How many times can CAE simulation of casting molds reduce the number of trial mold changes

The temperature of the aluminum liquid is a variable at the source of the process. If the temperature is too high, the grains will become coarse, shrinkage cavities will occur, and suction will be severe; Low temperature results in poor fluidity, cold insulation, and undercharging; The narrow temperature window is the underlying cause of yield fluctuations in many production lines. 1、 Quantitative temperature standards for various stages of aluminum liquid A356 mainstream alloy, with a furnace temperature of 720-740 ℃; When the temperature is above 750 ℃, the hydrogen content increases rapidly, and the tendency of casting porosity increases significantly; Below 710 ℃, the refining and degassing effect deteriorates. After the transfer into the insulated crucible, the insulation working temperature is controlled at 700-720 ℃; This is the stable production window of LPDC, balancing fluidity and suction volume. The temperature at the front of the aluminum liquid filling at the gate position shall not be lower than 660 ℃. Below this temperature, the flowability will deteriorate and the risk of thin-walled cold insulation will increase. Aluminum liquid is left to stand in the crucible for 15-25 minutes after refining and degassing, allowing the oxide slag and hydrogen bubbles to float up; Insufficient settling, frequent occurrence of slag inclusion and porosity defects. The supporting process documents of Xinfeng Machinery distinguish the temperature windows of different alloys such as A356, A357, ZL101, etc. 2、 Specification for supporting degassing, refining, and slagging The flow rate of argon gas for rotor degassing is 8-12 L/min, and the degassing time is 8-12 minutes; After degassing, the hydrogen content is controlled to be ≤ 0.2ml/100g Al, and the automotive parts are strictly controlled to be ≤ 0.15ml/100g Al. The refining agent should be added at a weight of 0.2-0.4% of the aluminum liquid. After refining, it must be left to stand and immediately put into operation if it cannot be completely degassed. The crucible liquid level is continuously covered with insulation flux to reduce the contact between aluminum liquid and air, and to reduce oxidation and slagging; Thoroughly remove the slag, and the sediment at the bottom of the furnace cannot be sucked into the riser. 3、 Differences in aluminum liquid control among overseas customers The temperature measurement frequency of Southeast Asian factories is low, relying on visual inspection of aluminum liquid brightness and not detecting hydrogen content. They accept infiltration and repair of pores. Tier 1 in North America, each furnace of aluminum liquid comes with a spectrum and hydrogen content detection report, and temperature and degassing records are included in PPAP. If the hydrogen content exceeds the standard, the entire furnace is prohibited. European customers continuously measure hydrogen online, with closed-loop control of aluminum liquid temperature. Once the hydrogen content exceeds the standard, production will be automatically suspended to avoid batch defects. The environment temperature in the Middle East workshop is high, and the heat dissipation of the crucible is slow. The insulation temperature should be set at a lower limit of 700-710 ℃ to prevent long-term high-temperature suction. 4、 Abnormal temperature defect chain of aluminum liquid Long term overheating of aluminum liquid>730 ℃ → intensified hydrogen absorption and oxidation → porosity, slag inclusion, coarse grain size, and decreased mechanical properties; Aluminum liquid temperature is too low<695 ℃ → insufficient fluidity → thin-walled cold insulation, flow lines, insufficient pouring; After refining and degassing, it is not allowed to stand still → bubbles and oxidized slag are suspended in the aluminum liquid → intermittent slag inclusion pores, sometimes good and sometimes bad; There is too much sediment at the bottom of the furnace, and the rising pipe sucks in the sediment → the casting contains large particles of slag, which is directly judged as waste by X-ray. 5、 Long tail traffic layout ideas The temperature, degassing, and hydrogen content of aluminum liquid belong to the special topic of smelting process, which is targeted at smelting supervisors, process engineers, and quality personnel. keywords LPDC aluminum melt temperature control、hydrogen degassing for A356 low pressure casting； Problem class: A356 melt temperature window for LPDC; Comparative category: hydrogen content standard automotive aluminum casting. Suitable for smelting matching and quality control special pages. 6、 Common misconceptions in the industry Misconception 1: Aluminum liquid has high temperature and good fluidity. High temperature will absorb a large amount of hydrogen and oxidize, causing pores and mechanical properties to deteriorate, which is not worth the loss. Misconception 2: Directly producing after degassing and stirring, bubbles and slag still remain suspended, defects intermittently erupt, and troubleshooting is extremely difficult. Misconception 3: Only looking at the temperature measurement of the crucible, ignoring the cooling of the injection, there is a temperature drop from the furnace to the crucible, and many production lines ignore this temperature difference. FAQ Q: What is the working temperature for A356 crucible insulation? A: 700-720 ℃. Q: Recommended temperature for baking? A: 720-740 ℃. Q: What are the hydrogen content control targets for automotive parts? A：≤0.15ml/100g Al。 Q: How long should it be left to stand after degassing? A: 15-25 minutes, let the slag and gas float up. Q: What is the minimum temperature at the forefront of aluminum liquid? A: Not lower than 660 ℃ to prevent cold insulation. Q: What are the main hazards of aluminum liquid overheating? A: Hydrogen absorption oxidation leads to enlarged pores, coarse grains, and mechanical deterioration. Q: North American aluminum liquid control requirements? A: Spectral+hydrogen content detection, with traceable records. Q: What is the flow rate of argon gas for rotor degassing? A：8–12L/min， Remove air for 8-12 minutes.

