What is a forged cylinder

The cylinder barrel is part of the steam engine containing the piston. Forged cylinders are generally stronger than cast cylinders and can withstand higher pressures without breaking. They are also much more durable than these two types because they do not wear quickly due to use or corrosion. Forging also makes it lighter and cheaper than casting cylinders, which is a huge advantage for small machinery manufacturers (such as agricultural equipment or construction machinery manufacturers).

Forging workers use high temperature to transform liquid metal (usually iron) into different shapes, thereby forming finished products by high-pressure compression at high temperature. The product shape formed by this process can not be realized by other methods. It can even produce materials lacking some impurities!

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What is a forged cylinder?

Forged cylinder barrel refers to the cylinder barrel that has been cast, machined and modified. The forging process produces an imperfect surface, which must be smoothed before using the cylinder. This step, called forging, involves heating the metal until it has sufficient ductility (usually around 2200 ° f) to be used. The final shape of the cylinder is hammered onto its surface. After completion, the forging surface is very fine, without rough edges or defects.
In the mechanical field, seamless cylinder is a forging that can be directly used by the machine. Seamless cylinder products are widely used in hydraulic equipment, pneumatic equipment and other machinery. In addition to seamless cylinders, seamless tubes with different wall thicknesses are commonly used.

Material of forged cylinder barrel

We mainly use carbon steel, alloy steel, stainless steel, tool steel and other metal materials.
Carbon steel is the most commonly used material because of its low cost and high tolerance. Alloy steel contains high content of alloy elements, such as nickel, chromium and manganese. It not only improves the strength, but also improves the plasticity to improve the processability, corrosion resistance, wear resistance and toughness. The chromium content in stainless steel exceeds 10% and the nickel content exceeds 20%. Due to the addition of these two elements, it not only has good corrosion resistance, but also has excellent plasticity. Tool steel can be divided into four categories according to its hardness grade (HRC): HRA50 tool steel is relatively soft, with HRC of 50-55; HRB65 tool steel is HRC65 – 70; HRC80 special material is HRC80-85; The hardening grade of HRA100 is hrc100 or higher.
Our products use the best materials. We can produce forged cylinders of different sizes according to your requirements.
What materials do we make.
Stainless steel
ASTM A403 304/L, 304H310S, 310H316/L, 316Ti, 316H317/L321/H347/HS31803S32750904L 254SMO (S31254)
Dual phase steel and super dual phase steel
ASTM A815 uns S31803, S32205, uns S32750, S32760
Nickel base alloy
Alloy 200, Monel 400, K500, Inconel 600, 625, Incoloy 800, 800H, 800ht, 825, alloy 20, alloy 28, Hastelloy C22, C276, etc.
Copper nickel alloy
Titanium alloy
Level 1, level 2, level 11, etc.
Carbon steel
Low temperature steel
Alloy steel
ASTM A234 WP5, WP9, WP11, WP12, WP22, WP91, WP911, WPR
High yield steel
ASTM A860 Wphy42, 46, 50, 52, 56, 60, 65, 70

  • The listed materials are for reference only, and the quantity of some materials will depend on the raw materials we may not have in stock. We have the strength to provide stainless steel 304 welding accessories, 316 accessories, dual-phase S31803 accessories and so on.
  • DIN/EM equivalent grade can be provided, but sometimes we will use ASTM / ASME materials instead. If the quantity is small or the materials are difficult to obtain. We will mark it in the quotation.

The reasons why different processing technologies should be adopted for different cylinder barrels.

In the casting of large diameter seamless steel pipe, the solidification structure is more complex and the defect rate is high. Therefore, it is necessary to roll it, which is different from small-diameter seamless pipe and welded pipe.
Large diameter seamless pipes need to be processed by large radius rolling (e.g., 1.5 times the wall thickness), because when rolling with small curvature radius (e.g., 0.7 times the wall thickness), a large amount of stress concentration will occur at the corner. This high stress concentration will not only cause deformation and deformation in the extrusion rolling process and directly affect the product quality, but also cause cracking in subsequent operations, such as hot forming or bending after welding. Large diameter seamless pipe is generally rolled by integral rolling method rather than extrusion by integral rolling method because of the large requirement of bending radius; However, it should be noted that there are some exceptions in which some types of large-diameter seamless pipes cannot be rolled on the roll due to processing constraints (such as lack of mechanical support or limited space available for forming tools, etc.)., Therefore, they are extruded instead of using an extruder with a sufficiently long tool length, so that they have enough space to operate while preventing damage that may be caused by collision between tools during high-speed operation of the production line
Small diameter seamless pipes are generally rolled or extruded by finishing rolling.
Small diameter seamless pipe has smooth surface, small diameter and thin wall, which is suitable for oil, natural gas and chemical industry. It also has good impact resistance and large diameter toughness.
High pressure seamless pipes are generally rolled or extruded by finishing rolling. High pressure seamless pipe has high strength; Therefore, it is used to transport oil and gas in harsh environment (such as underground).

