Failure Mode Trends of Refiner Plates Used in Mechanical Pulping Applications, 1993 Pulping Conference Proceedings

Refiner plates operate in the heart of the mechanical pulping process and have a direct effect on the resultant pulp properties. (1) Since they are constantly subjected to severe operating conditions, refiner plates eventually fail and need to be replaced. There are a number of different wear mechanisms, termed failure modes, that are used to identify the condition of the refiner plates after removal from the refiner. Deterioration of the refining bars is the most detrimental form of wear. Bar deterioration frequently occurs because of poorly cleaned chips or inadequate refiner controls. Bar breakage and bar edge rounding have been the most common forms bar deterioration. With the development of better methods for chip cleaning, more advanced refiner controls, better refiner plate designs, and harder, more wear resistant refiner plate materials, plate life has generally increased and in many cases, the reasons for plate removal have changed.

This paper traces the history of refiner plate wear conditions for mechanical pulp applications based on failure mode evaluations performed for the period 1985 to 1993. A breakdown of this period into 6 intervals allows the identification of trends in refiner plate application and performance. It appears that some of these results are correlated to simultaneous advancements made in the sophistication of mechanical pulping systems and in refiner plate designs and materials. Materials, in particular, have shown continual improvement over the periods involved in this investigation.

Predicting the performance of new, or modified, refiner plate alloys requires the ability to measure material properties. Tests have been developed over time to measure the mechanical properties of refiner plate alloys. Properties measured and tracked include wear resistance, corrosion resistance, cavitation resistance, impact strength, tensile strength, and hardness. The information compiled from these tests is very useful in explaining failure modes and assisting the alloy development process. Some of these results are presented to help explain the trends observed in the failure mode analysis.