Metal Cutting

HOW TO CUT METALWhile metal is generally hard and tough, it is still able to be cut by several different processes. Understanding what the processes are and which option is best suited for specific metal types and projects is important when determining how to cut metal (of course, you can always visit Metal Supermarkets and have your order cut to size). Here are some common ways to cut metal. Thermal Cutting ProcessesThere are several different thermal cutting processes that can be used to cut metal. These processes use an energy source to heat specific portions of the metal and cause it to become liquid. At that point, the molten metal is blown away from the rest of the solid metal, creating a cut. Thermal cutting is preferred over other processes in certain applications because of the speed in which the metal can be cut. Flame cutting is one example of a thermal cutting process. For example, oxy-fuel flame cutting uses the combination of oxygen and a fuel such as acetylene or propylene to create a flame that melts the metal. The flow of the oxy-fuel gas mixture is also used to blow the molten metal and create the cut.Plasma cutting is similar to flame cutting, but instead of an oxy-fuel gas mixture, it uses an electrical arc as the source of heat.Laser cutting is also a thermal cutting process, with laser energy being used to melt the metal. A monochromatic and coherent light beam is created within a laser resonator and focused through a lens onto the metal material. This causes the target sections of the metal to become heated and melt, resulting in a cut.Mechanical Cutting ProcessesMechanical cutting processes use physical rather than thermal means to sever metal material. There are several ways that mechanical cutting can be carried out. The speed and cut quality vary greatly depending on the mechanical cutting process used. Production saw cutting is performed using a band saw in the horizontal or vertical position. Production saw cutting is a relatively slow but very robust cutting process, as it can be used cut many different types and shapes of metal. Typically, a coolant is used in order to remove the heat that is caused by friction from the saw blade cutting the metal.Shearing is a mechanical cutting process that severs metal by using a sharp edge that is pressed down with a large amount of force. The blade deforms the sheet until it eventually creates a cut. Shearing can produce high-quality cuts, although it can leave the metal with a deformed edge. Shearing is typically used for cutting sheet metal.Miter cutting is another mechanical cutting process frequently used. Miter saws cut with a circular metal saw blade, often made out of carbides. The blade is spun and lowered into the metal material, making the cut. A unique feature of a miter saw is its ability to cut metal material at a wide range of precise angles.Hole punching is a cutting method similar to shearing. When punching, a metal tool (which can have a variety of shapes) with sharpened edges is depressed onto a metal material until it is severed. Punching is mostly used to cut certain shapes into a metal.Notching is frequently done by using the punching process. A common application of notching is removing material from a metal sheet or plate so that it can be shaped three dimensionally.Drilling is similar to hole punching. It typically is not used to sever a material, but to cut a shape into a material. Drilling pushes a drill bit into the metal to remove material. Most drill bits cut cylindrical holes into a material, however, a countersink bit can be used to make a conical cut into a metal.Water jet cutting is another type of mechanical cutting process in which water is forced through a nozzle at extremely high pressure. Water alone can be used to sever soft materials, however, the water is almost always combined with an abrasive material that helps to erode the metal being cut.