Forged cylinder VS cast cylinder

The cost of hot forged cylinder is lower than that of cast cylinder. Hot forged cylinders are also more economical than cast cylinders. This is because there is no separate process in manufacturing and casting. The whole process of making the cylinder can be completed at one time, which makes it much cheaper than similar products.
The cost of manufacturing a large number of parts will also be reduced by this method. In addition, it allows you to create complex shapes by easily adding different designs on both sides of the part.
The efficiency and environmental friendliness of this method are other reasons why people prefer it, such as cold forging or casting methods.
The weight of hot forged cylinder is 30% – 50% lighter than that of cast cylinder.
The strength of the hot forged cylinder is higher than that of the cast cylinder.
The preloading and hot forging process make the cylinder barrel safer, which means you don’t have to worry about safety when using these products.
It is cheaper than a cast cylinder because it uses less material in the production process, has more internal space, and can accommodate more products.
The hot forged cylinder barrel has high fatigue strength and crack resistance. This is because the hot forged cylinder barrel is made by heating the material to a high temperature and then applying force to form it. The high temperature makes the material itself have a stress relief effect, so the resulting product is more durable than the product manufactured by other methods. In addition, there are no welded joints in the hot forged cylinder barrel, so there are no residual stresses at these positions that may cause subsequent failure; It also lives longer than its competitors’ products. Hot forged cylinders also have fewer structural defects, such as voids or inclusions, because they are made of molten metal rather than solidified metal (such as casting).
Generally, cylinders with 1 inch (25 mm) or larger bore diameter are manufactured by hot forging technology.
Hot forging is the most advanced technology in the world. It is very important that the cylinder has a large and complex structure, because it is the key component of many agricultural machinery and mining equipment.
Hot forging is the only technology that can produce large, heavy and complex parts with high precision. Compared with other technologies such as casting or stamping, hot forging requires lower energy consumption and emits less pollution in the manufacturing process; Therefore, it is more economical and environmental friendly to use this technology to manufacture forged cylinder.
Our forged cylinder tubes enjoy domestic reputation and are exported to the United States, Europe, Asia and Africa. Our forged cylinders are not only made of high-quality materials, but also advanced technology.
We have forged many types of cylinder barrels, such as square piston rod return for electric valves of chemical equipment (such as ethylene glycol unit, hydrogen sulfide unit, etc.).
When should a forged cylinder tube replace a cast cylinder tube?
The main reason for replacing the cast cylinder with the forged cylinder is that the forged cylinder is more durable than the cast cylinder. Forged pistons have a low coefficient of thermal expansion, which means that they do not expand too much when heated by the exhaust valve. This makes them less likely to crack under pressure even when used in high-performance engines.
Cast pistons are also more prone to warpage, which may lead to uneven compression of each cylinder barrel throughout its service life, which can be solved by installing new rings. In contrast, forged pistons are not easy to deform because they are made of solid steel billets, rather than casting sand molds like cast cylinder barrels; In addition, since all parts of its design are processed after casting at high temperature (rather than pouring into molten metal), less processing is required before installation into the engine block. This reduces defects and improves overall performance (because compression is more consistent).

How to produce large forged cylinder?

What steps should be followed to manufacture the cylinder block of the hydraulic cylinder? As a cylinder manufacturer of hydraulic cylinders with more than 20 years of experience, there is no better place than us to get the correct answer. In this article, we will break them down in detail.

Design of cylinder block of hydraulic cylinder

The cylinder body of hydraulic cylinder has different requirements in dimension tolerance, surface roughness and shape. In the manufacturing process, if the tolerance is too poor, such as the inner diameter, outer diameter and height of the cylinder body of the hydraulic cylinder, or the out of round and burr caused by processing problems, the corresponding cylinder seal ring will be deformed, crushed, scratched or not dense. The sealing function of the oil cylinder will be lost and the normal operation of the equipment cannot be guaranteed. In order to avoid such problems first, the geometric accuracy of each part shall be ensured and the correct sealing ring shall be selected during design; During manufacturing, the upper and lower tolerances of each component shall be matched. Based on the factors affecting the leakage of the hydraulic system, effective measures are taken to reduce the leakage.

Select appropriate cylinder block metal material

There are three kinds of commonly used materials for hydraulic cylinder block. 20 # steel; 45 # steel; Cr40 steel; 20MnMo steel.
20 # steel has the lowest hardness and is usually used for the low-pressure hydraulic cylinder block of excavator and other places; 45 # steel and Cr40 are usually used for high-pressure hydraulic cylinder blocks with rated working pressure of 10000psi. The price of 45 # steel is usually less than half of the price of Cr40. The main role of Cr in heat treatment is to improve the hardenability of steel. Due to the improvement of hardenability, the strength, hardness, impact toughness and other mechanical properties of 40Cr after quenching (or quenching and tempering) treatment are also significantly higher than those of 45 steel. Generally, products with poor quality use 45 # steel on the body and Cr40 on the piston. Products with good quality use Cr40 on both parts, such as Enerpac, simplex, riverlake hydraulic cylinder block, etc. 20MnMo forged steel for low alloy pressure vessels is used to manufacture pressure vessel components and important forgings at – 40 ℃ – 470 ℃. The carbon content is 0.2%, and the content of Mn and Mo is less than 1.5%. The chemical composition of this forging mainly includes C, Si, Mn, Mo, Cr, Ni and other alloy elements. The chemical composition of SA508-3CL. 2 steel used for nuclear power pressure vessel is very similar to it.

