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A356 is the main alloy for wheel hubs and structural components, with T6 solid solution and aging to enhance strength, elongation, and hardness; But heat treatment is prone to deformation, foaming, and size deviation, which is the core control process for foreign trade wheel hub orders.
1、 T6 complete process
Solution treatment: insulation at 535-545 ℃, with insulation duration according to wall thickness; Rapid water quenching; Artificial aging: insulation at 150-170 ℃ for 4-6 hours. Solid solution allows Mg2Si to dissolve into the aluminum matrix; Aging precipitation strengthens the phase and achieves the target mechanical properties.
2、 Root cause of heat treatment foaming
Internal pores and subcutaneous bubbles in castings, gas expansion and bulging at high temperatures; For products with severe gas entrapment in die-casting, batch foaming and scrapping after T6, X-ray pre screening is a common method in foreign trade.
3、 Deformation control measures
Fixture shaping quenching; The quenching water temperature and water inlet speed are stable; Choose rigid positions for the support points of the casting runner and fixture; The uneven thickness of the parts reduces the heating rate and minimizes thermal stress.
4、 Mechanical performance boundary
Qualified T6 A356: Tensile strength ≥ 220MPa, yield ≥ 160MPa, elongation ≥ 6%; Insufficient insulation and strength; Excessive insulation results in coarse grains and decreased toughness.
5、 Front fitting of mold end
Reduce internal porosity in castings; Reasonably arrange the gate to compensate for shrinkage and reduce looseness; The casting is designed with uniform wall thickness to reduce heat treatment deformation caused by sudden thickness changes; Reserve allowance for heat treatment shrinkage deformation.
6、 Key points of foreign trade customer complaints
Bubbling, deformation, and failure to meet elongation standards; Many overseas customers require the attachment of heat treatment furnace temperature curves and mechanical sample reports. Google's A356 T6 heat treatment for die casting is aimed at heat treatment engineers.
FAQ
Can ADC12 do T6?
ADC12 is not suitable for T6 as it has poor reinforcement effect and is prone to foaming.
2. Water quenching causes significant deformation, can air cooling be used?
The air cooling speed is insufficient and the strength does not meet the T6 standard.
What will happen after T6 shrinkage casting?
Shrinkage will connect, and air tightness will directly leak.
4. Is the heat treatment deformation caused by the deformation of the casting itself or by the fixture?
Both are present, with uneven thickness being the internal cause and quenching impact being the external cause.
What will happen if the solid solution temperature exceeds the limit?
Overheating, coarse grains, and brittle castings.
6. Is it possible to perform advanced processing and reheating?
Generally, machining after heat treatment will consume the machining allowance due to deformation caused by heat treatment.
7. Can the bubbles generated during heat treatment be seen during the die-casting stage?
Subcutaneous stomata may not be clearly visible on X-ray, and only become apparent after T6.
8. Are the low pressure A356 wheel hub T6 and high pressure parameters the same?
Consistent alloy, close heat treatment window, less porosity in low-pressure castings, and lower risk of foaming.

The parting surface is the boundary between the fixed mold and the moving mold. If not selected properly, all subsequent problems will arise: difficult control of burrs, increased number of reverse buckles, loss of machining standards, and unfavorable exhaust.
1、 Four principles for selecting parting surfaces
1. Prioritize leaving the castings in the moving mold for easy ejection;
2. Avoid the appearance of side A and place the parting line at the edge, non visible position;
3. The sealing surface should avoid thin-walled sharp corners and prioritize wide, thick, and flat sealing strips;
4. Place the end of the material flow and the gas retention area on the parting surface for easy arrangement of exhaust overflow.
2、 Sealing surface (sealing adhesive surface) design
Sealing tape width: 10-15mm for small items, 15-30mm for medium and large items; the sealing surface should not have deep pits or grooves; The sealing surface should avoid the high-pressure area at the pouring channel and overflow end; Apply a micro pressure of 0.01-0.02mm on the sealing surface and seal it tightly by clamping the mold.
3、 Typical Type of Typing Surface
Flat parting surface: the simplest, with the lowest processing, molding, and maintenance costs; Step parting surface: follow the contour of the product and avoid reverse buckling; Surface parting surface: Surface parts with high machining difficulty and high requirements for CNC and mold matching accuracy.
4、 Taboo on typing surface
Do not place hot spots or gates directly on the parting sealing surface; Do not simultaneously arrange high-pressure gates and thin sealing materials on the same parting line; The parting line passes through the sealed pressure surface, and the risk of subsequent leakage is extremely high.
5、 Key points of foreign trade drawing review
Confirm the location of the parting line with the customer in advance and sign for confirmation; Once the product is frozen and the mold is changed, the cost of mold modification is extremely high. Alloy wheel mold wheel types are mostly located in the middle or back of the wheel rim. Google's "die casting parting line and seal design" is aimed at mold designers.
FAQ
What will happen if the casting is left in the fixed mold?
The fixed mold is not pushed out, sticking to the fixed mold makes it difficult to remove parts, and there are strains.
Is it better to have a wider sealing tape?