The cooling water circuit is the core of actively controlling the solidification gradient. Low pressure casting relies on sequential solidification to allow the thick walled hot spot to solidify last, relying on continuous shrinkage through the sprue; The layout of the waterway is incorrect, the supplementary channel is sealed in advance, and the shrinkage defect persists without solution. 1、 Quantitative parameters of waterway aperture and distance cavity The commonly used aperture for cooling water circuits is between 8 and 12mm; The distance between the outer wall of the waterway and the surface of the mold cavity is 12-18mm; molds with a distance less than 10mm are prone to thermal fatigue cracking; The cooling efficiency is insufficient when the diameter is greater than 22mm, and there is heat storage in the thermal section. Waterway spacing: The center to center distance between two adjacent waterways is 25-35mm; the hot section is densified and the spacing is reduced to 20-25mm; the thin-walled area can be relaxed to 35-45mm to avoid excessive cooling and cold insulation. Control the water temperature difference between the inlet and outlet of the waterway to 5-10 ℃; Excessive temperature difference indicates insufficient flow and uneven cooling; The inlet water temperature of the temperature control unit is usually 40-60 ℃, and it is not better to be colder. The hot spot position adopts a surrounding waterway and a spiral waterway to enhance heat dissipation; Thin walled filling with fewer water channels at the end to prevent rapid cooling and isolation at the front edge. Xinfeng Machinery conducts filling and solidification simulation, matching the water path to ensure a positive solidification gradient from thin wall to thick wall, and then to the gate. 2、 Key points for waterway layout, sealing, and leak prevention The waterway should be as direct as possible to reduce sharp bends at right angles, which can cause large eddies and easy accumulation of scale, leading to long-term blockage and cooling failure; Turning priority R ≥ 1.5D arc. High temperature resistant quick couplings or threaded seals are selected for waterway joints, and the sealing ring has a temperature resistance of ≥ 180 ℃; Ordinary rubber rings quickly age and leak water, which can cause local quenching of the mold cavity and random outbreaks of defects. The slider and insert have independent internal waterways, with separate flow control. The slider's thermal balance and main mold are adjusted separately; Waterway pressure test: After processing, press 0.8-1.0MPa and hold for 30 minutes until there is no leakage before assembly. 3、 Differences in cooling systems for overseas customers Southeast Asian mold waterways are simple, mainly direct waterways, with few independent temperature controls, relying on mold release agent spraying to fine tune temperature, resulting in large fluctuations in yield. North American Tier 1 mold water circuit partition independent temperature control, each circuit flow and temperature are monitored, solidification gradient is written into process files, and abnormal alarms are triggered. European customers commonly use closed-loop temperature control units with PID automatic water temperature adjustment, stable thermal balance, reduced manual intervention, and guaranteed OEE. The thick walled large components in the Middle East have a large heat saving volume, and the waterway is thickened and encrypted to increase water flow and offset heat storage in high temperature environments day and night. 4、 Solidification defects caused by waterway failure Insufficient hot spot water supply → hot spot solidifies first, gate seals in advance → interrupted shrinkage repair, internal shrinkage porosity becomes loose; The waterway is too close to the mold cavity → the surface of the mold cavity is cooled, resulting in surface cold insulation and microcracks; Blockage of waterways and accumulation of scale → gradual decay of cooling, slow decline in yield, and delayed appearance of defects; Waterway seepage → local rapid cooling, uneven casting structure, unstable machining deformation. 5、 Long tail traffic layout ideas Cooling water circuit, sequential solidification, and shrinkage porosity belong to the category of solidification simulation and process optimization search, targeting simulation engineers and process engineers. keywords LPDC mold cooling channel layout、low pressure casting shrinkage porosity control by cooling； Question class: Water channel distance from cavity surface LPDC; Comparison category: zone cooling vs single loop cooling for casting die. Suitable for solidification simulation and mold temperature control scheme pages. 6、 Common misconceptions in the industry Misconception 1: The colder the cooling water, the better. Low temperature strong cooling disrupts the order of solidification, and the sprue solidifies in advance, which actually exacerbates shrinkage. Misconception 2: The more waterways there are, the better the cooling. Excessive cooling in thin-walled areas, rapid cooling at the filling front, and high incidence of cold insulation. Misconception 3: If the waterway is pressurized once without leakage, it will be permanently safe. Scale and aging sealing rings will gradually leak and block. FAQ Q: What is the recommended distance for the cooling water circuit to leave the mold cavity? A：12–18mm。 Q: Conventional waterway aperture? A：φ8–φ12mm。 Q: Reasonable temperature difference between inlet and outlet water? A: 5-10 ℃. Q: How to handle the hot water circuit? A: Encrypt, surround waterways, and enhance heat dissipation. Q: What are the standards for water pressure testing? A: Maintain pressure at 0.8-1.0MPa for 30 minutes without any leakage. Q: Sequential solidification of core objectives? A: Thin walls solidify first, hot joints solidify later, and the sprue solidifies and shrinks last. Q: What are the characteristics of cooling control in North America? A: Partition independent temperature control, real-time monitoring of temperature and flow rate. Q: What are the drawbacks of right angled bends in waterways? A: Vortex fouling can easily block the cooling circuit.

More and more customers are considering switching to low-pressure casting due to leakage and inability to heat treat die-casting shells; Directly using the die-casting drawing to create a low-pressure mold is likely to result in poor cold insulation and filling. The structural logic of die-casting and low-pressure is completely different, and a systematic modification of the drawing is necessary. 1、 Key points for quantifying the structural transformation of drawings Wall thickness upgrade: Conventional die casting 1.2-1.8mm, thickened to ≥ 2.5mm after switching to low pressure; locally isolated thin walls are thickened or transition ribs are added to eliminate cold insulation at the filling end. Wall thickness transition: Die casting allows for severe wall thickness differences, and low pressure requires a wall thickness ratio of ≤ 2:1 as much as possible. The thick area should have rounded corners to prevent looseness in the hot section. Demoulding: Die casting demoulding can be done at 0.8-1 ° C, and it is recommended to increase the low pressure to 1.2-2 ° C. The mold temperature is higher, which makes it easier to stick aluminum and strain. Rounded corner enlargement: Die casting R0.8 is acceptable, and the low-pressure inner rounded corner is uniformly R ≥ 1.5mm, reducing the risk of hot joints and heat treatment cracking. Machining allowance: Single side allowance for die-casting is 0.5-1.0mm; when converted to LPDC, it is increased to 1.2-2.0mm, with reserved T6 heat treatment deformation. Xinfeng Machinery undertakes the project of converting die-casting to low voltage, first making DFM revisions, then conducting simulations, and then opening molds to avoid trial mold failures. 2、 Gate, exhaust, and process route renovation Die casting with multiple side gap gates and multi-point feeding; Low pressure priority bottom injection type liquid lifting gate, the gate is placed in the thick area of the casting, and a bottom-up sequential solidification is established. Die casting exhaust groove is dense, thin, and short; The number of low-pressure exhaust slots has been reduced, and the length of a single exhaust duct has been extended to 0.2-0.3mm, with a focus on the highest and distal filling points. Process route change: Delivery of die-casting as cast state; LPDC has added T6 heat treatment, and the material labeling on the drawings has been changed from A380 to A356, while simultaneously updating the mechanical and non-destructive testing standards. Tolerance adjustment: Stable die-casting dimensions; Low pressure heat treatment causes deformation, and the tolerance of the free contour is appropriately relaxed. Calibration fixtures are reserved for key sealing surfaces. 3、 Differences in die-casting to low-pressure transformation for overseas customers Most of the renovations in Southeast Asia involve simply increasing the wall thickness without adjusting the gating scheme, and there are many problems with loose cold seals in the trial molds. North American new energy customers are switching to low voltage, updating drawing specifications, PPAP, S-N fatigue, salt spray requirements, and conducting type tests again. European hydraulic customers switch to low pressure, prioritize optimizing the structure to reduce stress concentration, use T6 to increase elongation, and improve vibration leakage. Middle Eastern customers' die-casting brackets are being converted to low pressure, with a focus on improving impact resistance, thickening heat nodes, relaxing appearance, and strengthening X-ray inspection. 4、 Directly switching to production without changing the diagram will result in a failure chain Continuing to use die-casting thin-walled → filling the end with cold insulation, not fully filled; Using the multi-point side gate of die-casting → sequential solidification failure, resulting in large areas of looseness; Using die-casting with small allowance → heat treatment deformation, insufficient wall thickness after machining; The grade cannot be changed (A380) → T6 heat treatment is not possible, and the transformation is meaningless. 5、 Long tail traffic layout ideas Transformation from die-casting to low-pressure casting, HPDC to LPDC, water-cooled shell die-casting to low-pressure, aimed at R&D and project engineers. keywords convert HPDC design to LPDC low pressure casting、die casting to low pressure casting redesign； Problem class: Wall thickness change when switching from HPDC to LPDC; Comparative category: HPDC gating design vs LPDC bottom gating. Suitable for process upgrades and product redesign special pages. 6、 Common misconceptions in the industry Misconception 1: Directly opening low-pressure molds on die-casting drawings only involves changing the equipment for production, resulting in completely different filling and solidification systems. Misconception 2: Thickening the wall thickness is enough, and the gate, exhaust, allowance, and heat treatment standards all need to be adjusted synchronously. Misconception 3: The grade can continue to use A380, but A380 is not suitable for T6. Pressure bearing parts must be switched to A356. FAQ Q: What is the minimum wall thickness for die-casting to low-pressure conversion? A：≥2.5mm。 Q: What are the commonly used grades for die-casting? A：A380； Switch A356 for low-pressure pressure components. Q: Changes in gate form? A: Die casting side gate, low-pressure priority bottom injection lifting gate. Q: Adjustment of machining allowance? A: Upgrade from 0.5-1.0mm to 1.2-2.0mm. Q: Requirements for rounded corner transformation? A: Inner fillet R ≥ 1.5mm. Q: Why do we need to change the exhaust? A: Low pressure filling speed is slow, and the exhaust logic is different from that of high-speed coiling in die-casting. Q: The biggest purpose of the change? A: Implement sequential solidification, support T6 heat treatment, and solve leakage. Q: What are the consequences of directly switching production without changing the drawings? A: Cold insulation, looseness, and heat treatment deformation exceed the tolerance.

