SEALED BALL BEARINGS RUNNING HOT? CONSIDER USING NON-CONTACT SEALS

By Dave Deetz

A sealed ball bearing is probably the most commonly used bearing in the world. They are designed for industrial machines, appliances, electric motors, pumps, gearboxes and conveyors . . . just to name a few applications. Most sealed bearings incorporate two contact seals. These seals (usually nitrile rubber) are positively engaged in the outer ring and then rub against the inner ring producing a positive contact seal. This seal rubbing produces friction and heat and is the reason the bearing RPM rating must be reduced. A sealed bearing is often rated at only 65% of the RPM for an open or shielded bearing.

A non-contact seal might be a good choice to consider. This type of seal is also positively engaged in the outer ring, but the bearing inner ring incorporates a “V” shaped cut. The bottom of the non-contact seal is formed in the same shape. This produces a labyrinth seal to protect the bearing. But this seal does not make a positive contact with the inner ring, so there is no reduction in the rated RPM and no increase in bearing operating temperature.

The non-contact seal has become very popular where higher bearings speeds are found like the electric motor industry. NTN (LLB seal) and NSK (VV seal) have become industry leaders with non-contact seals.

Are non-contact seals a good choice for applications in your plant? Call an OTP Sales Engineer to receive help with your bearing selection. OTP Industrial Solutions’ team of bearing experts has the knowledge, training and experience to find the right bearing for any application. Please call or email us with your request.

KNOW WHEN IT’S TIME TO REPLACE YOUR ROLLER CHAIN

By Rob Raggard

How do you know for sure that you have consumed all of the useful life out of your chain?
With proper selection, installation, maintenance and lubrication, a system should achieve up to 2-3% elongation before the chain needs to be replaced.

CHAIN WEAR: WHAT IT IS AND HOW TO MEASURE IT

Chain wear or chain pitch elongation (“stretch”) is the increase in measured chain length due to wear or excessive load.

CHAIN WEAR

This is expressed as a percentage (%) increase in length.

Chain wear diagram
Chain Wear Diagram

HOW TO MEASURE CHAIN WEAR

how to measure chain wear
How to Measure Chain Wear

1. Pull the chain slightly until it is taut.
2. Use a vernier caliper to measure the distance of the inside (L1) and the outside (L2) of the rollers at both ends of the measured links.
3. The average of (L1) and (L2) gives you the measured length (L).
(L1) + (L2) / 2 = (L).
4. Calculate the standard length as: Chain Pitch x Number of Links.
5. Chain elongation percentage increase in length is calculated as:  Chain Elongation = Measured Length (L) / Standard Length x 100 (%)

Many manufacturers offer a chain wear scale, similar to the example below.

chain wear scale
Chain Wear Scale

Would you like more information about chain selection, maintenance and replacement? Call your OTP Sales Engineer today and speak with an industry expert who can answer all your questions and keep you moving forward.