In-depth Analysis Of The Three Major Failure Mechanisms And Prevention Of Sintering Furnace Mesh Belts

Mesh belt fracture,deviation, short service life?

Problems such as product damage caused by friction between the product and the furnace body due to mesh belt deviation of the sintering furnace, and a sharp increase in production costs due to frequent replacement of the mesh belt due to premature aging have become "major difficulties" in the production of many enterprises.

This article will deeply analyze the three major failure mechanisms of sintering furnace mesh belt fracture, deviation, and short service life from the perspective of materials science and mechanical principles, and provide a comprehensive prevention strategy from selection, installation to maintenance to help enterprises reduce maintenance costs.

1: Mesh belt fracture

1.1 Mechanical fatigue

The fracture of the sintering furnace mesh belt is an inevitable result of the accumulation of mechanical fatigue to a critical state. During the operation of the mesh belt, the driving point, as the core part of power transmission, is subject to much greater force than other areas, forming obvious stress concentration.

When the mesh belt carries products, if the products are placed unevenly, it will cause local overload of the mesh belt, further increasing the load on the stress concentration area.

Under the repeated action of such cyclic loads, tiny defects in the mesh belt material will gradually develop into microcracks. As the number of operations increases, the cracks slowly expand along the axial direction of the mesh wire. When the cracks penetrate the entire cross-section of the mesh wire, a sudden fracture will occur.

1.2 Material "aging" under alternating hot and cold conditions

The high-temperature working environment of the sintering furnace and the sudden temperature change when the mesh belt enters and exits the furnace will cause thermal fatigue, which is another important factor leading to the fracture of the mesh belt.

When the mesh belt is in a high temperature state of 400-1200℃ in the furnace, the material will thermally expand; when the mesh belt carries the workpiece out of the furnace, it contacts with normal temperature air and cools and shrinks rapidly.

This frequent "expansion-contraction" cycle and the repeated action of thermal stress will cause tiny gaps to appear at the grain boundaries of the mesh belt material, and at the same time accelerate the creep of the material, eventually leading to fracture failure.

2: Mesh belt deviation

2.1 Installation and commissioning

Many mesh belt deviation problems have "congenital hidden dangers" during the installation and commissioning stage, and their core root cause lies in insufficient system accuracy.

As the supporting and driving components for the operation of the mesh belt, the installation accuracy of the rollers directly determines the running track of the mesh belt.

First is the levelness of the rollers. If there is a deviation in the height of the two ends of the rollers during installation, the mesh belt will shift to the lower side under the action of gravity.

Second is the parallelism of the axes. If the axes of the driving roller and the driven roller are not parallel, it will cause uneven force on both sides of the mesh belt, generating a lateral force towards the side where the axis is inclined, causing the mesh belt to gradually deviate. Normal installation requires the axis parallelism to meet the standard.

In addition, the uniformity of the tensioning device is also crucial. If the tensioning force of the tensioning mechanism on both sides of the mesh belt is inconsistent, it will cause one side of the mesh belt to be tight and the other to be loose, and it will inevitably deviate to the loose side during operation.

2.2 Commissioning during operation

Even if the installation and commissioning are qualified, the commissioning of the mesh belt during long-term operation is crucial.

Local material accumulation is one of the most common causes. If debris such as oxide scale and powder generated during the sintering process of the workpiece accumulates on the surface of the rollers or in the gaps of the mesh belt, it will cause the surface of the rollers to be uneven, and the contact between the mesh belt and the rollers will become "point contact" instead of "surface contact", resulting in uneven force during operation and causing deviation.

Deformation of the mesh belt itself can also cause deviation. The long-term high-temperature environment will cause permanent tensile deformation of the mesh belt. If the deformation is uneven and the length of some areas changes, the stability of operation will be destroyed.

Roller wear is another important factor. After the pattern on the surface of the driving roller is gradually worn due to long-term friction, the driving force distribution on the mesh belt is uneven, further aggravating the deviation.

To solve these problems, in addition to regularly cleaning accumulated materials and checking the wear of the rollers, the use of anti-deviation rib design is an effective solution. Adding ribs on both sides of the mesh belt can limit its lateral displacement. Cooperating with infrared correlation sensors for real-time monitoring, when the deviation exceeds 5mm, an acousto-optic alarm is triggered, which can timely avoid the expansion of faults.

3: Is the mesh belt service life only 2 months?

3.1 Wrong material

The materials of sintering furnace mesh belts are mainly SUS310S/AISI314/Inconel 601 /2080.

In addition to the distinction between various materials, there are also differences between imported and domestic materials, whether the mesh wire uses the "two draws and two retreats" processing technology, and whether the mesh wire material uses recycled materials, all of which will have a great impact on the service life of the mesh belt.

