Screw retention force of building materials

Solution

  • Software-controlled tensile tester and software
  • Custom-designed fixtures to hold the batch specimen test piece

Benefits

  • Semi-automated testing for reqular batch testing QC checks
  • Confidence in meeting structural integrity requirements

Requirement

A leading manufacturer and distributor of metal building roofing systems for the construction industry wanted to ascertain the pull out force of screws fixed to building materials.

For reliable and repeatable test purposes, the system would need to perform routine batch sample evaluations. The company estimated loads would measure in the region of up to 20 kN, enabling a semi-automatic test to be performed.

Solution

Mecmesin provided a twin-column test system capable of measuring forces up to 25 kN. A bespoke fixture was designed to offer a suitable method of performing heavy-duty pull off tests, which gave the best possible accuracy.

The special fixture consists of two angled plates fixed directly onto the twin-column’s base. This enables a strip of roofing or cladding material, loaded with screw heads, to be positioned, ready for testing. The screw head extrusion fixture is attached to the system’s crosshead via a heavy-duty galvanised short link chain assembly.

The test was performed under laboratory conditions using the constant speed of the test stand and EmperorTM software to control and detect the break out force of the screw fixing from the roofing material or cladding. The test load range is up to 20 kN, depending on screw size and material. Mecmesin’s new proposed method proved more reliable as tests were repeatable and accurate in comparison to the existing test method.

Test equipment

  • MultiTest 25-i - computer-controlled test frame, rated to 25 kN
  • ILC-T 25 kN
  • Screw retention fixture
 

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