Metal Forming

What Is the Difference Between a Round Bar, a Drill Rod, and a Shafting?Metals are made in different shapes and sizes. Pipe and tubes look similar but somewhat different properties and use.Round bar, drill rod, and shafting are also forms of round shapes. Round BarA round bar is a long, cylindrical metal bar that is just as it looks. Round bar is available in a number of plastics, from hot rolled or cold rolled steel, stainless steel, titanium, alloy steel, brass, and more, and in a wide range of diameters from 1/4′′ to 24”. Aluminum Round BarsAluminum round bars are lightweight and corrosion-resistant, and they’re simple to mill and cut. The most use of aluminum round bars includes is trim, shafts, brackets, pins, and dowels are all popular uses for aluminum round bars.Brass Round BarsWhen power, electrical conductivity, corrosion resistance, and spark resistance are needed, brass round bars are used. When brushed, brass has an enticing sheen and is easy to machine. Sea hardware, instruments, fasteners, and fixtures are a few instances of brass bar uses.Stainless Steel Round BarsHot and cold rolled are the two types of SS Round bars. Hot rolled round bar is commonly used in building applications where a perfect finish and exact dimensions aren’t needed. Cold rolled round bar, on the other hand, is used for applications that require a superior surface finish and precise dimensions. Frameworks, supports, braces, shafts, and axles are all typical uses for steel round bar. Stainless Steel Round Bars are high corrosion resistant. The stainless steel can withstand elevated levels of acidity and can be used in chlorinated or alkaline conditions.Drill RodsDrill rods are made of tool steel that has been ground to a precise diameter resistance. Drill rods are usually oval, but they can also be made in square shapes. They are often tempered before being machined. This procedure entails heating the steel to soften it and make it more workable. Until machining can begin, the steel is air cooled. Drill rods are commonly used to make drill bits, taps, dowel pins, shafts, and reamers. They are also used in the production of hammers, files, and punches.There are 2 types of Drill rods Water Hardened Drill RodsWater hardened drill rods are less alloyed than oil hardened drill rods, allowing them to be machined more quickly. The rod is heated until it glows red and then immersed in a vat of water to cool during the water hardening process. As a result, a hard, robust metal that is easily machined is made. It is not, though, appropriate for welding. Drill rods that have been water resistant are used in the production of hammers and files.Oil Hardened Drill RodsWater hardened drill rods are less alloyed than oil hardened drill rods, allowing them to be machined more quickly. The rod is heated until it glows red and then immersed in a vat of water to cool during the water hardening process. As a result, a hard, robust metal that is easily machined is made. It is not, though, appropriate for welding. Drill rods that have been water resistant are used in the production of hammers and files.ShaftsShafting, also known as Turned Ground and Polished Shafting, is a term used to describe circular bars that are manufactured with fine quality and accurate steel. They are brushed to ensure that the surfaces are smooth and absolutely straight. The production process is engineered to achieve exceptionally tight tolerances for surface finish, roundness, hardness, and straightness, resulting in a long service life with minimal maintenance.Shafting bars are often used in high-accuracy applications such as temperature measurement instruments, laboratory equipment, high-speed motor shafts, drive shafts, pump shafts, and ball bushings. The bar is often expected to rotate at full speed in these situations. As a result, extreme straightness is crucial to prevent excessive vibration and bearing wear. Induction hardening is used to harden the shaftsInduction hardening is a non-contact heating method that employs electromagnetic induction to generate the required heat. A strong alternating magnetic field is applied to the material, causing an electric current to pass through the metal and generate heat. The steel’s heart remains unaffected and maintains its physical properties throughout this process. The steel is then quenched in water, oil, or a special polymer, causing the surface layer to develop an incredibly hard martensitic structure.

