Process Optimization of Fan Rotors and Enhancement of Autonomous Balance Rate

Imagine you are trying to spin a toy top. If the top is perfectly round and the weight is spread out evenly, it spins smoothly, humming a happy tune. But if one side is slightly heavier or the shape is a tiny bit wobbly, the top starts to shake, wobble, and eventually crash. In the world of big machines, like the fans that cool our computers or the engines that power our cars, this "wobble" is a serious problem. Engineers call this "unbalance." When a fan rotor (the spinning heart of a fan) is unbalanced, it vibrates, makes loud noises, wears out its parts too fast, and can even break.

To fix this, factories use special machines to measure the wobble and then add or remove tiny bits of weight to make the rotor spin perfectly. This is called "balancing." However, in the real world, things aren't always perfect. Sometimes the mold that makes the plastic blades is slightly off, or the machine measuring the wobble is confused by its own vibrations. This leads to a frustrating cycle: a fan is made, it wobbles, workers have to fix it, it wobbles again, and they have to fix it again. This paper dives into that messy, wobbly world to figure out how to make fans that spin perfectly right out of the factory, saving time, money, and a lot of headaches.

The Great Fan Wobble Hunt

This paper is like a detective story, but instead of solving a crime, a team of engineers is solving the mystery of why their factory-made fan rotors keep failing to spin smoothly. They used a famous problem-solving method called "Six Sigma," which is basically a super-organized way to find the root cause of a mess and fix it for good. Their main goal was to boost the "autonomous balance rate." In plain English, this means they wanted to increase the number of fans that pass the "spin test" on the very first try, without needing any extra fixing.

The Suspects: Why Was the Fan Wobbly?

Before they could fix the problem, they had to figure out what was causing it. They looked at the entire assembly line, from the plastic injection molding to the final riveting. They found five main suspects:

1. The Confused Measuring Machine: The machine used to detect the wobble was actually the biggest troublemaker. It was so sensitive to outside vibrations and had such a shaky internal structure that it was giving false alarms. It was like trying to weigh a feather on a scale that was sitting on a trampoline.
2. The Flawed Mold: The mold that shapes the plastic fan blades had a few design quirks. It was making the blades slightly uneven in thickness and shape, which meant they were heavy on one side before they even left the factory.
3. The Wobbly Riveting: When they attached the metal shell to the blades, the tools holding them in place weren't precise enough. This caused the parts to be slightly crooked, adding more wobble.
4. The Guesswork Magnet: The magnets inside the fan were being placed based on what the workers could see with their eyes. This "visual guesswork" meant the magnets weren't always in the exact right spot, throwing off the balance.
5. The Wrong Spin Speed: They were testing the fans at different speeds, and some speeds were hiding the wobble while others made it look worse. They didn't have a clear rule on how fast to spin the fan during the test.

The Fix: Tuning the Machine and the Mold

The team didn't just guess; they ran experiments to prove what worked. Here is how they tackled each suspect:

• Taming the Measuring Machine: They realized the machine's "heart" (its sensors and support structure) was too loose. They swapped out the old, bouncy spring parts for solid, rigid columns and added a special hole to let air flow smoothly underneath the rotor so it wouldn't float or wobble from air pressure. They also separated the signal source from the test area to stop vibrations from confusing the readings.
• Redesigning the Mold: They tweaked the fan blade mold like a chef adjusting a recipe. They made the blade edges sharper (reducing the curve radius), lowered the center of gravity, and added a clever feature: an adjustable balance weight that could be rotated to 32 different positions. This allowed them to fine-tune the weight of the blade right inside the mold. They also smoothed out the path for the hot plastic to flow, reducing stress that caused the blades to warp.
• Sharpening the Tools: They upgraded the riveting fixtures (the tools that hold the parts) by adding extra pins to lock the metal shell in place perfectly. They also replaced the "eyeball" method for placing magnets with a precise, adjustable fixture, ensuring every magnet went in at the exact same angle.
• Setting the Spin Rule: They ran tests at three different speeds: 6,000 RPM, 9,000 RPM, and 11,500 RPM. They discovered that for fans rated under 10,000 RPM, testing at a speed higher than half the rated speed (like 6,000 or 9,000 RPM) was the sweet spot. For faster fans, they needed to test at full speed. This gave them a clear rulebook for future tests.

The Result: A Smooth Spin

The changes worked like magic. Before the fixes, only 5% of the fans were perfect on the first try. After the team implemented their new mold designs, better tools, and clearer rules, that number jumped to 42% in the first round of testing and hit 70% in the second round.

They also looked at the "average number of balancing times." Before, a single fan needed to be fixed about 1.3 times on average. After the improvements, that number dropped to just 0.5 times, meaning most fans didn't need any fixing at all. The "jitter defect rate" (fans that were so wobbly they were useless) went from 0.5% down to 0%.

The team also measured how "capable" their process was using a score called Cpk. While some scores were still working toward perfection, the "magnetic entry angle" (how straight the magnets were placed) saw a massive leap, going from a score of 0.53 to 2.43. This proved that their new, precise fixture was a game-changer.

The Takeaway

This paper shows that you don't always need high-tech robots to fix a manufacturing problem; sometimes you just need to tighten a bolt, redesign a mold, and stop guessing. By treating the whole production line as one connected system and using data to guide their changes, the team turned a wobbly, frustrating process into a smooth, efficient one. They proved that with the right adjustments, you can make fans that spin so perfectly, they almost seem to defy gravity.