Stainless Steel Precision Casting

Processprecision casting, Investment Casting, lost wax casting, Silicon sol casting,MaterialStainless Steel, Carbon Steel, Aluminum, brass, iron, ductile ironMaterial GradeGB, ASTM , AISI , DIN , BS,Weight0.01 kg~70kgAccuracyClass CT4~CT7Surface RoughnessUp To Ra1.6~Ra6.3Applied Softwareproe, catia, ug, solidworks, cad, pdf, etcProduction CapacityMore Than 100T Per MonthHeat TreatmentAnneal, Quenching, Normalizing, Carburizing, Polishing, Plating, Painting, etcMachining EquipmentCNC Center , CNC Machines, Turning Machines, Drilling Machines , Milling Machines, Grinding Machines, etcMeasuring ToolCMM , Projector, Vernier Caliper, Depth Caliper, Micrometer, Pin Gauge, Thread Gauge , Height Gauge, etcQC System100% Inspection Before ShipmentReport100% Report with shipmentTransportAir or SeaFAQ: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 process Step 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.ROLE OF ALLOYING ELEMENTS IN STAINLESS STEELCARBONCarbon is always present in stainless steel. The amount of carbon is the key. In all categories except martensitic, the level is kept quite low. In martensitic grade the level is deliberately increased to obtain high strength and hardness. Heat treating by heating to a high temperature, quenching and then tempering develops the martensitic phase.Carbon can have an effect on the corrosion resistance. If the carbon is allowed to combine with the chromium (to form chrome carbides), it may have a detrimental effect on the ability of the “passive” layer to form. If, in localized areas, the chrome is reduced to below 10.5%, the layer will not formCHROMIUMChromium is a highly reactive element and accounts for the “passive” nature of all stainless steels. The resistance to the chemical effects of corrosion and the typical “rusting” (oxidation) that occurs with unprotected carbon steel, is the direct result of the presence of chromium. Once the composition contains at least 10.5% chromium, an adherent and insoluble surface film is instantaneously formed that prevents the further diffusion of oxygen into the surface and prevents the oxidation of the iron in the matrix. The higher the chromium level the greater the protection.NICKELNickel is the essential allying element in the 300 series stainless steel grades. The presence of nickel results in the formation of an “austenitic” structure that gives these grades their strength, ductility and toughness, even at cryogenic temperatures. It also makes the material non-magnetic. While the role of nickel has no direct influence on the development of the “passive” surface layer, it results in significant improvement in resistance to acid attack, particularly with sulfuric acid.MOLYBDENUMThe addition of molybdenum to the Cr-Fe-Ni matrix adds resistance to localized pitting attack and better resistance to crevice corrosion (particularly in Cr-Fe ferritic grades). It helps resist the detrimental effects of chlorides (316 with 2% moly is preferred over 304 in coastal and de-icing salt situations). The higher the molybdenum content (there are stainless steels at 6% moly), the better the resistance to higher chloride levels.MANGANESEGenerally manganese is added to stainless steels to assist in de-oxidation, during melting, and to prevent the formation of iron sulfide inclusions which can cause hot cracking problems. It is also a “austenite” stabilizer and when added in higher levels (from 4 to 15%) replaces some of the nickel in the 200 series stainless steel grades.SILICON & COPPERSmall amounts of silicon and copper are usually added to the austenitic stainless steels containing molybdenum to improve corrosion resistance to sulfuric acid. Silicon also improves oxidation resistance and is a “ferrite” stabilizer. In “austenitic stainless steels, high silicon contents improves resistance to oxidation and also prevents carburizing at elevated temperatures (309 and 310 are examples)NITROGENIn “austenitic” and “duplex” stainless steels, nitrogen increases the resistance to localized pitting attack and inter-granular corrosion. Low carbon “austenitic” grades (designated with an “L” since they contain less than 0.03% carbon), are suggested for welding operations, since the lower carbon minimizes the risk of sensitization. The low carbon levels, however, tend to reduce the yield strength. The addition of nitrogen helps to raise the yield strength levels back to the same level as standard grades.NIOBIUMNiobium additions prevents inter-granular corrosion, particularly in the heat effected zone after welding. Niobium helps prevent the formation of chrome carbides, that can rob the microstructure of the required amount of chromium for passivation. In “ferritic” stainless steels the addition of niobium is an effect way to improve thermal fatigue resistance.TITANIUMTitanium is the main element used to stabilize stainless steel before the use of AOD (Argon-Oxygen Decarburization) vessels. When stainless steel is melted in air, it is difficult to reducing the carbon levels. 302, the most common grade before AOD’s, was allowed to have a maximum carbon level of 0.15%). At this high level, something was needed to stabilize the carbon and titanium was the most common way. Titanium will react with the carbon to form titanium carbides and prevent the formation of chrome carbides, that could affect the formation of the “passive” layer. Today all stainless steel are finished in an AOD vessel and the carbons levels are generally low due to the absence of oxygen. The most common grade today is 304 (with 0.08 max carbon, although in reality the levels are lower).SULFURSulfur is generally kept to low levels as it can form sulfide inclusions. It is used to improve machinability (where these inclusion act as “chip breakers). The addition of sulfur, however, does reduce the resistance to pitting corrosion.