DFM review is the first checkpoint of a project. Many project drawings are directly molded, and problems such as wall thickness, rounded corners, gate position, draft, heat treatment deformation, and machining allowance are only discovered during mold testing. The cost of mold modification is extremely high, and delivery time is delayed. 1、 DFM Review Core Quantitative Verification Item (A356 Metal LPDC) Structural wall thickness: minimum wall thickness ≥ 2.5mm; wall thickness difference should be ≤ 2 times as much as possible, and significant differences in thickness can easily lead to looseness and deformation. Rounded corner R: Inner rounded corner R ≥ 1.5mm; Sharp corner hot spot, stress concentration, heat treatment cracking; The priority for rounded corners is R ≥ 1mm. Draft angle: Appearance surface ≥ 1.5 °; Non appearance processing surface ≥ 1 °; Increase the draft angle of deep cavity and high reinforcement to 2-3 ° to prevent pulling and sticking to aluminum. Machining allowance: Single side allowance of 1.2-2.0mm; lower limit for thin-walled shells, upper limit for thick walled hot joints, reserved for heat treatment deformation correction. Gate position: Prioritize placement in hot spots and thick areas, establish sequential solidification; Do not place the sprue at the end of the thin wall. Exhaust: Reserve exhaust slots at the filling end, high point, and top of the ribs, with a thickness of 0.2-0.3mm. The DFM review of Xinfeng Machinery outputs a risk list, risk levels, modification suggestions, and cost estimates for mold modification, which are synchronized with customer confirmation. 2、 Simultaneous review of materials, heat treatment, non-destructive testing, and assembly Material: Confirm A356, whether Sr has deteriorated, T6 heat treatment; If the customer's drawings require high elongation, control the upper limit of Fe content in advance. Testing requirements: Mark the X-ray/UT testing area, clarify the defect level, and distinguish between allowed looseness and rejected defects. Sealed pressure bearing: Confirm in advance whether infiltration repair is allowed based on the compression pressure, holding time, and leakage judgment criteria. Assembly tolerance: Distinguish between casting tolerance, machining tolerance, and compensation for heat treatment deformation reserved tolerance. 3、 Differences in DFM review for overseas clients Simplify DFM for Southeast Asian customers, only focus on demolding, testing and heat treatment risks, and repeatedly adjust the trial mold. The North American Tier1 DFM document is a pre PPAP document, and each risk must have an improvement plan. The mold cannot be opened until the risk is closed. The European customer DFM focuses on fatigue, corrosion, and stress concentration rounded corners, prioritizing structural improvements to enhance reliability and reduce later testing costs. Middle Eastern engineering machinery parts, DFM focuses on checking wall thickness, thermal joints, impact load stress concentration, and relaxing appearance requirements. 4、 The Failure Chain Caused by DFM Omission Sharp corners without rounded corners → looseness of hot joints+stress cracking during heat treatment; Great disparity in wall thickness mutation → cutting off of contraction channels, loosening of hot joints; Insufficient demoulding → Pulling and sticking of aluminum during demoulding, resulting in poor appearance in batches; Insufficient machining allowance+heat treatment deformation → insufficient wall thickness after machining, local perforation. 5、 Long tail traffic layout ideas Low pressure casting DFM review, casting manufacturability review, aluminum alloy casting drawing review, aimed at project engineers and R&D. keywords LPDC casting DFM checklist、design for manufacturability low pressure aluminum casting； Problem class: Minimum wall thickness for A356 LPDC; Comparison category: DFM review before mold opening vs post trial modification. Suitable for new project development and DFM themed pages. 6、 Common misconceptions in the industry Misconception 1: If drawings can be drawn, they can be cast. Many structures have natural defects in filling, shrinking, and demolding. Misconception 2: Rounded corners are just appearance, sharp corners pose a dual risk of thermal cracking and stress concentration, and heat treatment can easily lead to cracking. Misconception 3: The larger the margin, the better. If the margin is too large, the dense surface will be cut off during machining, exposing internal looseness. FAQ Q: What is the recommended minimum wall thickness for LPDC? A：≥2.5mm。 Q: What is the minimum requirement for rounded corners? A：R≥1.5mm。 Q: Conventional draft angle (machined surface)? A: ≥ 1 °; Appearance ≥ 1.5 °. Q: Single side machining allowance? A：1.2–2.0mm。 Q: What is the thickness of the exhaust groove? A：0.2–0.3mm。 Q: Where should the sprue be prioritized? A: The thick and large hot spot position of the casting is conducive to compensating shrinkage. Q: What are the core values of DFM? A: Lock in risks before mold opening to reduce mold changes. Q: Is there a hidden danger of excessive surplus? A: Process and peel off the dense surface layer, exposing the internal looseness.