How to drill chrome steel  Equipment you'll need; suitable drilling bit , cutting fluid, eye protection, ear defenders, heavy duty tape, marker pen or 3 corner pyramid punch, sturdy clamp, and felt or plastic to guard work piece within the clamp. Begin by clearing your workspace to make sure there's nothing which will catch within the drill once you start working. confirm you've got everything handy so you'll consider getting the work avoided interruption. this is often an honest time to line up your drill and ensure all cables are in fitness . The correct PPE is of paramount importance when drilling; chips and are sharp and travel at speed so confirm your eyes are well protected. If you wear prescription glasses confirm you wear additional goggles designed to wear over the highest as regular glasses won't provide adequate protection. Gloves aren't recommended when drilling as they pose a risk to becoming entangled within the drill; the acute forces, rotation, and speed encountered when drilling can easily break a finger or wrist. Ear defenders are recommended to guard your hearing, exposure to loud machining noise can permanently damage your hearing and contribute to developing tinnitus.  Mark the position of the opening with a marker pen, or if preferred, tap alittle indent with a 3-corner pyramid punch. If you're concerned about the damaging the encompassing area because it furls out of the drilling bit you'll use heavy-duty tape round the drill mark as protection. If the metal to be drilled is a smaller amount than 3mm thick it's going to be possible to use one bit to realize the specified size hole, however, if the metal is thicker it's recommended to start out with a touch half the dimensions of the specified hole diameter for an initial hole then intensify to the ultimate size drill for a second drilling. Firmly clamp the work piece into position ensuring it's secure. If the drilling bit grabs during operation, or when the drill exits on the side , it can spin the work piece which may cause bad cuts, broken bones and damage to equipment. If drilling with hand tools, drop a liberal amount of cutting fluid/ lubricant onto the marked metal. If you're employing a coolant delivery system, set that up as per the manufacturer’s guidelines. Coolant are often sprayed, dripped, or flooded, but it's important to use a liberal amount which there's good contact between the fluid and therefore the tool interface. Using cutting fluid will help to clear the faraway from the drilling bit to scale back the danger of becoming friction welded and reduces work hardening.  You are now able to start drilling. The table below shows suggested speed and feed rates for drilling different grades of chrome steel . When drilling chrome steel , one among the simplest indicators of whether the speed, pressure and feed rates are correct is to observe the ; the should cleanly exit the opening and be helical in shape and short long . Stainless should resemble the first colour of the stock metal or have a yellow tinge thereto . If it's darker or not helical, back the drill out, apply more coolant and check your machine settings. Then simply try again. Once the opening has been made confirm you are doing not touch the bit or the opening as they're going to be hot enough to cause a burn. Care should be taken when wiping the coolant off the metal because the held within the coolant may scratch the surface. These steps should have you ever drilling through chrome steel sort of a professional in no time, however, below is more information to offer you a way deeper knowledge of the way to drill chrome steel to urge the absolute best results whenever .

What Are Brinell and Rockwell Hardness Measurements? What is steel Hardness?The capacity of a steel or steel alloy to resist plastic deformation in a specific, localized region rather than a general location is described as hardness. It’s also the resistance of a steel to indentation, scratching, or abrasion.Hardness is an essential characteristic since a steel’s capacity to resist wear is directly proportional to its hardness. Within a particular kind of steel, hardness levels might vary based on alloying elements, heat treatment, work hardening, and other hardening processes utilized.Because of the diversity in hardness among steels and even within a family of steels, methods for measuring hardness such as Brinell hardness and Rockwell hardness were developed to provide a common understanding of hardness levels. What is Brinell hardness?Brinell hardness is a scale that assigns a numerical value to a material’s level of hardness. ASTM E10 specifies the procedure for performing a Brinell hardness test in detail. A certified Brinell indenter is pushed against a steel under a specified load for a predetermined length of time to conduct the test. All of this is described in order to limit the possibility of experiment technique variation impacting findings. For steels and other comparable materials, the indenter is typically a 10mm hardened steel ball with a force of 3,000 kg.The test varies somewhat depending on whether the material is softer or tougher. After applying stress to the steel, the indenter is withdrawn and the breadth of the resulting indentation is measured with a microscope. A Brinell hardness scale may then be used to translate the indentation measurement into a Brinell hardness value. What is Rockwell Hardness?Rockwell’s hardness is similar to Brinell hardness it is used to determine the numerical hardness of a material. A Rockwell hardness test and a Rockwell hardness scale are used to accomplishing this. ASTM E18 specifies the specific procedure. Rockwell hardness tests, like Brinell hardness tests, use an indenter of a given size applied with a predetermined force for a certain period of time. Using a Rockwell hardness scale, the indentation measurement is converted to a Rockwell hardness value. What is the Difference between Rockwell and Brinell Tests?While the two tests have similarities, there are several important differences, listed below:Depending on the material being evaluated, the Brinell test utilizes a 10mm hardened steel ball, whereas the Rockwell test uses either a 4mm steel ball or a diamond cone.The Rockwell test determines the depth of the indentation, whereas the Brinell test determines its width. A preload is used in Rockwell hardness testing to create a zero position before the main load is applied. The primary load is then removed, leaving just the preload. The Rockwell testing equipment then measures the distance traveled.It’s also worth noting that the conversion scales for Rockwell and Brinell hardness are not the same and should not be used interchangeably. Where are Brinell and Rockwell Hardness Tests Used?Almost every industry uses the Brinell and Rockwell hardness tests. They’re important for determining whether steels and other materials will withstand indentation, abrasion, scratching, and other kinds of wear in a specific application. Materials for engine pistons, jet turbine blades, ship hulls, bronze fixturing equipment, railcar wheels, and many other components that may be exposed to wear conditions are just a few examples.