There are two types of raw materials:

Steel pipe material and solid steel bar material. You need to choose the right one according to your application. If you need to manufacture a long stroke cylinder, use pipe material because it is really difficult to process the deep part of solid steel material. However, you need to purchase pipe material that has been quenched and tempered. Solid steel rod material is generally suitable for the production of short stroke hydraulic cylinder block. Some manufacturers will cheat consumers by using tube materials without heat treatment, and these oil cylinders will not be able to reach the 1.5 safe delivery specified in iso10100:2001 standard.

Guarantee of metal raw materials

The raw materials of stainless steel butt welding fittings are from famous factories to ensure their chemical composition and mechanical properties. The order will be accompanied by a material certificate conforming to EN 10204 3.1 / 3.2.

Forging process of cylinder block

Taking 20MnMo steel ingot as an example, the smelting process, forging process and heat treatment process of 20MnMo cylinder forgings are introduced, and the 20MnMo cylinder forgings meeting the technical requirements are successfully produced.

Technical indexes of 20MnMo cylinder forging

See Table 1 for chemical composition requirements and table 2 for mechanical property requirements of 20MnMo forgings.
Table.1 Chemical composition requirements of 20Mn Mo forgings (mass fraction,%)

Chemical composition (Wt,%)
20MnMo steel

Table.2 Mechanical property requirements for 20Mn Mo forgings
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Analysis on production principle of cylinder forging

The processing of cylinder forging blank is a process of forging production. The quality of forging blank and the productivity will have an important impact on the quality, performance, service life and economic benefits of the enterprise. The quality of forging blanks is determined by the processing technology, equipment accuracy and performance.
The quality of forging blank directly affects the turning accuracy, and the quality of turning affects the grinding accuracy and efficiency. Therefore, Shanxi yongxinsheng believes that the selection of forging blank plays a very important role in the whole forging processing. The principle of forging blank selection should be to reduce the production cost as much as possible on the premise of meeting the use requirements, so that the products can be competitive in the market. Next, the selection principles of forging blanks are as follows:
Technological principle:
The use requirements of forgings determine the shape characteristics of blanks. Different use requirements and shape characteristics form corresponding blank forming process requirements. The use requirements of forgings are specifically reflected in the external quality such as shape, size, machining accuracy and surface roughness, and the internal quality such as chemical composition, metal structure, mechanical properties, physical properties and chemical properties. For the use requirements of different forgings, the process characteristics of the forging materials (such as forging performance, welding performance, etc.) must be considered to determine the blank forming method. When selecting the blank forming method, the machinability of subsequent machining should also be considered. For some blanks with complex structure and difficult to be formed by single forming method, it is necessary to consider not only the possibility of combining various forming schemes, but also whether these combinations will affect the machinability of machining.
Principle of adaptability:
In the selection of blank forming scheme, the principle of adaptability should also be considered. According to the structural shape, external dimension and working condition of the forging, the appropriate blank scheme is selected. For example, for stepped shaft parts, when the diameter of each step is not much different, bar materials can be used; If the difference is large, forged blanks should be used. Different working conditions of forgings lead to different types of blanks.
Principle of giving consideration to production conditions:
The forming scheme of forging blank shall be selected according to the on-site production conditions. The on-site production conditions mainly include the actual process level, equipment status, outsourcing possibility and economy of on-site blank manufacturing, but at the same time, more advanced blank manufacturing methods should be considered due to production development. Therefore, when selecting the blank, the existing production conditions of the enterprise, such as equipment capacity and staff technical level, shall be analyzed, and the blank manufacturing task shall be completed by using the existing production conditions as much as possible. If the existing production conditions are difficult to meet the requirements, the forging materials and (or) blank forming method shall be considered to be changed, which can also be solved by outsourcing or outsourcing.
Economic principle:
The principle of economy is to make the cost of manufacturing materials, energy consumption and wages of forgings low. When selecting the type of forging blank and the specific manufacturing method, several preselected schemes shall be compared economically on the premise of meeting the use requirements of parts, and the scheme with low overall production cost shall be selected. Generally, when selecting the type and manufacturing method of the blank, the size and shape of the blank should be as close as possible to the finished parts, so as to reduce the machining allowance, improve the utilization rate of materials and reduce the machining workload. However, the more rough, the more difficult it is to manufacture and the higher the cost. Therefore, when the production program is large, the blank manufacturing method with high accuracy and productivity should be adopted. At this time, although the primary investment is large, the increased blank manufacturing cost can be compensated by the reduced material consumption and machining cost. The general rule is that free forging, manual arc welding, sheet metal fitter and other forming methods can be used for small batch production of single piece, and machine modeling, die forging, submerged arc automatic welding or other methods can be used for batch production.

