Standard dimensional tolerances for aluminum extrusions. Choose a dimension type and size to find the allowable deviation, or reference the full table below. For profiles that need tighter tolerances, contact our team.
Tolerance Lookup
Find Your Standard Tolerance
Choose the type of dimension, enter the specified size, and we'll pull the allowable deviation from the table.
Dimension type
Distance from base of leg
Where Each Column Applies
Profile Reference
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Standard Tolerances (Inches)
Extrusion Tolerance Table
| Specified Dimension in Inches | Metal Dimensions | Space Dimensions | |||||
|---|---|---|---|---|---|---|---|
| Allowable deviation from specified dimension where 75% or more of the dimension is metal | Allowable deviation from specified dimension where more than 25% of the dimension is space | ||||||
| All except those covered by Col. 3 | Wall thickness(4) completely(5) enclosing space 0.11 sq. in. and over (eccentricity) | At dimensioned points 0.250–0.624" from base of leg | At dimensioned points 0.625–1.249" from base of leg | At dimensioned points 1.250–2.499" from base of leg | At dimensioned points 2.500–3.999" from base of leg | At dimensioned points 4.000–5.999" from base of leg | |
| Col. 1 | Col. 2 | Col. 3 | Col. 4 | Col. 5 | Col. 6 | Col. 7 | Col. 8 |
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Table Notes
How These Tolerances Apply
- (1) These Standard Tolerances are applicable to the average profile. The extrusion conditions required to produce the wide variety of alloy-temper and profile combinations require close review between customer and producer to determine critical characteristics and tolerance capability. Aggressive profile characteristics may require wider than standard tolerance, and closer than precision tolerance may be feasible for other characteristics.
- (2) The tolerance applicable to a dimension composed of two or more component dimensions is the sum of the tolerances of the component dimensions if all of the component dimensions are indicated.
- (3) When a dimension tolerance is specified other than as an equal bilateral tolerance, the value of the standard tolerance is that which applies to the mean of the maximum and minimum dimensions permissible under the tolerance for the dimension under consideration.
- (4) Where dimensions specified are outside and inside, rather than wall thickness itself, the allowable deviation (eccentricity) given in Column 3 applies to mean wall thickness. (Mean wall thickness is the average of two wall thickness measurements taken at opposite sides of the void.)
- (5) In the case of Class 1 Hollow Profiles, the standard wall thickness tolerance for extruded round tube is applicable. (A Class 1 Hollow Profile is one whose void is round and one inch or more in diameter and whose weight is equally distributed on opposite sides of two or more equally spaced axes.)