Recently, the interest in the development of Oilless bearings, which is a kind of sliding bearing, has been attracting to industry. Oilless bearings are mainly used in areas where fluid lubrication is difficult to apply because of large contact area. The purpose of this study is to develop products with higher load and durability compared to the conventional oilless bearing. For this purpose, the optimal steel sheet was obtained and the porosity evaluation was carried out by evaluating bronze sinterability for various steel sheets. The conclusion obtained is as follows.; It was found that steel plate suitable for bronze powder plate is SPCC CR (Cold Rolled). The average porosity of KAG-23, KAG-23G and PBF-8 specimens was 16.8%, 17.8% and 22.1%, respectively, indicating that the porosity of PBF-8 specimen was the highest. As the number of rolling increases, the surface porosity decreases rapidly.

The object of this paper is to examine the optimum sintering condition which have excellent mechanical properties compared to the conventional oilless bearing. It is shown that the sintering rate is the most excellent at 850°C, especially KAB-23, KAB-23G, PBF-8 specimens. With increasing the nitrogen injection rate, the apparent porosity increased gradually. In contrast, with increasing the hydrogen injection rate, the apparent porosity decreased gradually. It is shown that the apparent porosity is very useful in the range of nitrogen injection rate 2Nm 3 and hydrogen injection rate 10Nm 3 .

Sintered oilless bearing using fluid-dynamic mechanism for high revolution of over 10,000 rpm was developed by Powder metallurgy Process. Developed bearing was composed of Fe-40-60%Cu of which inner face consisted of six-regular-prominence-and-depression. Inner face has controlled pore size and amount according to application. Jitter and friction properties were tested under assembled conditions with housing and motor. Bearing-own properties and precision were also tested because of demanding for assembled properties. Measurement-skill as well as mould-production-skill were investigated for the precision of bearing. Final precision reached 2 in inner diameter tolerance and 5 in coaxiality under assembled conditions.