What Is the difference between Hole Punching, Notching, and Drilling?Plate and Sheets undergo a variety of operation during its fabrication, all this is needed to fulfil a certain requirements. Material removal is a method of fabrication process that is widely used. Hole punching, notching, and drilling are three different methods of material removal processes. Although it has many similarities, but the difference between them should be understood. Understanding the difference between Hole Punching, Notching and Drilling. What is meant by Hole Punching?Hole punching is a shearing process used create gaps in the sheets and covers. Hardened tools which have a sharp edges are used in hole punching to shear out the unnecessary material or product by applying, electrical, hydraulic, pneumatic force or even manual power. Hole punching tools are found in variety of shapes and sizes. Advantages of Hole PunchingHole punching has several benefits over most types of content removal. One major advantage is its speed.All types of hole punching presses are moderately fast, but others, such as servo-driven presses, are incredibly fast. As compared to other hole-creating methods, this gives hole punching an even greater benefit in cycle time length.Since hole punching relies on shearing force rather than sharp tool movement, the tool does not have to be round.Hole punching can be used to make circles, triangles, ovals, and a variety of other shapes.Limitations of Hole PunchingHowever, there are certain drawbacks to hole punching. Tool wear will cause problems on the process by leaving huge burrs and badly formed holes.The thickness of material that can be pierced with a hole punch is also reduced. The thickness of the hole that may be punched depends depending on the material and the depth of the hole being punched.Hole punching is a popular technique used in high-volume sheet metal welding, such as vehicle parts, aero plane frames, and decorative work.What does Notching mean?Another process to remove extra material from sheets and plates is done through Notching them. Notching is also a shearing process like hole punching. Notching also necessitates the use of hardened, sharpened tools. Notching differs from hole punching in terms of where the process is carried out. Although hole punching may be done within the diameter of a piece of sheet stock or plate, notching is only done on the material’s outer edges. Notching is usually used prior to bending or shaping operations. Advantages of NotchingNotching has advantages and limitations same as of Hole Punching, since both methods use presses and rely on shear force to break the material on which the work is being done.Notching is simple, and shapes can be modified by simply switching out the notching tool.Limitations of NotchingNotching, is widely used in sheet metal manufacturing as hole punching. Common uses include those in which sheet metal will be bent or mechanically moulded in some way.What does Drilling mean?Drilling among the three methods that does not require shearing. Drilling is the process of removing material by using a drill bit. Drill bit is a long, sharp instrument, often with flutes, but it may have a variety of features depending on the work. As friction is applied to the drill bit, it turns quickly, and the cutting edges extract a small amount of material from each rotation. The force applied to a drill is often applied using a drill press; however, other equipment, including hand drills, may be used. Advantages of DrillingDrilling differs from hole punching and notching in that it involves drilling into the substrate by repeatedly scraping layers of material using a spinning tool with a sharp cutting point.The skill of scraping layers of material sequentially rather than all at once results in less component distortion.Limitations of DrillingOn the negative side, drilling geometry is limited.Drilling should only be used to make circular holes because it involves rotation.Drilling often allows more heat to be applied to the material than hole punching or notching.

Steel Melting & Refining Stainless Steels are usually melted by charging scrap and alloying elements (e.g. ferrochrome, ferronickel) into an EAF. After the initial melting the metal is transferred to an AOD or VOD/VD vessel for refining. Advanced steels for demanding and critical applications require vacuum melting in a VIM furnace followed by VAR or ESR remelting.  Primary Melting Electric Arc Furnace (EAF)Stainless steel is usually produced in an EAF. Scrap and various alloying elements (e.g. ferrochrome, ferronickel) are charged into the vessel. The charged material is heated by an electric arc (by passing current through carbon electrodes) until the metal is melted. An EAF also allows to charge 100 % scrap but in this case it is difficult to control the exact chemical composition. the typical tap-to-tap times are, depending on the power of the transformer and vessel size, between 50 – 80 minutes. Induction Furnace (IF)This is an electric furnace using electromagnetic induction to heat the charged scrap. This process for melting stainless steel is widely used in India and China because investment costs are lower than in an EAF. The major drawback of an IF is the lack of refining possibilities and size limits. The quality of the melted steel heavily depends on the quality of the charged scrap which should be clean of oxidation and the chemical composition must be known. As IF's tend to be smaller than EAF furnaces, their productivity is limited. The biggest IF’s are today 50 t while state of the art EAF’s are 3 times bigger (150t). Vacuum Induction Melting (VIM)This is a melting process under vacuum conditions using electromagnetic induction. It is used for the melting of high purity metal and alloys.   Secondary Melting / Refining Argon Oxygen Decarburization (AOD)This is a special converter, in which the carbon content of the stainless steel heats is reduced to the targeted specifications by injection blowing of argon and oxygen mixtures. Also final alloy additions can be made in the AOD to reach the exact chemistry. Usually this vessel is also used to ‘build up’ the liquid steel volume by approx. 10%. AOD’s provide a better Cr yield than VOD’s. Ladle Furnace (LF)This furnace is positioned between the melting and continuous casting facilities. It is used to exactly adjust the steel temperature and composition to meet the casting demands. It can also be used to transfer metal between the primary and secondary melting units and a ‘bumper vessel’ to build up volume for sequence casting. Ladle furnaces have a power supply via electrodes and are able to slightly increase the liquid steel temperature if required. Vacuum Oxygen Degassing (VOD) / Vacuum Degassing (VD)This process reduces the gas content, particularly hydrogen and carbon, as well as reducing non- metallic inclusions by subjection the molten metal to a vacuum. VOD’s and VD’s are used when very low C-contents have to be reached. Vacuum Arc Remelting (VAR)This is a secondary melting process where steel ingots (also called electrodes) are slowly remelted by an arc under vacuum to produce advanced steels and superalloys for the most demanding and critical applications, e.g. for aerospace or nuclear applications. Electro Slag Remelting (ESR)This is a process used for the remelting and refining of steels and special alloys which are used for critical applications e.g. in medical implants, aerospace components or power plants. Like VAR, the ESR process involves remelting electrodes, but a slag pool instead of a vacuum is used to isolate the melt from the atmosphere.CastingAfter melting, the liquid metal is either cast directly into slabs, blooms or billets in the continuous casting process or into blocks/ingots in the ingot casting process. Continuous CastingThe melted steel from the ladle furnace is cast directly into semi-finished shapes (slabs, blooms or billets). It is a casting process for the continuous, high-volume production of metal sections with a constant cross-section. It allows lower-cost production of metal sections with better quality, due to automated control throughout the process. Ingot CastingThe melted steel is poured into an ingot mould. After the metal solidifies into ingots, the moulds are stripped. Ingots are required to produce large forgings but they can also be transferred into slabs, blooms, or billets on a roughing mill. Ingot casting is an economic solution for producing small volumes of a specific alloy but not recommendable for high volume production of commodity steels due to lower yields compared with continuous casting.

