Sheet metal design guidelines are followed to design quality product. This helps in delivering the product at low cost and time. All design guidelines can not followed in one part. Therefore exceptions can be there for complex features design. In this article we will discuss about design of sheet metal parts for manufacturing using press bending.
Sheetmetal are available in standard thickness. Sheet manufacturer provide sheets thickness in gauge. But designers design products considering sheet thickness in mm. You can use this guide to convert sheet thickness from gauge to mm.
Sheet Metal Material Selection
Sheet thickness calculation and material selection is done using simulation studies. You can use this guide to know more about sheet metal material selection.
Inside Bend Radius
Sharp inside bend radius are not recommended in sheet metal parts. Because Small inside bend radius can cause material flow problems in soft material and fracturing in hard material. Which results in localized necking or fracture.
Recommended inside bend radius shall be equal to material thickness. But for harder materials ( e.g. CRCA) it can be kept 0.65 times of thickness.
Bend radius throughout the design is kept constant to take the advantage of using same tool during manufacturing.
Minimum Bend/Flange Length Guidelines
Minimum Hole Diameter Recommendation
Hole/Slot Distance from Bend Edge
Center to Center Distance Between Two Holes
Effect Of Grain Direction in Sheet Metal Bending
During sheet metal processing ( rolling operation), sheet metal grains are arranged in the direction of rolling.
When Sheetmetal is bend perpendicular to rolling direction grain rearranges. That has negligible effect on part strength.
But bending parallel to rolling direction can leads to cracks because of destruction in grain structure.
Extrude Hole Size & Position Recommendation
Creating extruded hole using punching process requires extreme pressure/Force. Extruded hole close to the part edge can lead to sheet metal deformation or tearing. Therefore minimum distance between extruded hole to edge if maintained.
Round Emboss Design Guidelines
Creating Emboss feature using sheet metal punching requires extreme pressure . Very close emboss to the part edge, can lead to deformation of the metal.
A – Distance From Emboss To part Edge = 3T + D/2
B- Distance Between Two Emboss = (5 + D)
C- Distance between Emboss and Sheet Metal bend = 3T + R + D/2
Dimple Feature Design Guidelines
Louver Feature Design Guide
Minimum distance between louver feature and bending edge is maintained to avoid metal deformation.
(P1) Distance Between Two lowers on Shorter Edge = 5 mm
(P2) Distance Between Two lowers on Longer Edge = 8 mm
Round Knockout Design Recommendation
Minimum distance between knockout feature and bending edge is maintained to avoid metal deformation.
(P1) Distance Between Two knockout = (5 + D) mm
To sum up, sheet metal design guidelines are followed to ensure good quality, reduced cost and robust design. All design guidelines can not followed in one part. Therefore exceptions can be there for complex features design. We suggest you to check electronics enclosure design guidelines. This will give you an overview of complete enclosure design process.
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