Excessive width increases the processing area and makes it difficult to process the mold surface, but it will not significantly improve the sealing.
Is it easier for curved surfaces to flash?
Yes, surface modeling is much more difficult than flat modeling and prone to misalignment.
Can the parting line pass through the tightly sealed cover?
Try not to, once the parting line has a sharp edge, it is easy to leak after polishing.
5. the first mock examination with multiple cavities, should the parting surface be of uniform height?
Try to unify as much as possible, otherwise it will be difficult to match the mold and the force will be uneven.
Is the exhaust groove on the parting surface located on the sealing tape?
The exhaust groove should be located on the inner side of the sealing tape and should not damage the main sealing surface.
How to make the corner of the step parting surface?
R transition to avoid stress concentration at sharp corners and prevent corner collapse.
What should I do if the customer requests the parting line to be placed on the exterior surface?
Notify risks in writing, provide alternative solutions, and keep communication records.

Threads are a difficult point in die-casting, and direct demolding can strain the thread profile. The three mainstream solutions have differences in cost, efficiency, and yield, and foreign trade orders need to be selected in advance for customers.
1、 Motor rotation core pulling (most commonly used external thread, large tooth internal thread)
The motor and reducer drive the threaded core to rotate and exit, while the casting remains stationary; Complete tooth shape, high precision, suitable for mass production; Disadvantages: Complex structure, high cost, occupying mold space, requiring matching of stroke and rotation number.
2、 Haff slider (half half closed)
Two sliders are aligned to form a thread, and the mold is opened by first separating the sliders and then extracting the core; Suitable for coarse teeth, large pitch, and short threads; Disadvantages: There are parting lines on the joint lines and threads, and airtight components should be used with caution, which can easily cause leakage at the joint positions.
3、 Detachable thread inserts (manually unscrewed)
Single piece inserts are pushed out together with the product and manually unscrewed; Suitable for small batches, low budgets, and low production volumes; Extremely low efficiency, not suitable for automated mass production of foreign trade orders.
4、 Pre constraint of thread design
Simplify the die cast thread profile as much as possible, and recommend trapezoidal teeth; Small tooth spacing and thin tooth tips are prone to erosion and aluminum adhesion; The threaded core must be nitrided or PVD coated to enhance wear resistance and anti sticking.
5、 Selection decision tree
Large scale, high-precision, seamless → motor rotation core pulling; Medium batch, allow seam splicing, coarse teeth → Haff; Small batch, low-cost samples → manual threaded inserts.
6、 Risk points
Rotating core pulling timing errors can cause tooth breakage; Insufficient cooling of the threaded core leads to aluminum adhesion, resulting in tooth loss; Haff misalignment and thread misalignment. Google's "die casting thread core pulling design" is aimed at mold designers.
FAQ
Can die-casting threads achieve machining thread accuracy?
Unable to achieve, priority should be given to coarse teeth for die-casting threads, and subsequent machining of fine teeth will be more reliable.
Can the Haff seam marks be eliminated?
No, it can only be placed in non sealed and non fitting areas.
3. Should there be signal timing protection for rotating core pulling?
It is necessary to prevent the tooth core from being pushed out or damaged before the rotation is completed.
Why is the threaded core prone to wear?
The surface area of the thread is large, and the combination of aluminum liquid flushing and demolding friction.
Is the internal thread and external thread scheme the same?
Internal threads often use rotary core pulling; More external thread Haf is used.
6. Should the threaded core be separately cooled by a water circuit?
Long threads and thick walled threads must be cooled separately.
7. Which solution is generally rejected for automated production lines in foreign trade?
Manually unscrewing the insert cannot match automation.
Can the inner gate be placed at the threaded position?
Try to avoid it as the sprue will quickly erode the tooth shape.

Sliding blocks are used to form side holes, reverse buckles, and lateral grooves, and are a high-risk mechanism for faults such as jamming, burning of sliding blocks, locking failure, and aluminum running. The failure rate of foreign trade sliding block molds is much higher than that of ordinary flat molds.
1、 Three components of slider: slider body, locking block, and core pulling drive
The locking block (wedge block) is responsible for supporting the sliding block during mold closing and bearing the lateral pressure of the aluminum liquid; Drive the inclined guide column, oil cylinder, and gear rack. The inclined guide column is suitable for small and medium-sized core pulling and low cost; The oil cylinder is suitable for large stroke, large lateral force, and wheel hub lateral buckling.
2、 Calculation of slider locking force
Lateral expansion pressure=lateral projection area x pressure ratio; The wedge block must provide a locking force greater than the lateral expansion force. The conventional wedge tightening angle is 16 ° to 22 °, but if the angle is too small, it will self lock and cannot be pulled; The angle is too large and the locking efficiency is low.
3、 Sliding block wear resistance and heat dissipation
Wear resistant plate (SKD61/nitriding) is made on the friction surface of the slider; The slider body has a separate waterway, and the thick walled thermal joints on the side are prone to aluminum adhesion and thermal fatigue; The clearance between the sealing surface of the slider is 0.01-0.02mm, and if the clearance is large, it will be directly stuck by aluminum.