Thermomechanical treatment of surface CarburizingThemomechanical treatment which is applied to a low-carbon steel in the austentic state to obtain surface enrichment with carbon which is in solid solution in the austenite. The subsequent hardening results in a hard and wear-resistant surface. NitridingIntroducing nitrogen into a solid ferrous alloy by holding steel at a suitable temperature (below Ac1 for ferritic steels) in contact with a nitrigenous material, usualy ammoins or molten cyanide of apropriate composition. Contrary to carburization and carbonitriding, hardening is not obtained by a subsequent quench hardening treatment. Quenching is not required to prouce a hard case. CarbonitridingIntroducing carbon and nitrogen into a solid ferrous alloy by holding above Ac1 in an atmosphere that contains suitable gases, such as hydrocarbon, carbon monoxide and ammonia. The carbonitrided alloy is usually quench hardening

What Is Penetrant Inspection (FPI And LPI)? Penetrant inspection is a popular detection method because it is relatively inexpensive, can be done remotely, and can be administered on a surface that is oriented in nearly any direction.  Penetrant Inspection may take the form of Fluorescent Penetrant Inspection (FPI) or visible Liquid Penetrant Inspection (LPI).  Each has its advantages, so the selected method will be based on an internal or customer specification, or the type of part being examined.  For example, FPI is often used on aircraft parts, while LPI is frequently used on machined surfaces, although neither alloy type nor product size limits which method is used. Penetrant InspectionIn the early 1900s, the railroad industry pioneered the oil and whiting penetrant inspection method using an oil solvent (the penetrant) and whiting or chalk coating (the developer) to detect imperfections. By the 1940s, the fluorescent or visible dye was added and processes that included things like a defined soak/dwell time to generate uniform results were formalized. Rules and specifications governing materials, process, training and certification of personnel have evolved over time.  An essential element of that has been the development of specifications that define what acceptance limits are.  That is, what differentiates between indications that are revealed during penetrant inspection that are critical, and which are not relevant?  The customer will define and dictate that in the spec. A limitation of penetrant inspection is that the defect or discontinuity must be open to the surface.  Penetrant materials range in sensitivity and are developed and chosen to match the nature of the part surface and desired detectability of flaws.  Highest sensitivity levels for demanding applications are used in a way that balances part manufacturability with engineering or performance needs.   Industry standards dictate how the process is managed to generate repeatable consistent results.  In general:  The penetrant method and sensitivity level are determined.  The part is cleaned with specified cleaners and allowed to evaporate dry.  Penetrant is sprayed or brushed on and allowed to dwell for a specified amount of time.  After rinsing, the part is again dried, perhaps with a lint free paper towel, or may be oven dried.  A white developer is then sprayed on the part, which acts like a blotter to draw penetrant from the discontinuity and appear as a contrasting color.  After a specified dwell time, the part is inspected using a black light for FPI or other appropriate lighting for LPI.  Any indications found are measured to determine if they constitute a rejectable defect.  As a reliable non-destructive means to discern potential defects in metal components, the various penetrant inspection methods are widely used.  Appropriate process controls are needed to ensure the reliability of the tests, and highly trained inspectors are a key part of that. 

