Quenching is very an important process to get high hardness and toughness of steel parts and tools. However, ununiformity of temperature during rapid cooling often results in undesirable distortion and residual stress, in addition cracking. Oil quenchants are used for quenching of steel parts and tools to avoid these problems. Cooling characteristics of oil quenching are controlled by selecting of base oil and additives. This article will introduce the cooling power and technology of quenching oils.

This paper describes some functions of working fluid in electrical discharge machining (EDM). EDM oil is usually used in die-sinking EDM, whereas deionized water is usually used in wire EDM. First, the effect of working fluid on material removal is explained. Heat flux and pressurizing at the discharge spot, prevention of reattaching of removed molten metal on machining surface and prevention of tool electrode wear are affected by the working fluid. Then, the effect of working fluid on stability of machining process is explained. Extension of gap width, cooling of tool electrode and workpiece and exclusion of debris from gap space are important functions of the working fluid.

There are different type of lubricating oils and some lubricating oils don’t aim to lubricate such as a rust preventive oil. In this paper, types and applications of the rust preventive oil defined by JIS K 2246 are explained. In addition, mechanisms of rust generation and rust preventive oil film adsorption are explained. Typical compositions of a rust preventive oil, evaluation methods,selection methods, recent trends of a rust preventing oil are also mentioned.

Cleaning is important in manufacturing process of automotive parts. Since the cleaning process is linked to the global environment, the design of cleaning process has to be decided after deep consideration of the environmental protection in addition to the overall quality and cost. This paper describes Eco-friendly Cleaning System which achieves “Resource and Energy saving”, “Recycling and Circulation”.

Insulating oil for electricity is mainly enclosed in a transformer for electricity for the insulation and cooling. Generally, I analyze enclosed insulating oil into the maintenance management of the oil-filled transformer, and it is performed to watch a state. In this report, I introduce about the summary of an abnormal diagnosis to be made as one of the transformer maintenance management and the characteristic examination of the insulating oil.

Process oil is used as “the oil which is mixed when producing rubber”. Some ingredients of rubber products are floury, and it is difficult to knead polymer rubber uniformly. Process oil which is one kind of softener is used to settle this problem. When the kind or the amount of process oil is not appropriate, stable rubber property is not obtained. Process oil is mainly derived from crude oil, and is classified by the type ratio of the composition of carbon into the paraffinic, the naphthenic and the aromatic. The most important requirement for process oil is compatibility with rubber. Solubility parameter of process oil and rubber is useful as an index of compatibility. Aniline point is also useful, and process oil with lower one tends to excel in compatibility. As aromatic and naphthenic process oil have low aniline point, they are used for the wide field. On the other hand, paraffinic process oil is almost colorless and clear, and there is a merit which does not affect the color of the rubber products. Aromatic process oil is used for the tire which is the biggest demand of the rubber industry. The EU Directive has placed restriction on aromatic process oil to reduce PAH(Polycyclic-Aromatic Hydrocarbons), and this rule is practically applied to mainly advanced countries. Process oil called T-DAE(Treated-Distillate Aromatic Extracts) which meets this restriction is one of the mainstream. In recent years, high performance aromatic oil for tires that both wet-grip and rolling resistance are good have developed.

Particle entrapment into the sliding portion is one of the serious problems affecting the life of sliding parts of the machine elements such as a sliding bearing and others. This paper focuses on the “progress” of the particle entrapment based on the results of the previous report, and a theoretical model to analyze it is developed. The model consists of two stages; the first is a stage where the particle is entrapped in the vicinity of the sliding portion by the fluid force surrounding the particle, and the second is a succeeding stage where the particle is forced into the sliding portion by the frictional forces between the particle and the mating surfaces. By applying this model, the conditions for the particle to be entrapped are clarified theoretically. The velocity ratio of the plate to that of the shaft, and the coefficients of friction between the particle and the mating surfaces are shown to be the predominant parameters for the entrapment of the particles. The theoretical results are qualitatively verified experimentally by using a test equipment simulating a rotor and a stator of a progressive cavity pump.

The viscosity of motor oil gets lower in order to decrease resistance at region of the fluid lubrication. On the other hands, this causes increasing of friction at the boundary lubrication region. For this reason, it is required to use a friction modifier to reduce the boundary friction. MoDTC is especially used as friction modifier. Although the decomposition mechanism of MoDTC has been presumed, it is considered only in the case of metal, not hard coatings. So, it is required to understand the effects of hard coatings to friction in motor oils. We tried to clarify the surface and tribo-film changes depending on the kinds of hard coatings by SEM-EDX, TEM and so on. As a result of experiment of hard coatings against metal, we clarified the process as follows when friction of CrN reduces. In the early stage of friction, Fe of the opposite metal transfers to CrN. Mo₂S₂O₂ intermediate product which is formed by MoDTC decomposition is formed on CrN divided into Fe oxide and Mo sulfide. At this time, crystal orientation between Fe oxide and CrN is matching because the lattice constant of Fe oxide is twice that of CrN. These results show that the crystal structure of hard coatings is important for formation of stable interface. And this newly knowledge is necessary to achieve low friction for systems using hard coatings.