Manufacturing process of 20MnMo cylinder forging


Ingot requires refining + vacuum degassing. See Table 3 for the test results of smelting chemical composition, which meet the technical requirements.
Watch 3 test results of smelting chemical composition of 20MnMo forgings (mass fraction,%)

Forging process of steel ingot

121T steel ingot is selected for forging, and it is forged by 3-4 fires on the press. The forging temperature is 1240-750 ℃, and the actual forging ratio is 6.4. A reasonable forging ratio can break the as cast dendritic structure, refine the internal structure grain, improve the material strength, and enhance the toughness and resistance to damage of the forging.
First fire: since there are many defects at the bottom of the ingot and the riser, first preheat the ingot to about 450 ℃, cut off the gas with an oxygen gun, and then press the riser out of the clamp.
The second fire: steel ingot upsetting. The purpose of upsetting is to prepare for punching. In addition, it can improve the transverse mechanical properties and reduce the anisotropy of mechanical properties. Punching shall be completed quickly at high temperature.
Third fire: ream the forging after punching. The key points are: the forging temperature shall not be too low, and the reaming amount shall be limited each time.

Heat treatment process

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Figure.1 Heat treatment process curve of cylinder barrel
Table.4 Mechanical property test results

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Heat treatment is one of the key processes in the production of the cylinder forgings. Since whether the materials can meet the final use depends on whether they have the required strength and plasticity indexes, the formulation of reasonable heat treatment process parameters is the key to the qualification of the cylinder forgings. See Fig. 1 for the heat treatment process curve. Heat it to 650 ± 10 ℃ and keep it for 5h. The reason is that when the surface temperature of the forging is about 650 ℃, it has entered the plastic state, while the core temperature is only 350 – 500 ℃, and it is still in the elastic state. The forging is easy to form cracks in the core or expand the original cracks. Therefore, keep it for 5h at this temperature to control the temperature difference between the surface and the core.
Tempering and high-temperature tempering treatment shall be adopted to heat to 610 ℃ for 16h, so as to eliminate the residual stress generated during quenching of forgings and prevent deformation and cracking. In addition, after high temperature tempering, the forging can obtain fine sorbite structure, high tensile strength, good plasticity and toughness, and obtain the best comprehensive mechanical properties.
To ensure that the yield strength, impact energy and other indexes of the cylinder barrel after heat treatment meet the requirements of the user, a normalizing is added before quenching and tempering to refine the grain and lay a structural foundation for the final heat treatment.

Performance test results

See Table 4 for the test results of mechanical properties.
It can be seen from table 4 that the performance of the 20MnMo cylinder barrel meets the user’s requirements. The product passes the first heat treatment and all performance results are better than the user’s technical requirements.

Forging conclusion

The following conclusions can be drawn from the cylinder production process:

  • (1) The smelting composition of the 20MnMo ingot fully meets the standard requirements.
  • (2) The forging temperature of the forging is 1240 – 750 ℃, and the forging ratio is 6.4.
  • (3) The normalizing temperature of cylinder barrel heat treatment is 900 – 910 ℃, and the high-temperature tempering temperature is 610 ± 5 ℃.
  • (4) The forging process and heat treatment process can be used to produce cylinder forgings that meet the requirements of mechanical properties.

Cutting of cylinder barrel metal materials

The forged cylinder barrel or steel pipe shall be cut with a sawing machine, and the length shall be determined according to the design.

Heat treatment of cylinder barrel

Quench and temper materials to obtain comprehensive mechanical properties and ensure processing and application quality.

Processing process of cylinder barrel

  • Turning. The chuck is used in conjunction with the middle point and one clamp one point. The cylinder is supported by the central frame to ensure the coaxiality of the cylinder and the machining allowance.
  • Boring. This is the main process for processing the cylinder barrel. In the manufacturing process, rough boring, semi fine boring, floating boring and rolling are generally adopted. The boring process of the cylinder bore is to form a stable processing structure through the boring cutter, iron bearing and bearing seat, and then complete the processing with the boring cutter. Before boring, place the cylinder on the support of the boring machine and fix it. Tighten with bolts and adjust the height of the boring tool tip to make it consistent with the center of the cylinder barrel., Automatic centering; The boring feed speed is controlled by the adjustment of the boring cutter. The rough machining and finish machining of the inner hole boring are completed separately. Floating boring process is the finishing stage of cylinder barrel. For the horizontal position, select the appropriate cutting speed and feed rate. According to the process requirements, select the appropriate processing times and keep the machining allowance. Rolling. During the rolling process, the tightness of the ball shall be adjusted according to the tolerance requirements of the cylinder barrel, so as to achieve the tolerance of the rolling head and meet the processing requirements. By using this method to process the cylinder, the tolerance of the hole on the cylinder can reach the required accuracy, while reducing the repeatability of the error, and the roughness and tolerance of the cylinder can meet the design requirements.
  • Secondary turning. According to the internal hole condition, adjust the thread and welding size of the cylinder barrel with the center frame. Check. Finally, check all machined surfaces.

Problems and control methods easily encountered during the processing of hydraulic cylinder barrel.