What Is Pitting Resistance Equivalency Number (PREn)? The Pitting Resistance Equivalency Number (PREn) is an objective way to do an initial comparison of the relative resistance to corrosion of various metals. It is based on a calculation that considers the weight percentage of alloying elements. PREn = % Cr + (3.3 x % Mo) + (30 x % N) A simple examination of the components of the PREn calculation indicates those alloys that contribute to corrosion resistance. Chromium, Molybdenum and Nitrogen are all included because their presence in the alloy grade, in combination, contributes to corrosion resistance.  Sometimes Tungsten is also included in the calculation because of its contribution to pitting resistance. As there are ranges of alloy percentages that define the alloy grade (MetalTek 304, for example contains 18-21% chromium), the PREn calculation also is a range. PREn ranges of 40 typically describe the Super Duplex or Super Austenitic families, describing a higher concentration of the key elements and, in the right conditions, more corrosion resistance. A few common alloys and their PREn values:GradeTypical PREn30417 – 2131623 – 29220531 – 38254 SMO42 – 48 

How to produce thin wall stainless steel tube? What is thin Wall Tubing?Thin Wall Tubing Thin wall tubing is precision tubing that typically ranges from . 001 in. (. 0254 mm) to about . 065 in. Deep-drawn seamless tubes are made from metal blanks in multiple deformation processes. They can be used for different industrial purposes and the manufacturing of metal bellows. Common materials for the production of our seamless metal sleeves and thin-walled tubes are stainless steels. Those materials come with different attributes that have to be considered in the selection to perfectly meet the application’s requirements. How is stainless steel tubing made?The tubing is manufactured through an extrusion process where the tube is drawn from a solid stainless steel billet and extruded into a hollow form. The billets are first heated and then formed into oblong circular molds that are hollowed in a piercing mill. How deep-drawn thin wall seamless tubes are made?The production of our thin-walled tubes starts with a metal strip that undergoes several sheet metal forming processes.1. Hot rolling line to punch the stainless steel tube blank2. Either soap or oil is used for each operation as lubricant to ensure smooth movements3. Depending on the used material and the designated final size of the tube, it has to be deep-drawn through multiple dies with decreasing diameter, wall-thickness decreases4. Annealing (in vacuum furnaces) after each plastic deformation process to restore the elasticity of the materialSpecial washing machines are used continuously in order to achieve an immaculate surface.If thin-walled stainless steel tubing is requested, our customers benefit of efficient multi-drawing technologies. we follow a sustainable approach. Due to our closed water circuits, eco-friendly technologies, and installed oil traps, we ensure that no pollutants are released into nature. why thin wall stainless tubes with very low tolerances?We are specialized in the manufacturing of seamless tubes with extremely thin wall-thickness. To guarantee a leak-free welding line with the “weld-end”, a consistent dimensional accuracy of the wall is needed. As an experienced precision bellows manufacturer, we are able to hold such very low tolerances, ensuring max. 0.1-0.4 mm tolerance in diameter and 0.004- to 0.015 mm in wall-thickness. The hydraulic presses allow maximum production lengths of up to 450mm and diameters of ca. 70mm. The closed bottom of our seamless cups and tubes can be designed in customized shape and also the open side may be formed to meet individual requirements. It is also possible to create holes in the bottom – for example stainless steel cups (bonnets) as housing for measurement and controlling devices Seamless vs. welded precision tubingSeamless thin walled metal tubes up to 450mm lengthWhile it is often almost impossible to distinguish a seam-welded from a seamless tube with the naked eye, there are some significant differences of stainless steel tubes that matter when it comes to ultra-precise applications. Welded tubes are made from a roll-formed metal strip. The welding process results in an inhomogeneous tube wall that has to be reworked first. Due to different working standards, the quality of the weld area can show great variances in the final product, resulting in a lesser reputation for welded tubes compared to seamless tubes. Since deep drawn seamless tubes are intermediate products in our manufacturing of metal bellows, we do only provide results in a smooth and homogeneous surface. Our seamless precision bellows are key components in highly sensitive systems. Their spring rate must exactly meet the requirements, e.g. for actuators and sensors in cars and aircrafts around the world, Why Thin Wall Thickness Tubes Difficult To ProduceWhy it is difficult to produce stainless steel seamless tubes with thin wall thickness?We get one order on June 13th, 2014, Stainless Steel Seamless Tubes, ASTM A213 TP304, Outside Diameter size in 23mm, Wall Thickness in 1.19mm, minimum wall thickness, length in 16400mm and 16650mm, Bright Annealing. The total quantity in 7 tons. At first, I treat this order as small order. The expected finished time is within June 30th. But after we start the production, I find it is not so easy as it looks like.In order to ensure the stainless steel tubes quality, we can't compress our production period. July 7 - 8th is the earliest time we finished the production.Even it is only 7 tons tubes. base on below reasons, the production velocity very slow:1. Wall thickness of the steel tubes very thin. The speed of cold rolling should be controlled. Only 500KG/day, so that LG-30 cold rolling cost 14 days!2. The length of steel tubes longer than 16000mm. The handle for degreasing will be slow.3. Shipment of condition of the steel tubes in bright annealing. (If Pickle annealing, we can choose cold drawn, cold drawn will be much sooner than cold rolling.)4. Outside diameter size of the tubes in 23mm, it is non-conventional size. We need make a new molding, and we only have 1 molding, because it is only 7 tons, we need save cost for our customer.Base on above reasons, the production speed very slow. By the way, if you have orders with OD size 23mm, we can produce for you in lower cost and high quality. Because we have OD 23mm cold rolling molding, the molding cost more than USD 1200. So we can cold rolling the tubes for you.Base on the same reason, we have 16mm, 18mm, 19mm, 19.05mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm, 25.4mm, 26mm, 27mm, 28mm, 30mm, 32mm cold rolling molding etc. 

