Q: You once said, “We’re not 3D printing metal, we’re printing defects.” What did you mean?
Prady:
Most people treat additive manufacturing like fancy welding with good marketing. They skip the materials science. Metals are not interchangeable—each has different melting points, cooling rates, and grain structures. If you ignore this, you’re just creating defects layer by layer.
Q: Is the problem mainly that the laser moves too fast and doesn’t allow the material to solidify properly?
Prady: Speed matters, but it’s more complex. Every metal has a specific profile—how it heats, cools, and grows grains. For example, copper behaves very differently from aluminum. Cooling rate alone can determine whether you end up with a strong fine-grained structure or a brittle coarse-grained one.
Q: What happens if you don’t heat the powder enough during printing?
Prady: You get incomplete fusion and voids. That’s why mechanical testing after printing is critical. But the real solution is designing the process scientifically—understanding your powder’s composition, the phase diagrams, and the thermal history you’re imposing.
Q: Would you say these are growing pains in industry that is in its early or mid-stage?
Prady: Unfortunately, yes. About 80% of companies I see don’t fully control their process. They’re essentially experimenting—cooking without a recipe. But the top 20% are getting much better, and maybe 1% have reached true precision, where they can produce aerospace-grade parts repeatably. A large majority of the companies do not need precision and for them, investing in material science is not viable. But the 20% need somewhat good precision and 1-2% high precision. Many of these have truly invested in R&D to understand material-laser interaction and dynamic processes. These companies are leapfrogging their competition.
Q: Have you seen examples of companies that do it right?
Prady: I can’t name names because of confidentiality, but there are startups—like Agnikul from IIT Madras—building entire rocket engines with additive manufacturing. Relativity Space 3D printed the body of the rocket and launched. This requires an extraordinary command of microstructure and process control.
Q: With all the hype about AI, how can machine learning realistically help improve 3D printing?
Prady: AI can’t invent new physics, but it can help predict outcomes. If you train it on high-quality data—like phase diagrams and prior results—it can recommend process parameters: laser power, scanning speed, cooling rates. That helps you approach the theoretical performance limits of a material instead of settling for trial and error.
Q: When people say “AI discovers new materials,” what does that mean in practice?
Prady: Typically, it means AI proposes new alloys or process combinations that yield better properties. For example, different heating schedules can create finer grains, or alloys can improve corrosion resistance. But AI still depends on human input and good data—it can’t reason beyond what it’s trained on.
Q: Can metals processed correctly really rival composites like carbon filament winding?
Prady: You can’t surpass a material’s fundamental limits—composites will still outperform metals in certain applications. But you can get much closer to the ideal properties if you understand and control microstructure precisely. Unfortunately, many printed parts today fall far short of that.
Q: Do you think additive manufacturing is finally maturing?
Prady: It’s improving rapidly. The sophistication I’ve seen in the past year is remarkable. But most of the industry still has a lot of catching up to do. The potential is there—especially for aerospace, defense, space, semiconductor and EV applications—but it requires a lot more rigor.
Q: You sound passionate about separating hype from reality.
Prady: I love material science because it deals with the real world. You can write software and it might work, but with materials, you’re bound by physics. And AI, if applied correctly, could finally bring the precision this field has lacked.
Q: Thanks for your insights.
Prady: Happy to help separate fact from fiction anytime.