6 Tips on Successful Sheet Metal Fabrication
Are you unsure how to approach your sheet metal fabrication project? If you fail, your entire project could be blown. Mistakes made during the fabrication process are often impossible to rectify.
If you want to avoid the pitfalls most novices face, learn from the experts before you begin. In the sections below you will find 6 tips from master fabricators. If you want to ensure your project goes off without a hitch, read on.
1. Pick the Right Material
Your material costs and labor costs are the most significant costs in metal fabrication. Plan to use stock sizes for your metal. It will save you up to 20% on metal costs.
You also must choose your metals carefully. Assuming size and thickness are comparable, as far as the raw material cost, Carbon Steel is your least expensive type of sheet metal flowed by Aluminum then Stainless Steel. More expensive choices include Brass & Copper
In regards to manufacturing cost, Aluminum is the lowest followed closely by Carbon Steel and Stainless Steel is the most expensive
If you have your heart set on a certain type of metal, ask yourself why. Is it a functional choice or a stylistic choice? If it’s stylistic, can you achieve the same results with powder coat, platings, anodizing or zinc-rich coating of industrial paint sheet metal fabrication needs?
If that’s the case, calculate the difference in price. It might just save you significant cost.
2. Limit Your Use of Tight Tolerances for Sheet Metal Manufacturing Designs
It is rare that more than a few surfaces of your design will be critical to your product’s function. Unfortunately, most inexperienced engineers build their prototypes using unnecessary tight tolerance call-outs on every dimension such as:
- Hole diameters
Unfortunately, the tighter call-outs you include in your design, the more expensive the finished product will cost. Instead of falling in this trap, only include features and surfaces critical to your project’s function.
Just think of it this way: if you want to fabricate a piece of sheet metal, a flat, unadorned sheet would be the least expensive. Each bend, countersink, hem, and the hole will increase the price. The more work you make for your manufacturer, the more you will have to pay.
Get back to the basics. Strip your design down to the bare minimum For your sheet metal manufacturing project.
3. Use a Stock Gauge for Sheet Metal Manufacturing
Once again, using a standard option will save you big bucks in the long run. Every sheet metal fabricator offers slightly different options. The most common sheet metal gauge for manufacturers runs up to one-quarter inch (6.35mm) thick. The thickness of the wall all depends on the project and the geometry of the part.
Thicker metals limit the angle of the bend you can achieve. If the bend is too sharp, not only is it difficult to achieve, it creates microscopic cracks in the metal. The cracks leave the metal brittle and easy to break.
You can also outright tear the metal. Many manufacturing machines are not set up to make such bends. You run the risk of expensive set ups and long production times.
If you want any complicated fabrication, just stay away from thick stock. Choose the thinner, more pliable metal.
4. Keep a Uniform Orientation to Your Bends
Fabrication machines have their limits. One of these is their inability to bend an object in a different direction without reorienting it first. Each time your manufacturer needs to physically adjust your sheet metal, it will cost you.
Instead, make sure all your bends located on the same plane bend the same direction. If you keep those bends the same radius, it will save you even more money. You might be surprised just how much the extra step in your bending and reliefs will cost you
5. Simplify Your Folds
In general terms, the more complicated your design, the more it will cost you. To save your pocketbook, simplify the angles you use in your bends. A good rule of thumb for best sheet metal folds is to choose a radius equal to, or greater than, the thickness of the metal you use.
Small bends on thick parts are less accurate than on thin parts. Avoid the small bends if you’re using thick parts unless they’re absolutely necessary. If they aren’t, head back to the design of your sheet metal fabrication process and see if you can work around them.
6. Other Quick and Dirty Rules to Sheet Metal Fabrication
Below you will find the most common specifications that novice fabricators mess up. Follow this quick and dirty chart and it will save you both money and hassle.
Minimum Clearance Between a Hole and Bend or Hem: Place holes at a distance at least equal to the radius of the Bend or Hem plus the thickness plus 2.5X the material thickness. Bend radii should be equal to, or greater than, the radius of the curl plus 6 times the thickness of the metal.
Keep the outside radius of your Rolled Hems (Curls) to at least twice the thickness of the metal.
Sheet Metal Fabrication Hem Styles
Hole Size: To prevent breakage of the punch the hole size must be equal or larger than the thickness of the material,
ideally 2-1/2 x the size of the hole
Flange Width: Should not be smaller than 4 times the thickness of the material
Bend Radius: This depends greatly on the material and the equipment; however the radius must be at least the thickness of the material.
Bend Relief: when bending a flange on the inside of the sheet metal edge a relief must be used so not to distort or tare the metal. The relief should be the length of the radius or greater and the width should be as this as the material or longer.
Countersinks: Separate each countersink from other countersinks by a distance equal to, or greater than, 8 times the metal’s thickness. They should also be separated from the corners by at least 4 times the thickness of the metal. They should be separated from a bend by at least 3 times the thickness of the metal or from an edge by 4 times the sheet metal thickness.
The depth of your countersinks should be no more than 3.5 times the thickness of your metal.
Tabs and Notches: Keep your notches at least one-eighth of an inch away from each other. If you bend the notches, they need to be at least 3 times the thickness of the metal plus the bend radius. Tabs need to be 0.04 inches away from each other or more.
As you can see, sheet metal fabrication can make for a tricky project. The key is to map out your needs, step by step. Start with the design of the final product and work backward, determining each step you need to accomplish that goal.
If you have more questions, or you would like to discuss your sheet metal fabrication with an expert, reach out to us today with any questions you might have or a DFM analysis on your concept.