Traditional ferrography only emphasizes on the characteristics of individual big debris. For diagnosing and monitoring the condition of machines, the traditional ferrography encounters trouble. Ferrography based on debris group theory thinks that there is a one-to-one correspondence between group characteristic of debris group and the operating condition. For this reason, the real wear condition will deduced by studying the group characteristic of debris group in the ferrogram. By drawing out the criteria of the studied machine, the failure of the machine components will be predicted. Theoretical analysis and experimental research show that the operating condition predicted by debris group theory are consistent with the practical condition.

通过对某矿井提升机滑动轴承工况的实际监测，考察了磁流体对铁谱仪中非铁磁性颗粒沉积的影响结果表明：磁流体可以使非铁磁性颗粒有效地沉积在铁谱仪的谱片上，使谱片携带更加全面的信息；磁流体对非铁磁性颗粒的"磁化"作用具有选择性磁流体可以用于监测非铁磁性颗粒。

In this paper, a fuzzy synthetic decision-making system which is based on the method of debris group analysis for wear condition monitoring and fault diagnosis in qualitative ferrographic analysis and the background to establish it have been introduced. Especially, the procedure to find out the membership functions of this fuzzy synthetic decision-making system and the method to arrange the importance sequence of severe wear particles have been explained in detail. The reliability of this fuzzy system has been tested by actual practices of wear condition monitoring and fault diagnosis, and the possibility to realize automation in ferrgraphic analysis has also been revealed.

提出了矿压监测及诊断处理应同时在井下进行的方法及其仪器系统构成。这对缩短发现问题到解决问题的时间周期，对提高支架液压系统故障的快速反映和解决问题的能力具有重要意义。

In this paper the difference in drawing group characteristics on different ferrographic instruments by using debris group analysis theory has been fully analysed. The feasibility of failure prediction about machine components based on group analysis theory has been proved by means of rolling bearing fatigue experiment.

In this paper the essential defects of traditional Ferrography and its analyzing methods have been discussed. A New instrument Rotary Ferrograph model KTP and its analying method about drawing characteristic of debris group have been introduced. The failure criterion for hydrostatic transmission systems and gearbox of shearer model AM-500 and EDW-170 have been given.

本文提出了利用KTP型旋转式铁谱仪提取机械设备工况特征参量的方法。给出了AM-500型采煤机的液压传动系统和齿轮传动系统的失效判据。突破了传统定性铁谱中单颗粒磨屑的讨论，把机械的工况与磨屑的各种类型和尺寸的总体情况联系起来。

This paper emphatically discusses the necessity of health monitoring for coal-cutters introducess the oil wear debris analysis and instruments used which are suitaable to health diagnose for coal-cutter of high production coalfaca, and presants the practice of condition monitoring and health diagnose for AM-500 coal-cutter at Yungang Mine, Datong by this technique.