  • Tool vibration. The error in the boring process will affect the cylinder barrel, and the accuracy tolerance and position requirements of the hole position cannot be guaranteed. In the production process, in order to eliminate the influence of boring accuracy, it is generally selected to carry out small boring quantity several times in the boring and floating processing stages to accurately control the dimensional accuracy of the bore in the cylinder. In the rolling stage, the size of the steel ball, the rotation speed and the cutting speed shall be adjusted to ensure the smoothness of the hole in the barrel. In addition, the coolant shall be clean and free of impurities, and its flow rate shall be sufficient to punch the iron scraps out of the cutting edge of the floating boring cutter in time to prevent the occurrence of cutting burrs and scratches on the surface of the cylinder barrel and affect the processing quality of the inner surface of the cylinder barrel.
  • Tool collapse. In the process of turning cylinder barrel and piston rod, the alloy cutter is prone to collapse when turning the outer circle. For cemented carbide bit, the impact toughness of this cylinder is not very high. With the increase of temperature, its hardness decreases obviously. When turning to the welding part of the cylinder, the tool temperature is already very high, but when the welding position is encountered, the hardness of the material suddenly changes, so it is easy to cause the edge collapse. Therefore, in the process of machining, the tool should be selected reasonably to improve its machining performance and safety. At the same time, during the machining process, the tool shall be continuously cooled and protected with coolant to take away excess heat and reduce the temperature of the cutting area; At the same time, it can also play a lubricating role, reduce the friction resistance between the turning tool and the workpiece, and improve the surface quality.

Problems needing attention during processing of large cylinder

During blanking, the size of the process chuck shall be considered. If the size is too small, the length of the positioning stop machined at both ends may be too short, resulting in inaccurate positioning of the forging on the boring machine and uneven wall thickness of the processed finished cylinder.
Heat treatment
The hardness and uniformity of the cylinder after heat treatment not only affect the quality of the cylinder, but also have a great impact on the subsequent processing procedures. For the cylinder barrel with uneven hardness, the wear of the tool will be intensified during subsequent boring of the inner hole, and even “cutting” may occur, resulting in scrapping of the forging. Especially when the floating boring tool is used for finishing, the quality of the finished inner hole will also decrease. For this kind of blank tube, it is best to use honing when machining the inner hole. The most commonly used heat treatment method for cylinder blanks is vertical quenching after heating in box type furnace or well type furnace, which is easy to cause uneven local hardness of cylinder. The seamless steel pipe is quenched on the medium frequency quenching line. Since the cooling medium is in uniform contact with the workpiece, the hardness of the cylinder blank is uniform, and the hardness of the workpiece is consistent, which is very favorable for the subsequent process. However, due to the size of induction heating coil, it is difficult to apply this quenching method in the production of single piece, small batch and special oil cylinder.
Boring machine adjustment and workpiece clamping
In the whole boring process, it is the key to ensure that the center lines of the boring machine spindle, fixture, forging, boring cutter, boring bar, oil receiver and boring bar seat are consistent. During the adjustment of the boring machine, the magnetic gauge base can be adsorbed on the spindle of the boring machine to check the concentricity of the boring tool bar and the oil receiver with the spindle. The vibration damping sleeve at the end of the oil receiver of the boring machine shall be inspected and adjusted frequently, and shall be replaced in time after wear. During rough machining, the forging can use the chicken chuck to increase the cutting amount and improve the productivity. However, in the finishing process, the chicken shaped chuck may cause the roundness at the cylinder outlet to be out of tolerance. Cone positioning and friction clamping can be used in finishing. In order to ensure reliable clamping, it is necessary to increase the clamping force of the oil receiver. If the friction is insufficient, the positioning cone surface of the pressure plate of the machine tool and the forging can be reduced.
Rough boring
Due to the difficulty of chip removal in deep hole boring, the chip breaking groove at the cutter head shall be opened deeper and narrower during the grinding of the cutter, so as to increase the chip breaking effect and facilitate chip removal. The inclination of the cutting edge shall be compatible with the chip removal form adopted during boring. The front guide block is made of hard alloy, and the rear guide block is made of plywood. The adjustment principle of the rough boring head is to ensure that the position of the tool tip and the front hard alloy guide block are compatible; The dimensions of the front hard alloy guide block and the rear bakelite guide bar are consistent; The radial dimension of each bakelite guide bar is consistent with each other.
Fine boring
At present, the most widely used form of fine boring is the floating boring tool. The fine boring tool can slide in the rectangular hole of the fine boring head and automatically adjust the cutting amount of the two cutting edges to reduce the error caused by the bending of the tool bar and the inaccurate clamping.
Rolling processing can improve the surface quality of the inner hole of the oil cylinder, but it cannot improve the geometric accuracy and positional tolerance of the inner hole. The higher the accuracy and roughness of the forging before rolling, the higher the surface quality after rolling. The surface roughness of the bottom hole before rolling is generally controlled around ral. 6.
The formulation of the processing technology of the oil cylinder barrel shall comprehensively consider the drawing requirements, batch, machine tools, tools, blank quality and workers’ technical quality. After the formulation of the process parameters, they shall be corrected in the actual production. In order to process high-quality forgings, in addition to the reasonable process and process parameters, there must be a set of practical process management system.

