Why do we test so much?
Of standards, standard tests, and our test laboratory for cables
Max Herrmann | 24. November 2021
That is a good and justified question. This is because tests take a great deal of time and money.
Isn’t there a standard test that every cable manufacturer has to perform? What information can the standard give us? What advantage do you as a customer gain from our decision to test cables under real conditions in the e-chain®? I will answer all these questions in today’s blog post.
The right cable for your application
First, let’s look at the importance of a cable in a machine. From a business point of view, cables are classified as C parts. In the customer’s mind, they usually play a minor role in a complex machine. A cable becomes significant only when it stops working.
But now let’s imagine that there is an unforeseen cable failure. I’m sure you can picture it. Suddenly, life-saving safety functions responsible for opening and closing a train door are no longer available. Motors in a large loading crane in the Port of Hamburg, responsible for loading and unloading large container ships, no longer work. In these examples, the C part suddenly becomes much more important. It is now responsible for injuries to personnel or damage to machines and means immense costs due to downtime. It is therefore especially important to select the right cable for your application and for the expected stress on the cable.
We want to know what our product can do. Our customer has the right to a clear statement.
There are lots of standard tests – aren’t they enough?
A cable’s electrical properties are tested during manufacture. After all, you want to be able to touch a wire without getting an electric shock. All cables are also subjected to so-called standard tests to determine whether they can withstand mechanical stress. The standard for this distinguishes between flexibly laid and permanently installed cables. We are focusing here specifically on flexible cables because, in theory, cables for energy chains are also laid flexibly. But there is no standard test for energy chain cables. If we look at the relevant test for these cables, we find little to no similarity to the application in which the cable will later be used. The “flexing test”, which standardises the cable’s alternating bending resistance, has nothing to do with realistic e-chain applications. The cable to be tested is merely guided over rollers under standardised conditions. The cable passes the test if it withstands a certain number of strokes – that is, movements over the rollers – with a defined radius (= cable bend radius).
Why a standard test is not enough for us
Now think about your application, which involves a cable guided in an energy chain. I am thinking here of adjusting a milling table on a machine tool. This involves completely different requirements with respect to abrasion behaviour, tensile and shear forces, and a recurring load at the same point due to the bend radius. The standard test does not take this into account.
The igus test lab
That is why we at igus® have decided to test our chainflex® cables in the e-chain® under real-world conditions, in addition to the standard test. We therefore install the chain for the relevant movement (long travel, short travel, etc.) in the chainflex test laboratory for cables and move it accordingly. And we measure electrical cable parameters. They show us such things as wear development.
In all these tests, we strive to keep quality level constant and give you a concrete statement about cable durability in the energy chain.