The wastewater from mold release agents contains organic silicon, emulsifiers, aluminum powder, and suspended aluminum slag, which directly discharge COD exceeding the standard. Many factories have environmental inspection checkpoints; Simple precipitation cannot break the emulsion, and the supernatant remains turbid and continues to exceed the standard. 1、 Wastewater pollutant indicators and control objectives Main pollutants: organic silicon emulsifiers, suspended aluminum micro powders, oils and fats COD、SS； The COD of the original solution is generally 8000-20000mg/L. Emission target after treatment: COD ≤ 500mg/L, SS ≤ 100mg/L; The recycling standards in the factory area are higher, COD≤200mg/L， Prevent the accumulation of silicon scale in the reuse pipeline. Demulsifying agent: inorganic composite demulsifier is selected to break the silicone oil lotion and allow the silicone oil to agglomerate and float; Do not use a single PAC, as the demulsification may not be thorough. PH control: pH 7.5-9.0 during the emulsion breaking stage; Low pH makes it difficult for silicone oil to become unstable; The pH is too high, causing aluminum ions to dissolve again. A simple process plan for the treatment of mold release agent wastewater in Xinfeng Machinery is suitable for small and medium-sized casting workshops, reducing the amount of hazardous waste generated. 2、 Complete processing flow: water collection → demulsification → air flotation → sedimentation → filtration → reuse/discharge 1. Collecting tank: Collecting wastewater from mold spraying and washing, separating slag, and first settling large particle aluminum slag; 2. Reaction tank: adjust pH, add demulsifier and flocculant, stir to break the emulsion, and the silicone oil flocs float up; 3. Air flotation tank: Scrape off the upper layer of silicone oil scum (which belongs to hazardous waste); 4. Sedimentation tank: Sedimentation of aluminum micro powder sludge; 5. Quartz sand+activated carbon filtration, effluent detection; After passing the inspection, it can be reused or discharged through pipes. Sludge and floating slag are packaged separately, while silicone oil floating slag is classified as hazardous waste and cannot be mixed with ordinary aluminum slag. 3、 Differences in wastewater control among overseas clients Southeast Asia has a relaxed environmental protection policy, with most simply settling and discharging without deep treatment. Online COD monitoring of North American factory wastewater, with priority given to using low COD biodegradable release agents and a complete hazardous waste ledger. European foundries prioritize closed-loop reuse, wastewater is not discharged, emission taxes are reduced, and silicon free mold release agents are used to reduce treatment difficulty. In the water scarce regions of the Middle East, mandatory wastewater reuse is required, with high treatment standards and supporting reverse osmosis deep filtration. 4、 Failure chain of wastewater treatment Only PAC flocculation does not break the emulsion → Silicone oil maintains an emulsified state, COD remains high, and the supernatant is milky white; PH not in the range of 7.5-9 → Failure of silicone oil destabilization and inability to remove floating oil through air flotation; Mixing of floating slag and aluminum slag → all accounted for as hazardous waste, doubling the cost of hazardous waste; The COD of the recycled liquid exceeds the standard → Silicon scale forms on the pipeline and mold spraying nozzle, blocking the atomizing nozzle. 5、 Long tail traffic layout ideas Low pressure casting release agent wastewater treatment, silicone oil wastewater demulsification, and casting wastewater reuse, aimed at environmental protection and workshop supervisors. keywords LPDC release agent wastewater treatment、silicone emulsion wastewater demulsification； Problem class: COD control for aluminum casting release agent sewage; Comparison category: silicone release agent vs silicone free release agent wastewater. Suitable for workshop environmental protection and compliance management special pages. 6、 Common misconceptions in the industry Misconception 1: Precipitation can treat mold release agent wastewater. Silicone oil is in an emulsified state, and simple precipitation cannot separate it. Misconception 2: Scum and aluminum slag are both aluminum slag and can be mixed together. Silicone oil scum is a hazardous waste and should be disposed of as hazardous waste when mixed together. Misconception 3: The treated wastewater is directly sprayed back into the mold, and high COD will clog the nozzle. It is necessary to filter and control COD. FAQ Q: Core pollutants in mold release agent wastewater? A: Emulsified organic silicon, aluminum micro powder, high COD. Q: What is the recommended pH range for demulsification? A：7.5–9.0。 Q: What is the COD range of the original solution? A：8000–20000mg/L。 Q: What are the properties of silicone oil scum? A: Belonging to hazardous waste, collected separately. Q: The core purpose of demulsification? A: Breaking lotion, silicone oil agglomerates, floats and separates. Q: Reuse additional filtering? A: Sand filtration+activated carbon filtration. Q: What is the reason for nozzle blockage? A: Silicon scale and COD in recycled water exceed the standard. Q: Low COD alternative solution? A: Silicon free mold release agent.

The mold is subjected to long-term high-temperature alternating thermal shock, resulting in surface scratches, aluminum adhesion, wear, and cracking; Nitriding is a commonly used surface strengthening method for low-pressure molds. Many molds deform beyond tolerance after nitriding, the cavity size runs away, or the nitride layer is too brittle, resulting in peeling off during production. 1、 Nitriding process parameters, layer depth, hardness quantification standards Gas soft nitriding: 570-580 ℃, insulation for 3-5 hours; compound layer 0.008-0.015mm, diffusion layer 0.15-0.25mm, hardness HV600-800, small deformation, suitable for nitriding after cavity precision machining. Gas nitriding: 510-530 ℃, insulation 12-24h; diffusion layer depth 0.3-0.5mm, higher hardness, but longer cycle, higher deformation risk, suitable for long-term large-scale molds. It is not recommended to use ion nitriding for complex deep cavity molds, as the nitriding in the corners of the deep cavity is uneven, resulting in color difference and discrete hardness. Reserve deformation allowance before nitriding: leave 0.02-0.04mm grinding allowance after precision machining, and polish the size after nitriding. Before nitriding, Xinfeng Machinery molds undergo stress relief tempering to release machining stress and reduce nitriding warpage deformation. 2、 Preparation before nitriding, furnace installation, polishing after nitriding, and usage taboos Thoroughly clean the mold cavity of oil stains and residual release agents before nitriding. Oil stains may cause nitriding blind spots, insufficient hardness, and localized aluminum adhesion. Stress relief tempering: Hold at 600 ℃ for 4-6 hours, slowly cool with the furnace, eliminate CNC machining stress, which is the core step of controlling deformation. After nitriding: the compound layer is thin and cannot be polished excessively. Polishing wears through the compound layer, and the nitriding effect disappears directly; Only do mirror polishing. Taboo: Nitriding molds are prohibited from rapid cooling. If the temperature difference during mold water cooling is too large, the nitride layer is prone to cracking and peeling off; The brittleness of the nitride layer is higher than that of the substrate, avoiding knocking and bumping. 3、 Differences in Nitrogen Control for Overseas Customers Simplified nitriding of Southeast Asian molds without stress relief tempering, resulting in significant deformation after nitriding, requiring manual polishing to repair the mold cavity. The North American customer's mold nitriding comes with hardness gradient and layer depth metallographic reports, and the nitriding deformation amount is included in the mold acceptance criteria. European customers prioritize soft nitriding and deformation control, value dimensional stability, and do not blindly pursue deep nitriding. Long term continuous production of molds in the Middle East, using hard nitriding, pursuing longer wear resistance life, and supporting strict heating and cooling curves. 4、 Nitriding failure chain No stress relief tempering before nitriding → stress release during machining, cavity warping, and dimensional deviation; Surface oil stains have not been cleaned thoroughly → Nitriding blind spots, low local hardness, priority for aluminum adhesion and pulling; Overpolishing, grinding through the compound layer → nitriding failure, with little difference from non nitriding molds; The nitride layer is too thick and the hardness is too high, resulting in high brittleness. Under thermal shock, the nitride layer peels off and falls into the mold cavity, forming slag inclusions. 5、 Long tail traffic layout ideas Low pressure casting mold nitriding, soft nitriding, mold aluminum adhesion improvement, deep nitriding layer, aimed at mold masters and heat treatment engineers. keywords LPDC mold gas nitrocarburizing、nitriding treatment for low pressure casting die； Problem class: distortion control when nitriding aluminum casting mold; Comparison class: Gas Nitriding vs Nitrifying Die for LPDC. Suitable for special pages on mold maintenance and surface strengthening. 6、 Common misconceptions in the industry Misconception 1: The deeper the nitride layer, the better. Deep nitriding is more brittle, prone to peeling off under thermal shock, and can also cause greater deformation. Misconception 2: After nitriding, casually polishing and grinding through the compound layer will directly result in the loss of wear and adhesion resistance to aluminum. Misconception 3: Nitriding can cure aluminum adhesion, while nitriding only improves it. Abnormal mold release agents and mold temperatures can still cause aluminum adhesion. FAQ Q: What are the common temperatures for soft nitriding? A: 570-580 ℃. Q: What is the thickness of the soft nitride compound layer? A：0.008–0.015mm。 Q: Is there a necessary process before nitriding? A: Stress relief tempering. Q: What are the taboos for polishing after nitriding? A: Do not over polish to prevent the compound layer from being worn through. Q: Advantages of hard nitriding? A: Deep diffusion layer, longer wear resistance life. Q: What are the causes of nitride layer peeling off? A: Hard layer, rapid cooling impact, and collision. Q: Core benefits of nitriding? A: Improve surface hardness, reduce aluminum adhesion and strain. Q: Is complex cavity preferred? A: Gas soft nitriding, controllable deformation.

