Intelligent quality inspection of glued joints in the wood industry

It creates a warm and inviting atmosphere. Its natural grain and color tones have a lively effect and add character to a room. We are talking about classic wooden flooring - usually parquet and optionally with a click system for easy installation. Scheucher Holzindustrie GmbH from Mettersdorf in Austria is now in its fourth generation of manufacturing high-quality parquet floors and combines tradition with modernity in its production. The company relies on image processing with artificial intelligence to inspect the glue joints of its multilayer parquet, or more precisely on IDS NXT, an all-in-one system for the use of intelligent cameras.

Application
Not all parquet floors are the same. In addition to solid variants, multi-layer parquet is particularly popular. Several aspects must be taken into account during its manufacture in order to obtain a high-quality, durable and user-friendly product. The choice of wood species, for example, influences the stability and appearance of the parquet. As the name suggests, it consists of several layers - in particular a core layer and a wear layer. Scheucher uses spruce or pine as backing. A variety of wood species can be chosen for the wear layer.



Structure of a 3-layer finished parquet for floating installation or full surface gluing with click system

A major advantage of "prefinished parquet" is its ease of installation. Many types can be laid as a floating floor, so do not need to be glued down. With a little manual skill, even inexperienced people can install their own wooden floor. A click system ensures the exact fit of the planks. They are simply clicked directly into each other. This saves time and reduces the workload. It is important that the click system is milled with high precision so that the panels interlock stably and precisely. Incorrect milling can lead to problems during installation and instability. The same applies to the adhesive bond between the core layer and the wear layer of the parquet. The adhesive must be applied evenly to ensure complete coverage and a uniform bond between the layers. Air inclusions or irregular application quantities can lead to cavities and impair the durability. "In the profiling for our MULTIflor parquet floors, a special click profile is milled into the planks. During this process, two intelligent IDS NXT cameras are used to check the presence of adhesive in the adhesive joint between the core and the backing layer," explains Dipl.-Ing. Klaus Bauer, Research & Development at Scheucher.



The individual panels fit together stably and precisely.

Intelligent quality control without a PC
Scheucher illuminates the already glued parquet planks with UV light. The adhesive fluoresces and adhesive residues become visible. Scheucher relies on image processing with artificial intelligence to detect faulty floorboards. Two IDS NXT rio cameras are used per system. The intelligent models become powerful inference cameras by loading a neural network. They detect the fluorescent adhesive joints and process the image data directly "on the edge" via FPGA and pass the result on to the downstream process. The embedded solution makes the host PC redundant and reduces energy consumption and system costs. Thanks to screwable and IP-protected connectors and a robust housing, they are also absolutely suitable for industrial use. The standardized OPC UA industrial protocol enables direct communication with machines and control systems.



IDS NXT rio camera detects faulty glue joints between parquet layers.

Image processing with AI without prior knowledge of deep learning
Application development and integration into the parquet manufacturer's existing production system was quick and easy with the help of the IDS NXT rio Experience Kit. The complete inference camera solution for AI applications in industrial image processing contains all the components that a user needs to create, train and execute a neural network in a productive environment. The package includes the required hardware - in the form of an IDS NXT rio industrial camera with 1.6 MP Sony color sensor including power and data cable, tripod adapter and lens - as well as the required software in the form of an IDS lighthouse license. This allows users to concentrate fully on the planned application without having to worry about deep learning, image processing or camera programming.

"In our profiling system we had not used any image processing, neither rule-based nor intelligent, for the quality control of our bonded joints until now. Nevertheless, it was our goal, even as a layman, to solve this requirement using AI. As we are looking for errors that only occur extremely rarely, our challenge was to find a sufficient number of "bad partial images" to train the neural network," explains Bauer. "And we succeeded. In the end, we needed around 60 good and bad part samples before the AI had learnt to recognize the threshold between OK and NOT OK." Faulty panels can be reliably sorted out and reworked. The system prevents planks with defects in the parquet bonding from being delivered to customers. "This makes us one of the few manufacturers on the market to achieve a 100% inspection in this regard," says Bauer. Especially as it takes less than 90 milliseconds to check a floorboard.



OK and NOK panels - The bad part shows a presumably insufficient bonding in the right third.

Outlook
In this example, the inspection of the glued joint could also be solved using classic, rule-based image processing, though with increased programming effort. However, it was important to Scheucher to find an intelligent solution. This means that the company is prepared for further applications, as Klaus Bauer emphasizes: "The task was a good introduction to AI-supported image processing for us. Especially because the learning curve was quick." This paves the way for further applications and future-proof, efficient production.

With the help of intelligent image processing systems, objects can be classified or checked for defects, deviations and quality problems. This can reduce errors and increase productivity - in a wide range of industries and applications. The AI-based all-in-one vision system from IDS shows that this is not highly complex and reserved purely for experts. Scheucher Parquet and IDS NXT have something in common: Thanks to sophisticated systems, even non-professionals can use it and achieve first-class results, such as the perfect parquet shown here.

Camera
The IDS NXT rio Experience Kit is the complete inference camera solution for AI applications in industrial image processing.

Model used: IDS NXT rio
Camera family: IDS NXT

Client
With one of the most modern prefinished parquet factories in Europe, Scheucher has developed into one of the leading parquet manufacturers in Austria over the last few decades. The optimal utilisation of resources, as well as the exclusive use of absolutely environmentally friendly methods and pollutant-tested materials in every single production step are among the principles of Scheucher Holzindustrie GmbH and guarantee high-quality products 100% manufactured in Austria.

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