Online inspection system for reliable detection of internal inclusions, shell defects and optically undetectable surface defects revolutionises quality assurance of tin plate and thin sheets

IMS presents magnet-based Inclusion Detection System (IDS) for strip steel up to 1 mm thick

Heiligenhaus, June 2023

2D Oberflächeninspektion von IMS
Figure 1 (Source: IMS Messsysteme GmbH): IMS Messsysteme GmbH is presenting the optimised version of its Inclusion Detection System (IDS) for cold-rolled strip steels at this year’s METEC in Düsseldorf (Hall 1, booth no. 1C67).

IMS Messsysteme GmbH is presenting the optimised version of its Inclusion Detection System (IDS) for cold-rolled strip steels at this year’s METEC in Düsseldorf (Hall 1, Booth 1C67).

The world innovation, developed in-house, works on the basis of the magnetic leakage flux principle and detects previously undetectable defects in coated and uncoated black plate and thin sheets 0.1 to 1 mm thick precisely, without making contact with the material and at high speed during the running process.

By using the Inclusion Detection System, steel cold rolling mills can ensure a homogeneous material structure and thus a perfect quality of strip before it is processed further with high degrees of deformation.

Perfect material purity and surface quality of cold-rolled steel is essential for subsequent processing into high-quality products. The smallest material defects of various types can cause material weaknesses in the form of inhomogeneities only becoming visible at the very end of a processing operation, such as coating, leading to material fractures in forming processes or even damaging tools in the production process. This involves not only high follow-up costs, but ultimately also a risk of losing customer confidence.

Until now, manufacturers have used optical inspection systems with camera and sensor technology as well as industrial image processing to check the surface quality of strip steels. However, if the material has internal inclusions, shell defects or optically undetectable surface defects, these have so far remained undetected when using conventional testing and measuring methods.


A world first for use in industrial production processes

IMS Messsysteme, the pioneer of innovative inspection and measuring systems for the steel, aluminium and non-ferrous metal industries based in Heiligenhaus, Germany, presented its first market-ready Inclusion Detection System (IDS) for black plate up to 0.6 mm thick for the early detection of internal inclusions and shell defects by means of magnetic leakage flux in spring 2022.

The response among experts to this worldwide innovation was tremendous, as IMS has succeeded in applying the magnet-based method for quality assurance in industrial processes at high speeds.

Just in time for METEC in Düsseldorf, the world’s largest metallurgy trade fair, which will take place in Düsseldorf from 12 – 16 June 2023, IMS is presenting the next logical development of the IDS that will revolutionise quality assurance in the sheet steel industry. With the new version of the Inclusion Detection System, cold-rolled strip steel up to 1 mm thick can now also be inspected; previously, the system was limited to the area of thinner black plate. Thus, from now on, not only tinplate producers but also, for example, manufacturers of steels for the automotive industry will benefit from the new inline measuring system.

“Unlike an optical surface inspection system, the Inclusion Detection System (IDS) is able to detect defects often lying completely within the material and for which there are no visible signs on the material surface.

With the improved IDS, we enable producers of black plate and now also thin sheet as well as their customers to check the quality of the material for internal inclusions, shell defects and minimal surface defects before further processing.

Internal inclusions lead to material fractures during, for example, deep drawing, and shell defects with minimal height differences and that are concealed by a coating often only become visible on finished painted car parts in the form of visual irregularitie”s,

explains Christian Knackstedt, Division Manager Sales & Marketing.

Figure 2 (Source: IMS Messsysteme GmbH): Comparison of the detectable areas of an optical surface inspection system and the Inclusion Detection System (IDS) based on the magnetic flux leakage principle

If the system detects such defective areas, which would lead to rejects and customer complaints in subsequent processing steps, at an early stage and during the ongoing process, these areas can be extracted specifically from the strip. In this way, manufacturers can ensure and document consistent high quality of their steel products. The customers who subsequently process the strip steel into high-quality products benefit from this most of all.

The IDS is particularly useful for manufacturers of fine sheet and black plate who have to guarantee the highest quality standards for the automotive or food industries. The image processing with feature computation and classification used distinguishes the material defects based on their size and type. The inspection system and the defect classification are adapted according to customer specifications and material.

By using the system, users can not only guarantee the high quality of their products, but also document the material structure verifiably thanks to the complete evaluation. The cost of purchasing the system can pay for itself in a short period of time, as companies reduce the need for reworking, their reject rate as well as possible costs for complaints or even recourse claims due to material defects.

In addition, resources are saved and costs reduced because the defective steel can be remelted. IDS thus sets a new standard in quality assurance and contributes indirectly to achieving the sustainability goals of the steel industry.

Figure 3 (Source: IMS Messsysteme GmbH): Representation of a rolling and coating defect, material thickness 660 µm, and its signal curve

Background information:

In steel production and the subsequent casting process, inclusions get into the melt during the metallurgical process. Some of these non-metallic particles remain in the steel products produced. In the subsequent rolling processes, a part of these internal defects are not rolled out of the steel, but instead take on an elongated shape due to the deformation of the material. If these internal inclusions and shells do not appear as open defects on the surface of the material, they cannot be detected with conventional optical measuring systems.

The relative magnetic permeability of such inclusions is significantly lower than that of the surrounding material. Based on this physical fact, detection by magnetic leakage flux is possible. In this method, the material to be tested is magnetised. If the structure is homogeneous, the magnetic field on its surface is also homogeneous. If there are local areas in the material with significantly lower permeability, caused by, for example, non-metallic inclusions, cracks or indentations on the surface, the magnetic resistance increases at this point. A part of the magnetic flux is thus forced to the surface of the material, thereby enabling detection.

