Everyone interacts with metal objects on a daily basis, yet few people stop to think about how they are made. Welding, bending, machining, there are plenty of ways to shape metal. Maybe you have a project you want to complete with metal, but can’t picture the process or how much work goes into it. Teems mechanical experts are sharing an introduction to what’s involved in the process of metal fabrication.
What is metal fabrication
Putting it in simple terms, it is the process of taking a piece of metal, like a block or a sheet, and turning it into something useful. There are many processes that allow a fabricator to do just that. There is usually more than one way to achieve the same end product, so it’s up to the craftsman to decide which technique best suits the project at hand.
Often times a machinist will see a project, and will have to decide between milling a block or running it through a turning machine or lathe first. Picking the “wrong” choice can mean dozens of hours unnecessarily added to a project. So an experienced machinist can save you hundreds or thousands of dollars. We’ll do a short explanation of what each of these processes consists of.
Milling and machining
When milling, the workpiece stays stationary, and the tool rotates at high speeds to cut the material. This allows mills, drills, and many other types of tools to cut away the metal and shape it into the desired form. Since the invention of computer numerical control machines (CNC) in the ’60s, milling machines evolved into machining centers.
Old milling machines required an operator to manually move the tool one axis at the time. Some of the most experienced master machinists could move the tool on two axes at the time at the most.
Servo motors and computer controls allow modern machining centers to move the tool in all the machine’s available axes simultaneously. While in the past, they used to be limited to three, modern machines are now usually equipped with five axes of motion. This allows for far more complex work done in considerably fewer hours and using unskilled operators.
Turning the workpiece
When a piece is run through a lathe or turning machine, the tool does not rotate like in the milling process. Instead, the workpiece rotates at high speed, and the tool moves in two axes, cutting into it and reshaping it.
This process is usually considerably faster than using a milling machine. However, it is far more limited in what endproducts it can achieve. Because the workpiece is rotating, running it through a lathe will always result in a cylindrical piece. Even though it is faster than milling, using a turning machine alone will probably not be enough to achieve your desired product. They are often used together with machining centers. Turning the piece first to approximate it to the final product, and then milling it the rest of the way. Doing this usually saves both time and money.
Sheet metal working
Sheet metal is probably the most common metal form an average person interacts within their daily lives. Everything from a car’s body, to appliances, shipping containers, etc. is done by working on sheet metal.
There are many things you can do with it, cut it, bend it, weld it, rivet it, etc. Just like machining, choosing the right technique can save your project countless manhours.
For example, when building a metal container that’s supposed to be watertight, bending it its always preferable than welding or riveting it. For example, building a metal box by cutting six squares and then welding them all together is highly inefficient. You would have to spend a lot of time welding everything together. If the sheet metal isn’t thick enough to sustain the heat, it will deform the material. It also gives you more failure points, where the welding can fail, and water or gasoline could leak through it. If you instead bend the material to create two “c” shaped pieces and then weld them together, you can save yourself a lot of work by having to weld less, and you now have fewer points of failure. It is little details like this why getting an experienced fabricator can help you save costs and time.
Welding and riveting
Welding is the process by which two pieces of metal are fused together, using heat to melt a filler material at their boundaries.
Riveting uses a permanent mechanical fastener to join two pieces of sheet metal together. The rivet is introduced through a hole drilled on both pieces and then it’s deformed to safely secure them both in place.
Riveting is especially useful when trying to fuse two pieces of different materials. For example, fusing an aluminum sheet to a stainless steel one can prove difficult. It is usually faster and cheaper to use rivets to fuse them together.
Sheet metal stamping or deep drawing
Metal parts can also be formed by using a press to stretch the material into a cavity, which is the negative of the desired form. This process is called deep drawing or stamping.
This process can create box and bowl shapes items very fast and precisely. It has the advantage of needing no welding or rivets, which means its more likely to be watertight. It is more practical to use with ductile materials like aluminum, copper, brass, etc.
This is the metal fabrication process commonly used to create car bodies. It is what allows them to be built so fast on such a massive level of production. Using it, thousands of pieces can be produced every day that would take hundreds of manhours if they were milled or cast instead.
The downside to this metal fabrication method is the upfront investment. It requires very expensive machinery and a new “mold” for every piece. The mold needs to be machined using a machining center. Because of this, it takes a considerable amount of time and money to manufacture.
Our machine experts here at Teems Electric are here to help make your next metal project a reality. Get in touch with us today to learn more about the services we offer and see how we can meet your needs!