Find The Cause of The Broken Bowl Liner by On-site Photos

During the daily operation of cone crushers, liners may be broken occasionally. When it happens, we shall stop the machine for inspection, and send some on-site pictures and descriptions of the scene to GUBT's engineers for preliminary judgment.

In this article, we will explain the most common causes for the broken Bowl Liners.

First, we introduce the jargon named “Metal Fatigue”.

In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure.

Fatigue has traditionally been associated with the failure of metal components which led to the term metal fatigue. In the nineteenth century, the sudden failing of metal railway axles was thought to be caused by the metal crystallising because of the brittle appearance of the fracture surface, but this has since been disproved.[1] Most materials seem to experience some sort of fatigue-related failure such as composites, plastics and ceramics.[2]

To aid in predicting the fatigue life of a component, fatigue tests are carried out using coupons to measure the rate of crack growth by applying constant amplitude cyclic loading and averaging the measured growth of a crack over thousands of cycles. However, there are also a number of special cases that need to be considered where the rate of crack growth is significantly different compared to that obtained from constant amplitude testing. Such as: the reduced rate of growth that occurs for small loads near the threshold or after the application of an overload; and the increased rate of crack growth associated with short cracks or after the application of an underload.

If the loads are above a certain threshold, microscopic cracks will begin to initiate at stress concentrations such as holes, persistent slip bands (PSBs), composite interfaces or grain boundaries in metals.[3] The stress values that cause fatigue damage are typically much less than the yield strength strength of the material.

1. Problem Analysis

The broken areas of Bowl Liners in different batches appear in the same location. The following are some photos of the Bowl Liners reported by customers. It’s a typical phenomenon.

 image1 image2
It can be seen from Figure 1 that cracks appear on the Bowl Liner
The mantle and the mantle head are attached to each other, and the
mantle head pushes the mantle to perform the eccentric movement.
The part that is attached between them will cause metal fatigue due
to friction, which will make the metal shiny. As you can see in the photo,
the outer metal of the Mark No.2 is shiny, which proves that the fit is good,
but the black part of the upper section is obviously not tightly fit.Becausethere is a black mark at No.2, it can be determined that
the causes are from the assembly of the mantle head and the mantle,
or the mantle head has a fault that needs to be repaired.It’s proved by picture 2.
We got a photo of the Mantle Head for analysis. The same black mark appeared on the mantle's
upper area, and its other parts were still in bright colors, which confirmed the previous judgment.

1. Conclusion
Based on the two on-site pictures sent back by the customer and the customer’s description, our judgment and suggestions are as follows:

1. The Bowl Liners of different batches are broken at the same location and on the same equipment, so the probability of casting defects and quality issues is low.

2. Through the judgment of the metal fatigue on the wear surface of the Bowl Liner and the analysis with the photo of the mantle head, it can be concluded that there is a high probability that the broken problem is from assembly or the mantle head.

2. Result
1. We recommended that the customer stop the machine immediately to check the mantle head when the problem occurs.

2. The customer found the problem after overhauling the mantle head, repaired the mantle head, and then it worked normally.

Post time: Jun-18-2021
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