Inspection and test of cylinder

Appearance inspection of cylinder

According to the drawings, check whether the physical objects meet the requirements of the drawings, check whether the appearance of the hydraulic cylinder barrel (such as the paint color) meets the requirements of the drawings, whether the paint surface is evenly sprayed, whether there is paint drop, whether there is color difference, whether there is subsidence, and whether there is obvious dust and Blister; Whether there is rust on the surface without paint, whether the appearance is smooth and flat, and whether there is indentation, pinch mark, scratch, scratch and other marks. Whether there is smooth coating on the surface of piston rod, and whether there are defects such as peeling, blistering and peeling.

Quality inspection of cylinder

  • PMI test to ensure the material quality
  • Dimension controlling during fabricating and finished
  • 100% Visual and surface examination
  • Tensile test per heat
  • Intergranular Corrosion test on request
  • NDT test of UT, PT, MT etc
  • Other requirement from Clients

Dimensional inspection

Inspection of cylinder barrel use vernier caliper and dial indicator to check the length and outer diameter of cylinder barrel. The inspection of the inner diameter requires an accurate inspection of the inner diameter gauge to confirm that the dimensional tolerance meets the requirements of the drawing, and check whether the plating thickness is qualified (generally not more than 0.04 mm).
In the process of checking the cylinder barrel, shallow linear friction or dot scar on the inner surface of the cylinder is allowed, which will not affect the use. If there are longitudinal deep marks (generally no more than 0.2mm), it is impossible to prevent oil leakage even if the piston sealing ring is replaced with a new one. The inner hole must be polished and can also be corrected with very fine sandpaper or oil. When the longitudinal tensile damage is a deep mark (usually more than 0.2mm) and cannot be corrected, the cylinder barrel must be repaired or replaced with a new one by means of brush plating.

Test method and project commissioning.

Adjust the system pressure, start the cylinder barrel of the tested hydraulic cylinder without load, and repeat several times throughout the whole process to discharge the air in the cylinder.

  • Start pressure test. After the test run, under the no-load state, adjust the overflow valve to gradually increase the pressure in the rodless chamber. When the cylinder barrel of the hydraulic cylinder is started, record the starting pressure.
  • Voltage withstand test. Stop the pistons at both ends of the measured hydraulic cylinder, input hydraulic oil of 1.5 times the nominal pressure into the working chamber, and maintain the pressure for more than 2 minutes.
  • Durability test. Under the rated pressure, the cylinder barrel of the tested hydraulic cylinder shall work continuously at the maximum speed required by the design, and each time it works continuously for more than 8 hours. During the test, the components of the measured hydraulic pressure cylinder barrel cannot be adjusted.
  • Leakage test: internal leakage: input hydraulic oil with rated pressure into the working chamber of the measured hydraulic pressure cylinder barrel, and measure the leakage from the piston to the non pressure chamber; External leakage: measure the leakage at the piston rod seal, and there shall be no leakage on the joint surface.
  • Buffer test. Loosen all the buffer valves of the measured hydraulic pressure cylinder, adjust the test pressure of the measured hydraulic pressure cylinder to 50% of the nominal pressure, and operate at the maximum speed designed. After all the buffer valves are closed, check the buffer effect.

Determine whether the oil cylinder is qualified according to the comprehensive inspection. If it is unqualified, it shall be handled according to the provisions of the nonconforming product handling procedure.
There are difficulties in the manufacture and inspection of hydraulic cylinders, which is a problem that manufacturers and users must face. During the processing of the hydraulic cylinder barrel, different parts have different processing requirements. At the same time, higher requirements for quality control are put forward in the production management. From the previous analysis, it is not difficult to see that in order to ensure the quality of the products, the necessary research and improvement of the process measures must be carried out first, so that the process measures can meet the requirements of the processing objects. During the inspection of the hydraulic cylinder barrel, the dimension and roughness of the parts around the machining point shall be inspected to ensure that they are within the tolerance range; In the test stage, the test operation shall be standardized and treated seriously according to the test process. In this way, the quality of the produced oil cylinder can be guaranteed.

Marking of forged cylinder

The Marking Works for Steel forged cylinder.
Every Standards have clearly requirements for steel forged cylinders’ marking style, usually the marking words include seller’s Logo, buyer’s Logo (OEM), standard number, forged cylinder’s type, forged cylinder’s pressure, forged cylinder’s size, forged cylinder’s material, place of origin, heat number and other words for convenient to trace. If the forged cylinders repaired by welding, it must mark on forged cylinders showing this forged cylinder repared by welding. If the forged cylinder’s dimensions (OD, ID, PCD, Thickness, Holes number, Holes diameter, Tolerance etc) are different with the normal standard, it also must mark on forged cylinders where it is different with normal ones. Another important place is heat number marking, it is the tracing base for every piece forged cylinder, and from the heat number we can trace to the beginning of raw material import.
The Marking Style for European Standards Forged Cylinder, DIN, UNI, EN 1092-1 norms etc

LOGO, EN 1092-1, TYPE 01, PN16, DN80, 88.9, P265GH, HEAT NUMBER, MADE IN CHINA

The Marking Style for ANSI, ASME Standards Forged Cylinder, ANSI, ASME, AWWA norms etc


The Marking Style For JIS, KS norms etc, special with KS Mark


The Marking Style for BS 4504 norms etc


The Marking Style for GOST 12820, GOST 12821 norms etc


The Marking Style for SABS 1123, SANS 1123 norms etc


The Rust Prevention for Steel Cylinders.