The difference between a pipe, tube, and hollow barMany people ask us the difference between a pipe, tube, and hollow bar so we’ve made this to explain the difference.  What is the difference between Pipe and Tube?The short answer is: A PIPE is a round tubular to distribute fluids and gases, designated by a nominal pipe size (NPS or DN) that represents a rough indication of the pipe conveyance capacity; a TUBE is a round, rectangular, squared or oval hollow section measured by outside diameter (OD) and wall thickness (WT), expressed in inches or millimeters.Overall, the difference is the application and the way they are measured. What is Pipe?Pipes are typically used to transfer liquid or gas, and are constructed to withstand high pressure. Pipes are always round. boiler pipe Pipe is a hollow section with round cross section for the conveyance of products. The products include fluids, gas, pellets, powders and more.The most important dimensions for a pipe is the outer diameter (OD) together with the wall thickness (WT). OD minus 2 times WT (SCHEDULE) determine the inside diameter (ID) of a pipe, which determines the liquid capacity of the pipe.EXAMPLES OF ACTUAL O.D. AND I.D.ACTUAL OUTSIDE DIAMETERSNPS 1 actual O.D. = 1.5/16" (33.4 mm)NPS 2 actual O.D. = 2.3/8" (60.3 mm)NPS 3 actual O.D. = 3½" (88.9 mm)NPS 4 actual O.D. = 4½" (114.3 mm)NPS 12 actual O.D. = 12¾" (323.9 mm)NPS 14 ACTUAL O.D. = 14" (355.6 MM)ACTUAL INSIDE DIAMETERS OF A 1 INCH PIPE.NPS 1-SCH 40 = O.D.33,4 mm - WT. 3,38 mm - I.D. 26,64 mmNPS 1-SCH 80 = O.D.33,4 mm - WT. 4,55 mm - I.D. 24,30 mmNPS 1-SCH 160 = O.D.33,4 mm - WT. 6,35 mm - I.D. 20,70 mmSuch as above defined, the inside diameter is determined by the oudside diameter (OD) and wall thickness (WT).The most important mechanical parameters for pipes are the pressure rating, the yield strength, and the ductility.The standard combinations of pipe Nominal Pipe Size and Wall Thickness (schedule) are covered by the ASME B36.10 and ASME B36.19 specifications (respectively, carbon and alloy pipes, and stainless steel pipes). What is Tube?Tubes are used for strength, mostly in structural applications, such as framing. Tubes can be round steel tube, square, or rectangle.The name TUBE refers to round, square, rectangular and oval hollow sections that are used for pressure equipment, for mechanical applications, and for instrumentation systems. Tubes are indicated with outer diameter and wall thickness, in inches or in millimeters.Pipes are measured by its nominal (or inner) diameter and its wall thickness. The wall thickness is called a schedule. We typically use schedule 40 or schedule 80. A schedule is a fixed number based on the nominal diameter. For example a 0.75 inch nominal pipe, schedule 40, will always have a thickness of 0.113 inches. Tubes are measured by their outer diameter and will have a wall thickness, typically measured in inches or fractions.Tubing is formed by running slit coils of metal through a tube mill to create a round, rectangular, or square tubular shape. The edges are then welded together using a process such as electric resistance welding or high-frequency welding. The method used depends on the type and thickness of the metal, as well as the preferences of the manufacturers. The tube is then refined with an annealing process to create the final product. A hollow bar is always round and can look like a pipe or a tube, however, typically the walls are much thicker. A hollow bar has the strength of a solid round bar, but since there is no center, there is less weight per foot which can sometimes save money, without compromising strength.A hollow bar, depending on the application, can be machined both on the inside and the outside.Hollow bars are measured by giving an inner diameter (ID) and outer diameter (OD). Copper and Brass Sales offers pipe, tube and hollow bar in aluminum, stainless steel steel tube, copper, brass, and bronze.Hollow bar is not welded together. Instead, hollow bar is created using one of two processes. The first, called drilling, involves sending a drill through a solid bar stock. The second, called centrifugal casting, is when molten metal is poured into a cast as it undergoes high-speed rotation. The high-speed rotation forces the metal to the outside of the frame, where it hardens as it cools to create a dense, uniform final product. Hollow bar typically only come in bronze and stainless steel.  Uses for Tubes and PipesTubes: The main use for tubing is for structural purposes. They are used in applications that call for precise outside diameters. They are defined by the outside diameter and wall thickness for construction stability. Tubes are always one whole piece from end to end. they can be flexible or orthogonal but continues in any case.Tubes are used:Gas line or hydraulic lineWater transferalProtect fiber optics / wires and electrical cablesLiquid & gas transportationMachine componentsVacuum tube in electrical circuitsScaffolding Pipes:Pipes are used mainly for transportation of fluids and gases like water, oil, gas, propane etc. The inside key measurement is the inside and outside diameter and pressure rating is important. Pipe Bollards use pipes because they require rigidity, resistance, and strength to cope with impact pressure. Pipes are the item that you lay in your house. in order to connect them, you weld (or screw) a flange to the end. They always go in straight lines. Pipes are used for:Plumbing systemsLiquid & gas transportationCompressed air systemsFluid delivery systemsHigh-pressure storage unitsParking Bollards ClassificationThe classification of pipes are schedule and nominal diameter. Pipe is typically ordered using the Nominal Pipe Size (NPS) standard and by specifying a nominal diameter (pipe size) and schedule number (wall thickness). The schedule number can be the same on different size pipe but the actual wall thickness will be different.Tubes are typically ordered to outside diameter and wall thickness; however, it may also be ordered as OD & ID or ID and Wall Thickness. The