Ductile Iron Casting

MaterialStainless Steel,Website:http://www.hhcasting.com, Steel, Ductile Iron, Grey Iron, Aluminum, Bronze, Copper, Brass, and customized material from clients.Material GradeASTM, DIN, GB, BS, JIS, AISI, NF, etcProcessSand Casting, ESR casting, Die Casting, Investment castingWeight0.01kg- 150kgToleranceCT 4-9 grade, and based on the custom drawingsDrawing (files) formatIgs, Stp, X-T PDF, Jepg, JpgCapabilities of ProductionAluminum: More than 80 Mt per month.Stainless Steel: More than 200 Mt per month.Surface TreatmentAnodize/Zinc Plating/ Nickel Plating, Tinting/ Polishing/Blacking, etcMOQDepends on the items, please contact us for freeHeat TreatmentQuenching, Normalizing, Annealing, Plating,CarburizingApplicationsAutomotive, Agricultural Machines, vessels, Tooling, Mining, Oil & gas industry, Locomotive industry, Aerospace, Hardware, Construction, Engineering Machine, Electrical Equipment, etcMachining EquipmentThreading, Turning, Milling, Grinding, CNC/NC, Boring, Test facilitiesMeasuring ToolsGauge, Thread gauge, Height Gauge, Vernier caliper, Depth caliper, Micrometer, CMM, etcQC SystemFully inspection before DeliveryAvailable ServiceOEM & ISOPayment TermsL/C, D/A, D/A,T/T, PayPalShipment TermsFOB, CIFSamplesFew Samples are acceptableCertificationIS9001:2008.Tooling leadtime10-15 working daysProduction leadtime15 working days, based on the quantity of demandFAQ:1. How to get a quotation?Please send us drawings in igs, dwg, step etc. together with detailed PDF.If you have any requirements, please note, and we could provide professional advice for your reference.2. What if we do not have drawing?Samples would be available, and we would send you drawing to confirm.Of course, we would ensure the safety of the drawing.3. How to pay?For small quantity, we could provide Paypal, Paypal commission will be added to the order.For the big one, T/T is preferred.4. How to ship?For small quantity, we have cooperation with TNT, FEDEX, UPS etc.For big quantity, air or sea would be available for you to choose.5. What about the packing details?We attached our normal packing details.If you have any special requirements, we would be willing to help.6. What about the delivery time?It would be 20-30 days normally for the parts to be ready and we had a system to ensure the time.When you made your order, you would know.Investment casting processStep 1: Mould engineering & productionWith precision investment castings, the first step involves the engineering and production of a mould also known as a wax tool. Moulds are made from aluminum or steel. This mould is developed in-house by hoohi engineers and serves as a negative of the final casting. It is important that the mould is made accurately, so that the required tolerances and surface roughness can be achieved. Depending on the size of the series, the mould is installed either onto a manual or automated press.Step 2: Wax model spraying & Tree buildingThe mould is filled with liquid wax. After the wax has been cooled down, ejectors in the mould push the wax model out. A wax model has now been sprayed which is identical to the final casting. These wax models are glued onto a so-called wax tree with a casting funnel on top, into which steel is poured in a later stage of the processStep 3: Rinsing the wax treesAfter the wax models have been glued onto a wax tree, they are rinsed. Any possible contaminations on the surface are removed to ensure a successful attachment of the ceramic onto the wax tree.Step 4: Building ceramic layersAfter rinsing the wax tree, the tree is given a fireproof ceramic shell. This shell is constructed after repeatedly submerging the tree (up to 7 or 9 times) in a slurry and sprinkling it with ceramic sand. The ceramic layers are then hardened in a drying chamber where they are exposed to air.Step 5: AutoclaveAfter the layers have been formed and dried, the wax is melted out of the ceramic tree by using steam (120°C) in an autoclave. This is why it is called “lost wax casting”. The majority of the molten wax can be regenerated and is reusable.Step 6: SinteringThe ceramic tree is then baked (stoked) at temperatures of around 1100°C and reaches its final strength through the sintering process. Any wax remains are burned out during this process.Step 7: CastingThe desired steel alloy is melted in a large furnace and brought to cast temperatures. The ceramic tree is, at the same time, heated in an oven to prevent thermal shocks during the pouring process. After the tree has been heated, it is removed from the oven by a robotic arm and filled up with a steel alloy by use of counter gravity. When the trees have been poured, they are placed on a cooling conveyor where they are cooled down. (with nitrogen).Step 8: Ceramic removalThe trees are then removed from their ceramic shell by using a fully-automatic hammer to break the shell. This removes the majority of the ceramic. The next step is to cut the products from the trees by sawing or vibrating. The steel leftovers will be sorted based on alloy and can be melted again during the next casting sessionStep 9: BlastingThe Finishing Department removes the last pieces of ceramic by means of steel, sand and/or water blasting.Step 10: GrindingThe ingate which remained after the sawing process, is grinded from the casting. To grind the product properly, a