3.2 Atmosphere corrosion

Compared with the intuitively visible high-temperature oxidation, process atmosphere corrosion is an invisible "invisible killer", and its damage to the mesh belt material is more hidden and fatal.

Carburizing, nitriding atmospheres commonly used in sintering processes, as well as sulfides contained in the workpieces themselves, will cause corrosion to the mesh belt material.

Carbon atoms in the carburizing atmosphere will penetrate into the grain boundaries of the mesh belt material, forming carbides and making the grain boundaries brittle; nitrogen atoms in the nitriding atmosphere will form nitrides, resulting in increased hardness and decreased toughness of the material. What is more dangerous is intergranular corrosion. In carburizing, nitriding or sulfide atmospheres, the grain boundaries of the mesh belt material will be preferentially corroded, forming tiny cracks. Such cracks are difficult to detect in appearance, but they will cause a sharp decline in the mechanical properties of the mesh belt, which will break even with slight force.

To solve such problems, inert gases such as nitrogen can be introduced into the furnace as a protective atmosphere to isolate the contact between corrosive media and the mesh belt.

4: Guide on how to prevent

4.1 Matching process

The reliability of the mesh belt starts with scientific selection. Only by matching the mesh belt material, structure with the process conditions can the risk of failure be reduced from the source.

The core of selection is to determine the appropriate mesh belt type according to key parameters such as sintering temperature, process atmosphere, workpiece weight and size.

For detailed methods on selection, please refer to how to scientifically select mesh belt materials and specifications.

4.2 Installation

Correct installation is the basis for the long-term operation of the mesh belt, and it must be carried out in strict accordance with the installation specifications to eliminate "congenital hidden dangers".

Before installation, the installation foundation should be leveled first to ensure that the flatness error of the foundation is ≤2mm/m; when installing the rollers, use a level to calibrate the levelness to ensure that the error is ≤1mm/m, and at the same time use a laser collimator to calibrate the axis parallelism of the driving roller and the driven roller, and control the error within 0.5mm/m. When installing the tensioning device, it is necessary to adjust the tension on both sides to be uniform, which can be verified by measuring the tension on both sides of the mesh belt to ensure that the sag in the middle of the mesh belt is ≤10mm/m when empty.

After the installation is completed, a no-load test run must be carried out, and the test run time should not be less than 2 hours. Observe whether the running track of the mesh belt is stable, and whether the distance deviation between the edge and the track is ≤2mm. If deviation occurs, adjust it in time.

After the test run is qualified, carry out a load test run, gradually increase the load to 110% of the rated value, check the running stability and stress of the mesh belt, and put it into formal use only after ensuring no abnormalities.

4.3 Daily monitoring and maintenance

Establishing a sound daily monitoring and preventive maintenance system is the key to extending the service life of the mesh belt and reducing the risk of failure. Daily monitoring should adopt a combination of "manual inspection + intelligent early warning": operators in each shift need to check whether the mesh belt is broken, has broken wires, or has deviation signs, and whether there is material accumulation on the roller surface, and deal with abnormalities in a timely manner; install infrared correlation sensors on both sides of the mesh belt, and when the deviation exceeds 5mm, an acousto-optic alarm is triggered to realize real-time early warning.

Preventive maintenance requires formulating a detailed list and strictly implementing it, which specifically includes the following contents:

(1) Daily maintenance: After each shift, use high-pressure air to purge the gaps of the mesh belt and the surface of the rollers to remove accumulated materials and oxide scale;

(2) Weekly maintenance: Check the tension of the mesh belt, adjust it in time if the sag exceeds the standard, and lubricate the chain pins with high-temperature resistant grease (such as molybdenum disulfide);

(3) Monthly maintenance: Conduct a comprehensive inspection of the mesh belt for cracks, broken wires, and falling solder joints, focusing on the driving end and turning points. When the broken wire rate exceeds 5% or the local deformation is >3mm, replace the local part in time;

(4) Quarterly maintenance: Calibrate the levelness and axis parallelism of the rollers, check the purity of the furnace atmosphere, and ensure that the content of corrosive media meets the requirements. The schematic diagram of the preventive maintenance checklist can clearly present each maintenance item, cycle and standard, which is convenient for implementation and recording.

Problems such as fracture, deviation, and short service life of the sintering furnace mesh belt are not isolated faults, but the result of the combined action of multiple factors such as material, structure, installation, and maintenance.

High-quality mesh belts and systematic solutions are the key to ensuring continuous production.

By building the first line of defense through scientific selection, laying the foundation with precise installation, and reducing risks through preventive maintenance, the management of the mesh belt is transformed from passive replacement to active management. It seems to be an investment in the reliability of the mesh belt, but in fact it is a core investment in productivity.

Only by attaching importance to the whole life cycle management of the mesh belt can we effectively improve production continuity, reduce maintenance costs, and gain an advantage in the fierce market competition.