Permanent connection - Tried and tested: Insulation displacement connection technology (IDC) in movable cable systems from igus® & HARTING

Profile

What was needed: Testing and reliable test statements of dynamic cable systems with insulation displacement connections (IDC) according to the relevant standard EN 60352-3
Requirements: Fail-safe and long service life of the plug connection, constant vibrations and several thousand bending and movement processes
Product: chainflex® CFBUS cable & HARTING RJ Industrial 10G connector
Area of application: industrial automation
Success for the customer: Assurance that CF cables in conjunction with insulation displacement technology fulfil the highest reliability requirements (although not mentioned in EN 60352-3)

HARTING insulation displacement contact connectors

Insulation displacement contact (IDC) technology**:** It may come as a surprise that, in view of the high requirements, insulation displacement contact (IDC) technology is also gaining acceptance in the industry. In this method, the insulated conductor is pressed into a tapered gap with cutting edges. The cutting edges cut through the insulation and then come into contact with the actual conductor, which is deformed during this process. If the process is carried out correctly, the result is a long-term stable cold weld and a gas-tight, i.e. non-ageing connection. Originally developed for office communication and IT network technology, this technology enables a simple, time-saving and solder-free connection without the need for special tools. And it is precisely these advantages that we want to utilise in industry.

The challenge

In view of the fact that hundreds or thousands of these cables and connections are used in larger systems, extremely high demands must be placed on each individual core and each individual connector in terms of service life and reliability. This requirement is not easy to fulfil because the cables are exposed to high mechanical, climatic and chemical stresses, depending on the application. This applies in particular to those applications in which the cable travels with moving system components such as linear and handling axes or robot arms.

What applies to the cable also applies to the plug connections. Even constant vibrations or several thousand work cycles per shift with correspondingly many bending and movement processes of the cable must not cause the individual cores to come loose from the terminal. This requirement is easy to formulate and write down. However, compliance with it in practice requires great care when selecting the connection technology and great care when connecting the cable and connector.

There is a standard for such connections: Part 3 of EN 60352 "Solderless electrical connections" contains specific regulations for the product area "Solderless accessible insulation displacement connections" and specifies "General requirements, test methods and instructions for use". This standard refers to cables whose core consists of one wire or is made up of seven wires. In industry, however, cables with 19 wires are often used, which are needed to ensure the dynamics required for moving cables. This means that the Ethernet and Profibus cable cores with 19 wires, which are connected to their connectors via insulation displacement connectors, do not comply with the letters of the standard. The connector approval is also not given under these conditions.

Solution

As the Ethernet and Profibus cable cores with 19 wires, which are connected to their connectors via insulation displacement connectors, do not comply with the letters of the standard, igus® and HARTING took the logical step of testing the successful cable systems in practice in accordance with the requirements of EN 60352-3. HARTING's accredited test laboratory in Espelkamp and the comprehensive test facilities in the igus® test centre were used for this.

The scope of testing included long-term tests with prefabricated cable systems that were stressed according to defined requirement profiles. The possibility of processing in the connector and the contacting of stranded wire to insulation displacement connector was tested. Adverse environmental conditions such as frequent temperature changes and humidity were also simulated. The aim of the tests was to apply the test methods specified in EN 60352-3 and to subject both the cable and the insulation displacement connections to the highest stresses.

To summarise, the tests were carried out to the complete satisfaction of HARTING and igus®. Even after intensive dynamic use, the micrographs showed a flawless cold-welded connection, which can be expected to have a long service life even if the tests are continued. The tests described were carried out on the standard bus cables from the chainflex® programme. For Ethernet systems, these are the CFBUS.04x series, for Profinet the CFBUS.060 series. Also included were cables with sheaths made of PVC (for use in the wood industry), PUR (for applications where oil resistance is required), halogen-free TPE and cables with UL approvals. The CFROBOT8.045 (Ethernet) and CFROBOT8.060 (Profinet) cables for robotics applications, which are particularly resistant to dynamic loads, have also been successfully tested.

chainflex® Ethernet cables