Material defects in the form of internal inclusions and shell defects can lead to material fractures and thus to an increased reject and complaint rate, significantly disrupt the production process or even cause cost-intensive damage to the tools, especially in manufacturing processes with high degrees of deformation – such as deep drawing. The Inclusion Detection System (IDS) developed by IMS Messsysteme detects and visualises the described defects continuously, without contact and non-destructively in the running production process at a strip speed of up to 1100 m/min in strip thicknesses of 0.1 to 1 mm – and this on both uncoated and coated material. The detectable equivalent defect size for holes is 70 μm in diameter. The system detects grooves up to 10 μm deep, 100 μm wide and 1,000 μm long. The actual minimum defect size must be determined depending on the application.

Electromagnets are used transverse to the rolling direction to magnetise the material. Their power can be adapted to the properties, structure and geometry of the material being inspected and can be switched off for maintenance and cleaning purposes. One magnet and the sensor line inside each magnet are combined to form a compact sensor module. The modules are implemented in protection class IP 64, which enables direct use in harsh environments. To ensure mechanical stability, the sensor module rows and their carriers are kept at the right temperature with water.

The digitised sensor signals from up to eight sensor modules are fed to a common Gig-E hub and converted to the Gig-E camera standard. The Gig-E hubs are connected to a camera computer that handles signal pre-processing, defect detection, feature computation, classification as well as control and adjustment of the sensor modules. Visualisation of the defects as well as the connection to the customer database is effected via a higher-level database server, where the defect images are stored and the production and training database are also located.

In our media area you will find supplementary image material of the
IMS Messsysteme GmbH for free use in the context of your public relations.

Our responsible contact person for press & media will of course be happy to answer any questions you may have. We look forward to hearing from you!

Sonja Koch
Dipl. Eng.
Umfangreiche Dienstleistungen zum
Betrieb, Wartung und Reparatur Ihrer Anlage

Unsere Service Hotline steht Ihnen während der Geschäftszeiten kostenfrei zur Verfügung. 

Halten Sie bitte zur schnelleren Bearbeitung die Projekt- und Auftrags-Nr. bereit.


In dringenden Fällen steht Ihnen außerhalb der Geschäftszeiten unser telefonischer Bereitschaftsdienst zur Verfügung. Für diese Leistung können Zusatzkosten entstehen.

Aktuelle Events

Lassen Sie sich von unserem Team vor Ort über das beeindruckende Produktportfolio aus der IMS Welt der Messsysteme informieren und von aktuellen Entwicklungsprojekten inspirieren. Wir freuen uns auf Sie!


Stuttgart, Deutschland
07. – 11. November 2023


Aachen, Deutschland
09. – 10. November 2023

Werden Sie Teil der Community beim Weltmarktführer für Röntgen-, Isotopen- und optische Messsysteme für die Stahl-, Nichteisenmetall- und Aluminiumindustrie.

Wir überzeugen Sie gerne mit unseren hervorragenden Arbeitsbedingungen, einem tollen Team und spannenden Jobs mit großem Entwicklungspotenzial. 

Weltweit für Sie da

20 der 20 international größten Stahl- und Aluminiumhersteller vertrauen im Rahmen ihrer Qualitätssicherung auf die Präzision unserer Messysteme. Vertrauen, das verpflichtet.

Über 30 Tochterunternehmen, Joint-Ventures, Handelspartner und Agenten garantieren die maximale Zufriedenheit unserer Kunden rund um den Globus.

Wie können wir Ihnen unterstützen?

Sie haben Interesse an unseren Messsystemen oder suchen einen starken Partner für kundenspezifische Sonderlösungen?


Sie wünschen sich eine neue berufliche Herausforderung bei einem ganz besonderen Arbeitgeber, mit besonderem Team? Bewerben Sie sich jetzt.


Unser Service Team unterstützt Sie rund um die Themen Inbetriebnahme, Wartung und Service, Technischer Support, sowie bei Ersatzteil- und Reparaturanfragen.

You need support?

We will be happy to advise you!

Before you leave!


Why not subscribe to our newsletter?

You will receive all relevant news about our measuring systems and services conveniently by mail. No advertising and no spam. That’s a promise! And you can unsubscribe at any time.

For the distribution of our newsletters, we use rapidmail. By registering, you consent to the transfer of the provided data to rapidmail. Please also refer to the terms and conditions and privacy policy.

Comprehensive services for the
operation, maintenance and repair of your system

Our service hotline is available to you free of charge during business hours. 

Please have the project and order number at hand for faster processing.

Emergency Service

In urgent cases, you can contact our emergency service by telephone outside business hours. Additional charges may apply for this service.

Current Events

Visit us and find out from our team first-hand about the impressive product portfolio from the IMS world of measurement and learn about current development projects. We look forward to seeing you!


Stuttgart, Germany
7th - 11th November 2023


Aachen, Germany
9th - 10th November 2023

Join the community at the world market leader for x-ray, isotope and optical measuring systems for the steel, non-ferrous metal and aluminium industries.

Find out more about our outstanding work conditions, our fantastic team and exciting jobs with excellent opportunities for professional growth.

Working for You Worldwide

Twenty of the 20 largest international steel and aluminium manufacturers rely on the precision of our measuring systems for their quality assurance. A trust that comes with responsibilities.

More than 30 subsidiaries, joint ventures, trading partners and agents guarantee maximum customer satisfaction around the globe.

How can we support you?

You are interested in our measuring systems or are looking for a strong
partner for customised special


You are looking for a new professional challenge with a very special employer and a special team? Apply now.


Our service team will support you in all aspects of commissioning, maintenance and service, technical support, as well as with spare parts and repair requests.