Keep on Crushing
• Do operate the VSI at the right speed needed to balance the product gradation and wear costs. (Incorrect speed can result in higher wear rates and reduced product efficiency.)
• Do feed the crusher at full capacity to maximize production and minimize wear costs.
• Do inspect the crushing chamber daily for broken and worn parts.
• Do use a magnet on the VSI feed conveyor to to remove any tramp iron that may enter the system. (Parts broken by tramp iron can lead to catastrophic failure.)
• Don’t operate the VSI with a larger clearance than 1/2 inch between the bottom of the accelerator and the top of the pedestal skirt ring. (This can damage the pedestal.)
• Don’t operate the VSI with a gap larger than 3/8 inch from the feed tube to the top of the accelerator. (This will allow wear on the top of the accelerator and introduce shock loading into the bearings.)
• Don’t introduce water directly into the VSI. (Moisture accelerates the wear in the VSI.)
Top Maintenance Tips for Rock Crushers
Comprehensive daily inspections — Daily visual inspections will catch the majority of impending failures that could cause unnecessary and preventable down time. The pressure of business demands and operational commitments often thwarts good preventive maintenance practices. However, operations with the best, well-managed maintenance plans have proven that preventive maintenance pays over a reactive style maintenance plan. Visual inspections should be performed inside areas that can’t normally be seen such as crusher discharge areas, drive guards, and inspection covers. These inspections can identify such things as wear, build-up, and loose/missing components that could be damaged just waiting on the right “inopportune” moment to shut your plant down.
Housekeeping/material build-up — Build-up of material is nearly inevitable in the aggregate business. It will find its way in guarding, shrouds, and any horizontal surface on framework. Especially when the material is wet or sticky, it can build up in places where an operator will not normally see without further inspection. If left ignored on conveyors, it will take out rollers, head/tail pulleys, and rip belting, as well as cause tracking issues, but it won’t take long before it will cause severe damage to a cone crusher. The crusher doesn’t just have to stall out due to a plug-up to cause damage. Wear can also occur due to build-up in the crusher discharge area.
Contamination (fuel/hydraulic/oil) — Are you buying dirty fluids? In many cases, the fluids you buy may not pass a contamination analysis for particulates or even water. Bulk fluids going into your storage tanks should be pre-filtered when you get them, and again when servicing the unit/model. The days of transferring oil out of an open bucket are over. Don’t overlook fuel contamination. As emission standards push engine producers to make cleaner burning diesel engines, fuel atomization is accomplished by very high pressure injector systems. Contamination in these systems will cause extensive and expensive damage. Invest and believe in an oil analysis/preventive program.
Misapplication — Operating a crusher outside of its designed operating parameters can cause damage internally without it being readily visible. Failures can occur long after the abuse has occurred. Expect a reduced lifespan of components if a machine has been operated beyond the application for which it was designed.
Manganese wear liners wearing beyond scheduled replacement — A manganese wear liner should be considered worn out when its weight equals 40 to 60 percent of when it was new. Depending on the lifetime application, a liner may wear thin (or wear through) in certain areas before the 50-percent lifecycle has been reached. For this same reason, the liner may develop a crack or become loose before the designed liner lifespan. Daily visual inspections are critical for monitoring for loose/damaged/worn liners to prevent further damage to the crusher liner seats and retention components.
Crusher discharge/feed — The crusher will fill with material, plug, and stall if operated with the discharge belt not running. Often times, this conveyor is not visible to the operator. An operator should NEVER restart the crusher without a thorough inspection inside the discharge area and verification of damage or material trapped between the wedge plate (eccentric) and the cone head. They should turn freely of each other with consideration given to the anti-spin mechanism. There should be adequate clearance for the discharge material to exit and transition out the discharge belt. Also, it is important to keep the drop height of the feed into the crusher to a minimum distance and that it is centered. It may be necessary to install a rock box or rock ladder.
Keep daily records for trending — Keep daily written logs of as many critical items as possible. By proper written trending, preventive measures can be identified and planned before a costly failure occurs. Typical things to monitor are normal operating temperatures, lube oil flow (GPM), lube oil filter restriction, crusher coast down time from shutdown, running amps empty, and amount of oil used/added.
Cold weather start-up issues are preventable — One of the biggest benefits about roller bearings is the ability to operate at a wider temperature range. A roller bearing cone crusher’s ability to start is not limited by a “minimum operating temperature,” but is typically limited by the ability for the lubrication pump to provide sufficient minimum oil flow. This is seen as tripping of the current overload breaker for the lube pump or too low of oil flow to meet the flow trip setting and the alarm continues to sound. Common solutions are: cover the crusher opening to retain heat during shut-down periods, change to synthetic oil, and install/use an after-hours oil recirculation kit.
Use the correct lube oil — Don’t go cheap when it comes to the life-blood of a crusher. Stick to the manufacturer recommended oils and brands. There are many emerging oil manufacturers making lots of claims of higher performance, but remember, it won’t be the oil company standing behind you when you have a failure. The EP (extreme pressure) additive package specified in roller bearing cones is critical.