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close this bookQuality Control Guidelines - Fibre or Micro Concrete Tiles (SKAT, 1991, 79 p.)
close this folder3. Production process
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View the documentDemoulding / Size and shape

Demoulding / Size and shape

Field test

Why this test

Only the correct size and shape of all tiles ensures a proper fixing on the roof. Poorly fitting tiles easily crack under load and wind driven water may enter the roof.

Tiles that are not square will not fit properly and the overlap will not be sufficient.

Tiles that are too thin will leak and are not strong enough.


Check every tile that it has the right dimensions, shape and profile during the demoulding operation. For tiles the special quality control jig developed by JPM Parry can be used.

Hold the mould on edge and place the tile against the quality control jig. Roll the mould with the tile over on the jig’s pivots until upside down. Lift the mould off. Remove the plastic interface sheet by pulling straight across from the side edge.

Run around tile edge with a knife to remove any excess flash. Check carefully that the tile fits the jig and does not wobble.

The edge of the bar should be seen, but should not have a gap showing beneath it.

If the jig is not available the test can also be done on a mould.

Always use an especially assigned mould only used for this purpose. If a plastic mould is used then it must be adequately supported to prevent flexing.


Test on a standard mould that the edges of the tile are parallel with the mould.

Thickness at the edges:

Check if the thickness of the upper part of the tile (a) differs from the thickness of the lower part of the tile (b). For a 6 mm thick tile it should range between 5.5 and 6.5 mm. Check on both ends of the tile.

Thickness in the middle:

Occasionally, check also the thickness of the tile in its center, by breaking the tile.






During demoulding


Record keeping: yes
The product should be within the following tolerances:

Tolerance on length


10 mm

Tolerance on width


5 mm

Tolerance on profile


3 mm

Tolerance on thickness


0,5 mm

Tolerance on squareness


3 mm

If test fails
Discard tiles that fail the test. If the thickness varies too much the mix has to be examined and/or the worker should improve his performance.