Bend Allowance Sheet Metal K Factor Chart

When metal is bent the top section is going to undergo compression and the bottom section will be stretched.

Bend allowance sheet metal k factor chart.

K value of k factor. R inside bend radius. The inside radii are based off of a standard air bend force chart. The k factor is fundamental to designing precise sheet metal products.

Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1. 60 90 and 120 and we will calculate k factor bend allowance and bend deduction for them. Calculate unfold size with bend allowance chart. After bending the sheet insert the inner radius and flanges a and b.

While modern bend deduction charts now are reasonably accurate historically bend calculation charts both for bend allowances and bend deductions were notorious. Mathematically bend allowance during sheet metal bending can be calculated as. The location of the neutral axis varies and is based on the material s physical properties and its thickness. 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 below microsoft excel chart is for even numbered gauges 8 through 24 and has a default k factor of 33 for each. Bend allowance ba π 180 r k t a. 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. You can easily modify the material thickness inside radius and k factor for each thickness at the top of each column.

Bending angle is 90. The line where the transition from compression to stretching occurs is called the neutral axis. The k factor is usually somewhere between 0 3 and 0 5. Sheet metal bend allowance chart pdf.

Should you wish to calculate the k factor rather than use a chart you will need some test pieces four or five pieces should do nicely for this purpose. As shown in figure 1 below k t t. A bending angle. We are going to review three bending scenarios with three different bending angles.

All other values are known to the user. There is a direct relationship between bend allowance and the k factor. To calculate the bend allowance the k factor and the derived coefficient called the y factor insert the thickness and initial length of the sheet into the cells on the left. It allows you to anticipate the bend deduction for a large variety of angles without having to rely on a chart.

T sheet thickness. The k factor in sheet metal working is the ratio of the neutral axis to the material thickness. In above bend allowance formula except sheet metal k factor and bend allowance values.