4、 Slide timing taboo
First, extract the core before opening the mold, and then close the mold in place before returning to its original position; Prohibit the sliding block from retreating during the injection process; The oil cylinder slider must be equipped with position signal feedback, and the model lock protection will stop the machine when there is a lack of signal.
5、 Common failures of sliders
Aluminum material enters the sliding block mating surface and locks up; The wedge block is worn and cannot be locked tightly, resulting in continuous flying edges; No independent cooling, the slider is overheated and sticky with aluminum; Insufficient travel time, back button strain. The valve holes of the alloy wheel mold hub are mostly extracted from the cylinder slider. Google's "die casting slide core design" is aimed at structural designers.
FAQ
Can the inclined guide column slider withstand significant lateral pressure?
Not suitable for high pressure and large lateral projection, prioritize oil cylinder+wedge block.
2. Should the sealing surface of the slider be polished?
Fine polishing, following the direction of demolding, while strictly controlling the clearance between fits.
3. Do sliders need to be separately cooled?
Lateral hot joints and thick walled buckles must be done, while thin small holes can be omitted.
How to determine the wear of the wedge block?
The slider surface continues to flash, and adjusting the locking is ineffective.
5. How to determine the distance of slider core pulling?
Inverted depth+safety margin of 2-5mm to prevent scratching of castings.
6. Will multiple sliders move simultaneously and interfere?
Interference inspection and CAE motion simulation verification must be performed.
7. If the slider is stuck, how should we prioritize handling it?
Cooling down, it is forbidden to forcefully open the mold, otherwise the inclined guide column will be broken and the mold cavity will be pulled.
Is the low-pressure casting slider the same as the high-pressure design?
The structural ideas are similar, but the lateral pressure is low and the locking requirements are lower.

Locking force is the first threshold for die-casting selection. Insufficient locking force will cause the parting surface to expand and continuously flash, while excessive locking force will waste equipment and accelerate mold wear.
1、 Basic formula for locking force
Locking force F=total projected area of the casting x specific pressure of the sprue x safety factor. The projection area includes the projection of castings, runners, overflow, and exhaust all on the parting surface, and cannot be solely counted as the product body. Select specific pressure according to product type: ordinary shell 40-60MPa; Airtight pressure bearing components 60-90MPa; Thick walled components with high requirements of 90-120MPa. The safety factor for foreign trade orders is generally set at 1.25-1.4.
2、 Easy to miss projection areas
Diverting cones, transverse runners, branch channels, overflow slots, and large exhaust chambers all bear the pressure of pressurization, and many beginners only consider products, resulting in underestimated mold locking estimates. The projection area of the alloy wheel mold hub is large, and the entire pouring system must be fully selected.
3、 Typical phenomenon of insufficient mold locking
Thin flying edges on the parting surface and aluminum channeling on the sliding surface; The locking curve of the injection boosting stage machine drops pressure; The casting size is too large and the burrs are difficult to clean; Long term mold expansion causes deformation of the mold frame and pulling of the guide column.
4、 The drawbacks of excessive mold locking
Excessive clamping force, high pressure stress on the parting surface, and accelerated fatigue on the surface of the mold; The exhaust groove is tightly closed, the exhaust becomes worse, and the air hole rises; The energy consumption of the equipment increases and the template deforms.
5、 Points to note when accepting foreign trade orders
The customer's existing die-casting machine has a fixed tonnage, first calculate the required clamping force; If the customer's machine is too small, either change the pouring arrangement to reduce the projection area, or inform the risk in advance and not forcefully accept the order. Low pressure casting does not rely on high-pressure rapid injection, and the locking force requirement is much lower than that of high-pressure die casting. Google's "die casting clamping force calculation" is aimed at mold engineers.
FAQ
Does the higher the specific pressure, the denser the casting?
It is established under the premise of sufficient mold locking and non solidification of the gate. When the mold locking is insufficient, high pressure will only cause the mold to expand and flash.
Why can't the safety factor be set to 1.0?
Fluctuations in aluminum liquid pressure, mold wear, and material flow impact can cause instantaneous peak pressure.
Should the projection of the slider area be included?
The pressure bearing area of the slider should also be included in the mold locking calculation.
4. Is the projected area directly accumulated for the first mock examination with multiple cavities?
Yes, the total projection of all cavities and channel overflow.
5. Do ADC12 and A356 have the same locking requirements for the same product?
A356 has good liquidity and can moderately reduce specific pressure; The standard for airtight components remains unchanged.
6. Is the flying edge necessarily due to insufficient mold locking?
It is also possible for the parting surface to wear out, the gap between the inserts to increase, and the timing of pressurization to be too early.
7. The locking force is calculated to be exactly stuck at the upper limit of the machine. Do you want to connect it?
Not recommended, long-term production fluctuations can easily cause mold expansion. It is recommended to replace the machine or optimize the plan.
8. Are the boost ratio pressure and injection filling pressure the same?
No, the filling pressure is low, and the pressure during the pressurization stage is the core that determines the locking of the mold.