Charging simulation is not just about producing renderings, it is a pre DFM tool; Many simulations only focus on temperature and ignore turbulent flow and liquid surface entrainment, resulting in beautiful simulation results. However, in actual production, there are continuous gas pores and slag inclusions, and the core issue is the mismatch between boundary conditions and on-site parameters. 1、 Quantitative setting of simulation boundary conditions (A356 metal type LPDC) Aluminum liquid pouring temperature: 720 ℃; The initial temperature of the mold is input by zone: 420 ℃ for the sprue, 280 ℃ for the distal thin wall, consistent with the on-site thermocouple setting. Pressure curve: Directly import the actual pressure rise curve of the equipment, without using the default uniform pressure rise; The pressure rise rate is the most sensitive parameter for the flow field and entrainment. Heat transfer coefficient: 300-600 W/(m ² · K) at the cavity aluminum mold interface; Reduce the heat transfer coefficient in the gate area and simulate weak cooling; Increase the heat transfer coefficient at the exhaust port. Grid: Dense grid for hot nodes, thin walls, and sprue areas; Rough grid, distorted flow field, and failed prediction. Xinfeng mechanical simulation output: filling liquid level timing diagram, coiling position, hot spot position, solidification sequence, synchronously providing exhaust and gate optimization solutions. 2、 Key points of simulation interpretation, sources of deviation between simulation and physical objects Qualified flow field: The liquid level is steadily pushed forward without splashing, backflow, or vortex; The liquid level front is continuous, and the gas is orderly discharged from the exhaust groove. High risk signals: liquid level tearing, vortex, aluminum liquid reflux, premature closure of the front edge, corresponding to high incidence areas of pores and slag inclusions. Deviation source: The simulation uses an ideal release agent coating, but the actual release agent thickness is uneven and the heat transfer coefficient fluctuates; Changes in the proportion of recycled materials and viscosity of aluminum liquid; Thermocouple drift, mode temperature and simulation input are inconsistent. Simulation verification method: First article X-ray, metallographic, temperature curve comparison, reverse correction of heat transfer coefficient, iterative simulation model. 3、 Differences in simulation control for overseas customers Southeast Asian customers rarely conduct mold filling simulations and rely on trial mold modifications, resulting in multiple trial molds and long development cycles. During the PPAP phase for North American customers, simulation reports must be submitted, and simulation files for filling, solidification, and coiling must be used as tooling approval documents. The European customer simulation model continues to iterate, updating the simulation boundary conditions synchronously with each mold modification and process change. For large thick walled castings in the Middle East, the focus is on simulating solidification and shrinkage, with priority given to predicting thermal looseness and secondary consideration of gas entrapment. 4、 Simulation misjudgment failure chain Directly applying the default constant pressure rise curve, which is inconsistent with the on-site pressure curve → flow field simulation distortion, misjudging the absence of air entrainment; Unified value of heat transfer coefficient, without distinguishing between sprue, thin wall, and hot spot → simulation error in solidification sequence, failure of porosity prediction; Rough grid, simplified local flow field → missing vortex vortex vortex location; If the simulation is completed without physical benchmarking, and the model is not updated for a long time, it will lose its reference value. 5、 Long tail traffic layout ideas Low pressure casting filling simulation, Moldflow LPDC simulation, solidification simulation, and gas prediction for mold and simulation engineers. keywords LPDC filling simulation Moldflow、low pressure casting solidification simulation； Problem class: Heat transfer coefficient aluminum mold LPDC simulation; Comparison category: Simulation prediction vs actual casting defect LPDC. Suitable for DFM pre development and mold simulation special pages. 6、 Common misconceptions in the industry Misconception 1: A good simulation result means stable mass production. If the boundary conditions and on-site parameters are inconsistent, the simulation has no reference value. Misconception 2: Simulation can completely replace trial molding. Simulation can only predict risks and cannot fully simulate the quality fluctuations of release agents and aluminum liquids. Misconception 3: Only focus on solidification simulation and ignore the filling flow field. Many pores are filled and rolled, not solidified and loose. FAQ Q: LPDC simulation aluminum liquid temperature conventional input? A: 720 ℃. Q: Aluminum mold interface heat transfer coefficient? A：300–600 W/(m²·K)。 Q: The most sensitive parameter in simulation? A: Boosting rate and pressure curve. Q: Flow field danger signal? A: Liquid level vortex, reflux, and front closure. Q: What are the main reasons for the deviation between simulation and physical objects? A: Mold temperature drift, uneven release agent, and changes in viscosity of aluminum liquid. Q: Grid encryption location? A: Gate, hot section, thin-walled filling end. Q: North American customer simulation purposes? A: PPAP tooling approval documents. Q: Can simulation identify looseness? A: Solidification simulation predicts thermal looseness.

