Advanced Manufacturing Processes

Chu, C.N.; Oktay, T.; Saka, N.; Suh, N.P.

1987 Advanced Manufacturing Processes

doi: 10.1080/10426918708953189

Experimental work on impingement casting process of Pb-Zn, Pb-Zn-Sn and Al-Pb systems was carried out. Rapid mixing of immiscible liquid metals was achieved in an arrow-shaped mixing chamber due to vigorous turbulence. The particle size distribution in the castings fitted lognormal curve well. Pb-Zn-Sn system showed the smallest geometric average particle diameter and geometric standard deviation due to low interfacial tension. Various mechanisms of agglomeration were examined and related to the particle sizes. Gravitational sedimentation was shown to be a major parameter governing the agglomeration and hence the final microstructure. The geometric connectivity effect of volume fraction was studied by graphical simulation. When the volume fraction of the dispersed phase was above 30 percent, major portion of the particles were interconnected.

CHU, C.N.; SAKA, N.; SUH, N.P.

1987 Advanced Manufacturing Processes

doi: 10.1080/10426918708953190

Theoretical analysis for turbulent mixing in an isotropic turbulent field was carried out. Depending on the material properties and flow field, either viscous shear force or dynamic pressure force breaks-up the globules. From an order of magnitude analysis, generalized equations for predicting globule sizes were derived. Experimental work on turbulent impingement mixing of kerosene and water revealed that macromixing and micromixing vary dramatically depending on the mixing chamber geometry. Best mixing (fast macromixing and small globule sizes) was obtained in an arrow shaped mixing chamber where the incoming jets were opposite to each other and slanted upward toward the mixing head. The coefficients of the equation for predicting the maximum globule size of immiscible liquids were obtained from the experimental results of arrow-shaped impingement mixers.

Singh, Durgesh K.

1987 Advanced Manufacturing Processes

doi: 10.1080/10426918708953191

Statistical Process Control is becoming more important than ever in the industries for better quality and high productivity. The author wants to emphasize the importance of SPC as an important tool, giving new dimensions to the industries. Various steps involved in implementing the program are also discussed with a detailed process analysis flow chart. SPC success depends on the support at all levels. The implementation of the program is not an overnight process and once the problem is solved, continous monitoring of the process is necessary. Different steps of continual quality improvement are also discussed in the article.

Toenshoff, H.K.; Bartsch, S.

1987 Advanced Manufacturing Processes

doi: 10.1080/10426918708953192

Ceramic cutting materials like aluminum oxide and silicon nitride are used for machining of metallic materials. Especially during steel cutting with A12 O3 -tools cracks and notch wear occur at the tools. For this reason extended investigations were carried out to understand the mechanisms of cracking and notch wear formation. In doing so cutting tests, stability calculations and chemical experiments were executed. During cutting tests the influence of cutting parameters and cutting geometry on notch wear was investigated. Stability calculations with the Finite Element Method elucidated critical load conditions and weak points of the tool material. Chemical experiments and x-ray-analysis show that chemical reactions are going on during the cutting process and can influence decisively wear progress.