Bend Allowance Sheet Metal K Factor Chart

Sheet metal bend allowance chart pdf.

Bend allowance sheet metal k factor chart. The k factor is fundamental to designing precise sheet metal products. 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. K value of k factor.

The location of the neutral axis varies and is based on the material s physical properties and its thickness. The k factor is defined as a constant that is greater than 0 and less than 1. 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. 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.

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. In above bend allowance formula except sheet metal k factor and bend allowance values. 60 90 and 120 and we will calculate k factor bend allowance and bend deduction for them. You can easily modify the material thickness inside radius and k factor for each thickness at the top of each column.

After bending the sheet insert the inner radius and flanges a and b. 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. L unfold length a outside size b outside size k k factor none 90 bend unfold according to the neutral layer the distance from neutral to sheet inner side is t 3 inner r can refer to the above chart. Consider a sheet with a 20 mm thickness and a length of 300 mm as shown in figure 1.

R inside bend radius. Bend forming 0 l a b 0 43t t thickness deduction 0 43t. There is a direct relationship between bend allowance and the k factor. T sheet thickness.

When metal is bent the top section is going to undergo compression and the bottom section will be stretched. It allows you to anticipate the bend deduction for a large variety of angles without having to rely on a chart. Mathematically bend allowance during sheet metal bending can be calculated as. A bending angle.

Calculate unfold size with bend allowance chart. The inside radii are based off of a standard air bend force chart. As shown in figure 1 below k t t. All other values are known to the user.

Bend allowance ba π 180 r k t a. While modern bend deduction charts now are reasonably accurate historically bend calculation charts both for bend allowances and bend deductions were notorious. Bending angle is 90.