The normal rust prevention treatment for steel cylinders include yellow (Golden) paint Coating, black paint coating or black phosphating treatment, varnish paint coating, varnish antirust oil coating, electro galvanizing coating (Cold), hot dip galvanizing coating etc.

Packaging of cylinder

Forged cylinders must be packed with seaworthy packing method then delivery to customers, usually the packing way include wooden box, wooden pallet, iron & steel cage, iron & steel pallet etc. Because of the normal wooden boxes or wooden pallets have to do fumigation treatment, we usually use plywood pallet or plywood case or box to pack steel flanges without fumigation treatment. Whatever plywood or iron & steel packing way, they must be seaworthy, strong, waterproof and easy for loading and unloading. Shipping mark stick to outside of package.

What industries use forged cylinders?

Forged cylinders are used in a variety of industries, including:

  • Automotive
  • Heavy equipment
  • Marine
  • Trucking
  • Construction
  • Mining

Forging technology helps manufacturers create complex parts with smooth surfaces that are both durable and aesthetically pleasing.
Forged cylinders are used in a variety of industries and applications. They are more expensive than cast cylinders, but they offer many benefits that make them worth the money. If you need to replace an old cylinder barrel with a new unit, consider using a forged product instead of a cast one.

How to deal with hydraulic cylinder barrel failure?

The cylinder barrel is the main body of the hydraulic cylinder, its bore is generally manufactured by boring, reaming, rolling or honing and other precision machining processes, requiring a surface roughness Ra value of 0.1-0.4μm, as well as the piston and its seals and support parts can slide smoothly and ensure the sealing effect and reduce certain wear. The cylinder barrel has to bear a lot of hydraulic pressure, so it needs to have a certain strength and rigidity. Due to the high manufacturing process requirements, in order to ensure that the piston moves smoothly in the hydraulic cylinder, the bore of the hydraulic cylinder has cylindrical requirements, the bore axis has straight requirements, the bore axis and the two end faces have vertical requirements, the bore axis has coaxial requirements on the axis of the outer circle of the two end supports.
The material requirements of hydraulic cylinder.

  • (1) Annealed cold drawn or hot-rolled seamless steel pipes are generally used as the blanks of the cylinder barrel. There are semi-finished products with honed or finished inner holes in the market. The seamless steel pipes can be cut according to the required length. The materials include 20, 35, 45 steel and 27SiMn alloy steel;
  • (2) For hydraulic cylinder barrel with working temperature lower than – 500C, 35 or 45 steel must be used, and quenching and tempering treatment shall be carried out;
  • (3) The cylinder barrel welded with the cylinder head or flange shall be made of 35 steel, which shall be mechanically pre processed and then tempered. If the cylinder barrel is not welded with other parts, the quenched and tempered 45 # steel shall be used;
  • (4) The cylinder barrel with thick cylinder wall shall be made of cast iron or forging, or rolled into a cylinder shape with thick steel plate, and annealed after welding. The welds shall be inspected by X-ray or magnetic flaw detection. Commonly used materials are carbon steel: 20, 35, 45, etc; Ordinary low alloy structural steel, such as 15MnV and 27SiMn; Alloy structural steel such as 30CrMo, 35CrMo, 35CrMo ala, etc; Stainless steel such as Cr18Ni9, etc.; aluminum alloy such as ZL105, LF3, LF6, etc; Cast steel such as zg230-450, zg310-500, etc; Antirust aluminum alloy, such as SA03, sa06, etc.

As mentioned above, the hydraulic cylinder barrel in the process is quite demanding, so the production and use need to be careful, once the problem occurs, should be disassembled as soon as possible, check the key parts of the important parts, to determine which parts can continue to use or repair and then use, which should be replaced or adjusted accordingly.
Failure of the specific operation method.

  • (1) Dimension and tolerance of cylinder bore (generally H8 or H9, H7 for piston ring sealing and H6 for clearance sealing);
  • (2) The inner hole surface roughness Ra is 0.2 – 0.8;
  • (3) Geometric accuracy of cylinder hole (the reference value is roundness and the cylindricity error shall be less than 1 / 3 – 1 / 2 of the diameter tolerance);
  • (4) Straightness error of cylinder hole axis (it shall be no more than 0.03mm in 500mm length);
  • (5) Perpendicularity Error of cylinder end face to axis Hu (no more than 0.04mm on 100mm diameter); (6) Check the position error (reference value is 0.03mm) and Perpendicularity Error (no more than 0.1mm in 100mm length) of the ear ring hole Hu axis of the ear ring type hydraulic cylinder to the cylinder barrel axis;
  • (7) Check the position error (no more than 0.01mm) and Perpendicularity Error (no more than 0.1mm on the length of 100mm) of the trunnion hydraulic cylinder on the trunnion axis;
  • (8) Inspection for cylinder bore surface damage.

