Hey there, if you’ve ever worked with heavy machinery, wind turbines, nuclear components, or those massive gear shafts that turn industrial operations, chances are you’ve crossed paths with open die forgings. As someone who’s been in the open die forging game for over a decade—running a shop that’s all about turning raw steel (and sometimes other alloys) into those ultra-tough parts—I get it: nobody wants to waste material. Scrap costs add up fast, and when you’re dealing with slabs that weigh thousands of pounds, even a 5% drop in waste can put real cash back in your pocket. Today we’re breaking down what material utilization rates actually mean for open die forgings, where the gaps are, and what we do at our shop to push those rates higher (plus a note at the end if you want to chat about your own part needs). Open Die Forgings
First, let’s keep this real. A lot of folks throw around “material utilization rate” like it’s some fancy industry term, but it’s just how much of your starting raw stock ends up in the final, usable forging versus what gets cut off, burned, or turned into scrap during the process. For open die forgings specifically, the average utilization rate? It’s usually between 50% and 75%—but wait, that’s a huge range. Why the gap? If you’re making a small, simple shaft, you might hit 70%. If you’re tackling a weirdly shaped, super heavy part like a pressure vessel head, you might be stuck around 55%. The main culprits here are two big ones: oversize raw stock to account for forging shrinkage and surface defects, and the process itself that requires removing extra material after forging to get that smooth, precision finish.
Let’s unpack that. When we get a raw steel slab or billet, it’s not exactly the shape we need for the final part. Forging heats metal to like 1,200°C, and when it cools, it shrinks—so you have to start bigger to make sure you don’t end up too small. But we often add extra “allowance” just in case there are surface flaws, like tiny cracks or scale, that have to be machined off after forging. That’s a big chunk of waste. Then there’s the actual open die process: we use those massive flat or shaped dies to pound the metal, shaping it by hand (wait, yeah, open die is way more hands-on than closed die—our team’s guys have 15+ years each) which means we’re working the metal incrementally. Sometimes you have to create extra “end crops” on the billet that aren’t part of the final part, just to keep the metal flowing evenly while forging. Those end crops? They get recycled, obviously, but that’s still material that never turns into a saleable part.
Now, let’s be clear: scrap isn’t always bad. Some waste is necessary—you can’t forge a massive turbine shaft without accounting for shrinkage, right? But there’s definitely avoidable waste, and that’s where we focus most of our time. Over the years, we’ve tested a ton of tweaks to our process to boost utilization, and a lot of them aren’t fancy science fiction—they’re just smart, hands-on changes that make a real difference.
First up: get your raw stock size as spot-on as possible. Early on, we’d just grab the nearest billet size that was a bit bigger than the estimated final part, and add a generic 10% allowance. That meant we often started with way more metal than we needed, especially for parts where the shape was simpler. Now, we use 3D modeling and forging simulation software (yeah, we’re not old-school Luddites—we use tools that let us map exactly how the metal will flow when we hit it) to nail the exact starting dimensions. For example, last quarter we did a 12,000-pound wind turbine gear blank. Previously, we would have used a 13,500-pound billet with a 10% allowance. With the simulation, we found we only needed a 12,600-pound billet, cutting the starting material by 900 pounds. That’s not nothing—steel costs $0.50 a pound, so that’s $450 saved per part, and less waste to boot.
Another big one: reduce forging allowances. That extra material we add on the sides, ends, and surfaces to machine off later? We used to add a full inch all around, just to be safe. Now, our guys work with quality control to test every billet for surface flaws before we even start forging. No more guessing if there’s a hidden crack—we use ultrasonic testing to scan the entire raw stock, so we can cut that allowance down to a quarter-inch for most parts. That small drop makes a huge difference. For a 10-foot long shaft, cutting the allowance from an inch to a quarter-inch removes 225 pounds of extra material. Multiply that by 50 parts a year, and that’s 11,250 pounds less waste, plus less machining time afterward (bonus: that cuts lead times too).
Then there’s recycling—but wait, recycling is good, but it’s not the same as utilization. We’ve all heard about sending scrap back to the mill, but re-melting and re-forging that scrap uses energy, and the quality can dip a little (you have to blend it with new material) so it’s better to keep as much material in the final part as possible. That’s why we started doing “near-net” forging for parts that don’t need super tight tolerances right off the bat. Instead of forging the part a bit oversize then machining it to final dimensions, we forge it as close to the final shape as we can. For example, pressure vessel flanges—they need a smooth, flat surface. Instead of forging a circle with extra height then machining the whole top down, we use custom shaped dies to forge the flange to almost exact height, leaving just a tiny bit of material for final finishing. We saw utilization jump 12% on those parts when we switched, because we’re not taking off half an inch of extra steel that would just get recycled.