grinding fixture is often applied.Step 11: Visual inspectionThe Quality Department checks all products visually for possible casting failures. This check takes place according to a quality standard sheet to ensure that all possible surface failures are corrected properly. Thanks to this procedure, you can be assured that hoohi only delivers high quality castings.Step 12: Machininghoohi has the capabilities to machine castings in house, such as drilling holes, tapping threads and turning & milling activities. This enables hoohi to deliver a completely machined component that is ready-to-install.Step 13: Heat and- or surface treatmentSome alloys require heat treatment to achieve a certain hardness, tensile strength or elongation according to 2D drawing specifications. The standard heat treatments are performed in-house, the complex treatments are outsourced. hoohi also has the know-how to perform a surface treatment for a casting. Surface treatments involve the coating process of a steel surface, to enhance the looks of the surface or protect it against external influences such as corrosion (rust) and natural wear (damage).Step 14: Final inspectionThe final step in this process is another visual check and when necessary composing a measurement report and material analysis. After the final inspection, the products are ready for shipment to another satisfied Hoohi customer.The Details of Ductile IronCast iron is generally thought of as a weak, dirty, cheap, brittle material that does not have a place in applications requiring high strength and defined engineering properties. While gray cast iron is relatively brittle by comparison with steel, ductile iron is not. In fact, ductile iron has strengths and toughness very similar to steel, and the machinability advantages make an attractive opportunity for significant cost reductions. Gray and ductile iron bar stock is commercially available and can be used as a direct replacement in gear and other applications using carbon steel bar.Automotive gears, for example, are being converted to ductile iron for its damping capacity and cost reductions. Ductile iron bar stock conversions are also prevalent in many fluid power applications, including glands and rod guides, cylinders, hydrostatic transmission barrels, and in high-pressure manifolds. Both gray and ductile iron has been used for years in the machine tool industry because of their performance in sliding wear applications and vibration damping.Understanding the metallurgical concepts of ductile iron is the key to understanding its potential use as an engineered metal and allows the design engineer to determine its suitability in specific applications and to intelligently select the best grade. Recent developments in understanding the variables that influence the machinability of gray and ductile iron grades have allowed the process engineer to quantify the expected cost savings when converting from carbon steel bars to continuously cast gray and ductile iron.The following material includes a background on the development of continuous casting of gray and ductile iron, definitions of ductile irons, the metallurgical characteristics of the engineered grades, and some basic material properties. An update on recent studies in the machining characteristics of ductile iron is also presented.IntroductionThe process of selecting the best material to be used for any application involves two primary concerns: is the part most likely to break, or will it most likely wear out? Parts that do not break or wear out, theoretically, could last forever. Using that logic, it would make sense that whenever a design engineer specifies a material for any application, the strongest, most wear-resistant material should always be used. Naturally, this is not practical because of the cost to obtain the material, and the cost to machine or otherwise fabricate the material into a useable part.In very general terms, strength and wear resistance is inversely proportional to machinability, and it can be concluded that as strength and wear resistance increase, the cost of machining increases. Because of this concern, it is extremely important that a designer know as much as possible about all the materials that are available so that the one having the best combination of engineering and machining properties can be selected.Ductile iron was invented somewhat by accident when a metallurgist was trying to find a replacement for chrome in wear-resistant gray iron castings. Magnesium was used in one of the experiments, and it was discovered that what were normally flake graphite shapes were now spheroidal. Castings made with spheroidal rather than flake graphite had high strength and ductility, good fatigue life, and impact properties. Other properties such as vibration damping, machinability, and wear resistance have made ductile iron a suitable replacement for steel in gears and a number of other applications. Table 1Ductile Iron DefinedIron is a ferrous alloy consisting primarily of iron with carbon, silicon, manganese, and sulfur. Other elements are also present and controlled to produce the various grades and to influence other mechanical properties, machinability, and castability. Carbon is added to iron in amounts that exceed the solubility limit, and during solidification, graphite precipitates