|

Put to the Ultimate Test – Part 2: Bending Tests by HELUKABEL

September 5, 2023

Put to the Ultimate Test – Part 2: Bending Tests

During the development of HELUKABEL cables and wires, they vigorously test each product in their testing laboratories. In the second part of their series, they will introduce you to bending tests.

In dynamic applications typical to mechanical and plant engineering or drive and automation technology, cables and wires are frequently subject to mechanical bending stresses. Although these stresses also occur in static installations, they are much higher in dynamic applications because the force and direction of movement are constantly changing. Such situations are pure stress for the cable. The wires, conductor insulation and jacketing material are squeezed on the inside and stretched on the outside, and the cable can tear. Degradation, up to and including cable damage, leads to faults and functional failures.

To make sure their cables and wires reliably withstand day-to-day stresses, HELUKABLE perform bending tests on them in their testing laboratories. These tests are normally laid down in the specifications from customers or in standards such as those from the VDE. Their testing equipment simulates bending stresses with diverse loads and bending radii in order to verify the mechanical strength of the cable. Their test methods include alternate bending tests using two rollers (as per DIN EN 50396 6.2) and three rollers (as per DIN EN 50396 6.3). Parameters such as speed, acceleration and traverse path can be easily varied to create realistic test conditions for a diversity of use cases.

Every cable they develop must comply with the strict test criteria. The copper wires, insulation material and jacketing material must show no signs of degradation after testing. Moreover, the entire stranding as well as braiding and twisting must maintain their original form. Only in this way can it be guaranteed that the cable will function reliably in day-to-day use, even after millions of bending cycles.

Even more, they have purpose-designed drag chain tests for cables used in drag chains. You can read about these in the next part of their series.

Click here to read more about the bending test equipment they use and the performance criteria they can evaluate.

Ask the expert

What is the minimum bending radius and what does this value tell me?

The minimum bending radius is the smallest possible radius to which the cable can be bent without damaging it. It is specified as a multiple of the cable diameter. The smaller the value, the more flexible the cable. There are several industry standards defining the minimum bending radii for different cable types. The values differ greatly, depending on whether the cable is used in a fixed or moving application.

A MULTIFLEX 512®-C-PUR UL/CSA drag chain cable, for example, has a minimum bending radius of 4 x Ø in a fixed application, but only 7.5 x Ø in moving one. The reason for this is that the bending stress in a permanently moving cable is significantly higher as the force and the direction of the bending motion are constantly changing. A suitable minimum bending radius is hence an important criterion when choosing cables and wires.

How can the flexibility of a cable be improved?

There are various ways to improve this, starting with using the best materials. In most cases, copper wires comprising of fine or finest stranded conductors are sufficiently flexible. Alloys can be used as well for some custom applications. Care must be taken that the insulation and jacketing materials are likewise flexible. The choice of materials makes a big difference, especially in applications at extreme temperatures. PUR or TPE jacketing are suitable for cold temperatures as they don’t get very stiff. The diameter and construction also have a major impact on the cable’s bending properties. The shorter the lay length, i.e., tighter twisting inside the conductor stranding, the more flexible the cable.

Source

More Information

HELUKABEL

Related Story

Put to the Ultimate Test – Part 1: Torsion Tests by HELUKABEL

Cables and wires in industrial robots and other moving machine parts are often required to withstand extreme stresses caused by torsion. Constant repetitive movements put materials under considerable strain. At the same time, operators expect components to function perfectly and reliably throughout their entire service life to avoid disruptions, outages and safety hazards.

Related Articles



Editor’s Pick: Featured Article

Weidmüller’s u-control 2000: The Automation Controller

Weidmüller’s u-control 2000: The Automation Controller

Weidmüller’s scalable engineering software, u-control 2000, adapts individually to your requirements. And, the u-control is powerful, compact and fully compatible with Weidmüller’s I/O system u-remote. This article looks at what makes u-control the heart of your automation.

Programmable logic controllers (PLCs) are one of the main components of any automated system. A typical control system has inputs, outputs, controllers (i.e., PLCs), and some type of human interaction with the system, a human machine interface (HMI), for example.

Read More



Latest Articles

  • Omron’ Advanced Safety Services 101

    Omron Offers Advanced Safety Services – What You May Not Know Yet April 16, 2024 In any industrial setting, safety is of the utmost importance. Omron Offers Advanced Safety Services to help you and your staff navigate the challenges of complex industry standards and compliance regulations. They also can provide machine safety technology to protect… Read More…

  • Emergency Lockdown Solutions with ControlByWeb

    April 16, 2024 Emergency lockdown solutions are important. Ensuring the safety of workers and students is crucial in today’s society. In situations that are changing quickly, traditional emergency response techniques might not be sufficient. To solve this issue, ControlByWeb provides creative solutions, including an extensive and effective emergency lockout system for offices and schools. Overview… Read More…