“As you can see, you can’t see anything!”

03. April 2019

We check back again and again. But nothing has happened for over 40 years. We measure, examine and test, but there haven’t been any changes. The anchor simply hasn’t budged during our long-term test at our headquarters in Waldachtal. Read on to find out why a standstill isn’t necessarily a bad thing.

The beginnings of the long-term test

It all began on Monday, the 21st February in 1977, with the long-term test with the fischer frame fixing S10 R-G 135. The innovative anchor was the first frame fixing for facades at the time, thereby taking fixing technology to a new level. The product enabled higher loads to be installed in porous construction materials such as brick, for instance. A particularly solid and tough plastic was used in order to manufacture the product: polyamide. But how long does the product hold for? It is still being tested in a long-term test to this day, with no end in sight.

A comfortable temperature for the anchor

In comparison, nowadays an anchor has to be tested for 3,000 hours in order to be approved. “We have been testing the frame fixing S10 for approximately 368,000 hours”, reports Joachim Lehmann, Head of the fischer development test room at the headquarters in Waldachtal. The frame fixing test is set up as follows: The anchor is placed in concrete with a suitable galvanised screw through a tension adapter that serves as an attachment part. A 160 kg weight is attached to the tension adapter, which is equivalent to double the permissible load, and then the test setup is complete.

And now all that’s left to do is observe and document the process? Not quite. Important general conditions must first be met, as the test results would otherwise be falsified. This is why the test room has a pleasant room temperature of +23° C at a humidity of between 45% and 50%. Now is the time to observe and document.

The long-term behaviour of the S10 R-G 135 is examined with precision through the constant centric tensile loading under temperature-controlled conditions.

A tenth of a millimetre in 42 years

So what has happened in the last 42 years? “The anchor has barely moved”, Lehmann explains. He points to the test report and laughs: “As you can see, you can’t see anything”. Because the frame fixing carried the constant load without issue, the initial low axial displacement can be attributed to the fact that the anchor’s polyamide expands through the screw’s setting process, which recovers within a relatively short period of time. From this point onwards, the curve profile indicates consistent values. The dial gauges also show that the anchor has merely moved by a tenth of a millimetre over the past 42 years.

“The quality of the products is of the highest priority to us” Lehmann says. “This long-term test allows us to prove our standard of quality to customers across the globe. This makes us both proud and happy, of course. Every time I check the long-term experiment I am pleased with the non-existent movement”.