By: Zac Knoll, Application Engineer
Proper ball screw lubrication is an essential component to ensure precise operation and long-term product life. Constant lubrication between the ball bearings and raceways are needed for smooth and accurate operation to reduce heat generation and prevent premature ball screw fatigue. Many manufacturers invest in costly centralized lubrication systems to reduce maintenance requirements; however, NSK recommends some alternative solutions. Special seal designs are available to retain lubrication and reduce the environmental impact.
The L1 seal is a non-contact seal that is designed to prevent grease from accumulating on the screw shaft surface. No friction loss is generated from the L1 seal due to the non-contact design that prevents direct contact with the shaft. The L1 seal is designed for smaller diameter ball screws (15-32 mm) where a clean operating environment is necessary. This seal prevents grease splatter in common applications that can be found in semiconductor, food processing and medical industries.
Ball screws that frequently run to the same end position on the screw shaft have a tendency to push excess grease to this location, which causes the grease to build up over time. At low speeds this can lead to excess grease or dripping that can contaminate the area directly below the ball screw.
Applications using high rotational speeds and high acceleration rates for the ball screw can create grease splatter. As the speed increases, the centrifugal force that is generated by rotating the ball screw shaft causes excess grease to fling off the screw shaft surface and contaminate the surrounding area. Use of a L1 seal reduces the risk of excess grease when the shaft is in rotation.
The A1 seal is designed to retain grease for high speed and heavy load applications. Injection molding and press/clamping machines are common applications that utilize high load ball screws (50 mm diameter and larger) within the machine tool industry. Grease is pre-packed and retained in the A1 seal eliminating any grease splatter caused by grease build up on the shaft. Grease build-up is a common disadvantage of centralized lubrication systems. Utilizing an A1 can help your plant reduce costs as well as their environmental impact.
Lubricants with EP additives are commonly used and can withstand high operating pressure. Use of these additives, however; increases the manufacturing cost of lubricant. The A1 seal minimizes grease loss which has a positive impact on the overall cost of ownership. Scheduled maintenance for lubrication intervals can also be decreased by equipping high-load ball screws with an A1 seal option. The A1 seal is an excellent solution that counteracts premature ball screw failure resulting from insufficient lubrication and minimizes excessive grease discharge that is not optimal for clean-room production environments.
A1 vs L1 Seals
Both A1 and L1 seals help to reduce grease splatter and prevent grease build-up on ball screw shaft’s surface. Each seal design provides excellent grease retention to reduce maintenance cost and environmental impact. The L1 seal is optimal for smaller diameter sized ball screws in clean-room environments; whereas the A1 seal was specifically designed for high speed, heavy load applications for larger diameter sized ball screws commonly found in machine tool applications.
Dependent on the industry and application requirements, NSK can work with you to recommend the best solution. Interested in discussing ball screw seals with one of our Application Engineers, please contact 800-255-4773 or firstname.lastname@example.org.