strength of a tube depends on the wall thickness. The thickness of a tube is defined by a gauge number. Smaller gauge numbers indicate larger outside diameters. The inside diameter (ID) is theoretical. Tubes can come in different shapes such as square, rectangular and cylindrical, whereas piping is always round. The circular shape of the pipe makes the pressure force evenly distributed. Pipes accommodate larger applications with sizes that range from a ½ inch to several feet. Tubing is generally used in applications where smaller diameters are required. Pipe vs Tube, 10 basic differencesPIPE vs TUBESTEEL PIPESTEEL TUBEKey Dimensions (Pipe and Tube Size Chart)The most important dimensions for a pipe is the outer diameter (OD) together with the wall thickness (WT). OD minus 2 times WT (SCHEDULE) determine the inside diameter (ID) of a pipe, which determines the liquid capacity of the pipe. The NPS does not match the true diameter, it is a rough indicationThe most important dimensions for a steel tube are the outside diameter (OD) and the wall thickness (WT). These parameters are expressed in inches or millimeters and express the true dimensional value of the hollow section.Wall ThicknessThe thickness of a steel pipe is designated with a "Schedule" value (the most common are Sch. 40, Sch. STD., Sch. XS, Sch. XXS). Two pipes of different NPS and same schedule have different wall thicknesses in inches or millimeters.The wall thickness of a steel tube is expressed in inches or millimeters. For tubing, the wall thickness is measured also with a gage nomenclature.Types of Pipes and Tubes (Shapes)Round onlyRound, rectangular, square, ovalProduction rangeExtensive (up to 80 inches and above)A narrower range for tubing (up to 5 inches), larger for steel tubes for mechanical applicationsTolerances (straightness, dimensions, roundness, etc) and Pipe vs. Tube strengthTolerances are set, but rather loose. Strength is not the major concern.Steel tubes are produced to very strict tolerances. Tubulars undergo several dimensional quality checks, such as straightness, roundness, wall thickness, surface, during the manufacturing process. Mechanical strength is a major concern for tubes.Production ProcessPipes are generally made to stock with highly automated and efficient processes, i.e. pipe mills produce on a continuous basis and feed distributors stock around the world.Tubes manufacturing is more lengthy and laboriousDelivery timeCan be shortGenerally longerMarket priceRelatively lower price per ton than steel tubesHigher due to lower mills productivity per hour, and due to the stricter requirements in terms of tolerances and inspectionsMaterialsA wide range of materials is availableTubing is available in carbon steel, low alloy, stainless steel, and nickel-alloys; steel tubes for mechanical applications are mostly of carbon steelEnd ConnectionsThe most common are beveled, plain and screwed endsThreaded and grooved ends are available for quicker connections on site QualityThe difference in manufacturing makes for a big difference in quality. Hollow bar can be created to be flexible and fit into tight dimensions in a way that tube can’t. Tubing can also result in a lower quality product when the manufacturer is unskilled.Avoid a reduction in quality by removing the excess weld metal and heat-treating, or annealing, the tube after welding. Otherwise, crystalline structures may affect the strength and structure of the metal that develop. MaterialsMost materials can be formed into tube using the welding process. This process is appropriate for any material that conducts electricity. While hollow bars can also be made out of most materials, it can be challenging to extrude strong and hard materials.The choice between hollow bar or tube is ultimately up to you. Take into consideration what type of project you’re doing, your desired material, budget, and your project’s final application. MeasurementTube is typically ordered outside diameter and wall thickness. Tubing is usually held to tighter and more stringent tolerances and specifications than pipe. Pipe is typically ordered using nominal pipe size (NPS) standard and by specifying the nominal diameter (pipe size) and schedule number (wall thickness) Telescoping AbilitiesTubes can be telescoped. Telescoping tubes are perfect for applications different pieces of material to sleeve or expand inside one another. RigidityPipe is rigid and cannot be shaped without special equipment. With the exception of copper and brass, tubes can be shaped with some effort. Bending and coiling tubing can be done without excessive distortion, wrinkling or fracturing. Different Dimensional TolerancesAchieving tight dimensional tolerances can be more challenging for steel tube but hollow bar can be made to be extremely homogeneous and can also possess very tight dimensional tolerances.Welding processes can create different crystalline structures near the weld zone which could affect the desired mechanical properties of the tubing.The excess weld metal should be removed to avoid stress concentrators in the welded tubing.The tube should be annealed or heat-treated after welding to ensure that a homogenous product is being created.Also, if care is not taken by the manufacturer, the welding process used for manufacturing tube can potentially create a lower quality product than desired. MaterialsA wide variety of materials can be formed into welded tubing. If the material can conduct electricity, electric resistance welding can be used to weld the material onto itself to create tubing. Hollow bar can be created out of most materials as well. However, harder and stronger materials may prove to be too difficult to extrude so the piercing method could be used instead.In the end, the choice between using tube or hollow bar will ultimately come down to the application, as one is not universally better or cheaper than the other. Depending on the material type and tolerances, several design considerations should be taken into account before a choice between the two is made. 