Know the difference between Blanchard Grinding and Precision Grinding Grinding is a machine process that uses abrasive materials or steels to get to its required dimensions and top layer finishing. There are various methods of grinding that are followed in the industries. Blanchard grinding and Precision Grinding are two methods of grinding. Blanchard grinding is used on materials with a wide surface area to extract stock from one side. Precision grinding is used on materials with limited surfaces to produce a superior surface finish, high degree of parallelism, or flatness. What is Blanchard Grinding?Blanchard grinding is used to properly remove the stock from one side of the material which has a large expanded surface area. Blanchard Grinding is also known as Rotary Surface Grinding which was invented in 1900’s by Blanchard Machine Company. As this method of grinding is much productive then the precision grinding, it is suitable for grinding large pieces of material. This method is not used to grind materials which have the tolerance which is less than 0.001 inch.It can leave a surface finish of about 65 RMS as well as a signature grinding label, which some people find appealing. Magnets are often used to keep massive ferrous materials in place when grinding takes place. Blanchard grinding may be used on a wide range of nonferrous materials; however, different methods of storage mechanisms must be used. Blanchard grinding is mostly used on large castings and forgings, large sections of plate stock, large stampings, Mold and die. What is Precision Grinding?Precision grinding is used for materials with limited surfaces that need a high degree of flatness, parallelism, or a superior surface finish. It is used for applications that need tolerances of up to +/- 0.0001 inch and surface finishes of about 10 RMS. It is often used as one of the final machining processes on a component. Horizontal Spindle Surface Grinding: This process involves bringing an abrasive wheel into contact with a smooth surface of a part as it is being rotated at high speeds.Cylindrical grinding: It is equivalent to horizontal spindle surface grinding, except that it is used to grind circular surfaces and therefore involves a separate work keeping system. The abrasives used in cylindrical grinding may be dressed in a way that aids in part shaping.Aluminum oxide, zirconia alumina, and silicon carbide are some popular abrasives for both horizontal spindle surface grinding and cylindrical grinding. Lubricants can be used, depending on the application, to reduce the high temperatures generated by the grinding operation.Center less grinding, internal diameter grinding, and creep-feed grinding are examples of precision grinding methods. Examples of typical applications include:Molds and diesStampingsShaftsBushingsMachine componentsPistonsCylinders

Turned, Ground and Polished: Meaning and ApplicationsMetal shafts are used of Higher Speed applications which need a higher-level of precision. Premature wear on either the shaft or the bearing will occur if the shafts has a rough finish or lack concentricity and straightness. Steel shaft manufacturers often use the turned, ground, and polished method to achieve the high degree of precision necessary. The name itself tells us that the method comprises of 3 essential steps the Transforms the Scratches and Rough dimensioned metals rod into a shaft which has a straight and even finish. What does Turned mean?The large steel rod is twisted into a Lathe-Chuck, followed by the cutting instruments, which are put down in a lathes tool holder. The lathe has to be started, and the rod begun to rotate automatically. When the steel rod exceeds the desired speed, of the cutting tool which is inserted into the rod, thus by initiating the operation. The turn process repeats until the length of the steel rods is achieved. Depending on how large the rod is, several passes with the cutting tool can be needed. What does Ground and Polished mean?About the fact that the shaft seems Flat, Concentric, and Smoother after rotation, it cannot yet be used as the accuracy of the shaft. Its surface is still relatively rough, which can cause premature wear. The rod is then ground to boost the surface quality. A grinding wheel is used instead of a cutting the tool in, the ground rod to the required dimensional tolerances. To achieve the necessary accuracy, the grinding wheel extracts very small quantities of material at a time. When all of the rod dimensions have been approved, the process is completed by using a polishing wheel. This polishing procedure creates a flawless finish on the top layer. What does Drawn, Ground and Polished mean?It is also important to note that shafts can be drawn, ground, and polished. With one of big exception, this procedure is almost identical to rotated, ground, and polished. Rather than spinning the metal rods before rubbing, it is directly cold drawn in to the desired and appropriate sizes before being Ground and Polished. Because of the cold work done to the rod during the drawing process, this process will allow for improved mechanical properties in some of the metals. Applications of Turned, Ground, Polished Shafts: Tool shanksPistons rodsBoltsPinionsAxlesMotor ShaftsMandrelsTie-Rods

