New Reducer, Why Does the Keyway Fail First?

So you just installed a new reducer, but the keyway wore out or got damaged way too fast. Super annoying, right? Usually, it comes down to a few common issues.

1.The key size is off.

Maybe the key itself is too narrow, too thin, or just the wrong height. It might seem fine after installation, but once force is applied, it gets loose or wobbles. All that impact goes straight into the keyway, causing damage.

2.Misalignment during installation.

The motor shaft and the reducer input shaft (or the output shaft and the machine shaft) aren’t properly lined up. If the axes are off, the contact between the key and the keyway becomes uneven. That means extra stress on one spot, leading to quick wear.

3.Poor keyway machining.

The new part might have burrs or rough surfaces inside the keyway. Or the fit is just wrong — too tight (forcing it in can cause hidden damage) or too loose (leaving gaps). Both will concentrate stress on certain points.

4.Overload or shock in operation.

The actual load during operation might exceed what the reducer and this key connection were designed to handle. Or maybe there’s frequent starting, sudden stops, or heavy impact loads. All that force gets transmitted through the key, and the keyway takes the hit — leading to fatigue failure.

So, what should you do?

•Check the fit: Make sure the key dimensions match the keyway exactly. Don’t just go by feel.

•Align properly: When installing, always use the right tools (like a dial indicator) to ensure the shafts are tóng xīn

•Verify the load: Confirm your machine’s operating load stays within the reducer’s rated capacity.

•Inspect the keyway: Before assembly, take a look inside the new keyway. Make sure it’s smooth and clean.

If you’ve checked all these and the problem still happens, well… maybe it’s time to give us a shout. Our tech support can help dig deeper and figure things out with you.