into tiny spheres. Silicon and other alloys are used to control the morphology of the precipitated graphite and to control the amount of carbon that remains as a solid solution in the iron. Steel, by comparison, contains carbon in amounts that are completely soluble in iron; therefore, precipitated graphite nodules do not exist, and the entire structure consists of a metal matrix.As more carbon is added to steel, strength and wear resistance increase, and machinability decreases. Low carbon steels such as 1018 and 1117 contain less than 0.20 percent carbon and have tensile strengths of approximately 67ksi. The higher strength grades such as 1040 and 1141 contain 0.40 percent carbon and will have tensile strengths on the order of 90 ksi. Machinability decreases as strength increases, and by comparison with 1212 steel, 1117 has a rating of 91 percent and 1141 has a rating of 81 percent (source: ASM Handbook).In the case of ductile iron, the amount of carbon that remains in solid solution depends on the rate of solidification and cooling, on the inoculation practice, and on other elements that are added to either promote graphitization or to promote the formation of pearlite. Similar to steel, ductile irons with less carbon in the matrix (low-combined carbon) will be lower in strength, higher in ductility, and will have better machinability than ductile iron with high amounts of combined carbon.It is possible to produce the different grades of ductile iron by controlling the process variables to precipitate the desired amount of graphite particles and obtain the desired amount of combined carbon remaining in the matrix.Steel grades are designated primarily by chemical composition, and the composition determines the mechanical properties. Ductile iron grades cannot be distinguished by chemistry because the properties are influenced by the graphite morphology and by the composition of the matrix, which is strongly influenced by other variables. The ductile grades are typically designated under ASTM A536 in the form of xx-xx-xx, representing the tensile and yield strength in ksi and the percent of elongation. As with steel, increased tensile and yield strength results from a higher amount of dissolved carbon in the matrix, creating a higher ratio of pearlite to ferrite. Higher strength results in decreased elongation, increased hardness and wear, and decreased machinability.The photomicrographs in Figure 1 show the pearlite to ferrite ratios in three ductile iron grades at 100X magnification. As the percentage of pearlite (etched dark) increases, strength increases. The graphite nodules are also visible as round spheres, and the nodularity in each of the photos is similar.The mechanical property requirements for each of the ductile iron grades listed in ASTM A536 are minimum values obtained from a separately cast test coupon. They can be used for design purposes as long as the data has been generated that correlates the strength in the casting to the strength in a separately-cast test coupon. Tensile test specimens are easily obtained from continuously cast ductile iron, and the mechanical properties in parts machined from bar stock directly correspond to the properties in ASTM A536.Selecting the best grade of ductile iron for any application involves the same consideration as selecting the best grade of steel or other metals, determining the property requirements and finding materials that meet them. Ductile iron can be a suitable replacement for most of the plain carbon steels because the mechanical properties are similar with similar matrix structures. The primary advantage in making conversions from steel bar stock to ductile iron bar stock is lower processing cost through improved machinability.Ductile Iron AdvantagesSince its development in the mid-1940s, ductile iron casting production has grown dramatically. Ductile iron has engineering properties similar to steel, and near-net shaped castings are replacing forgings, weldments, and steel castings in a variety of applications. Ductile iron is also available in continuously cast bar stock and can be a direct replacement for carbon steel bars in a number of gears in the automotive, hydraulic, machine tool, and other industries.Machinabilty advantages of continuously cast ductile iron bars over carbon steel bars are the primary reason for its growth during the past 40 years. Improved tool life and faster cycle times mean more parts produced per hour and less cost for consumable items such as machine tool inserts. Ductile iron contains precipitated graphite nodules acting as natural chip-breakers, causing less friction of the chip on the insert and allowing for a larger depth of cut because of the reduced forces required during machining.The presence of graphite nodules offers additional benefits. Noise and vibration is reduced because of the damping properties of graphite--a key consideration in gear applications--and wear resistance is also improved. Ductile iron is less dense than steel, and the same parts made from ductile iron will weigh 10 percent less than if they were made of steel.The final step in this process is another visual check and when necessary composing a measurement report and material analysis. After the final inspection, the products are ready for shipment to another satisfied Hoohi customer.