Many products are made from sheet metal, which is nothing more than metal which is rolled into very thin sheets. Sheet metal can be made from any number of metals, including aluminum, titanium, copper, and brass. The thickness of sheet metal is called “gauge,” with a higher gauge number equivalent to the thinner thickness. The gauge required depends upon the use the sheet metal will be put to. Each used for sheet metal requires a specific thickness or gauge. A higher gauge number indicates a thinner piece of sheet metal.
Some products which use sheet metal include:
- Automobile bodies
- Wings and fuselage coverings on airplanes
- Roofing, gutters, ductwork other building materials
- Furnaces, air conditioners, and other appliances
Sheet metal is versatile, durable and strong. It can be easily shaped and fitted for both visual and functional benefits, which gives it a great advantage for use in manufacturing and building. It is the visual and functional uses that determine both the design and the fabrication.
While design and fabrication are two separate and distinct operations, the sheet metal designer must understand fabrication processes and requirements in order to provide workable designs. The fabrication process requires many complicated and sometimes dangerous processes. Proper attention to design can help to eliminate complications and reduce dangerous processes.
Typical Challenges with Sheet Metal
Ensuring that parts fit together seamlessly, bends are angled properly and counterbores and countersinks work are just some of the challenges faced when designing for sheet metal fabrication.
Bends are probably the most frequent feature of sheet metal parts and can be formed by a variety of methods and machines. Here are two tips that one of our sheet metal engineers shared with me:
- When multiple bends are on the same plane try and design the part so the bends all face the same direction.
- Avoid large parts when possible, and especially large parts with small or detailed flanges.
Counterbores and Countersinks require care to preserve the strength of the material and prevent deformation of the features during forming. For instance:
- The distance between two countersinks should be kept to at least 8 times the material thickness.
- To ensure strength the distance between a countersink’s edge and the edge of the material should be 4 times the material thickness.
- To prevent any deformation of the hole the edge of the countersink should be at least 3 times the material thickness from the tangent point of the bend.
3D CAD for Sheet Metal Design
3D CAD has helped to make sheet metal fabrication both easier and safer by enabling designers to visualize fabrication processes in virtual 3D, ensuring that parts fit together seamlessly, bends are angled properly and counterbores and countersinks work.
I’m not an expert at sheet metal design, but I do understand 3D CAD and know that using the right 3D CAD software package can make many design processes faster, easier and more accurate. One of the 3D CAD software packages that our engineers work with regularly is SOLIDWORKS.
We like the flexible design approach that SOLIDWORKS offers. For instance, when doing sheet metal design for customers we find that SOLIDWORKS lets us convert imported CAD models, which is important when we’re working with a client that has a design, or a partial design in another format.
Here are some of the sheet metal design tasks we routinely use SOLIDWORKS for:
- Generating Base, Edge, Miter, and Swept Flanges
- Generating bends, including Lofted Bends, Sketched Bends, and more
- Using Bend Tables for bend allowance/bend deduction
- Using Forming Tools to create features like ribs, louvers, lances, embosses, and extruded flanges
- Adding weld details to sheet metal parts on models or drawings
- Automatically flattening parts to generate flat patterns for manufacturing with bend compensation
- Automatically estimating sheet metal part manufacturing costs for our clients as we design