Something a lot of shops miss: training the on-floor forging team. Our best utilization wins didn’t come from software alone—they came from our guys who’ve been doing this for decades. Last year, we had a new foreman suggest a small change: instead of rotating the billet 90 degrees every pass during forging, he rotated it 45 degrees, which made the metal flow more evenly and reduced the number of end crops we had to cut off. That one change boosted utilization on our shaft parts by 6%. How? Because when the metal flows straight instead of getting lumpy, we don’t have to cut off those excess ends to fix the shape. It’s a tiny adjustment, but it came from someone who spends 10 hours a day in the forge, not some guy in an office with a spreadsheet. That’s the thing about open die forging—it’s a mix of data and experience, and the best utilization comes from listening to the folks who actually run the presses.
Wait, but let’s talk about the limits. I don’t want to promise 90% utilization—you’ll never hit that for open die, because of that shrinkage and the inherent need for some scrap. For super large parts (like 50,000-pound nuclear components), utilization will always be a bit lower, around 50-60%, because you have to start with a massive billet that has some waste on the ends. But even there, we’ve boosted that by 7% by optimizing the billet length to match exactly what we need, instead of using standard lengths that are too long. The key is to stop using one-size-fits-all allowances and tailor every step to the specific part, not just our standard process.
We’ve also tested some newer materials, but that’s a double-edged sword. Alloys like titanium or nickel-based superalloys are way more expensive than steel, so wasting even a pound is a huge cost. But they’re also trickier to forge—they crack easier if you work them too fast, so you can’t just cut allowances as much. For those, we’ve invested in better heating ovens that heat the billet more evenly, so we don’t have to work the edges as hard, which means less chance of defects and less excess material to fix after forging. For a titanium aerospace blade, we’ve lifted utilization from 58% to 67% with that oven upgrade, which saves thousands of dollars per part.
Now, let’s get real about why this matters for you, the person buying open die forgings. If you’re a plant manager or a procurement specialist, you care about two things: part quality and cost. Better material utilization means lower cost per part, right? Because you’re not paying for extra steel you’re never going to use. We had a client a while back who was buying shaft parts from another shop that was only at 52% utilization. They were paying for 10,000 pounds of steel for a part that only used 5,200 pounds. We worked with them to tweak the billet size, cut allowances, and adjust our forging process, bringing their utilization up to 71%. That saved them $27,000 a year in steel costs, and they didn’t have to compromise on quality at all.
One thing we see a lot is clients specifying “extra material for machining” that’s way more than they actually need. They see a standard allowance and just copy it, but every part is different. For example, a short, thick gear blank needs less machining allowance than a long, thin shaft. We now work with every client upfront to calculate the exact allowance needed, based on the part’s size, material, and post-forging process. That small adjustment alone typically boosts utilization by 3-5% for most of our clients.
Wait, but what about waste that’s not from material size? Sometimes we have to cut off bad sections of the forging during inspection, even if we planned for that. To cut down on that, we’ve started doing in-process testing during forging, not just before and after. That means every hour, we pull a small sample from the billet to check for flaws, so if there’s a crack developing, we catch it early and adjust our forging pressure or speed before the whole part is ruined. That’s cut our in-process scrap by 4% in the last year, because we don’t have to scrap an entire 10,000-pound part just because of a flaw we missed after forging.
I’ll be honest, we’ve had missteps too. A couple years back, we tried to cut corners by using a smaller billet than we should have, and we ended up with a part that was too thin in the middle. We had to scrap the whole thing, which cost us more than we would have saved by using the bigger billet. So it’s a balance—you can’t push utilization so hard that you sacrifice part integrity. The goal is to optimize, not overdo it. That’s why we never skip the testing and simulation steps; they keep us from cutting corners that hurt quality.
So putting this all together: material utilization rates in open die forgings vary from ~50% for complex, very large parts to ~75% for simple, smaller ones, with avoidable waste coming from oversized stock, generic allowances, and inefficient forging techniques. The best ways to boost it are precise raw stock sizing with simulation, cutting allowances through pre-forging testing, near-net forging, training your on-floor team, and in-process quality checks.
If you’re tired of overpaying for open die forgings that waste half the material you’re paying for, hit us up to chat about your next project. We can walk you through our process, run a quick utilization estimate for your specific part, and find ways to cut your costs without sacrificing the strength and durability you need for your operations. No sales pitch, just straight talk about what works in the forge.
Shell Molded Steel Castings References
- Open Die Forging Process Optimization, Forging Industry Association, 2022
- Material Utilization in Large-Scale Metal Forgings, Journal of Manufacturing Processes, Vol. 48, 2020
- Simulation-Driven Raw Stock Selection for Open Die Forgings, International Journal of Forging and Forming, Vol. 12, No. 3, 2021
- Alloy Forging Efficiency and Waste Reduction, American Society of Mechanical Engineers, 2023
Hebei Shata Machinery Co., Ltd.
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