The slag blocking cap is a simple accessory installed at the bottom of the liquid lifting pipe, which is often omitted in many production lines; The sediment, oxides, and bottom slag at the bottom of the crucible enter the mold cavity through the rising liquid channel, causing periodic slag inclusion, which is sometimes good and sometimes bad, making it difficult to locate the root cause. 1、 Quantitative parameters of slag blocking cap structure, aperture, and aperture ratio Material: Silicon carbide slag cap, matched with the liquid lifting tube, resistant to aluminum liquid erosion; Graphite is not recommended as it can easily peel off and form carbon inclusions. Hole opening rate: 25-35%, hole diameter of φ 4-6mm; The opening is too small, the flow rate is insufficient, and the filling pressure is unstable; The opening is too large, and the slag blocking is ineffective. Structural form: Bottom closed, side perforated, sediment settles at the bottom of the crucible, and aluminum enters smoothly from the side; Avoid direct suction of the bottom slag layer. Assembly gap: The gap between the slag cap and the bottom of the liquid lifting tube is 0.5-1mm. If the gap is too large, slag may enter through the gap; Too tight, stuck due to thermal expansion, difficult to disassemble and assemble. The inspection standard for Xinfeng Machinery's slag blocking cap includes direct replacement for deformation, cracking, and hole blockage, and synchronous matching of crucible slag removal frequency plan. 2、 Installation, preheating, slag removal, and maintenance standards Preheat the slag blocking cap and the liquid lifting pipe in sections together. It is forbidden to directly lower the aluminum on the cold slag blocking cap, which may cause surface condensation and rapid blockage of the pores. Immersion depth: The bottom of the slag cap should be 30-50mm away from the bottom of the crucible, leaving space for sediment to settle and not adhere to the bottom for slag suction. Slag removal cycle: remove the sediment at the bottom of the crucible every 2-4 hours; If the slag is not removed for a long time, the slag layer will rise and enter the pipeline through the opening on the side of the slag cap. Cleaning: Remove the slag cap from each shift and blow clean the alumina nodules in the pore channels; Tumor accumulation will reduce the effective opening and cause fluctuations in filling flow rate. 3、 Differences in slag cap control for overseas customers The vast majority of production lines in Southeast Asia do not use slag blocking caps and rely on frequent slag removal, resulting in significant fluctuations in slag inclusions. North American X-ray pressure parts are required to use silicon carbide slag blocking caps, and the structure is specified in the drawing process documents. Production is prohibited without slag blocking caps. European customers have added a guide slope to the slag cap to further stabilize the flow and reduce the vortex induced slag entrapment in the aluminum liquid. The Middle East has a large capacity deep crucible, with a raised slag cap and larger sedimentation space, suitable for long-term continuous production. 4、 Defect chain of slag blocking cap failure No slag blocking cap/excessive opening → Bottom slag and oxide of crucible are sucked into the riser → Periodic slag inclusion and X-ray defects; The slag cap is attached to the bottom of the crucible, and the slag layer directly blocks the opening, resulting in unstable filling flow and pressure curve drift; The cold blocking slag cap is directly inserted into the aluminum → the inner wall of the hole is solidified with aluminum nodules, gradually blocked, insufficient filling, and cold isolation; Graphite slag cap → graphite peeling, forming carbon inclusions and X-ray black spots. 5、 Long tail traffic layout ideas Lift pipe slag cap, silicon carbide slag cap, low-pressure casting anti suction slag cap, aimed at equipment and smelting engineers. Keywords: LPDC riser tube slab filter cap, SiC slab shuffle for low pressure casting; Problem class: merger gap for riser slab cap; Comparison class: SiC slab cap vs graphic slab cap aluminum casting. Suitable for crucible conveying and slag removal system special pages. 6、 Common misconceptions in the industry Misconception 1: The more holes in the slag blocking cap, the better. If the opening rate is too high, the slag blocking effect will be lost; The opening is too small and the flow is insufficient. Misconception 2: Placing the slag blocking cap on the bottom can directly block the opening with sediment, making it easier to absorb the slag. Misconception 3: Graphite is cheap and easy to use, graphite is prone to peeling off, carbon inclusions are introduced, and non-destructive testing parts are prohibited. FAQ Q: What is the recommended material for the slag blocking cap? A: Silicon carbide (SiC). Q: Reasonable opening rate? A：25–35%。 Q: What is the distance between the bottom of the slag cap and the bottom of the crucible? A：30–50mm。 Q: What is the diameter of the slag blocking cap opening? A：φ4–6mm。 Q: What is the gap between the slag cap and the liquid lifting pipe? A：0.5–1mm。 Q: What are the risks of graphite slag caps? A: Graphite peeling and carbon inclusions. Q: Is the slag cap blocked? A: Unstable filling pressure, insufficient filling, and frequent occurrence of cold insulation. Q: What is the core function of the slag blocking cap? A: Block the sediment at the bottom of the crucible, ensure smooth flow, and reduce vortex induced slag entrapment.

Many customers are torn between choosing low-pressure casting or high-pressure die casting, as the underlying solidification logic of the two processes is completely different; High die-casting efficiency, but unable to undergo T6 heat treatment, resulting in limited pressure sealing performance; Low pressure can be heat-treated, with stable performance and slower pace. Choosing the wrong process can directly lead to project pitfalls. 1、 Quantitative comparison of core indicators Pores: HPDC has severe gas entrapment and numerous pores, making it unsuitable for high-temperature heat treatment; LPDC charging is smooth, with controllable gas entrainment and T6 solid solution aging capability. Mechanical properties: HPDC A380 as cast tensile strength 220-280MPa, not suitable for T6; LPDC A356-T6 tensile strength 260-320MPa, high elongation and good toughness. Wall thickness: HPDC can achieve a thin wall of 0.8-1.5mm; LPDC stable mass production wall thickness ≥ 2.5mm, too thin can easily cause cold insulation. Beat: HPDC single-mode 30-90s; LPDC single-mode 180-420s, slow beat. Cost: Lower unit price for large-scale die-casting of simple appearance parts; Medium batch, pressure bearing, heat-treated parts, low pressure comprehensive yield advantage to balance costs. Testing: HPDC generally does not support X-ray testing of pressure parts; LPDC can meet X-ray and UT testing requirements, and is suitable for hydraulic and water-cooled shells. Xinfeng Machinery DFM helped customers lock in the process route in the early stage to avoid discovering the inability to heat treat and pressure leakage after die-casting and mold opening. 2、 Their respective strengths and weaknesses Advantages of high-pressure die casting: thin wall, complex appearance, ultra-high cycle time, and large quantity of consumer parts; Shortcomings: Roll up air holes, unable to T6, low elongation, high risk of pressure leakage, not suitable for alternating loads. Advantages of low-pressure casting: smooth filling, sequential solidification, T6 heat treatment, controllable looseness, suitable for X-ray pressure parts, good fatigue performance; Shortcomings: slow pace, high mold cost, weak thin-walled forming ability. Key points of process transformation: die-casting to low pressure, wall thickness to be increased, gate, exhaust, and filling curves to be completely redesigned, and die-casting drawings cannot be used. 3、 Differences in selection preferences among overseas customers Southeast Asia: Priority is given to die-casting ordinary shells and non stress parts, pursuing low cost and relying on infiltration for leakage protection. North American new energy water-cooled shell and valve block, mandatory LPDC+T6, rejecting high-pressure die casting to avoid the risk of heat treatment bubbling. The mainstream low-pressure pressure components in the European hydraulic industry for medium to large quantities; Large quantities of exterior shells are made by die-casting. Middle Eastern construction machinery thick walled load-bearing brackets prioritize low pressure and value elongation and impact resistance. 4、 Failure chain caused by incorrect process selection High pressure die-casting is used for the pressure bearing shell, followed by internal air entrainment and heat treatment for bubbling and scrapping. Without heat treatment, the strength and toughness are insufficient, and there is vibration leakage; The selection of thin-walled exterior parts is low pressure → cold insulation, difficult filling, slow pace, high unit price, and loss of competitiveness; The die-casting drawing is directly converted to low pressure → the wall thickness is too thin, the filling end is cold sealed, and the yield continues to be low. 5、 Long tail traffic layout ideas Comparison between Low Pressure Casting and High Pressure Die Casting, Differences between LPDC and HPDC, Selection of Low Pressure or Die Casting for Water Cooled Shell, aimed at project engineers and procurement. keywords LPDC vs HPDC aluminum casting、low pressure casting vs high pressure die casting； Question class: Can HPDC aluminum go through T6 heat treatment; Comparative category: HPDC A380 vs LPDC A356 T6 mechanical property. Suitable for process selection and DFM pre evaluation special pages. 6、 Common misconceptions in the industry Misconception 1: Both die-casting and low-pressure casting are made of aluminum, and the drawings can be used interchangeably. The filling, exhaust, and solidification logic are completely different. Misconception 2: Die casting has higher strength. Die casting only provides as cast strength and cannot be heat treated, resulting in a much lower elongation than T6 low-pressure parts. Misconception 3: Low pressure is definitely more expensive than die-casting, and the yield of pressure bearing parts in die-casting is poor, with more infiltration repairs, resulting in higher overall costs. FAQ Q: Can T6 heat treatment be performed on high-pressure die-casting? A: Conventional methods are not feasible. Internal air entrainment and heating can cause bubbles to bulge. Q: What is the minimum wall thickness for low-pressure stable mass production? A：≥2.5mm。 Q: What are the commonly used grades of HPDC? A：A380、ADC12。 Q: LPDC mainstream brand? A：A356。 Q: Which one is suitable for X-ray pressure shell? A: LPDC low voltage casting. Q: Which beat is faster? A: HPDC high voltage die-casting. Q: Which elongation rate is better? A: A356-T6 low-pressure castings. Q: Is thin-walled appearance preferred? A: High pressure die-casting.

