In selecting a crusher liner for the crushing cavity care is taken to obtain a design that will permit the top size of the feed to enter the crusher in sufficient volume throughout the entire wear life of the liners.
Since the most efficient crushing action takes place when the feed is reduced is a series of 4 or 5 blows as it passes through the cavity, it becomes important to select a design that will effect some reduction in the upper portion of the cavity as well as the lower or parallel sizing zone. In other words, too large and opening for the feed will prevent crushing in the upper zones and can develop excessive power draw.
Since the crusher feed rate is governed by the power draw, an incorrect cavity can reduce the crusher capacity and, on occasion, create unnecessary maintenance. On the other hand, if the cavity will only accept the feed when the liners are new but as the liners wear the feed opening closes off reducing the feed rate, a more efficient cavity is required.
Since no two ores or crushing applications are exactly the same, a large number of cavity designs have become available through the years. Therefore, the optimum in cavity designs is one which permits close to the rated power draw throughout the entire wear life and results in a scrap loss between 25 and 40 percent. Frequently, where crushing plants are not meeting rated capacity, or increased capacity is required, a crushing cavity investigation is warranted.
As a guide, the initial liner selection is made based on the feed analysis, abrasiveness of the rock, and crusher product required. The feed should be generally no larger than 80 percent of the liner open side dimension shown on the cavity table. Subsequent observations of the crusher in operation will dictate the optimum design. Since crusher performance depends on proper liner design, the sheet entitled “Data Sheet For Liner Study” is useful in analyzing a specific application.