When producing seamless pipes, they are inserted into the inside of the pipe body and rolls and other tools are used to form the annular hole to form the pipe. Mandrel bars are used in continuous pipe rolling, tube diagonal rolling, tube rolling, pipe jacking, and tube cold rolling.The mandrel is a very long round rod that participates in the deformation of the pipe in the deformation zone like the head. The difference is that the mandrel moves axially in the pipe as the pipe rotates while being rolled; In the case of periodic tube rolling and pipe jacking), the core rod does not rotate but also moves axially with the tube.On floating mandrel and restricted mandrel continuous rolling mills (see continuous tube rolling mill rolling), mandrels are important tools. They require high strength and high wear resistance, but they also require High surface quality, such as grinding and heat treatment after turning. Floating mandrels are long (up to 30m) and heavy (up to 12t). The length of the mandrel is slightly shorter, but the material requirements are higher. The mandrel should be able to withstand a large jacking force on the mandrel used. The mandrel of the cyclic tube rolling machine is heated for a long time during operation. The mandrels of the diagonal rolling extension machine include tensile mandrels, floating mandrels, limited mandrels and retracted mandrels.A tensile mandrel is a mandrel whose axial movement speed is greater than the axial movement speed of the pipe during operation (see Pipe Rolling Extension). The mandrel applies a tensile force to the inner surface of the pipe. The retractable mandrel is a mandrel whose axial movement direction of the mandrel is opposite to the axial movement direction of the pipe and which applies a rear tension. The requirements for mandrels for diagonal rolling stretchers are lower than those for longitudinal rolling stretchers.

Technological approaches to improve the plasticity of forgings and reduce the resistance to deformation To facilitate the flow of metal billets during forging, and to take reasonable measures to reduce deformation resistance and save equipment energy, the following methods are generally used to achieve:1) Grasp the material characteristics of forgings, and choose a reasonable deformation temperature, deformation speed, and degree of deformation.2) Promote the homogenization of the chemical composition and structure of the material, such as high temperature homogenization treatment of large high alloy steel ingots, so that the plasticity of the material is improved.3) Choose the most favorable deformation process. For example, when forging high-alloy steel forgings that are difficult to deform and have low plasticity, in order to make the surface of the material under pressure during upsetting and prevent tangential tension from cracking, you can use Forging with upset process.4) Using different tools to operate, the correct use of tools can improve the unevenness of deformation. For example, when drawing long shaft forgings, V-shaped anvils or circular anvils can be used to increase the surface pressure of the forging, thereby improving the plasticity, and preventing cracks on the surface and core of the forging.5) Improve the operation method to reduce the influence of friction and temperature during forging of the forging billet, and avoid the occurrence of cracking. For example, for wafer-like forgings of low-plasticity material, two pieces can be stacked and upset once, then each piece is turned 180 °, and the second upset process is used to solve it.6) The use of better lubrication measures can improve the surface conditions of forgings and dies, reduce the impact of friction, obtain uniform deformation, and reduce deformation resistance.