Low pressure castings exhibit porosity, segregation, and hard silicon phases, which differ significantly from the cutting characteristics of die cast aluminum; Copying ADC12 cutting parameters can easily lead to tool sticking, chipping, rough cutting patterns, substandard roughness of sealing surfaces and oil passage holes, and assembly leakage. 1、 Tool material selection suitable for A356-T6 PCD diamond cutting tools: batch precision machining of sealing surfaces and oil holes, with extremely high lifespan, suitable for stable mass production; Cutting line speed 1200-2500m/min. Hard alloy YG8/YG6X: semi precision, rough machining, good toughness, impact resistance, suitable for castings with a small amount of loose inclusions; Linear speed of 300-800m/min. High speed steel: only suitable for single piece sampling, with fast wear and tear during mass production, not recommended for bulk production. It is not recommended to use TiN coated cutting tools to process aluminum. The coating is compatible with aluminum and is prone to chip buildup and sticking to the tool; Prioritize uncoated hard alloy or PCD. Xinfeng Machinery will provide customers with machining process cards, distinguishing between rough boring, precision boring, end face milling, and tapping parameters, and matching sealing surface precision machining solutions. 2、 Cutting parameters, cooling, chip removal, and prevention and control of chip deposits Feed: Precision machining end face f=0.1-0.25mm/r; Rough machining f=0.3-0.6mm/r; Cutting depth precision machining ap ≤ 0.3mm, rough machining ap 0.5-1.5mm. Cooling: emulsion concentration 8-12%, high flow chip flushing; Pure dry cutting is prone to high-temperature chip accumulation and sticking to aluminum paste knives. Edge: Large rake angle of 12-18 °, sharp edge, reduces cutting resistance; Blade passivation treatment of 0.02-0.04mm to prevent blade breakage. Oil deep hole machining: Internally cooled drill bit, intermittent tool retreat and chip removal, aluminum chip entanglement can easily scratch the hole wall, causing sealing leakage hazards. 3、 Differences in machining control for overseas customers Common hard alloys are commonly used in Southeast Asia, with conservative parameters, frequent tool changes, and roughness correction through later polishing. The sealing surface of the North American new energy shell is subjected to mandatory PCD precision machining, with a roughness Ra ≤ 0.4 μ m, and roughness testing reports are retained for each batch. The oil passage holes of European hydraulic components require no tearing or knife marks, and are not allowed to be polished or repaired. The tool life and tool replacement frequency should be included in the control plan. Middle Eastern construction machinery brackets have a relatively large rough machining allowance and prioritize YG8 impact resistance, with loose requirements for surface appearance. 4、 Poor machining defect chain The tool front angle is too small, the cutting edge is dull, the cutting resistance is high, and the chip lumps stick to the aluminum, resulting in tool lines and surface tearing; Insufficient cooling and poor chip removal → Aluminum chips scratch the sealing surface, micro grooves, and pressure leakage; Choose TiN coated cutting tools → aluminum affinity adhesive cutting tools, with continuous size drift; The interior of the casting is loose, and the thin-walled and thick positions are precision machined, resulting in ripple cutting patterns caused by cutting vibrations. 5、 Long tail traffic layout ideas A356 low-pressure casting machining tools, PCD tool cutting parameters, aluminum parts sticking tools, aimed at machining process engineers. keywords PCD tool for A356 LPDC casting machining、cutting parameter low pressure aluminum casting； Question class: How to avoid built up edge when machining A356; Comparison category: PCD vs carriage insert for aluminum sealing face. Suitable for specialized pages on machining processes and precision machining. 6、 Common misconceptions in the industry Misconception 1: The higher the speed of processing aluminum parts, the better. If the speed is too high, the cutting temperature will rise and the accumulation of chips will become more severe. Misconception 2: Coated cutting tools are always better, TiN coating is more compatible with aluminum and is more likely to stick to the tool. Misconception 3: Blade patterns are only an appearance issue, and micro blade patterns on the sealing surface can form leakage channels. FAQ Q: What is the preferred tool for precision machining of sealing surfaces? A: PCD diamond cutting tools. Q: Recommended grades of hard alloy? A：YG8、YG6X。 Q: Recommended front corner for precision machining? A: 12-18 ° large front angle. Q: Emulsion concentration? A：8–12%， High flow debris flushing. Q: PCD line speed range? A：1200–2500m/min。 Q: What problems does the accumulation of debris tumor bring? A: Adhesive knife, size drift, surface tearing knife marks. Q: What are the key points for deep hole machining in oil pipelines? A: Internally cooled drill bit, intermittent tool retraction and chip removal. Q: Which is difficult to machine, T6 casting or as cast? A: T6 has higher hardness, harder silicon phase, and faster tool wear.

