Sheet metal fabrication is the process of turning flat sheet metals, typically 0.15 mm to 10 mm thick, into parts and structures of various shapes. The stock materials for this process are flat metal sheets. Sheet metal fabrication is used to create objects such as enclosures, chassis, brackets, stamped features, curls, etc. It is also used for decorative purposes to make patterns in metal sheets.
For more sheet metal housesinformation, please contact us. We will provide professional answers.
The transition from stock material to the finished product usually requires one or more of the following three processes: material removal (cutting), deforming, and assembly. If all these processes are required, they are usually performed chronologically.
This involves cutting out pieces of the stock material to produce the desired shape. For maximum accuracy, speed, and efficiency CNC waterjet, plasma, and laser cutting technologies are usually employed. EDM (electrical discharge machining) could be also an option in some cases.
In laser cutting, a high-density laser beam is directed onto a workpiece to melt, vaporise, or burn through it, effectively cutting the material. Laser cutters are used for cutting, boring, and engraving. There are three types of lasers used in laser cutting; CO2 (carbon dioxide), Nd (neodymium), Nd:YAG (neodymium-doped yttrium aluminium garnet).
CO2 lasers have high energy efficiency and high power output ratio, and are used for cutting thin material, engraving, and boring. Nd lasers have high energy but low repetition efficiency. They are used for engraving, boring, and welding. Nd:YAG lasers have a very high power output and can cut thicker materials. However, they are more expensive to operate than CO2.
Laser cutters can work with aluminum, steel, copper, stainless steel, and other metals. They are best used for cutting thin workpieces (maximum thickness of 15 mm for aluminium and 6 mm for steel), engraving, and boring
Laser cutting icon animationIn water-jet cutting, a nozzle is used to focus a jet of water at very high pressures to cut a workpiece. For relatively soft material like rubber and wood, only water is used. A mixture of water and abrasive granular substances is used to cut harder material such as metals.
Waterjet cutting can cut material of various thicknesses. The maximum thickness that can be cut depends on the material. Of all CNC cutting methods, waterjet cutting is the most precise with tolerances between 0.05 mm and 0.1 mm. One of the reasons for its high precision is that unlike plasma and laser counterparts, waterjet cutting does not generate heat hence there is no heat affected zone in the workpiece.
Waterjet cutting is very versatile as it is used to cut hard material such as aluminum, steel, copper, stainless steel, and other metal alloys as well as softer materials like polymers, elastomers, wood, and foam.
Waterjet cutting icon animationPlasma cutting works by applying heat and energy to a gas to turn it to plasma. A jet of hot plasma is then accelerated using an inert gas or air, out of the cutting nozzle and onto the workpiece. The plasma completes an electrical arc with the workpiece, melting and cutting it. Being an electrical process, plasma cutters only work with electrically conductive material.
Plasma cutters can cut through very thick material, up to 300 mm for aluminium and 200 mm for steel, with a tolerance of 0.2 mm. Other materials that are processed using plasma cutters are stainless steel, copper, and other metal alloys. Depending on the complexity of the part to be produced, 2-axis or 3-axis cutters may be used.
Although plasma cutters are not as diverse or precise as waterjet and laser cutters, they are the best choice for thick electrically conductive metal parts, as they are faster and more cost-effective for cutting such materials.
Plasma cutting icon animationThis process is the controlled application of force to bend or form sheets into desired shapes. Deforming processes included bending, forming, stamping, and stretching using dies as well as hydraulic and magnetic brakes.
This is the process of joining various processed workpieces together to form a final product. Assembling processes include welding, brazing, riveting, and sometimes, the use of adhesives.
The most suitable metals for this process are aluminium and its alloys, steel, copper and its alloys, and stainless steel. The table below contains the most popular metal grades for sheet metal fabrication:
Common post-processing operations used in sheet metal fabrication are bead blasting, anodizing, powder coating, and painting. For deformed or welded materials, heat treatment is carried out to relieve residual stresses.
Sheet Metal Laser Cutting SteelSome of the benefits of sheet metal fabrication are as follows.
Any industry that makes use of metal parts would likely find the need for sheet metal fabrication. Some of the industries which employ the process are:
At Xometry Europe we offer high-precision, fast and quality sheet metal fabrication services for the creation of parts out of sheet metal such as aluminium, steel, copper alloys and many others. Using automated cutting technologies such as CNC laser cutting, plasma cutting, water-jet cutting as well as deforming and assembling technologies, we guarantee high precision and quality of ready parts.
We also carry out post-processing upon your request. To get an instant quote, upload your models on our instant quoting platform.
These basic guidelines for sheet metal fabrication include important design considerations to help improve part manufacturability, enhance cosmetic appearance, and reduce overall production time.
What is sheet metal?
Sheet metal is one of the shapes and forms that can be purchased. Sheet metal is any metal with a thickness between 0.5 and 6 mm.
Basic Principles
Sheet Metal Fabrication is the process of forming parts from a metal sheet by punching, cutting, stamping, and bending.
3D CAD files are converted into machine code, which controls a machine to precisely cut and form the sheets into the final part.
Sheet metal parts are known for their durability, which makes them great for end use applications (e.g. chassis). Parts used for low volume prototypes, and high volume production runs are most cost-effective due to large initial setup and material costs.
Because parts are formed from a single sheet of metal, designs must maintain a uniform thickness. Be sure to follow the design requirements and tolerances to ensure parts fall closer to design intent and cutting sheets of metal.
FORMING BASICS
Bending
Bending is a process whereby a force is applied to sheet metal which causes it to bend at an angle and form the desired shape. Bends can be short or long depending on what the design requires.
