What is the replacement standard of wearing parts of papermaking equipment?

There is no absolutely fixed timetable for the replacement of vulnerable parts of papermaking equipment, but a set of scientific and comprehensive evaluation standards is needed. Generally, enterprises will decide when to replace or repair the products by following core standards, taking into account the manufacturer's suggestions, actual working conditions and product quality requirements:

1. Physical wear and size limit standard

This is the most intuitive replacement basis. When the wearing degree of the wearing parts reaches the critical point, and the continuous operation will cause more serious secondary damage, they must be replaced immediately.

Thickness and size reduction: For example, the sieve plate of pulper needs to be replaced when its thickness is reduced to 60% of the original value.

Surface morphology changes: the blade appears notch and crack, or the surface of sizing metering rod appears groove and deformation.

Decline of performance parameters: such as overheating of bearings, increased noise, or slippage of transmission belt due to tension relaxation.

2. Running time and workload standards

Based on the suggestions of the equipment manufacturer and the actual production load, make a planned replacement prevention plan to avoid unexpected failures.

Time/cycle: It is evaluated according to the running time or the number of cutting cycles. For example, the replacement cycle of high-load bearings is usually 3-5 months, and the sealing assembly is 2-4 months; The service life of hardwood pulp treated by refiner blades is about 1200-1500 hours.

Load intensity: The working environment with high load and continuous operation will accelerate wear. In a heavy load environment, the replacement cycle of some blades or consumables may be shortened from several months to several weeks.

3. Product quality and process accuracy standards

For the papermaking process that pursues extremely high cutting accuracy and surface quality, even if the parts are not completely scrapped, as long as the slight passivation or wear leads to product defects, they need to be replaced in advance.

Cutting and trimming quality: When the edge of the paper is not smooth enough, the size deviation or the trimming quality decreases due to the slight passivation of the blade, a new blade must be replaced for quality control.

Uniformity of sizing and coating: when the wear of metering rod affects the uniformity of paper sizing, it needs to be replaced in time to ensure the quality of finished products.

4. Raw material characteristics and operating environment standards

The physical characteristics of the processed materials and the environment in which the equipment is located will significantly affect the service life of consumables, and the replacement frequency should be dynamically adjusted accordingly.

Raw material impurities and abrasiveness: If the treated waste paper or slurry contains more mineral fillers, sand particles, glue residues or metal fragments, these impurities will produce micro-abrasive action, which will increase the wear rate of blades or sieve plates by several times, and it is necessary to greatly shorten the inspection and replacement cycle.

Environmental temperature and humidity: too high humidity will lead to rust and corrosion of hydraulic system and structural components, and too dry will easily cause electrostatic interference. The harsh environment will accelerate the hardening failure of sealing ring and the dimensional change of precision parts, so it is necessary to increase the maintenance frequency.

5. Evaluation standard of repair value (TCO principle)

Not all parts that meet the wear standards must be scrapped and replaced directly, and repair and renovation can often optimize the total cost of ownership (TCO).

Surface coating and welding repair: for the pump body, beating disc or rotor damaged by erosion and corrosion, it can be repaired by thermal spraying, arc spraying (such as applying Ni-Cr alloy coating) or special welding technology. This can improve the durability without changing the base metal, and the service life can be increased by more than 200% to 300%.

Economy and downtime cost: If the cost of repair is much lower than that of purchasing new parts, and the downtime can be greatly shortened (for example, the downtime can be shortened from 10 weeks to 2 weeks), repair is preferred.

Enterprises should establish a data-driven decision-making mechanism, record the time, reason and working conditions of each replacement/repair in detail, and gradually accumulate data. Through the strategy of "regular inspection status+preventive maintenance", instead of waiting for the complete failure of components to take action, efficient and stable production can be realized.