Even performing minor clean-up and inspections around and on cone crushers on a daily basis can yield increased service life. But doing a bit more can boost production performance and product quality. Kraig Thistle, a regional service technician for Telsmith in the US, shares some top tips for getting the most from cone crushers.
CHOKE FEEDING IS A MUST
At the top of Thistle’s list is keeping the cone crusher choke fed during operation — a practice that maximises the effectiveness of rock on rock crushing, which in turn maintains maximum manganese wear life and ensures a quality product shape. He stresses that it is common to see crushers operating with too little feed or with too many fines in the feed.
{{image2-a:r-w:250}}A lack of feed causes side loading of the machine, which means crushing forces are affecting all internal components. Similarly, in the case of an overabundance of fines, crushing forces subject components to damage and premature wear. Additionally, when not choke feeding, one is increasing recirculating loads, which affects components such as screens or other crushers that are downstream of the circuit.
OIL LUBRICATION A PRIORITY
The importance of timely oil changes cannot be stressed enough because your crusher uses the oil supply for cooling and lubrication. Allowing the crusher to operate with worn out or contaminated oil could lead to a reduction in bearing, gear and liner life. Check your oil and filters daily and change them at the proper intervals recommended in your owner’s manual.
Always uncover the source of contaminants. For instance, where oil leaks out, contaminants such as dust particles and water can get in. Inspect all your hydraulic systems and tag any leaks for corrective action on the very next maintenance cycle. Completely drain and thoroughly clean out the inside of the oil tank to eliminate any contaminants before refilling.
It is important to note that establishing a scheduled oil sampling program indicates a baseline of normal wear and can help indicate when abnormal wear or contamination is occurring. Oil that has been inside any moving mechanical apparatus for a period of time reflects the exact condition of that assembly.
If your crusher is equipped with an external-mounted oil pump, the following must be carried out:
• Lubricate the oil pump bearings every 500 hours.
• Check reservoir oil level daily and change oil every 600 hours of operation.
• Perform a weekly inspection of the oil pump shaft seal. A slow drip of oil from this seal is normal while the pump is operating. If oil leakage is greater than a small drip, evenly tighten the packing gland (seal) until about one drip per minute is visible with the pump operating. Do not over-tighten the seal so no oil drip is present. The small drip must be present when the pump shaft is rotating.
Lubrication systems with tank-mounted oil pumps allow oil to be circulated before crusher start-up to provide pre-lubrication of the crusher internal components. An alarm system is an integral part of this lube system. During the operation of certain cone crushers, an alarm may sound if any of the following abnormal conditions occur for more than five seconds: a low feed-line oil flow; a low feed-line oil pressure; or a high return-line oil temperature. If these conditions continue to occur, a time-delayed shutdown of the crusher may occur.
{{image3-a:l-w:250}}The cone crusher may be equipped with either an air/oil cooler or a water cooler to help dissipate heat from the lube oil. The air/oil cooler will require periodic cleaning of the cooling fins to remove debris or build-up of dust and dirt. When cleaning the cooler fins, the fan blades should also be checked for build-up that could unbalance them.
The water cooler will need to be drained on a seasonal basis to keep it from freezing in winter conditions. At the time the cooler is drained, the passages should be blown out to check for debris or scale build-up.
When upgrading to modern cone crusher designs, ask your supplier about the engineering of the system’s tank and oil cooler. Certain crushers feature clean and simple designs that allow reduced maintenance and provide greater protection against environmental hazards.
For example, new designs may offer a streamlined approach to plumbing, with an oil pump, suction line, motor coupling and bypass line all mounted inside the tank. This significantly reduces the risks of costly environmental damage caused by oil spills. To further simplify the plumbing, an oil distribution manifold is used, incorporating a bypass relief valve and a thermal bypass valve into the manifold. The integrated manifold protects the crusher from high oil pressure and offers better temperature control — a benefit particularly to those who operate in extreme climates.
USE THE CORRECT OIL
The type and condition of your lubrication oil is critical to successful operation of your cone crusher. Crushing with worn out oil or oil of the wrong specification can significantly reduce crusher life. Your crusher is designed to work with lube oil in the range of 10oC to 51oC.
A sensor switch at the reservoir return line controls the maximum oil temperature. If your crusher is being used regularly in extreme heat (38oC plus) or cold temperatures (-23oC) and it is hard to maintain crusher oil in the correct operating range, it may be helpful to switch to synthetic oil.
INSPECT THE MAIN FRAME
{{image4-a:r-w:250}}Inspect the main frame bore for nicks, burrs, scoring or other damage. Attempt to remove any imperfections with a file or emery cloth. Use a micrometer to measure the bore at the top, bottom and centre. At each position, check the dimension at two places 90 degrees apart.
The average of all six measurements must fall within an acceptable range. If high spots cannot be filed down to an acceptable range, the bore will need to be re-machined into tolerance. Check the bore carefully after re-machining for burrs, particularly at the keyways and grooves. A main frame ?bore that is worn outside the tolerance limits will need to have the worn spots welded up and the complete bore re-machined to tolerance.
CHECK YOUR ALARMS DAILY
If electrical changes are made or programs are altered in automated systems, verify that all alarms and interlocks still function properly. Don’t be afraid to replace switches or timers that appear damaged or are in poor condition. This is much cheaper than the completion of a major overhaul. Never disable or alter any alarms or interlocks!
KNOW YOUR MACHINE, REACT ACCORDINGLY
Record vital machine information such as motor amps and oil pressure in a variety of operating conditions. This will allow you to identify trends and will also help to detect problems before they cause costly damage or downtime.
“Bottom line, don’t take any shortcuts,” Thistle says. “It’s only going to come back and cost you more down the road.”
Carol Wasson is a veteran freelance writer for the aggregates and construction equipment industries. Information for this article was provided by Telsmith Inc.
This article was published in the July 2012 issue of Aggregates Manager (US) and is reprinted with kind permission. Visit www.aggman.com
