With Director Zhao's approval, Liu Li didn't dare to delay—repairing an emergency is like putting out a fire; every minute of delay increases the risk to the order.
Instead of immediately dismantling it, she circled around the C620 lathe, like an old Chinese medicine doctor diagnosing a patient, first "observing, listening, inquiring, and feeling the pulse".
First, she checked everything. She shone her flashlight, scrutinizing every nook and cranny. The oil level in the oil window was sufficient, but the color was considerably darker than when it was first changed. She inspected the gaps between the spindle box and the bed, and the seals on the drive shaft, one by one. Finally, her gaze settled on the rear end of the spindle—there was a faint oil stain there, slightly darker than the surrounding area, almost invisible without close inspection.
“Squad Leader Li, look here.” Liu Li pointed to the oil stain, her tone quite polite. “It seems like the oil has been seeping in for a while, the kind that leaks slowly.”
Old Li leaned closer, squinted at it, and touched it. His expression changed: "It really is! I usually only check if there's enough lubricant during maintenance, I haven't paid attention to this little place. If it slowly seeps out, the lubricant will naturally decrease..."
Next, she smelled it. With permission, Liu Li opened the inspection hole cover of the spindle box, and a smell wafted out—a mixture of rancid smell from old machine oil and a hint of burnt metal. It wasn't strong, but her heart sank as soon as she smelled it. This smell was exactly the same as the smell of burnt bearings she had experienced during her internship at the factory.
Then she asked, "Mr. Zhang, who usually operates this lathe, asked in detail: 'Mr. Zhang, have you noticed any muffled sound when you're operating this lathe lately? Or does the motor seem to be struggling to spin when the spindle is idling?'"
Master Zhang frowned and thought for a moment: "Now that you mention it, it's true. It doesn't feel as light as before. I thought it was because the oil was too thick in the cold weather."
Finally, there's the "touch" – judging by touch. She asked Director Zhao and Master Wang, "Could you turn on the power and tug it a little? Just for a second, just to make the spindle move slightly, I want to feel the vibration."
"No way! The spindle is already seized up; if we turn on the power, the motor will burn out!" Old Li immediately objected.
"Squad Leader Li, just light it once, then turn off the power immediately. Nothing will happen." Liu Li looked at Master Wang with earnest eyes.
Master Wang squatted down beside him without saying a word, only nodding. Director Zhao also reassured him: "Be careful, just once!"
The moment the switch was turned on, the workshop lights dimmed, and the motor made a weak "hum," but the spindle didn't move. However, Liu Li's hand remained on the spindle box, and in that instant, she clearly felt that the vibration coming from the box was not even, but a sharp, metallic "click" sound, accompanied by a teeth-grinding friction sound.
After the power went out, Liu Li opened her eyes and had a pretty good idea of what was going on.
“Director, Master Wang, Foreman Li,” her voice was clear and could be heard in the workshop, “the oil leak is causing insufficient lubrication, there’s a burnt smell in the gearbox, Master Zhang said it’s hard to turn, and just now when he started it up, he could feel the metal sticking out—I think the problem is with the main bearing in front of the spindle. It’s probably because the lack of oil wore down the cage, the ball bearings broke, and the spindle is stuck. The spindle journal might be a little damaged, but it’s mainly a bearing issue.”
Her words were logical and well-reasoned, and the evidence was presented clearly. Old Li was stunned. He had been a mechanic for decades, relying on experience, and he had never seen a young female worker analyze a fault so thoroughly, as if she were writing a report.
"Now that you mention it, it really makes sense!" Old Li stroked his chin. "Especially the 'clunking' sound you mentioned, it's most likely that the ball bearing broke and squeezed it."
Master Wang also stood up, tapped different parts of the spindle box with the copper rod in his hand, listened carefully, and didn't say anything, but a hint of approval flashed in his eyes.
Director Zhao, seeing that things were going well, immediately approved: "Okay! Check it this way! Disassemble the spindle box and focus on the front bearing! Liu Li, you follow Squad Leader Li, and tell me if anything is missing!"
"Okay!" Liu Li replied. Old Li's gaze towards her was no longer dismissive, but rather showed more approval: "Little Liu, you have sharp eyes and a meticulous mind! Come on, let's get the tools; this 'operation' needs to be done carefully!"
Liu Li followed Lao Li to the tool cabinet, already thinking about the order of disassembly—what to disassemble first, what to disassemble later, and which parts to mark to avoid mistakes. Under the workshop lights, a group of people busied themselves around the lathe, racing against time to fix the "sick" lathe.
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