How to resist vibration imprint in steel body
How to resist vibration imprint in steel body
(OP)
Hi guys,
I have a nitrided, hardened, steel puck that sits and is held in a milled steel (4145 HTSR) pocket. The pocket of the body is gradually showing an imprint of the bottom of the puck, due to vibration and contact on the top of the puck. So basically, the contact is on the top of the puck, and the bottom of the puck (the puck bottom has a couple of grooves) is leaving an imprint in the pocket. This also results in the puck not being to size anymore, since it now sits about .030" lower (because of the imprint) after time, even .080", and that would be the maximum it would be. After that, the pocket is damaged, and is discarded.
We want to increase the life of the pocket without changing the puck. Material would be the best.
1. Would a higher material charpy impact test help? Currently we show about 55-60 ft-lbs charpy impact test.
2. We thought of using a sacrificaial 'disc' underneath, about .020-.030 thick. Haven't tried it yet.
3. We must have the puck nitrided and hardened, to resist the constant pounding on the top of the puck. Otherwise, it doesn't last.
4. Would gas nitriding the pockets help?
5. Would hardening the pockets help? Ideas?
Thanks.
I have a nitrided, hardened, steel puck that sits and is held in a milled steel (4145 HTSR) pocket. The pocket of the body is gradually showing an imprint of the bottom of the puck, due to vibration and contact on the top of the puck. So basically, the contact is on the top of the puck, and the bottom of the puck (the puck bottom has a couple of grooves) is leaving an imprint in the pocket. This also results in the puck not being to size anymore, since it now sits about .030" lower (because of the imprint) after time, even .080", and that would be the maximum it would be. After that, the pocket is damaged, and is discarded.
We want to increase the life of the pocket without changing the puck. Material would be the best.
1. Would a higher material charpy impact test help? Currently we show about 55-60 ft-lbs charpy impact test.
2. We thought of using a sacrificaial 'disc' underneath, about .020-.030 thick. Haven't tried it yet.
3. We must have the puck nitrided and hardened, to resist the constant pounding on the top of the puck. Otherwise, it doesn't last.
4. Would gas nitriding the pockets help?
5. Would hardening the pockets help? Ideas?
Thanks.





RE: How to resist vibration imprint in steel body
OR, you could make the pocket of material with a higher Brinell hardness.
Since it's not suffering brittle fracture, higher Charpy values wouldn't help.
Mike Halloran
Pembroke Pines, FL, USA
RE: How to resist vibration imprint in steel body
2. No, increasing toughness (higher Charpy) will not help.
3. Hardening the pocket would likely help. 4145 HTSR has hardness below 30 HRC, I believe. You could surface harden using flame or induction, up to 50-57 HRC, for a depth of ~ 1 to 2 mm.
4. Alternatively, make the existing pocket larger and make some inserts that can be pressed into the pocket. These inserts could be tool steel like D2 @ 58-62 HRC or similar.
5. Lots of other options include case carburizing or nitriding the pocket or inserts. Bearing steel like 52100 @ 60+ HRC?
RE: How to resist vibration imprint in steel body
I have no idea what your application is tooling, multiple installations, or what, but generally fighting steel on steel contact wear with hardness when motion is involved only gains 2 or 3X. Lubrication can gain 100X.
I'm thinking dry film MoS2?
How is the upper end of the puck doing? How is it secured?
If the upper joint could be a rubber biscuit allowing transverse motion via internal shear maybe the motion in the pocket would stop?
RE: How to resist vibration imprint in steel body
Ted
RE: How to resist vibration imprint in steel body
It's entirely possible that the puck's interests would be better served by a more resilient support, like rigid polyurethane. ... but there's no way for us to know that.
Mike Halloran
Pembroke Pines, FL, USA
RE: How to resist vibration imprint in steel body
Hope that helps.
Terry