Tightness and technical cleanliness of joints - FASTENER EUROPE MAGAZINE
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Tightness and technical cleanliness of joints

Technical cleanliness is a quality feature that is becoming increasingly important. Particularly with regard to electromobility, the relationship between technical cleanliness and tightness also plays a decisive role in the reliable functioning of the connection.

Clean & tight – this inevitable technical connection is the basis for watertight connection solutions such as those required in the field of electromobility. ARNOLD UMFORMTECHNIK GmbH & Co. KG examines the fundamentals for ensuring tightness and cleanliness, specifies applications and analyzes the factors influencing the system. The company has been active in the field of technical cleanliness for many years and was one of the pioneers in this area. For the Forchtenberg-based manufacturer of connection solutions, it is important to create an awareness of the fact that a specific tightness requirement also requires a defined level of cleanliness.

Requirements for technical cleanliness

The requirements for technical cleanliness were born in the automotive industry. Today, generally applicable regulations define a standardized framework for the implementation of technical cleanliness, such as VDA 19.1 for testing technical cleanliness, VDA 19.2 for technical cleanliness in assembly, ISO and a guideline on technical cleanliness for the electronics industry from the German Electrical and Electronic Manufacturers' Association (ZVEI).

ARNOLD UMFORMTECHNIK has a comprehensive range of equipment available for leak and technical cleanliness tests. These include two leak test benches that measure with test gas: mass spectrometry, which uses helium as the test medium, and a differential pressure method, which uses air as the test medium. A further leak test stand, which uses water as a test medium, can also be used to provide additional IPX7 verification.

For the cleanliness analysis, it is important to record the actual particle contamination of the components. At ARNOLD, the dirt particles are removed from the component and collected in an extraction cabinet. There are various approaches for the subsequent evaluation required. For example, an optical microscope can be used to determine the length and width of the dirt particles and classify them as shiny metallic or non-shiny metallic. A laboratory balance can be used to determine the mass of the particles. New at ARNOLD is a scanning electron microscope. This can be used to determine exactly which chemical elements a protective particle is made up of. Conclusions can also be drawn about the source of the defect. A residual magnetism tester is also available.

Solutions for individual customer applications

Clean & tigth plays an important role for many fasteners. In particular, the focus is on tightness applications such as battery boxes, end or connection assemblies. It is also very important in the electronics industry, for example when conductor tracks are close together. Clean connecting elements are also essential for oil-carrying systems and sensor technology for autonomous driving. Complex multifunctional and multi-stage components – the Conform Next parts manufactured by ARNOLD – can also be included in these cleanliness assessments.

The aim of the Clean & Tight tests at ARNOLD UMFORMTECHNIK is to ensure a reliable assessment of the tightness of the fasteners in relation to customer applications. In addition to determining how tight the components are, long-term influences such as corrosion or environmental influences should also be evaluated. The results of all these tests can be used to determine which fastening solution meets which tightness requirements.

The Cleancon concept developed and patented by Arnold guarantees technical cleanliness across all process steps.


The ARNOLD GROUP, internationally renowned for innovative fastening technology, has developed into a leading supplier and development partner for complex fastening systems thanks to its extensive expertise in the production of intelligent fasteners. Under the umbrella of "BlueFastening Systems", the company positions itself as a comprehensive provider of engineering, fasteners, functional parts, feeding systems and processing technology. This holistic combination of experience and know-how offers efficient, sustainable solutions on an international level. ARNOLD has been part of the Würth Group since 1994.