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Nordberg Symons cone crusher

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Nordberg Symons cone crusher

June 25, 2023 nflg 0 Comments

Nordberg CS 5½ std. cone crusher

The Nordberg Symon cone crusher has for many years been produced by Nordberg Manufacturing Co., USA. Cone crushers is used for medium and fine crushing of minerals. The CS standard cone crusher is significant because of the fact that it has no top bearing. The cross axl is resting on a spherical roller bearing.

The oil system is both a gear and a hydraulic system. The circulating oil enters under pressure through the bottom of the casing to lubricate the pressure bearing. The oil is from here divided into two streams. One stream lubricates the cylindric bushing and the shaft. Another stream is pushed through the channel in the shaft and lubricates the wear plate and the conical shaft. Both streams are then entering and lubricating the gear system and pushed further back into the system tank.

In some newer models of the crusher another stream of oil is used to operate 4 cylinders to install the distance between the crushing surfaces. These are operated with servo valves.

The CJCTM Fine Filter, type HDU 27/54 P-Y

The CJCTM Fine Filter, type HDU 27/54 P-Y is a cellulose fine filter dimensioned to remove particles, resin and water in a off- line circuit on the oil reservoir. It is supplied with its own pump that circulates the oil from the bottom of the tank through the filter element and back to the reservoir as near to the system suction as possible.

As protection to the filter pump this type of Fine Filter is equipped with a 125 micron UCC suction strainer . The HDU 27/54 P-Y is supplied with 2 CJCTM Fine Filter elements type B 27/27. This cellulosed based filter element removes: 98,7% of all particles > 3 micron in one pass 50% of all particles > 0,8 micron in one pass. 2 litres of water per B 27/27 resin and oxidation deposits.

Condition of oil and machinery before installation of fine filter

Before installation of the fine filter 2 samples was taken on 2 identical cone crushers and the analysis report showed and estimated contamination code of ISO 25/22 (ISO 4406).

To above spare parts expenditure the annual expenditure must be considered:
1. the cost of labour for above maintenance and occasional cleaning of oil tanks
2. the cost of production stops for maintenance
3. handling, storage and environmental costs for disposal of oil

The testing procedure

After consideration of the theoretical life time improvement of both system components and oil in connection of the installation of off-line filtration equipment it was decided to carry out a trial test. The test was to be carried out as a comparison test on 2 identical cone crushers, one of them fitted with a efficient off-line filtration system.

The 7th of December 1999 the CJCTM Fine Filter, type HDU 27/54 P-Y was installed on crusher no 3 and the comparison crusher was decided to be no. 4. The following terms were agreed upon:
1. 3 months trial period
2. minimum cleanliness level to be reached ISO 16/13
3. 4 element changes per year as maximum

The oil samples

The oil condition was monitored by independent oil laboratories in Chile and Holland and samples were taken after installation of fine filter, after 300 hours, after 1200 hours and after 1700 hours.

It is important to notice that the samples from the crusher no. 3 with filter was taken from the bottom of the tank and the samples from the crusher no. 4 was taken from the middle of the tank and therefore is the oil in crusher no. 4 without doubt a lot more contaminated than measured by the particle counts.

Comments to the oil analysis results

From the spectral analysis it is obvious that the particle removal has reduced machinery wear considerably.

The amount of wear metals have fallen dramatically and the filter removes a large amount of copper that in connection with the oil will act as a catalyzer for the oxidation process of the oil.

The rise in contamination level on the crusher with filter is probably due to the fact that most oils have been added an additive which gives the oil an ability to encapsule particles and water to a certain limit. This is done to keep the particles and water suspended in the oil and not have the contamination settle in the system on sensitive components and create system wear.

In an as contaminated system as this the oil has reached its limit of this properties and therefore millions of particles have been settling in the system. When a fine filter is installed on a dirty system it will first and foremost remove the particles flowing in the oil. This will enable the clean oil to attract the particles lying around in valves, pipes etc and transfer these to the tank and thereby to the fine filter. In such cases the contamination level will often fall – raise – and fall and stabilize at a low level. This is most likely the reason for the small rise in contamination.

It is without doubt that the CJCTM Fine Filter, type HDU 27/54 P-Y with time is able to keep a ISO code of 16/14. It is important to notice that dimensioning of off-line filtration systems often can be difficult due to the unmeasurable particle ingress, changing from system to system.

The dramatic increase of viscosity is due to the rapid oxidation of the oil. Catalysts like metals, especially copper, accelerates the speed of this oxidation process rapidly. Please note, that according to Nordberg specifications the oil viscosity of 128,1 cSt made the oil due for replacement already after 314 hours as the max. recommended viscosity is 74,8 cSt.. As “new” oil is often delivered with ISOcodes above 17/15 the oil on crusher no. 3 can be considered as better than new oil. In contrary the oil on crusher no. 4 was already due to change after 314 hours.

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