Bending is performed by a press brake machine that can be automatically or manually loaded. Press brakes are available in a variety of different sizes and lengths (20-200 tons) depending on the process requirements.
The press brake contains an upper tool called the punch and lower tool called the die between which the sheet metal is placed.
The sheet is placed between the two and held in place by the backstop. The bend angle is determined by the depth that the punch forces the sheet into the die. This depth is precisely controlled to achieve the required bend.
Standard tooling is usually used for the punch and die. Tooling material includes, in order of increasing strength, hardwood, low carbon steel, tool steel and carbide steel.
Parts to be bent are supplied as flat patterns with bending information. Sometimes bend positions are etched with bend notches, or these notches can be cut out to show the benders where to bend.
Once the laser has cut the flat parts out they can be sent for bending. A press brake forms the flat pattern into a bent part.
CRITICAL DIMENSIONS
The following are some terminology that are used in sheet metal. Designers need to adhere to machinery guidelines when designing for bending. Bends can be characterised by these parameters. Some critical dimensions that need to be considered when setting up sheet metal in CAD software are sheet metal thickness, the k-factor and bend radius. One needs to check that these factors are consistent with the tooling that will be used in manufacturing. This guide gives important guidelines for good design practice.
For more information, please visit Steel Structure Seafood Storage.
Bend line– The straight line on the surface of the sheet, on either side of the bend, that defines he end of the level flange and the start of the bend.
Bend radius – The distance from the bend axis to the inside surface of the material, between the bend lines.
Bend angle – The angle of the bend, measured between the bent flange and its original position, or as the included angle between perpendicular lines drawn from the bend lines. Sometimes specified as the inside bend radius. The outside bend radius is equal to the inside bend radius plus the sheet thickness.
Neutral axis – The location in the sheet that is neither stretched nor compressed, and therefore remains at a constant length.
K-factor – The location of the neutral axis in the material, calculated as the ratio of the distance of the neutral axis T, to the material thickness t. The K-factor is dependent upon several factors (material, bending operation, bend angle, etc.) and is greater than 0.25, but cannot exceed 0.50. K factor = T/t
Bend allowance – The length of the neutral axis between the bend lines or the arc length of the bend. The bend allowance added to the flange lengths is equal to the total flat length.
K-Factor
The K-factor is the ratio between the the neutral axis to the thickness of the material.
Importance of the K-factor in sheet metal design
The K-factor is used to calculate flat patterns because it is related to how much material is stretched during bending. Therefore it is important to have the value correct in CAD software. The value of the K-factor should range between 0 – 0,5. To be more exact the K-factor can be calculated taking the average of 3 samples from bent parts and plugging the measurements of bend allowance, bend angle, material thickness and inner radius into the following formula:
WALL THICKNESS
Parts need to maintain a uniform wall thickness throughout. Generally capabilities of of 0,9mm – 20mm in thickness are able to be manufactured from sheet (<3mm) or plate (>3mm) but this tolerance depends mainly on the part.
When considering sheet metal thickness, a single sheet with punches (holes) is a good rule of thumb. Some features such as countersinks are doable but counter bores and other machined features are difficult to produce as they require post machining.
BEND RADIUS
Sheet metal bend brakes are used to bend material into the parts desired geometry. Bends that are in the same plane need to be designed in the same direction to avoid part re orientation, to save both money and time.
Keeping the bend radius consistent will also make parts more cost-effective. Thick parts tend to become inaccurate so they should be avoided if possible. Small bends to large.
SPRINGBACK
When bending a piece of sheet metal, the residual stresses in the material will cause the sheet to springback slightly after the bending operation. Due to this elastic recovery, it is necessary to over-bend the sheet a precise amount to achieve the desired bend radius and bend angle. The final bend radius will be greater than initially formed and the final bend angle will be smaller. The ratio of the final bend angle to the initial bend angle is defined as the springback factor, KS. The amount of springback depends upon several factors, including the material, bending operation, and the initial bend angle and bend radius.
To prevent parts from fracturing or having distortions, make sure to keep the inside bend radius at least equal to the material thickness
A +/- 1 degree tolerance on all bend angles is generally acceptable in the industry. Flange length must be at least 4 times the material thickness.
It is recommended to use the same radii across all bends, and flange length must be at least 4 times the material thickness.
MINIMUM BEND RADII, R
Minimum bend radii requirements can vary depending on applications and material. For aerospace and space applications, the values may be higher. When the radius is less than recommended, this can cause material flow problems in soft material and fracturing in hard material. Localised necking or fracture may also occur in such cases. It is recommended that minimum inner bend radius should be at least 1 times material thickness.
MINIMUM FLAGE LENGTH, b
This is the minimum length of the The bend must be supported all the way until the bend is complete the flange must be long enough to reach the top of the die after it’s been fully formed. Brake press operators should know the minimum flange lengths for their tooling before attempting bends that may not work and while it is possible to calculate the minimum flange having an Air Bend Force Chart on hand certainly makes it more convenient.
MATERIAL THICKNESS, t
The thickness of the material is not proportional to the tonnage like the v opening. Doubling the thickness does not mean doubling the tonnage. Instead the bending force is related by the square of the thickness. What this means is that if the material thickness is doubled the tonnage required increases 4 fold.
WORK PIECE LENGTH, L
Like the v opening the tonnage required is directly related to the length of the work piece. Doubling the work length means doubling the required tonnage. It should be noted that when bending short pieces, under 3” in length, the tonnage required may be less than that which is proportional to its length. Knowing this can prevent damaging a die.
Published in an online article on Geomiq.
If you want to learn more, please visit our website light steel villa price.