# Effects of Refiner Plates with Different Fillings on TMP Properties
## 1 Introduction  
Refiner patterns are important in thermomechanical pulping (TMP) because they play a crucial role in the fiber development process, which affects the quality and properties of the resulting pulp. TMP is a process in which wood chips are heated under pressure and then mechanically pulped to separate the fibers. During the refining stage, the fibers are subjected to mechanical shearing forces that break down their structure and improve their bonding ability. Thus, the refining process is considered to be the heart of the papermaking process [1]. Refiner patterns refer to the design and configuration of the refining plates in the refiner, which determine the intensity and direction of the shearing forces applied to the fibers [2]. The refiner pattern affects the properties of the pulp in several ways. For instance, a refiner plate with a more aggressive pattern design characterized by wider grooves and bars can cut fibers to a greater extent. On the other hand, a less aggressive refiner bar pattern has narrower grooves and bars and is designed to prevent fibers from being damaged [3]. In addition to affecting the quality of the pulp, the refiner pattern also has an impact on the energy consumption and operating costs of the refining process. A more aggressive bar pattern may require more power to operate and result in faster wear on the refining plates, while a less aggressive bar pattern may require less power and have a longer lifespan. Therefore, the choice of refiner pattern is an essential consideration for pulp mills to optimize the quality and efficiency of their TMP process [4]. One important factor in the design of refiner plate fillings is the size and shape of the grooves and bars that make up the refiner pattern. Different filling designs can produce varying degrees of fiber fibrillation and pulp quality and affect energy consumption and plate wear. For example, some refiner plates may have a \"stutded\" or \"knurled\" pattern that creates small, raised bumps on the plate surface. This design can produce a high degreeof fiber fibrillation and increase the bonding between the fibers, resulting in a stronger pulp with improved paper properties. Other refiner plates may have a more \"corrugated\" or \"serrated\" pattern with larger grooves and ridges that create a more aggressive shearing action on the fibers. This design can produce a higher degree of fiber damage and fines, which may be desirable for certain paper grades but can increase energy consumption and plate wear [5]. The exact design and composition of refiner plate fillings will depend on the specific application and performance requirements of the pulp mill. Pulp mills may work with refiner plate suppliers to develop custom plate designs and fillings that optimize pulp quality, energy consumption, and plate wear [6]. The manufacturing process for refiner plates is complex and requires specialized equipment and expertise. Many pulp mills rely on dedicated suppliers to produce their refiner plates. These suppliers can provide custom designs and ensure consistent quality and performance. Refiner plate patterns for TMP are typically composed of three main zones: the high-intensity zone, the transition zone, and the low-intensity zone. The high-intensity zone is located at the center of the plate and is characterized by larger and more aggressive grooves and bars. This zone is responsible for the majority of fiber development and fibrillation, which increase the bonding between the fibers and improve the strength and stiffness of the resulting paper. The high-intensity zone is also associated with higher energy consumption and plate wear. The transition zone surrounds the high-intensity zone and has a less aggressive pattern with smaller grooves and ridges. This zone helps to gradually transition the fibers from the high-intensity zone to the low-intensity zone, reducing the likelihood of fiber damage or over-refining.