DFMPro is an automated tool which supports several common sheet metal design guidelines which helps to produce parts economically at a better quality and shorter time. Some of the common sheet metal design guidelines include minimum distance between holes, cutouts, slots; distance between holes, cutouts, slots to part edge and bends; multiple bends in same direction, minimum bend radius; minimum radius of rolled hem, open hem and tear drop hem; minimum flange width; minimum size of slots, holes and many other design guidelines.

DFMPro provides flexibility to configure the available sheet metal rules. It also provides the ability to add new design rules requiring very basic programming knowledge.


Design guidelines for sheet metal

The section below contains examples of some design guidelines for sheet metal. These guidelines may help companies to avoid rejections and rework due to engineering errors leading to higher cost of quality and delay in the delivery to customer.


Sheet Metal Fabrication

Minimum distance between hole to part edgeSheet_Metal_Fabrication

Distance between hole to part edge is an important factor in sheet metal design. When punching holes very near to an edge, the edge will be pushed out by stress of punching the metal. This introduces variables in the accuracy of the hole location. For example, the ratio of the minimum distance between the edge of a counter bore hole and the edge of the part to the sheet thickness should be greater than or equal to 4.


Minimum_distance_between_holesMinimum distance between holes

Every punched hole introduces stress in the sheet metal. If a part has closely spaced holes, the sheet metal can expand causing unwanted variation between holes. An example for this rule is — the ratio of the minimum distance between two holes to the sheet thickness should be greater than or equal to 4.


Minimum distance between hole to bendMinimum_distance_between_hole_to_bend

If a hole is too close to a bend, the hole will distort during bending. The ratio of the minimum distance between the hole and a bend is recommended to be above 2.


Minimum hole diameter

If the diameter of hole is too small, the punch bends or breaks before it can be pushed through the material. If smaller holes are required, laser cutting should be used. The minimum hole diameter to be punched should be at least equal to the sheet thickness.


Multiple_bends_in_same_direction_partial_holesMultiple bends in same direction Partial Holes

For the ease of manufacturing, all the bends on the same plane should occur in the same direction.


Minimum bend radiusMinimum_bend_radius

A general guideline is to keep the inside radius approximately equal to the sheet thickness. However, depending on the material being used, this value may have to be increased; otherwise the part may crack during bending.


Note: The guidelines and related parameters mentioned above are only indicative and may change depending material, process and applications.
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