What is the lubrication cycle of grease for sliding bearings?

Update:24-05-2021
Summary:

Occasionally working, unimportant parts: shaft speed &l […]

Occasionally working, unimportant parts: shaft speed <200r/min, lubrication cycle once every 5 days; shaft speed> 200r/min, lubrication cycle once every 3 days.
Intermittent work: shaft speed <200r/min, lubrication cycle once every 2 days; shaft speed>200r/min, lubrication cycle once a day.
Continuous work, working temperature is less than 40℃: shaft speed <200r/min, lubrication cycle once a day; shaft speed> 200r/min, lubrication cycle once per shift.
Continuous work, working temperature 40-100℃: shaft speed <200r/min, lubrication cycle once per shift; shaft speed> 200r/min, lubrication cycle twice per shift.
It is necessary to make the journal and the sliding bearing evenly and closely contact, but also to have a certain matching clearance.
It refers to the central angle of the contact surface between the journal and the sliding bearing. The contact angle cannot be too large or too small. If the contact angle is too small, the pressure of the sliding bearing will increase. In severe cases, the sliding bearing will be deformed greatly, accelerate wear and shorten the service life; if the contact angle is too large, it will affect the formation of the oil film, and good liquid lubrication will not be obtained.
Experimental studies have shown that the limit of the contact angle of sliding bearings is 120°. When the sliding bearing wears to this contact angle, the liquid lubrication will be destroyed. Therefore, the smaller the contact angle, the better without affecting the pressure conditions of the sliding bearing. From the theoretical analysis of the friction torque, when the contact angle is 60°, the friction torque is the smallest. Therefore, it is recommended that for sliding bearings with a speed higher than 500r/min, a contact angle of 60° and a sliding bearing with a speed lower than 500r/min should be used. The contact angle can be 90° or 60°.
The actual contact between the journal and the surface of the sliding bearing can be expressed by the actual number of contact points per unit area. The more contact points, the finer, and the more uniform the sliding bearing is, the better it is. On the contrary, the sliding bearing is not good. Generally speaking, the more dense the contact points, the more difficult it is to scrape. In production, the contact point should be determined according to the performance and working conditions of the sliding bearing. The information listed in the following table is for reference:
Sliding bearing speed (r/min) Contact point
(Number of contact points per 25×25 mm area)
Below 100 3~5
100~500 10~15
500~1000 15~20
1000~2000 20~25
2000 or more 25 or more
The data in the above table can be used for machines with class I and class II accuracy, and the data in the table above can be halved for machines with class III accuracy.

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