Dimensioning Formed Sheet Metal

Hit the hem just right and the numbers work.

Dimensioning formed sheet metal.

Trilux manufactures more than 9 000 sheet metal products including intricate luminaire bodies that form the basis of a commercial lighting unit. Fortunately hems are rarely specified on tight tolerance flanges. There are other measurement units used to categorise metals by thickness though. Their standard measuring process involved traditional equipment visual exams conducted by floor operators and templates that were often created in house.

It is always better to specify hole diameters that are greater than the sheet s thickness t. Sheet metal is any metal that has a thickness in between 0 5 6 millimetres. One needs to check that these factors are consistent with the tooling that will be used in manufacturing. When producing drawings of sheet metal components i dimension from inside the flange walls.

Hem measurement forming hems is one of those aspects of sheet metal that is very operator dependent. Form height to thickness ratio to determine the minimum form height for sheet metal use the following formula. My boss dimensions from outside the flange walls and thinks this is the. 5 edge distortion an exaggerated example of edge deformation is pictured in figure a below.

D 2 5t r see below the height can be less but it required secondary operations and is far more costly. In a sheet metal design specifying hole sizes locations and their alignment is critical. Sheet metal is one of the shapes and forms metal can be bought in. Some critical dimensions that need to be considered when setting up sheet metal in cad software are sheet metal thickness the k factor and bend radius.

Hit it softer or harder than necessary and the flange dimension changes. I think this is the better way because you can acquire your cutting length without a flat pattern by adding the inside lengths fold allowance. Since each metal fabricator has its own tooling bend factors and equipment to develop the flat blank it is better to fully dimension to formed views for that manufacturer.