How to apply high-temperature alloys in mold manufacturing?

一, Correctly matching the physical qualities of high-temperature alloys to the needs of the mold
High-temperature alloys are metals made of iron, nickel, and cobalt that can last a long period in situations with high temperatures and a lot of stress, like above 600 ℃. Three dimensions show its main benefits:
Nickel-based high-temperature alloys can still hold a yield strength of over 600MPa at 800 degrees Celsius, which is three times stronger than standard H13 mold steel. K403 nickel-based alloy molds can survive the impact of titanium alloy billets at 1200 ℃ while forging aircraft engine turbine discs. The lifespan of a single mold has improved from 200 times for traditional materials to 1500 times.
Thermal fatigue resistance: High-temperature alloys can generate a special "self-healing" oxide coating by changing the size and distribution of the 'phase (Ni ∝ (Al, Ti)). There are only 1/5 as many surface cracks in GH2135 iron-based alloy molds used in automotive exhaust manifold die-casting molds after 5000 thermal cycles as there are in 5CrNiMo steel molds.
Corrosion resistance: The Cr ₂ O3/Al ₂ O3 composite oxide layer that forms on the surface of high-temperature alloys can effectively block the passage of chloride ions when engineering polymers with flame retardants break down. In electronic connection injection molds, molds made of Inconel 718 alloy last 8 times longer than DC53 mold steel, and the surface of the product has no corrosion spots.
2, Technological advances in common application settings
1. Aerospace: Copying structures in very harsh operating circumstances
When making lightweight connections for drones out of PEEK material, the mold needs to be able to handle a melt temperature of 380 ℃ and an injection pressure of 150 MPa. Under these working conditions, traditional mold steel shows a lot of creep, however molds made of cobalt-based high-temperature alloy HS-21 do not:
By improving the design of the topology, the core wall thickness went from 12mm to 6mm, which cut the weight by 55%.
The TiAlN coating made by physical vapor deposition (PVD) has a surface hardness of HV3200.
In real production, size changes of less than 0.02mm must happen within 500,000 injection cycles.
2. The new energy vehicle industry: find a balance between long life and high efficiency
When making battery pack cooling water pipes with PA66+GF30 compression molding, the glass fiber wears down on the mold at a rate of 0.03mm every thousand repetitions. Nickel-based high-temperature alloy molds made using the powder metallurgy process:
The hardness of the working layer can reach HRC58 by making gradient functional materials (FGM), while the matrix stays tough at HRC42.
Instead of standard electrical discharge machining, use ultra-high pressure water jet cutting to make the surface of the cavity less rough, going from Ra1.6 μ m to Ra0.4 μ m.
In real life, the mold life has gone up from 80,000 uses to 400,000 uses, and the cost per piece has gone down by 65%.
3. Packaging for semiconductors: a long-lasting assurance of accuracy at the micrometer level
The pin spacing in QFN packaging molds is only 0.3mm, hence the mold's coefficient of thermal expansion (CTE) has to be very close to that. Nickel-based single crystal high-temperature alloy mold made by the directional solidification process:
The CTE is lowered to 12 × 10⁻⁶/℃ by regulating the crystal orientation, and the compatibility with ceramic packing materials is enhanced by 40%.
The conformal cooling water channel made with laser selective melting (SLM) technology makes the mold temperature more even, going from ± 15 ℃ to ± 3 ℃.
In real production, the product warpage rate went down from 0.5% to 0.15%, and the yield rate went up to 99.8%.
3, The new and improved ways of making things
1. Additive manufacturing used in ways that change things
The usual problem of making things out of metal molds that can handle high temperatures is being solved by 3D printing technology:
Design for topology optimization: Using Altair OptiStruct software, we made the design lighter, cutting the weight of a certain aircraft engine blade mold from 1.2 tons to 680 kg and making it 25% stiffer.
Structure with a functional gradient: LPBF (laser powder bed melting) technique makes a hardness gradient transition zone between the mold working layer and the substrate layer to get rid of stress concentration.
A random cooling system: Using Magics software to improve the architecture of the waterway has made the cooling of a large cover mold 40% more efficient and cut the cycle time by 35%.
2. A big step forward in technology for reinforcing surfaces
Spraying flames at supersonic speeds (HVOF): The surface of the mold cavity is coated with WC-12Co, which has a hardness of up to HV1400 and is five times more resistant to wear than the substrate material.
Plasma nitriding is a process that uses plasma to make things harder. Deep nitriding (0.3 mm) raises the mold's surface hardness to HV1100 while keeping the core's toughness the same.
Repair with laser cladding: Inconel 625 alloy powder is utilized to fix the worn area, and the binding strength between the repair layer and the substrate is more than 400MPa.
4, Trends in the economy and the industry
High-temperature alloy molds cost 3 to 5 times more than regular molds at first, but their entire lifecycle cost benefit is big:
In the automotive industry, using high-temperature alloy for the bumper mold of a certain car model cost 800,000 yuan more for each set of molds, but it saved 12 million yuan in annual production costs because the cycle time was cut by 25% and the yield rate went up by 12%.
In the field of aerospace: Using cobalt-based alloy in the forging die of a certain type of engine turbine disk extended the mold life from 50 pieces to 300 pieces and cut the cost of making one piece by 78%.
Digital twin technology has made it possible to anticipate the maintenance cycle of high-temperature alloy molds with an accuracy of ± 50 hours. It has also increased the overall equipment efficiency (OEE) to over 85%. The global market for high-temperature alloy molds is predicted to be worth more than $4.5 billion by 2028, with a compound annual growth rate of 12.3%. Additive manufacturing molds will make up more than 30% of this market.