Using Gauges to Specify Aluminum Material Thickness
An issue that frequently occurs on prints we receive is using gauge callouts to specify the material thickness on aluminum sheet metal parts.
The problem occurs when it is not realized that aluminum gauges are different than cold rolled steel (CRS) and stainless steel (SS) gauges. For example: 16ga CRS and SS are nominally .06 thick. However 16ga aluminum is .05 thick, which is significantly different. Staying with our 16ga example, if we receive a print that specs the material as 16ga aluminum, we will quote the parts from .05 thick material. Often though we find that in this situation the customer's intention was for the parts to be .06 thick, because they did not realize that aluminum gauges are different.
Our recommendations to avoid this confusion are:
1.Don't use gauges when calling out aluminum on sheet metal prints, just state the thickness as a decimal (.040, .050, .063, .080, etc...).
2.Always dimension the material thickness in one of the part views on the drawing.
3.If possible, send the CAD models with the prints when requesting quotes or orders.
4.Review the notes on our quotes, we state the material type and thickness we plan to use.
5.Familiarize yourself with the gauge charts for aluminum, CRS and SS. Click on the link under the image (above, right) to view a gauge chart. Notice on this chart that CRS (sheet steel) and SS gauges are not always the same either, see the 7ga for example (.179 & .187).
Sample gauge and weight chart from Engineering Toolkit.