Know the difference between Blanchard Grinding and Precision GrindingGrinding is a machine process that uses abrasive materials or metals to get to its required dimensions and top layer finishing. There are various methods of grinding that are followed in the industries. Blanchard grinding and Precision Grinding are two methods of grinding. Blanchard grinding is used on materials with a wide surface area to extract stock from one side. Precision grinding is used on materials with limited surfaces to produce a superior surface finish, high degree of parallelism, or flatness. What is Blanchard Grinding?Blanchard grinding is used to properly remove the stock from one side of the material which has a large expanded surface area. Blanchard Grinding is also known as Rotary Surface Grinding which was invented in 1900’s by Blanchard Machine Company. As this method of grinding is much productive then the precision grinding, it is suitable for grinding large pieces of material. This method is not used to grind materials which have the tolerance which is less than 0.001 inch.It can leave a surface finish of about 65 RMS as well as a signature grinding label, which some people find appealing. Magnets are often used to keep massive ferrous materials in place when grinding takes place. Blanchard grinding may be used on a wide range of nonferrous materials; however, different methods of storage mechanisms must be used. Blanchard grinding is mostly used on large castings and forgings, large sections of plate stock, large stampings, Mold and die. What is Precision Grinding?Precision grinding is used for materials with limited surfaces that need a high degree of flatness, parallelism, or a superior surface finish. It is used for applications that need tolerances of up to +/- 0.0001 inch and surface finishes of about 10 RMS. It is often used as one of the final machining processes on a component. Horizontal Spindle Surface Grinding: This process involves bringing an abrasive wheel into contact with a smooth surface of a part as it is being rotated at high speeds.Cylindrical grinding: It is equivalent to horizontal spindle surface grinding, except that it is used to grind circular surfaces and therefore involves a separate work keeping system. The abrasives used in cylindrical grinding may be dressed in a way that aids in part shaping.Aluminum oxide, zirconia alumina, and silicon carbide are some popular abrasives for both horizontal spindle surface grinding and cylindrical grinding. Lubricants can be used, depending on the application, to reduce the high temperatures generated by the grinding operation.Center less grinding, internal diameter grinding, and creep-feed grinding are examples of precision grinding methods.Examples of typical applications include: Molds and diesStampingsShaftsBushingsMachine componentsPistonsCylinders