The user can carry out the following in the repair of the hydraulic cylinder barrel after the above inspection.
For bore hair pulling, local wear and rust spots due to coolant into the cylinder bore, or shallow grooves, even if deeper linear grooves, but the grooves are circular direction and not axial long straight groove shape, can use finer metallographic sandpaper or essential oil stone sanding, or can be polished. However, if it is axially deeper in the long groove, the depth is greater than 0.1mm and the length is more than 100mm, then boring or honing the bore and grinding the bore should be considered. Accuracy and surface roughness according to the above dimensions to ensure, if the repair conditions are not available, you can also first oil and decontamination, silver welding to fill the gap. In addition, you can also purchase “precision cold-drawn seamless steel pipe”, currently some domestic manufacturers have production, can be used directly as a cylinder barrel, without additional processing bore. In terms of grinding, honing can be divided into two kinds of rough honing and fine honing, the two methods are basically the same, only the particle size of the oil stone used is different. When choose rough honing, oil stone Hu grain size is 80, fine honing oil stone grain size is 160-200. After finishing, then use 0 gauze wrapped in honing surface to polish the hole, if there is condition, you can operate on special in honing machine, if not, you can also honing on machine tool. If the surface inside the cylinder is damaged, you can also use manual honing method or honing on the vertical drilling machine.
Honing stage, the cylinder speed is about 200r/min, honing head reciprocating moving speed is 0.1-0.15mm. honing cast iron cylinder, can use kerosene or diesel oil lubrication, honing steel cylinder, cooling lubrication using a mixture (kerosene 80%, lard 18%, sulfur 2%), if the cylinder hardness is high, you can add about 10% of the appropriate oleic acid. After repairing the cylinder, both ends face axis in the verticality error of 0.04mm, cylinder bore in roundness Ken cylindricity error shall not exceed half of the bore diameter tolerance, the surface roughness of the cylinder bore shall be Ra0.2-0.4μm.

How to find a suitable forged cylinder manufacturer

Choosing the right forged cylinder manufacturer can be an important decision, especially if you’re planning on using their products for years to come. This article is supposed to help you consider some key aspects of the manufacturing process so that you can make an informed decision about your future supplier.
Consider their expertise.
When you’re looking for a forged cylinder manufacturer, it is important to consider their expertise. The quality of the forged cylinders produced by the company should be high, so you should look at how long they have been in business and how much experience they have in producing cylindrical containers. Also consider whether their reputation within their industry is good or not.
Consider the scope of their specialty.
When considering which forged cylinder manufacturer to work with, you should consider the scope of their specialty. For example, if you need a specific type of material for your forged cylinders and your company does not have experience in this area, it may be best to choose a company that does. The same goes for size and industry.
Consider compatibility issues.
When selecting a forged cylinder manufacturer, it is important to consider compatibility issues. What equipment does your supplier use? Does the company have the right equipment to make your forged cylinders? This includes lathes and boring mills, end boring machines (to bore out the ends), shaft grinders for grinding forged cylinder bores into shape, hydraulic press brakes (for bending sheet metal), water jet cutters (for cutting holes in sheet metal) and tube cutting machines.
When you need to test your product before packaging it up, this is where things get tricky as there are many different types of testing methods available on the market today. Some of these include hydrostatic pressure testing stations which can apply pressures up to 20 times higher than atmospheric pressure; tensile testing machines which can determine whether an object will break under stress by measuring how much force must be applied before breaking occurs; static load balancers which measure how much weight an item can withstand when placed under constant load; vibratory tester units for determining whether an item has any cracks or defects in its structure; rolling road testers that simulate road conditions by applying vibrations at specific frequencies etcetera
Consider budget requirements.
When you’re looking for a suitable forged cylinder manufacturer, one of the most important factors to consider is your budget. While the price of a new forged cylinder can vary depending on its size and features, it’s important to make sure that you have enough money set aside for all aspects of installation, maintenance and repair.
In addition to these costs, there are also certain charges associated with recycling old forged cylinders that should be taken into account when calculating your budget requirements. If your company produces hazardous waste in large quantities (such as chemicals), it’s likely that you will need to purchase specialist equipment in order to safely dispose of it at an approved facility.
Consider their versatility.
Look for a company that can do more than just forged cylinders. You’re looking for a company that knows how to make custom products, so it’s important to find one that can do more than just forged cylinders.
Look for a company that can do large and small orders. In addition to doing custom work, you should also look for a manufacturer who works with both small and large orders. This is because larger companies often have limitations on their minimum order size (MOQ) but may be able to produce high-quality products if your MOQ is low enough.
If a company meets your needs, and you can afford them, they are probably the right choice for you.
There are many things that go into finding the right forged cylinder manufacturer, and it’s important to consider all of them before making a decision. First, you need to know your needs. For example, if you’re looking for a container for holding liquid or gas, there are various types of forged cylinders with different characteristics that might fit your needs better than others (for example: plastic vs aluminum).
Then it’s important to look at price. If a company meets your needs, and you can afford them then they are probably the right choice for you. However if they don’t meet your needs or if they’re too expensive then another option may be better suited for you.
If you are looking for a forged cylinder manufacturer, we hope that this guide has given you some insight into what to look for in a company. As with all things, it’s important not only to find someone who can do the job but also that they have experience doing so. If they don’t have the necessary skills or knowledge of their field, then there will be problems down the road when it comes time for repairs or maintenance work on your forged cylinders.

Source: China Forged Cylinder Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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