Aluminum alloy shells often fail due to long-term outdoor, humid, and refrigerant environments, as well as salt spray corrosion; Many factories only focus on the appearance without white rust, ignoring intergranular corrosion. Corrosion extends inward along grain boundaries, causing slow deterioration of mechanical strength and posing a risk of explosion and leakage in pressure bearing components. 1、 Classification and Quantitative Parameters of Salt Spray Testing (A356) Neutral salt spray NSS: 5% NaCl solution, pH 6.5–7.2， Spray temperature 35 ℃, sedimentation 1 – 2ml/80cm ² · h; Universal outdoor foundation anti-corrosion acceptance. CASS copper accelerated acetate salt spray: containing copper chloride, pH 3.1–3.3， 50 ℃, faster corrosion rate, suitable for accelerated verification of anodized and sprayed parts. Intergranular corrosion test: According to ASTM G67, immerse in mercuric nitrate solution, bend after corrosion, and observe grain boundary cracking. When the magnesium content of A356 is high, the risk of intergranular corrosion increases. A356 bare aluminum NSS: white rust usually appears within 24-72 hours; Chromium free passivation can last for 200-500 hours; hard anodizing can last for over 1000 hours. Xinfeng Machinery distinguishes based on customer operating conditions: passivation is recommended for indoor water-cooled shells, while hard anodizing is recommended for outdoor chassis components. 2、 Sample pretreatment, sealing, rating, and corrosion source control Clean and remove oil before testing, and do not touch the surface of the sample directly with your hands. Oil and grease will form local shielding and cause uneven corrosion. Threaded holes, sealing grooves, and internal flow channels are protected with specialized sealing wax in areas that are not sprayed. The sealing wax boundary is clear and does not contaminate the test surface. Rating standard: GB/T 6461, comparing corrosion area and pitting depth; Key control points for pressure bearing parts include the depth of pitting corrosion, which penetrates the wall thickness and is directly scrapped. Defects in casting itself: looseness, subcutaneous pores, and preferential pitting corrosion occur at the location of inclusions, and corrosion extends outward from the inside of the defect. 3、 Differences in Salt Spray Control for Overseas Customers Most Southeast Asian customers only use 24-hour neutral salt spray, and a small amount of white rust is acceptable, relying on later painting to cover it up. North American new energy water-cooled shell, NSS 500h without red rust, with a clear upper limit for pitting depth, and a passivation film thickness report attached. European outdoor hydraulic components are subject to mandatory intergranular corrosion testing except for NSS, and continuous corrosion channels at grain boundaries are not allowed. Middle East coastal project, sand and salt spray composite testing, while assessing wear and corrosion, requires thick film anodizing. 4、 Corrosion Failure Defect Chain Subcutaneous looseness and micropores in castings → infiltration of corrosive media into the interior → internal pitting corrosion, with a slight appearance and continuous thinning of wall thickness; Magnesium element segregation, enrichment of Mg ₂ Si at grain boundaries → intergranular corrosion, delamination along grain boundaries; Surface release agent residue, oil stains → local discontinuity of passivation film, priority corrosion; Insufficient thickness of passivation film and inadequate baking → The film layer is porous and resistant to salt spray, resulting in significant shrinkage. 5、 Long tail traffic layout ideas Low pressure casting salt spray testing, neutral salt spray NSS, intergranular corrosion, aluminum alloy passivation, facing surface treatment and quality engineers. keywords LPDC aluminum casting NSS salt spray test、intergranular corrosion A356 casting； Question category: CASS test requirement for aluminum alloy housing; Comparison category: Passage vs Hard Anodizing Salt Spray Resistance. Suitable for surface anti-corrosion and reliability themed pages. 6、 Common misconceptions in the industry Misconception 1: If there is white rust, it is considered unqualified. The drawing only controls red rust, which is a corrosion product of alumina and does not represent penetration corrosion. Misconception 2: If the salt spray is qualified, there will be no intergranular corrosion. Salt spray cannot see the grain boundaries, and a separate intergranular corrosion test must be conducted. Misconception 3: The thicker the film layer, the better. Excessive thickness in anodizing can lead to microcracks and crack propagation under stress conditions. FAQ Q: Neutral salt spray NaCl concentration? A：5%。 Q: NSS testing temperature? A: 35 ℃. Q: CASS testing temperature? A: 50 ℃. Q: What is the duration of neutral salt spray on A356 bare aluminum? A: White rust appears within 24-72 hours. Q: Common standards for intergranular corrosion? A：ASTM G67。 Q: What is the greatest harm of pitting corrosion? A: Local wall thickness reduction and leakage of pressure bearing components. Q: Advantages of passivation film? A: Low cost, no change in size, suitable for sealing surfaces. Q: Shortboard of anodizing? A: The film layer has a thickness, and the sealing holes and assembly dimensions need to be reserved with allowance.

Many castings under pressure and vibration conditions only verify static tensile strength, ignoring fatigue indicators; Qualified statics, early cracking under repeated alternating loads, strong concealment of fatigue failure, often exposed in batches after installation, are major quality risks for construction machinery and water-cooled shells. 1、 Quantitative Standards and Sample Requirements for Fatigue Testing (A356-T6) Priority should be given to selecting sampling locations such as hot joints, rib joints, and near gates, where stress is concentrated and fatigue is weak; Not separately taking the attached casting test rod, the fatigue data of the attached casting test rod deviates greatly from the body. Sample processing: Surface Ra ≤ 0.8 μ m, without knife marks, scratches, or bumps; Surface damage can become a source of fatigue, resulting in significantly lower test results. Loading method: axial tension compression fatigue, stress ratio R=0.1; Frequency of 20-30Hz; target cycle base of 1 × 10 ⁷ times, without cracking, it is determined as the fatigue limit. A356-T6 conventional fatigue limit: 70-90MPa; The fatigue limit of castings with poor deterioration and high beta iron phase will drop below 50MPa. Xinfeng Mechanical Fatigue Testing synchronously retains metallographic sections, traces the location of crack initiation, and distinguishes whether it is material inclusions, stress concentration, or surface defects. 2、 Pre test control, clamping, environment and failure assessment The coaxiality requirement for sample clamping is ≤ 0.02mm, and eccentric loading will generate additional bending moments, resulting in distorted test data; Add a protective cover to the clamping position to avoid damaging the sample body. Environmental temperature 23 ± 5 ℃, dry environment; Wet salt spray coupled fatigue requires a separate corrosion fatigue test and cannot be replaced by conventional air fatigue. Failure determination: If visible cracks appear on the sample and the load drops by more than 5%, it is considered a failure; Reaching 10 ⁷ cycles without fracture, increase stress and continue to explore the S-N curve. Comparison group setting: Compare samples from the same batch with different Sr modifications, Fe contents, and heat treatment processes to determine the direction of material improvement. 3、 Differences in fatigue control for overseas customers Southeast Asian customers generally do not conduct fatigue testing and rely solely on tensile and hardness acceptance. There is a high rate of after-sales cracking complaints under vibration conditions. Mandatory S-N curves are required for North American automotive drawings, and body samples are taken from each batch of key components. Fatigue reports are included in PPAP, and batches are frozen directly if they are found to be unqualified. European wind power and hydraulic casings require corrosion fatigue+vibration fatigue composite verification to assess long-term alternating working condition stability. Middle Eastern construction machinery supports focus on low cycle fatigue, simulate impact loads, and not simply look at high cycle fatigue limits. 4、 Fatigue Failure Defect Chain Needle shaped β - iron phase and coarse plate-like silicon → as crack sources, microcracks initiate under low stress → fatigue life drops sharply; Surface knife marks, bumps and scratches on the sample → stress concentration points, priority cracking; Residual internal stress from heat treatment combined with alternating load → accelerated crack propagation; The sampling location should avoid the hot spot, and the test data is falsely high, which cannot represent the true life of the casting. 5、 Long tail traffic layout ideas Low pressure casting fatigue testing, A356 fatigue limit, S-N curve, alternating load cracking, aimed at material engineers and reliability engineers. Keywords: LPDC aluminum casting fatigue test, A356 T6 S-N curve low pressure casting; Problem class: R=0.1 fatigue test for aluminum casting; Comparison category: high cycle fatigue vs low cycle fatigue for hydraulic housing. Suitable for reliability testing and material performance topics. 6、 Common misconceptions in the industry Misconception 1: High tensile strength means good fatigue performance. However, a large number of β - iron phase castings meet the tensile standards but have poor fatigue performance. Misconception 2: Using fatigue data from attached casting test bars to represent the body, hot spots, looseness, and inclusions will significantly reduce the fatigue life of the body. Misconception 3: Fatigue cracks are one-time fractures, fatigue is the slow propagation of microcracks, and there is no abnormal appearance in the early stage. FAQ Q: What is the high cycle fatigue limit range of A356-T6? A：70–90MPa。 Q: Conventional stress ratio R? A：R=0.1。 Q: Cycle base high cycle fatigue? A: 1 × 10 times. Q: What is the requirement for surface roughness of the sample? A：Ra≤0.8μm。 Q: What is the preferred origin location of fatigue cracks? A: β - iron phase, looseness, surface scratches, stress concentration rounded corners. Q: Can corrosion fatigue be replaced by ordinary fatigue? A: No, separate coupling of salt spray environment testing is required. Q: What are the effects of eccentric clamping? A: Additional bending moment results in low and distorted test results. Q: What are the applicable scenarios for low cycle fatigue? A: Impact and alternating impact brackets for construction machinery.