THE DIFFERENCE BETWEEN FLAME CUTTING, PLASMA CUTTING AND WATERJET CUTTINGWhen you need metal cut-to-size, there are a variety of cutting processes to choose from. However, not all processes are suitable for every job or every metal type. A method such as flame cutting, plasma cutting or waterjet cutting may be suitable for your project, but it is important to know the differences between cutting processes. The Difference Between Flame Cutting, Plasma Cutting and Waterjet CuttingFlame CuttingFlame cutting is a thermal cutting process that uses oxygen and a fuel source to create a flame with enough energy to melt and sever material. The use of oxygen and fuel in the flame cutting process is why it is also often referred to as “oxyfuel cutting”. Flame cutting uses a neutral flame to heat the material up to its kindling temperature. When this is reached, the operator presses a lever that releases an additional high-flowing stream of oxygen to the flame. This is used to sever the material and blow away the molten metal, or dross. The Advantages and Disadvantages of Flame CuttingFlame cutting has the advantage of being very portable as no power supplies are needed. A cylinder for oxygen, a cylinder for fuel gas, hoses, a torch, and a striker are all that are required. This makes it an excellent choice for field work. Another benefit of flame cutting is that it can cut very thick metals. With the right equipment and gas flows, steel several feet thick can be cut using the flame cutting process. Flame cutting also has low equipment costs. Flame cutting is at a disadvantage when it comes to material types that can be cut. Flame cutting is generally limited to carbon steel, low alloy steels, and cast irons. Most other types of materials will not be cut cleanly by the flame cutting process. Flame cutting is also typically slower than plasma cutting and waterjet cutting. Due to the heat involved in flame cutting, the metal edges being cut can often form a thin and brittle layer of solidified steel, known as the decarburized layer. This may need to be removed based on the application. The area near the decarburized layer (known as the Heat Affected Zone) may also be altered by the heat from the flame cutting. Without post-cutting heat treatment, such as annealing, this can cause the metal in the Heat Affected Zone to become hard and brittle which can lead to cracking. Plasma CuttingPlasma arc cutting is another thermal cutting process. However, unlike flame cutting, it uses an electrical arc to ionize and heat a gas to form plasma that is used to cut the material. The electrical arc is created at the plasma cutting torch through the use of a tungsten electrode. The workpiece is made to be part of the electrical circuit with the torch by using a grounding clamp. The plasma, once ionized by the tungsten electrode, becomes superheated and interacts with the grounded workpiece. A variety of gases can be used for the plasma gas, and the best one depends on the material being cut. The jet of superheated plasma gas severs the metal and also blows away the dross. The Advantages and Disadvantages of Plasma CuttingPlasma cutting can make high quality cuts much faster than flame cutting. The kerf of some plasma cutting systems can also be much smaller. Plasma cutting can be used on most metals that conduct electricity relatively well. This means that plasma cutting is not limited to steel and cast iron like flame cutting. Rather, plasma cutting can be used to cut aluminum, stainless steels, copper, titanium, and many other types of metals. The process is also easily automated. However, plasma cutting cannot cut materials as thick as those that can be cut by flame cutting. Generally, plasma cutting is not a great choice for materials over a few inches thick. Plasma cutting can also only cut materials that can be part of its electrical circuit. Waterjet CuttingWaterjet cutting is a mechanical cutting method that employs a high speed, high pressure stream of water to cut a material. The water is forced out of a waterjet cutting head by a high-pressure pump. For materials that are harder and more difficult to cut, such as metals, an abrasive material is usually added to the water to increase the cutting capability and help increase travel speeds. The excess water and material that is lost during the cutting process is collected in a tank on the side of the material opposite of the waterjet cutting head. The Advantages and Disadvantages of Waterjet CuttingWaterjet cutting can cut many different types of materials, and is not limited to just metals. Waterjet cutting is also much cleaner than plasma or flame cutting as it does not emit dangerous fumes. Waterjet cutting is also not a thermal process, and the water cools the material as it cuts which means there is no heat that can impact the mechanical and chemical properties of the cut area. Waterjet cutting can also be paired with automation. Waterjet cutting is not well suited to thick cuts on hard metals. Thicker and harder metals can slow the cut speed and reduce the quality of the cut. Waterjet cutting equipment is also expensive and can require quite a bit of maintenance. Should I Use Flame Cutting, Plasma Cutting or Waterjet Cutting?While there are other factors to consider, here are some guidelines for which cutting process you should use: Flame Cutting: You should use flame cutting when you need to cut thick steels or cast irons, and equipment costs need to be kept to a minimum. Plasma Cutting: You should use plasma cutting when high quality cuts are needed on metals under 3-4 inches thick. Waterjet Cutting: Use waterjet cutting to cut precise parts without having the cuts impacted by heat. Waterjet cutting is also good for automated cuts and cutting nonmetallic materials.

The rolled billet must be cut, because: a, should cut off the shrinkage hole part or the head part of the steel ingot; b, cut off the uneven deformation part of the steel ingot tail; c, in order to meet the fixed length of the finished product It is required that the ingot must be cut to a fixed length; d, is also required to be cut due to the limitations of the process and equipment conditions of the workshop. The cutting the steel is mainly for cutting the irregular parts of the steel ends and obtaining the specified length.Both the billet and the steel are sheared on the shearing machine. Depending on the process requirements, some are sheared before rolling, some are sheared during rolling, and some are sheared after rolling.According to the temperature of the sheared steel, the shear can be divided into two types: hot shear and cold shear. Most of the hot shears are made on the line, while cold cuts can be made outside the line.

