The Significance of Flat Layout in Sheet Metal Design

How flat layouts can ensure convenient manufacturability of sheet metal parts

Continuing with the last article about sheet metal design guidelines, in this writeup we look at typical issues with the “Flat layout” of a sheet metal part. The designer should give more attention to the flat layout of the part during design. On the shop floor, the manufacturing process is typically selected based on the availability of tool, machine and material. Additionally, feature parameters and locations will also determine the choice of process.

Take a look at the following sheet metal part & its flat layout shown in Fig. 1.0. Internal flanges, tabs as shown in Fig 2.0 and their associated width “W” decide whether the part can be stamped, laser-cut, or punched/nibbled from the sheet stock. Very small width “W” can be manufactured with laser cuts and which is more expensive as compared to simple punching.

DFMPro checks such a design error which may add to the operation cost of the part.

Minimum Width of Cutout

The designer should maintain the minimum width of cutout based on sheet thickness which ensures that the cutout can be manufactured with a simple punching operation rather than laser cut. General guideline suggests that minimum width of cutout should be 2 times sheet thickness.

The second advantage of the flat layout will be an interference check. Many a times, the designer creates a part using design features in the bent state but misses to check the flat layout of the part where interference between flanges may be introduced. DFMPro assists the designer by checking the flat layout interference and avoiding rework and downstream issues.

Flat Pattern Interference Check

This rule internally flattens the part and find out the interfering regions – at the same time the rule also ensures minimum clearance between flattened areas which again helps confirm whether the part can be punched rather than cut by laser or water jet.

Preferred Sheet Sizes

A flat layout helps in material planning to minimize shop floor inventory and standardize the shop floor sheet sizes.  While designing a sheet metal part If the designer knows the availability of typical sheet sizes available on the shop floor this information can be effectively used to minimize inventory overheads and material wastage. Manufacturing team can configure the standard sheet sizes & the rule will check if the part can be manufactured with the available standard sheet sizes.

Where

CL & CW = Trimming Clearance

Recommended Enclosure Sizes

When it comes to two or more closed open bend <Enclosure, U channels >, the designer should know the sequence of bends & maximum depth limit of the flange taking consideration of machine parameters like bed & punch sizes. Many a times, a higher flange height may be specified which may lead to rework on the shop floor. During manufacturing, the first flange can easily bend however for the second bend the flange interferes with the punch as shown in Fig. 3.0. DFMPro identifies such potential shop floor issues at the design stage.

Was this helpful? Want to know more about ways to address real shop floor issues? Stay tuned for upcoming articles.