3D Hubs is the world's leading provider of 3D printing, CNC machining, sheet metal fabrication, and injection molding services. Engineers who use the 3D Hubs online manufacturing platform can access a free DFM analysis and generate an instant quote for their chosen manufacturing method.
Design for manufacturing (DFM) is a philosophy used to create viable designs that are easy to manufacture. DFM is particularly important for sheet metal fabrication, where small design flaws could result in cracks, tears, or unwanted bends in the metal. Following these essential DFM guidelines will result in parts that are strong, durable, and identical to engineering specifications.
Choosing the right manufacturing process
Sheet metal fabrication is just one of the many online manufacturing processes offered by online manufacturing shops. Before you order your part, make sure that you've selected the most efficient way to create that item.
Sheet metal parts are created by bending or cutting a sheet of metal which is usually no more than 6 millimeters thick. This process is well-suited for creating large, flat, or hollow metal parts. Soda cans, metal boxes, car doors, and similar structures are all made with sheet metal fabrication.
Sheet metal fabrication is not a good choice for three-dimensional objects with complex geometries. If the object is significantly thicker than a piece of sheet metal, has many fine details, or would require significant bending or sculpting to reach the desired shape, engineers should choose another manufacturing process instead.
CNC machining is a popular manufacturing choice that allows engineers to work with metal bars in different shapes and sizes. 3D printing can be used to create complex geometries out a variety of materials ranging from thermoplastics to metal. When large batches of identical parts are needed, injection molding services are almost always the most affordable option.
When uploading a design, engineers can compare all of these different manufacturing methods. The automatic DfM analysis will check the viability of the design against each chosen process, and engineers can choose the one that works for their part while meeting budget requirements.
Following basic DFM guidelines
Design for manufacturing (DFM) is an engineering philosophy that takes the limits of current manufacturing capabilities into account. Shapes that might be very easy to design in a CAD program aren't always possible to create with the chosen manufacturing process. Engineers should be aware of the specific tools that are available and the way that the material will react when those tools are applied.
No matter which manufacturing process you choose, there are several guidelines that are an essential part of DFM philosophy.
- Minimized part count: Lowering part counts reduces costs, encourages an easy assembly process, and increases the strength of the final design. Parts should be combined if they can be made from the same material, do not need to move relative to each other, and will not complicate assembly or maintenance if they are connected.
- Simple manufacturing: All designs should be easily completed with the chosen manufacturing process. In the case with sheet metal fabrication services, this means requesting bends, cuts, and perforations that can be easily performed with standard fabrication tools.
- Easy assembly: Most assembly is conducted after the parts are delivered by the manufacturer. Engineers can simplify the process and reduce assembly time by designing parts that have obvious orientations and fit together smoothly. Successful designs frequently include a large base part upon which smaller parts are attached.
In addition to these universal DFM principles, there are several specific guidelines that need to be followed when working with sheet metal. The thickness of the sheet metal is frequently taken into consideration.
- Hole sizes: Hole diameters should always be greater than the thickness of the sheet metal; if they are smaller, the punch may leave burrs or burnishes on the finished product.
- Hole location: Holes should be at least two thicknesses apart from each other and one thickness away from the edge. If the hole is near a bend, it should be 1.5 thicknesses away from the bend radius.
- Punch-to-die clearance: If there is no clearance between the hole punch and the die used to keep it in place, the metal will catch and pull as the punch is retracted. Engineered clearances and loose tolerances will reduce manufacturing costs and result in a smoother final product.
- Collars and coining: Designing collars or coins around punched holes will strengthen the metal and prevent collapse or cracking near the perforation.
- Bend relief: Bend reliefs are essential to prevent the metal from snapping or cracking when pressure is applied to the bend.
- Beads and chamfers: Placing a metal bead near a bend will reduce the spring-back effect and help the metal keep its shape after manufacturing.
- Grain structure: Engineers should be aware of the grain structure of the chosen metal sheet. Lugs and tabs that are created parallel to the grain have a tendency to tear when pressure is applied; instead, orient the lugs at a perpendicular angle.
- Bends at edges: Small bends or rims at the edge of a part will help keep the metal from tearing once it's in use.
- Corners and points: Avoid sharp corners or unnecessary points; these areas are the first to break when the object experiences pressure.
- Wall thickness: In general, maintain a uniform wall thickness across the entire design. Avoid thin walls, deep pockets, and other areas that could easily bend under stress or pressure.
- Clamping surfaces: If the final manufactured part will serve as a mount or an attachment, provide large mounting surfaces with plenty of room for the clamps to be attached. Remember to provide collars and support structures as needed.
Checking your work with a DFM analysis
After creating a part based on these DFM specifications, engineers should upload their design to the online manufacturing platform for a free DFM analysis. The intelligent software will automatically compare the CAD file to the requirements of the chosen manufacturing method, and any issues will be flagged for review or correction.
