Daemar’s tips on better seal performance through equipment designMarch 23, 2020 REDWIRE is news you can use from leading suppliers. Powered by FRASERS.
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As a major provider of essential components for industry, Daemar Inc. plays two important roles for its customers: a supplier of products, and an expert team offering advice on getting the most out of these products. Take sealing components. For optimal seal performance, the bore and the shaft – the two components with which seals interact – must be designed properly. Here is Daemar’s expert advice on designing shafts and bores to get better performance from seals.
Extending seals’ operational life
Appropriate bore and shaft design will not only improve seal performance, but also extend the seals’ operational life. Bores should have adequate lead-in chamfer and proper tolerance to enable the correct press fit of the seal’s outer casing after installation, thereby eliminating leaks between seals and bores. This also prevents seal rotation or movement during operation. Shafts also require proper lead-in chamfer, as well as appropriate diameters and surface finish. Minimal shaft movement and misalignment boost performance – and limit seal lip wear.
Material, hardness, finish, lead-in chamfer, and tolerance should be considered when designing bores. Cast iron and steel provide good surfaces for accepting metal and rubber O.D. seals. Bores should be hard enough to withstand the seal’s O.D., while the finish should be 0.8 to 1.6 μm Ra for metal O.D. seals, or 2½ to five μm Ra for rubber ones. The lead corner should be chamfered and bore-free.
Daemar recommends the following design considerations:
- Eccentricity – Dynamic run-out and shaft-to-bore misalignment can affect seal performance. Dynamic run-out is twice the distance of displacement between the shaft centre and actual rotation centre. Misalignment means the distance between centre of shaft rotation and the bore centre.
- Finish – Plunge grinding can attain surface roughness of 0.2-0.8 μm Ra.
- Hardness – Minimum Rockwell C45.
- Lead-in chamfer – Shaft ends must be chamfered, and the corners rounded and free from burrs and sharp edges.
- Material – Stainless steel or medium-to-high carbon steel results in top performance from sealing components.
- Tolerance – Daemar’s website offers convenient shaft tolerance tables.
To learn more, contact Daemar.