Is copper alloy suitable for 3D printing of mold cooling systems?

1. The main performance benefit of copper alloy is that it can conduct heat and resist heat at the same time.
The most important things that the mold cooling system needs to do are get rid of heat quickly and be able to work in high-pressure and high-temperature settings. Copper alloy is a great material for 3D printing cooling systems since it has great physical qualities.
Very high thermal conductivity: Pure copper has a thermal conductivity of 401 W/(m · K), which is 8 to 10 times that of mold steel. Even after being treated with an alloy (like CuCrZr alloy), its thermal conductivity stays between 200 and 300 W/(m · K), which is much higher than that of standard cooling materials. This property lets the copper alloy cooling system quickly get rid of mold heat, which shortens the molding cycle. After using copper alloy 3D printed cooling water channels for a certain automobile bumper mold, the time it took to make one piece went from 18 seconds to 12 seconds, and the amount of energy used went down by 22%.
Resistance to heat fatigue: The mold's surface temperature changes a lot in situations with high pressure and speed. Copper alloy is far more resistant to thermal fatigue than steel, and its thermal expansion coefficient is a good match for mold steel. This lowers the likelihood of cracking due to thermal stress. After 10,000 cycles at a high temperature of 600 °C, experimental data shows that the CuCrZr alloy still has more than 90% of its initial strength. Its lifespan is more than three times that of typical molds.
Copper alloys are naturally resistant to chloride ions, sulfides, and other corrosive substances in coolant. They are especially good for corrosive situations like naval engineering and chemical molds. Adding small amounts of nickel, zirconium, and other elements can make it even more resistant to corrosion and help the cooling system last longer.
2. 3D printing process adaptability: overcoming the limitations of conventional manufacturing
There are two main problems with traditional copper alloy processing: first, the high thermal conductivity of the molten pool makes it lose heat quickly, which can cause flaws such delamination and curling; Second, the high reflectivity (up to 98% for a 1064nm laser) makes it hard to use typical SLM technology. Process innovation has helped 3D printing technology overcome several problems:
Green laser SLM technology: A 515nm wavelength green laser increases copper's absorption rate of green light to 40%, which is 8 times higher than that of a near-infrared laser. The TruPrint 5000 green version equipment from Germany's Tongkuai firm can print pure copper RF quadrupole accelerators with a density of 99.95% and a conductivity of 100% IACS. By adjusting the concentrating spot (25 μm) and scanning approach, this technology makes printing copper alloy three times more efficient than existing methods.
Electron beam melting (EBM) technology uses an electron beam as a heat source to avoid problems with high reflectivity and a vacuum atmosphere to stop copper from oxidizing. The surface roughness Ra of copper alloy parts printed by EBM is ≤ 6.3 μm, which means they may be utilized right away for precision molds without any extra procedures. But this technology costs a lot to set up, and for now it is mostly used in high-end areas like aerospace.
Laser Directed Energy Deposition (LP-DED): The "welding bead" problem in copper alloy additive manufacturing is fixed by "increasing laser energy." When printing CuCrZr alloy, the research team from the Indian National Institute of Technology used a low power of 200W for the first three layers to make sure they stuck to the substrate. They then raised the power to 1000W to match the material's thermal conductivity, which led to a density of 97.47% and a thermal conductivity of 168.3 W/(m · K).
3. An example of how an industry works: going from the lab to the manufacturing line
Tesla's Shanghai facility employs a 3D-printed copper alloy cooling system to fix huge die-casting molds in the automotive mold industry. It only takes 72 hours to fix mold damage and get production back on track, which is 90% faster than normal repair processes. The conformal cooling design makes the mold temperature more even by 80% and the product qualification rate goes up from 92% to 98%.
A mobile phone maker employed copper alloy 3D printing to swiftly make trial production molds, which cut the time it takes to develop a new device from 18 months to 12 months. The cooling water circuit has a topology-optimized construction that makes heat transmission 120% better at the same pump power. This greatly lowers the chance of the product warping or deforming.
In the aerospace area, Ursa Major made the first copper-based 3D-printed rocket combustion chamber. Its integrated cooling channel design lowered the temperature of the combustion chamber wall by 300 °C and its weight by 40%. The part is built of CuCrZr alloy and has been tested 1000 times at a pressure of 6MPa without breaking, proving that 3D printed copper alloy is reliable in harsh conditions.