analyzed using an EPMA. The results showed that the high hardness of the casting surface eould be decreased using the experimental investment. The hardness of the castings made from the experimental investment at a 25-50"m depth was lower than these frem the other investments, and the thickness of the hardened casting surface was 125/im. Layered structures with fewer layers were formed on the s...

Several technical papers are available on casting defects in the literature. However, quality costs in steel foundries are still mainly due to the rework and scrap related to casting anomalies, which are not acceptable to customers. In order to minimize the castings which do not meet the customer acceptance specifications, it is not only necessary to identify the process parameters related to t...

AIM Relating the marginal fit of the castings, to the accuracy of the impression produced using laminated hydrocolloid impression technique, alginate and double-mixed polyvinyl siloxane. Basic objective of the study is to check the feasibility of the use of laminated hydrocolloid impression technique in the fixed partial denture. MATERIALS AND METHODS The precisely machined metal die was desi...

X-ray-based inspection technique is well applied to identification and evaluation of internal defects in castings, such as cracks, porosities, and foreign inclusions. Combining X-ray inspection with digital image processing and automatic image assessment is now the preferred approach for the continuous inspection of castings. However, in practical application, the quality of the X-ray image is ...

OBJECTIVE The aims of the study are to assess the marginal accuracy of base metal and titanium alloy casting and to evaluate the effect of repeated ceramic firing on the marginal accuracy of base metal and titanium alloy castings. MATERIALS AND METHODS Twenty metal copings were fabricated with each casting material. Specimens were divided into 4 groups of 10 each representing base metal alloy...

It has been reported in the literature that impingement of the casting at the axial-occlusal line angle of the tooth preparation may be a major cause of incomplete seating following cementation. It has been suggested that an additional coat of spacer applied to these areas on the laboratory die before the fabrication of the casting may alleviate this discrepancy. This study evaluated the effect...

Among many factors which affect the dimensional accuracy of dental castings, several mechanical factors have been selected and studied theoretically and experimentally by the authors1-4). The analytical method employed in those studies showed clearly the effects of mechanical conditions on the deformation of wax patterns and castings in molds during the casting process. The results of the analy...

The purpose of this study was to evaluate mechanical properties, surface characteristics and castability of Zr-14Nb dental castings. The mean 0.2% proof and ultimate tensile strengths of Zr-14Nb were approximately 68% and 76% those of Ti-6Al-7Nb, respectively, while they were comparable to Co-29Cr-6Mo. Elongation of Zr-14Nb was the highest of all alloys tested. The hardened reaction layer was f...

A model is developed that predicts the motion and growth of oxide inclusions during pouring, as well as their final locations on the surface of steel sand castings. Inclusions originate on the melt free surface, and their subsequent growth is controlled by oxygen transfer from the atmosphere. Inclusion motion is modeled in a Lagrangian sense, taking into account drag and buoyancy forces. The in...