Avoiding OD and ID Concentricity Requirements in Tube SourcingCu018Like a circle in a spiral, like a wheel within a wheel, tubing OD and ID measurements with concentricity requirements can add up to one big headache! We all know that small parts sourcing is not a perfect world. (Heck, that’s why tolerances exist in the first place!) Yet, sometimes, a drawing will indicate that concentricity is required — and perfect concentricity is almost as hard to measure as it is to achieve. But, why?1. Concentricity vs. EccentricityIn geometric dimensioning and tolerancing (GD&T), concentricity is a complex tolerance used to establish a tolerance zone for the median points of a cylindrical or spherical part. As a measure of the constancy of the wall thickness of a tube or pipe, concentricity controls a central axis that is derived from the median points of the part, measured in cross sections. If concentricity were “perfect,” then the wall thickness between the OD and the ID would be the same in every cross section, at every point around the diameter of the tube.Tubing concentricity is a complex feature because it relies on measurements from a derived axis as opposed to a tangible surface — creating a theoretical 3D cylindrical tolerance zone into which all the derived median points of the tube must fall. That is exactly why concentricity is usually reserved for high-precision parts where there is a critical need to control those median points.When you have variations in a tube’s wall thickness, you have an eccentric tube — one in which the center of the circle formed by the OD is at a different point from the center of the circle formed by the ID. (In other words, the two circles are not concentric.) Eccentricity is measured by looking at a cross section to determine a tube’s minimum and maximum wall dimensions, and then calculating the difference between the minimum and maximum thicknesses, and dividing that figure in half.2. Expressions of OD/ID ConcentricityTubing OD/ID requirements may be indicated on a drawing in several different ways, including:GD&T concentricity symbolEccentricity percentageTIR (Total Indicator Reading)Written statements such as OD and ID must be concentric within 0.00X”Another term sometimes used when talking about concentricity is wall runout, which is the same thing as TIR. Wall runout is calculated by putting the indicator on the part while it spins on its axis, measuring not just the concentricity but also the circularity of the part. Wall runout is derived from a tube’s eccentricity and describes the variation in wall thickness compared with a specified nominal wall — also stated as the maximum wall thickness minus the minimum wall thickness. Wall runout can also be expressed as “eccentricity times two.”Where these (and other) terms are used in drawings to describe concentricity requirements, material suppliers and precision metal cutting shops are challenged to determine not only what machine process to use, but also how to measure the concentricity so that it will meet the specification.3. Complexities of Measuring ConcentricityThis brings us to the difficulty of measuring concentricity to determine if the specified OD and ID are achieved. Concentricity is considered one of the trickiest GD&T traits to measure for, because of the difficulty in establishing the (theoretical) central axis. It also requires taking many measurements across a series of cross sections (however many is realistic), and exactly mapping out the surface and determining the median points of these cross sections. Then these series of points must be plotted to see if they fall within the cylindrical tolerance zone. This can only be done on a coordinate measuring machine (CMM) or other computer measurement device and is quite time-consuming — which of course means added cost.4. When Concentricity Is NeededWith all of this complexity, concentricity is usually reserved for parts that require a high degree of precision in order to function properly. Whether concentricity is critical depends on the end use, such as whether some physical entity with its own OD needs to fit into the tubing. In general, if you have a tube that needs to go inside an opening and another part that needs to fit into the tube ID, then the OD, ID, and concentricity may all need to line up in order for all those parts to work together.If your application requires liquid or gas to pass through a tube, concentricity may not matter at all, because tube non-concentricity would not impede flow-through. However, even where concentricity is not critical, it may be important to know how far out of concentric the OD/ID can be. For example, suppose that in your application, the liquid or gas flowing through the tube will be under pressure. In this case, you may need to specify a minimum acceptable wall thickness to ensure that the pressure does not cause a break in a thin spot on the non-concentric tube wall.To some extent, the choice of material may also relate to concentricity or minimum/maximum wall thickness. For instance, if you have chosen to use welded tubing that will undergo grinding to form a part, you may want to specify a minimum thickness to prevent the tube wall from being ground too thin and causing a break in the weld. Likewise, if your end application will use a tube to move liquid under high pressure, a seamless material that is drawn and not welded might be a better material choice, to minimize the risk of breakage. But again, if the tube will simply release air into the environment, then seamless tubing would be a case of over-engineering.5. An Alternative to ConcentricityIn some cases, you can avoid the time and cost of verifying concentricity by replacing concentricity requirements with wall runout, which is easier to measure and more readily achievable. As long as you know the minimum and maximum wall thicknesses, those tubing specs can be converted to wall runout using simple formulas:Maximum wall thickness – Minimum wall thickness ÷ 2 = EccentricityEccentricity x 2 = Wall runoutSo, for example, a maximum eccentricity of 0 .001” converts to a wall runout of 0 .002”. A maximum eccentricity of 10% converts to a wall runout of 20% of nominal wall.With wall runout, you can physically touch and measure the surface of the part. Controlling wall runout will also control the concentricity, although admittedly, not to the same extent as when concentricity is applied on its own.ConclusionRemember, the feasibility of producing parts that are within your acceptable tolerances is a critically important consideration when doing your drawings. That is why most machinists, measurement techs, and design engineers recommend avoiding concentricity whenever possible. Instead, you can use other applicable geometric GD&T symbols in your tubing drawings and designs — preventing the pitfalls of concentricity by avoiding designing it into the part in the first place.The right metal fabrication partner can help you make wise choices when it’s time to turn your design and drawings into reality. For tips on how to make the most of your contract partner relation-ships, download a free copy of our guide to choosing a contract partner.

