Maintenance of the gearbox on the extruder

The maintenance of the most important part of the extruder is of course the gearbox, because of its high value and long delivery period. There are many steps and process to maintain it. Today we sorted out some key points of the daily inspection and maintenance of the gearbox from several different aspects. Let's take a look together.

Daily monitoring point

Daily/Weekly Monitoring:

- Oil level ("middle of sight glass", only applies when gearbox is stop)

- Oil temperature (should be below 65-70°C)

- Filter pressure drop (typically<2bar)

- Vibration/noise

- Oil spill

I、Maintenance of gearbox of the extruder

① The gearbox should be well ventilated, and the working environment temperature should be within the range of 5°C-35°C.

② Regularly check the amount of lubricating oil in the gearbox to ensure good lubrication of the all parts in the box(such as gears and bearing).

③ Pay attention to check the bearing in the gearbox frequently, and the temperature change should not exceed 45°C when it is working.

④ After the machine works about 300-500 hours, the dirty oil should be Cleaned in the gearbox and the lubricating oil should be replaced.

⑤ The gearbox should be regularly maintained and inspected once a year, and the work step as follow: 

• Remove the cover of the gearbox, and check the wear and meshing of the working surfaces of the reduction gears. If there are burrs or shallow pits on the meshing surfaces, they can be smoothed with oilstone; If the gears with serious wear the spare should be prepared foror replacement at the next maintenance.
  

• Check the wear of each bearing. Clean the bearing first, check whether there are cracks in the inner and outer sleeves; observe the noise of idling running and the size of the radial clearance, if no problem is found, add some grease and continue to use.

• Check whether the lubricating oil in the gearbox is cleaned. If there are impurities or metal powder in the oil, filter and remove impurities in the lubricating oil, and then make up the amount of lubricating oil or change the complete the oil, be sure there is no impurities or metal powder in the lubrication oil.

• After cleaning and checking the parts in the gearbox, install the box cover; add enough grease to each bearing part and replace the oil seal with a new one, and tighten the bearing cover.

• Clean the outside of the gear box to keep the equipment clean.

II、Principles for replacing parts in the gearbox

① If there are deep wear pits on the involute meshing tooth surface of the gear, or the noise is loud and irregular during the working rotation, and there is often shock and vibration, this kind of gear should be replaced.

② The inner sleeve or outer sleeve of the ball bearing has cracks; the ball frame is damaged; the radial clearance of the inner sleeve is large; the bearing rotation noise is louder when the outer sleeve is rotated, etc. After the rolling bearing is cleaned, if one of the above damage phenomena is found, the rolling bearing should be replaced.

III、Precautions for gear and bearing replacement and installation

① Gears and bearings should be cleaned and trimmed to remove burrs before installation.

② Detect and replace the size of the gear hole, assembly shaft, key and keyway, and it should meet the matching tolerance requirements specified in the drawings; the replacement rolling bearing should be the same as the original bearing model.

③ The gear hole and the shaft should be fitted with H7/k6 or H7/r6.

④ The outer shell of the rolling bearing and the box adopt k7/n6 fit, and the hole and shaft adopt H7/m6 or H7/k6 fit.