....components to create final products. These can be smaller objects or full-sized buildings.
Fabrication shops get jobs by bidding on them. They will usually be given engineering drawings, but smaller shops may have customers who bring in ideas or sketches on a single piece of paper. If both parties are happy enough with a bid, the job is awarded. There are several ways in which a shop can add value to raw materials or components, including cutting, welding, forming and machining.
The clients of fabrication shops can include contractors, OEMs and VARs. The shops typically produce loose parts, structural frames for buildings or vehicles, stairs or other components (like hand railings) and anything else a client needs or wants that can be made out of metal.
Metal fabrication can be done largely by automated processes, but as the machinery to do this is expensive and extremely complex, there is usually a lot of labor involved, especially in smaller shops.
Though other common types of metalworking (machining, metal stamping, forging, and casting) may produce similar products, these processes are not classified as fabrication.
THE FABRICATION PROCESS
CUTTING
This entails sawing, shearing or chiseling, whether using manual or powered tools, torching using hand-held torches (oxy-fuel or plasma) or numerical control (CNC) cutters, such as lasers, mill bits, torches or water jets.
BENDING
This entails sawing, shearing or chiseling, whether using manual or powered tools, torching using hand-held torches (oxy-fuel or plasma) or numerical control (CNC) cutters, such as lasers, mill bits, torches or water jets.
ASSEMBLING
This entails joining pieces together through any of a variety of methods, including welding, binding with adhesives, riveting, using threaded fasteners such as bolts, or even bending the metal pieces into a shape that interlocks. Structural steel and sheet metal are common materials for fabrication.
FABRICATION IS LINKED WITH OTHER METALWORKING
Fabrication shops and machine shops offer several of the same services, but fabrication shops (fab shops) usually focus on metal preparation and assembly, and machine shops on machining parts on machine tools. Some shops operate as both machine and fabrication shops in one location.
Blacksmithing involves fabrication too, but usually involves older techniques and a focus on working iron by hand.
Weldments – welder-produced products – are examples of fabrication.
Boilermakers used to specialize in fabricating boilers, but with the advancement of boiler technology, the term is now used more broadly.
Millwrights were also more specialized in the past, setting up gran and saw mills, but now perform a broader range of services.
Iron workers, or steel erectors, often assemble prefabricated components, some of which are very large, and so they are also considered fabricators.
RAW MATERIALS
Fabrication materials vary widely, but some of the most common are plate metal, formed and expanded metal such as tube stock, welding wire and rods, and castings.
CUTTING AND BURNING
The most common method used to cut materials is shearing. Shearing uses large tools similar to scissors. Band saws are also used to cut metal. These have hardened blades capable of cutting metal without wearing down too quickly. Grinding wheel saws, often called chop-saws or abrasive cut-off saws, are also commonly used. Cutting torches can cut with less effort than most methods, but are expensive and require special fuel.
Some cutting torches are integrated into a table, called a burn table, which is computer operated (CNC) and usually powered by natural gas. There are also laser cutting tables, water jet tables, and plasma tables. Plate steel is placed on the table and the programmed arm moves around it, cutting as directed. Some tables have punch capability, which works like a high-powered cookie cutter. In some systems, robots move the cutting head in three dimensions, all the way around the cut material. These generally use plasma or laser cutting technology.
FORMING
Forming does not remove or add material from the raw material you start with. Instead, it applied force to bend and shape metal into the desired form. Punches and dies are used to control the final shape, and the amount of pressure applied depends on the type and thickness of material. This method is often used in conjunction with other methods of fabrication.
The benefit of this machinery is that many identical components or forms can be created, rather than each piece being hand-made and slightly unique, even if similar. The higher the spec necessary (in other words, the more perfect the copy has to be to suit the purpose), the higher the quality and precision of the machine.
MACHINING
Machining creates a specific shape by removing material from the original piece of raw material. Fab shops use mills, drills, and lathes, among other machines. Common items created using machining include bolts, screws, nuts and gears.
WELDING
The main technique used in steel fabrication is welding. It is an old technology, but has been greatly improved over the last several centuries. Parts are formed and machined, then tack-welded into place. Measurements are taken to ensure that everything is the right shape and size, and then the welder finishes the work, putting permanent welds in place.
The heat of welding can sometimes cause raw materials to warp, changing the shape from the specs needed by the original plans. Welders need a high level of skill to prevent this, but even then, getting it right may require redesigning the object to require less welding, using staggered welding techniques, covering the weld in sand to keep it stable, or even straightening the finished product with an acetylene torch after welding has been completed. This uses additional heat to correct bends, and requires significant skill on the part of the welder.
Steel weldments are often heated (annealed) in a low-temperature oven to relieve residual stresses, increasing reliability, durability, and strength.
FINAL ASSEMBLY
After the weldment has cooled, it can be sandblasted and painted or powder-coated. The finished product is then inspected for quality control, and if passed, can be shipped.
Contact us at www.weldersghana.com or call us at 027 011 3723 if you have any more questions or to get your metal fabrication works done