Quenched steel must be finished after heat treatment to ensure the dimensions and surface roughness required by the drawings. However, the quenched steel after heat treatment is difficult to machine due to its high hardness. Some workpieces require intermittent cutting or high surface accuracy. The grinding method was often used to improve the quality of hardened steel. Workpiece accuracy, the following briefly describes the machining process of several hardened steel. Gear processing technology: blanking - forging - normalizing - roughing - heat treatment (quenching + high temperature tempering) - finishing car - tooth surface grinding - inspection storage. Ball screw processing technology: blanking - forging - annealing - cutting - heat treatment - grinding - inspection and storage. Automotive axle machining process: blanking - forging - normalizing - turning - pull spline - heat treatment - grinding. From the processing point of view, the above several quenched steel parts need to be grinding to ensure the size and roughness requirements of the drawings, the gear is due to intermittent cutting, turning tools can not be processed; and the ball screw and the car axle belongs High surface precision, using grinding to achieve surface finish.

Sandblasting is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove surface contaminants. 

Milling fixes the blank and uses a high-speed rotating cutter to advance the blank and cut out the desired shape and features. Traditional milling is more used for simple contour features such as milling contours and slots, and CNC milling machines can perform complex shapes and features.Milling cutters are rotary tools with one or more teeth for milling. Each knife tooth intermittently cuts the surplus of the work piece in turn. Milling cutters are mainly used for machining planes, steps, grooves, forming surfaces and cutting off workpieces on milling machines.Milling machining is a common cold metal machining method. The difference between turning and milling is that in milling, the tool rotates at high speed under the drive of the spindle, and the workpiece being machined is relatively stationary.

Lathe machining mainly uses a turning tool to turn a rotating workpiece. Lathes are mainly used to machine shafts, discs, sleeves and other workpieces with rotating surfaces. They are the most widely used type of machine tooling in machinery manufacturing and repair factories.Turning machining can be mainly provided by the workpiece rather than the tool. Turning is suitable for machining rotary surfaces. Most workpieces with rotary surfaces can be machined by turning methods such as inner and outer cylindrical surfaces, inner and outer conical surfaces, end surfaces, grooves, threads, and rotary forming surfaces. The tools used are mainly turning tools.Lathes are the most widely used category in all types of metal cutting machine tools, accounting for about 50% of the total number of machine tools. The lathe can be used to turn a workpiece with a turning tool, but can also use drills, reamers, taps, and knurling tools for drilling, reaming, tapping, and knurling.