Aluminum profiles: size and shape requirements

When you see a batch of shiny aluminum profiles, you can think about them, how about flawless and high-precision products! Actually aluminum profiles also produce in tolerances, as well as more familiar steel.

Tolerances of sizes and shapes

In the production of aluminum profiles, least, the following deviations in size and shape - tolerances:

  • cross-sectional width;
  • wall thickness and shelves;
  • cross-sectional shape (parallelism of walls and shelves, angles and t. P.);
  • straightforwardness;
  • flatness;
  • twisting.

Standards for aluminum profiles

The requirements for the maximum permissible deviations in the size and shape of aluminum profiles during their production and delivery determine the relevant standards.

In Russia:

  • GOST 8617-81 - general purpose profiles of alloys according to GOST 4784-97;
  • GOST 22233-2001 - profiles for protecting building designs – aluminum windows, doors, facades – “precision” profiles made of alloys AD31, 6060 and 6063. Word “enclosing” here means “not structural”.

In Ukraine:

  • GOST 8617-81 - general purpose profiles of alloys according to GOST 4784-97;
  • DSTU B V.2.6-3-95 (GOST 22233-93) – profiles for building envelopes – window, doors, facades, partitions – “precision” alloy profiles AD31, as well as alloy 1915 GOST 4784-97.

In the countries of the European Union:

  • EN 755-9 - for general purpose alloy profiles according to EN 573-3;
  • EN 12020-2 – for precision alloy profiles 6060 and 6063 by EN 573-3.

Dimensional tolerances of profiles: normal and "precision"

General purpose profiles - from various aluminum alloys - are made with so-called "normal" tolerances, for example, according to GOST standards 8617-81 и EN 755-9.

Aluminum profiles for building envelopes, for example, window, made only of alloys 6060/6063 (AD31) are made as normal accuracy, and with tighter tolerances. for instance, GOST 22233-2001 provides for the production of profiles with three accuracy options: "normal", “Elevated” and even “special”. Tolerances for normal accuracy somewhere on 25-35 % wider, than for increased accuracy. Extra precision at 20-30 % tougher.

Window aluminum profiles

Profiles for aluminum windows usually pressed with high precision. These tight tolerances are really necessary for the production of aluminum windows.. The thing is, that the window is made up of many details and is very important, so that they all fit together well. Otherwise, the window will be difficult to assemble., between its various details there will be excessively large gaps and it will, for example, to warp, poorly closed-open or easy to pass air and water.

Formulas for aluminum profile tolerances

Normal profile width tolerances can be estimated using the following approximate formula:

(Width tolerance) ≈ ± (0.3 +w/200) mm

Where w - profile width in mm.

This formula generally complies with the requirements of the European standard EN 755-9 with a width of more 100 mm and gives too large tolerances for narrower profiles. At the same time, this formula is useful for understanding, that with an increase in the width of the profile, the tolerances on it increase.

A similar ratio for the profile thickness tolerance is:

(Thickness tolerance) ≈ ± (0.2 +w/600 + t/150) mm,

where is the width w and thickness t are given in mm.

This thickness refers to the main elements of the profile., and not to small details like ribs. This formula also overestimates tolerances with small profile widths.. However, it is also useful to those, which gives an understanding of, that the thickness tolerance increases as the thickness itself increases, and overall profile width.

Important factor, which affects the thickness of the profile, is matrix wear. In case of excessive wear of the matrix, it is taken out of service and replaced with a new one.. To maintain tight tolerances, this has to be done more often..

Source: John Dwight, Aluminium Design and Construction, Taylor & Francis e-Library, 2002