Cone crusher liners that exceed their intended operating life will cause mechanical problems with the crusher. A liner that is pushed too long will flex and crack, and the flexing of a thin or cracked mantle will cause severe seat surface damage.
Although there is no foolproof way to tell when the liners are worn out, here are Three indications it is time to change the liners:
1. Production level
When you see a 10% or more drop in production level or throughput, it is a good indication the Cone Crusher liners need to be changed.
2. Liner thickness
If the liner is wearing evenly throughout the chamber, you should consider changing it when it has worn down to about 1” (2.5 cm) thick at the bottom. At about 3/4” to 5/8” (1.9 cm to 1.6 cm) thick, the liner will crack, causing the backing material to begin to disintegrate. This will cause the liners to break loose. If the liners break loose, the continued operation could destroy the seat on the support bowl or the head of the Cone Crusher.
Some Cone Crushers feature an automatic liner change reminder. When new mantle and concave liners are installed, the automatic reminder is reset. As the crusher operates, the system tracks production capacities and calculates the liner wear rate. When the cone liners reach the maximum wear point, the system sends a flashing reminder to “Change Cone” on the cone setting meter. After the wear parts are changes, reset the automatic reminder system and continue efficient and reliable crushing.
An important item to note: You should never place a new concave liner in a crusher with a worn mantle or a new mantle in a crusher with a worn concave liner. Mating new and worn components will change the profile of the crushing chamber and restrict the feed from entering the crushing chamber, which will reduce the tons per hour produced.
3. Change the liner before you start to suffer significant production losses.
On top-adjust/screw adjust cones this is especially true as the feed size starts to shrink pretty dramatically as soon as you get to the last 1/3 of life and as you near the end the feed size can get very small, losing as much as 30% of feed size. This is less of an issue with hydrocones as the feed size remains constant throughout the life of the manganese.
You should have a pretty good idea when you will need to change manganese and be able to have all of the parts on hand prior to needing to change. By having an accurate belt scale, you can know to the day when your production starts to tail off to the threshold and schedule the change immediately.
What is the threshold for a liner change? We believe the maximum threshold for a liner change is as follows: Change your liners no later than a 10% decline in production.
Why?
Production rate: 200 tons per hour of sellable? minus Crush Margin $2.50 per ton hours per day 10 production hours per day.
Therefore a 10% reduction in production results in a loss of $2,000 per day in gross profit. All of the other fixed and “variable” costs of labor and fuel keep adding up at the same rate. At $10,000-12,000 per week it doesn’t take too long to rack up serious losses, in two weeks you could afford at least two new sets of liners!
Some may say that times are tough and we can’t sell everything we can produce so why not get the last ton out of that set of manganese? If you conduct four liner changes per year and you delayed each change by two weeks, you add forty-four hours of operation time to your season, that’s a whole week of wages and fuel!
Simple, have an accurate belt scale, plan your liner change and do it no later than when you notice a 10% decline in production.