Air End Repair -AC - 03/Sept/2009

Common Air End Failure and Repair

WHY ?

Its Bearings need to replace regularly ?

The bearings are to hold both the rotors in horizontal position;

they are not to rub against each others.

A failed Rotary Screw Air Compressor's Air End:= Atlas Copco GA132, we dismantle on Thursday, 3rd September, 2009 from a factory in Prai Industrial, Penang. 

 A female rotor of the twin screw rotary screw air compressor. 

The male [drive rotor], note; the DE bearing side. 

  

Four Point Ball bearing position and set clearances of rotors end cover clearances !!!!!

  

  Air End Bearings:= 

 Types and size of bearings: 

QJ 315 = 2 sets 

NU 315 ECJ/C3 = 4 sets 

 Note:= 

There are three types of bearing cage to choose from, there are NU 315 ECJ = Steel cage 

NU 315 ECP = Polyamide cage [ a type of plastic material ] 

NU 315 ECM = Brass cage

Air End Overhaul -IR - 04/Sept/2009

Rotary Twin Screw Oil Flooded Air Compressors !

Typical Air End Failure

The Bearings that hold the Twin Rotors in position; need to replace regularly, 

Otherwise !!!!!

The Twin Rotors :

The Male - usually the drive,

The Female - usually follow

 

 

The Male Rotor After Repair ! 

Air End Bearings: 

Type and sizes of bearing for this air end are:

HM 911210 = 4 pcs HM 911244 = 4 pcs 

NU 211 ECM/C3 = 1 set 

NU 311 ECM/C3 = 1 set 

 Note:= 

There are three types of bearing cage to choose from, there are NU 311 ECJ = Steel cage 

NU 311 ECP = Polymide cage [ a type of plastic material ] 

NU 311 ECM = Brass cage 

 A sample of a different air end using ECM bearings. 

That is bearing with Brass Cage. 

 Looking for Branded new Air Compressors to save on Electrical Energy ?????

Typical Bearings Failures

Prevent over 60% of Premature Bearing Failures

Poor Fitting [16%]
About 16% of all premature bearing failures are caused by
1. Poor fitting (usually brute force ...)
2. Being unaware of the availability of the correct and proper fitting tools
3. Laziness

Individual installations may require mechanical, hydraulic or heat application methods for proper, correct and efficient dismounting or mounting.

The use of specialised tools, equipments and techniques will make the above job easier, faster and more cost effective.

These is one positive step towards long bearing life, thurs achieving maximum compressor uptime.


Poor Lubrication [36%]
About 36% of premature bearing failures are caused by incorrect specification and inadequate application of the lubrication.

Any bearings deprived of proper lubrication will long before its normal service lifespan. Bearings are usually the least accessible components of the compressors, therefore, neglected lubrication compounds the problem.

Effective lubrication, using recommended lubrication [grease, oil, coolant], Special tools, equipments, and techniques, really helps to greatly reduce downtime.


Contamination [14%]


Bearings are precision components that will not operate efficiently, unless both the bearings and its lubricants are isolated from contamination. At least 14% of all premature bearing failures are attributed to contamination.






Fatigue [34%]
Whenever compressors are overloaded, incorrectly serviced or neglected, bearings will suffer, resulting in 34% of all premature bearing failures.

Sudden or unexpected failure can be avoided, because neglected or overstressed bearings emit "early warning" signals, which can be detected and interpreted using Condition Monitoring Equipment.








Condition Monitoring Equipment
CME includes hand-held instruments, hard-wired systems and data management software for periodic or continuous monitoring of key parameters.


edited from
http://www.skf.com

A failed QJ bearing, behind is the Controller for Screw Air Compressors.