Development of temperature controlled bingham semi-solid/fluid isostatic pressing (BIP) method

Bingham semi solid/fluid isostatic pressing (BIP) was developed recently by the author. Advantages of this method are as follows: cracks in powder compacts that are likely to occur because of the mold's springback at the time of unloading can be avoided; the density is almost uniform in the products. On the other hand, it is not easy to form the mold of a complicated structure from wax or the semi solid material, which is of a small yield stress. Accordingly, wax with a higher yield stress is needed. However, this easily induces cracks in the mold itself as well as in the compacts. In this research, therefore a new process, named "the Temperature Controlled BIP" is developed, and the characteristics of this new process are discussed. In this process, we first form a mold by wax of a higher yield stress, and we then raise the temperature of the mold to decrease its yield stress before pressing. We liquefy the mold completely by raising the temperature before unloading and take out the compact.