Near-isothermal forging technology is an advanced forging technique that solves the problem of forming some low-plasticity and difficult-to-deform materials. This technology is developed on the basis of the idea of isothermal forging technology. The biggest difference from isothermal forging is that the mold is heated to a temperature lower than the workpiece temperature of about 30-80 ° C and forging.In this way, on the one hand, the demanding requirements for the mold material are reduced, the selection range of the mold is expanded, and the near-isothermal forging of the titanium alloy is made possible in the atmospheric environment, and at the same time, the application range of the isothermal forging technique is expanded;There is a certain temperature difference between the forging and the mold, which can provide a certain heat dissipation path for the heat generated by the deformation heat effect in the forging. By reasonably selecting the deformation speed, the temperature loss of the forging can be compensated to a certain extent, so that the deformation of the forging under the approximate isothermal condition is achieved, and the effect of isothermal forging is achieved.Near-isothermal forging not only reduces the influence of mold chilling and material strain hardening, improves the plasticity of the material, but also reduces the deformation resistance, which is beneficial to simplify the forming process and form forgings with complex shapes with fewer deformation steps. . In terms of materials, near-isothermal forging is mainly applied to metal materials with a narrow forging temperature, especially for titanium alloys and high-temperature alloys with very sensitive deformation temperatures;in terms of part shape, near-isothermal forging is suitable for thin webs and high Forgings and thin-walled forgings, because the heat of the blanks of such parts will be quickly absorbed by the mold, and the temperature will drop rapidly. The ordinary forging method not only needs to greatly increase the tonnage of the equipment, but also easily cause cracking of the mold. Near-isothermal forging will become one of the most reliable technologies for producing difficult-to-deform metal, narrow forging temperature range and large-scale complex structure forgings in the present and subsequent periods.According to the characteristics of forgings, the company uses cast high-temperature alloy as the mold material. Under atmospheric conditions, it not only realizes the formation of near-isothermal forging die forgings (the required tonnage of the press is small, and the forging structure is even and small, realizing the small equipment in the true sense. Preparation of large forgings; therefore, near isothermal forging technology is an economically viable process for preparing forgings such as high performance powder alloy forgings and large complex structural parts.

Roll forging is a plastic forming process in which a material is plastically deformed by a pair of rotating molds in the opposite direction to obtain a desired forging or forging blank. As an advanced plastic forming process, roll forging has a series of advantages such as high material utilization rate, excellent product quality, good working conditions, easy realization of mechanical automation, high production efficiency and long die life, in aerospace, automotive, It has been widely used in industries such as agricultural tools, weapons and daily hardware. For example, automotive front axles, crankshafts for engine engines, connecting rods, engine blades, shovel and wrenches are commonly used for roll forging. Compared with ordinary die forging, the equipment required for roll forging is small, the required number of fires is small, the labor cost is low, the product quality is excellent, the material utilization rate is significantly improved, and the single piece can save about 30^ of raw materials, and the size can be accurately obtained. And rough and rough forged surfaces.

A multi-forging die forging method has certain constraints (or unsuitable conditions), as long as one of the following contents is not suitable for one-time multi-forging (especially unsuitable for one-die multi-forging, continuous multi-forging, turning forging and forging) Forming die forging and other forming methods): If the weight of the forging is large, the horizontal projection area of the forging is large, the shape of the forging is too complicated, the forging temperature range is too narrow, the forging die has a large depth, and the direct forging deformation of the blank is too large. The number of steps of the blanking work in one fire forging is ≥3, the number of forging dies to be used is increased, and the number of forging equipment to be used is increased. A multi-forging die forging method is a systematic project. Effectively determining the constraint conditions and suitable conditions is one of the prerequisites for realizing the reliability, effectiveness and timeliness of a multi-forging.

Precision forging refers to the forming technology that meets the dimensional accuracy requirements of parts without a small amount of machining or machining. There are two main ways to achieve precision forging: refined blanks, that is, directly forged blanks that meet the requirements of precision machining. Precision forgings, all or parts of the parts are directly processed by precision forging, thus reducing the amount of machine added. There are many precision forging processes currently used in production. According to different forming temperatures, it can be divided into hot forging, cold forging, warm forging, and composite forging.1. Hot precision forging processHot forging refers to a precision forging process in which forging is performed at a temperature above the recrystallization temperature. Since the deformation temperature is high, the deformation resistance of the material is low and the plasticity is good at the time of forging, so that it is easy to form a part having complicated geometry.2. Cold precision forging processThe cold forging process is a precision forging forming technique for forging at room temperature. Due to the forming at room temperature, the dimensional error caused by thermal expansion and contraction is avoided, so the shape and size of the workpiece for cold precision forging are easier to control, and the surface of the forging does not produce oxidation and burning, etc., and has a high surface quality, so the hot essence The forging precision of forging and warm precision forging is lower than that of cold precision forging.3, warm precision forging processWarm forging is a precision forging technique in which a metal is heated to a temperature suitable for a temperature below the recrystallization temperature. It has the advantages of hot forging and cold forging, avoiding their defects, effectively reducing the load on the equipment and the mold, improving the plasticity and fluidity of the metal, without forging annealing.4, composite precision forging processThe composite precision forging process combines cold, warm and hot forging processes to complete a forging technique of workpiece forging. It can exert the advantages of cold, warm and hot forging, and avoids the disadvantages of cold, warm and hot forging. At the same time, the parts produced by the composite precision forging process have improved mechanical properties, dimensional accuracy and surface quality compared to those produced by a single forging technique. At present, the common composite forging process mainly includes warm forging - cold finishing, hot forging - cold forging, warm extrusion - cold pendulum, warm precision forging - cold extrusion, hot precision forging - cold pendulum and so on.