Sheet Metal Hem K Factor

As shown in figure 1 below k t t.

Sheet metal hem k factor. Sheetmetal me is a community and comprehensive knowledge base for the engineering design and fabrication of sheet metal. The k factor is the ratio between the distance from the neutral layer to the bent inner surface and the thickness of the sheet metal. The k factor itself is a multiplier used to calculate the new. The inside radii are based off of a standard air bend force chart.

As i mentioned in my last post you need to do some tests to calculate these values for a specific sheet. In my previous post i talked about k factor bend allowance and bend deduction and what they mean in sheet metal design. In sheet metal design the k factor is used to calculate how much sheet metal one needs to leave for the bend in order to achieve particular final dimensions especially for between the straight sides next the bend. In sheet metal hemming means to fold the metal back on itself.

Attempting to calculate the allowance for a hem like this will just lead to frustration. The same holds true for both the teardrop and open hems. Because of the specific properties of any given metal there is no easy way to calculate that value perfectly hence the chart in figure 2. The k factor is defined as a constant that is greater than 0 and less than 1.

Hems can be flattened left open or in a variety of tear drop shapes. The k factor of a 180 bend hem the k factor for a 180 bend is going to be meaningless because it s tied to the outside setback which approaches infinity as the bend approaches 180. The below microsoft excel chart is for even numbered gauges 8 through 24 and has a default k factor of 33 for each. K factor k the ratio of the position of the neutral axis to the material thickness.

Our pages on. Sheet metal bend allowance chart pdf. Air bending one of the three types of bending for sheet metal where the outside mold line is not pressed against the die. Hem a flange that reaches 180 or more.

The k factor in sheet metal working is the ratio of the neutral axis to the material thickness. The k factor is usually somewhere between 0 3 and 0 5. You also asked about the k factor which happens to be one of the most commonly misused terms in precision sheet metal. You can easily modify the material thickness inside radius and k factor for each thickness at the top of each column.

The k factor is defined mathematically as t mt where t is the neutral axis location and mt is the material thickness. Now let s see how we can obtain these values for a specific sheet.