.dedup.....b87e31c6cdd0d862b3f9bd8ffd855704