Published 12/01/2025

How Industrial Molds Conquered a Complex Impeller Fan Mold Challenge

Expert engineering team overcomes complex impeller fan mold challenges through innovation, precision and collaborative problem-solving.

Christina Fuges

Editorial Director, MoldMaking Technology

The Team & The Mold

Moldmaker Bill Palakie builds the mold, while Project Manager and Director of Engineering, Randy Hanson, communicates with customers to ensure the parts are practical. He then collaborates with Engineering Manager Sasha Stojanovic, who handles the technical details and works with Bill to meet his requirements. The process is seamless: customers communicate with Randy, who briefs Sasha, and Sasha coordinates with Bill. They use checklists and conduct meetings to keep everything on track.

The mold’s reengineered compounded slide and creative 180-degree redesign transformed a tough challenge into a long-term solution built for a decade of production.

The Challenge

Right from the outset, the team knew that the original part didn’t work right. It was similar to others they’ve made, but it failed in its function. Unlike a simple mold where you pull it straight apart, this impeller fan mold has a radial pull with two stages — one slide comes out, then another moves while lifting the mold. It’s tricky because it involves 16 individual slides, all powered by hydraulic cylinders with switches and precise timing.

In a typical impeller mold, hydraulic cylinders drive slides — the top pulls back, the bottom raises via a catch in the B side, clearing the undercut. However, the customer wanted robotics on the A side. The original setup wouldn’t allow the customer’s desired internal changes, like adjusting gates and actions.

The Solution

After some math and planning (credited to Sasha), they turned it 180 degrees. Now, the gates sit inside, changing how the mold fills and operates. This made a tough mold even trickier, but the result was worth it.

“The undercut slide moved up top, and the main slide sat below. I added a tower through tight clearance to link them, using a catch in the middle instead of the core. The bottom slide pulls out, the top drops down a dovetail cam to clear the undercut, then a ramp locks them together to retract. Timing these catches precisely is critical — any mismatch risks a crash,” Sasha explains.

Bill used design software but says nothing replaces his manual timing for this mold. “No program can fully simulate that yet,” Bill says. “The design matters, but the real challenge is machining everything accurately, so it fits together perfectly the first time.” He notes that fitting the mechanical pieces and shutoffs was the toughest part. If anything’s off, figuring out the mismatch is a headache, so they aim to get it right up front.

Manual hand-fitting and CMM checks ensured the impeller mold’s complex components aligned with micron-level precision.

The radial, double-action slides couldn’t just be pushed together and closed. Normally, he could assemble parts on a table outside the mold’s base, but not here. Everything is located on the B side, so he flipped the A side upside down to drive hydraulics from the B side to the A side and then got creative to ensure all the pieces lined up with the base, aligning ribs split between the core and slides. The tool’s size — long and circular — made it hard to hold and align. He used square blocks and shims, adjusting piece by piece by hand, recutting or grinding as needed. If something bumped, he’d start over, circling the mold until everything fit.

“For this mold, Sasha added a threaded rod stop with a nub for forward timing, leaving slight clearance that I tuned by hand. If the base shifts, everything adjusts, so I check it first, then fit the rest,” Bill says.

“We took a difficult mold and made it more difficult, but the end product is better.”

The ribs were burned and machined at high speed, using coordinate measuring machines (CMMs) for critical dimensions. For the 43-inch base, which is too big for the CMM, they analyzed it separately.

“Our two CMMs set inspection files for quality checks. I measure against a zero point, not absolute size, telling me if I’m plus or minus steel and by how much (e.g., half a thousandth). I might request shutoffs slightly oversized to stay steel safe, adjusting after initial runs,” Bill says. Basically, the CMM shows if Bill’s heavy or light on steel where parts meet, guiding his adjustments — whether to cut, grind or hand-fit.

The mold produces impeller fan parts approved for high-performance use, serving as a model for future designs and decades of production runs.

The Results

After assembly, they shoot a part, and if it looks good, everyone’s happy. They measure it, tweak a few dimensions if needed, and move forward. Randy sought approval from the customer in Germany, which took a few months, followed by a 16-week build. “Normally, molds like this one take months of trial and error to sort out problems before measuring, doubling the time from start to production. But this team’s experience with complex molds cuts that down,” Randy says.

Watching this mold run was exciting. Bill felt a weight lift off his shoulders. The team credits this project’s success to skill and collaboration. Usually, the team suggests changes to simplify parts and cut costs. Customers ask, “Can you make this?” They reply, “Yes, but it’s expensive — here’s how to make it cheaper.” In this case, the customer pushed back, saying, “Make it harder; it’ll be better.” So they did.

“It’s a pricier mold, but it performs better! The customer plans to run it for a decade, producing countless parts and using it as a model for future designs. Customers love proving concepts like this, setting the stage for 20 years of similar projects,” Randy says.

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