Showing 4 results for Rafiei
M. Aghdasi, F. Mokhatab Rafiei and G. Moslehi,
Volume 17, Issue 1 (7-1998)
Abstract
This paper presents a summary of the results from the simulation of a given two-stages production system which uses JIT. The system consists of an assembly line with two automated assembly cells and two assembly stock points and one manufacturing cell with three manufacturing stock points for storing reserved parts and one receiving stock. Carts with fixed capacity are used for handling the parts. A kanban is attached to each cart. The minimum number of kandbans required to operate the system without shortage in stock are estimated. The effects of changing the demand's mean and its variation on the number of carts are also investigated. Finally, a different simulation model is developed for the same production system using conventional job shop decipline and some main characteristics have been compared to the results, from the first model.
F. Mokhatab-Rafiei and M. Moattar Hosaini,
Volume 17, Issue 2 (4-1998)
Abstract
This paper considers the Economic Lot Scheduling Problem, that is, the problem of scheduling several products on a single facility so as to minimize holding and setup costs. Combination of frequency and timing as well as production quantity make this problem Np-hard. A heuristic is developed to obtain a good solution to ELSP. The proposed heuristic makes use of the Simulated Annealing Technique. This heuristic gives a sharper upper bound upper bound to holding and setup costs.
M. Poorkabirian, H. Mostaan, M. Rafiei,
Volume 36, Issue 2 (Journal of Advanced Materials-Summer 2017)
Abstract
In this research, dissimilar welding between 4130 low alloy steel and austenitic stainless steel 316L has been investigated using Gas Tungsten Arc Welding (GTAW). Two types of filler metals, including ERNiCr-3 and ER309L, were used for this purpose. Moreover, the joint microstructures including the weld metals, heat affected zones and interfaces were characterized by optical and Scanning Electron Microscopy (SEM). The mechanical behavior of the joint was tested by impact and tension tests. Observations by SEM showed that in impact test, the fracture is soft. In the tensile test, the welded sample by ER309L filler metal was fractured from 316L base metal, but welded specimen with ERNiCr-3 was fractured from welded zone. Also, the results showed a dendritic structure in the nickel-based weld metal. No crack was found in the cellular-dendritic microstructure of ER309L weld metal due to the existance of delta ferrite between them.
M. Jafari, M. Rafiei, H. Mostaan,
Volume 39, Issue 2 (Journal of Advanced Materials-Summer 2020)
Abstract
In this research, the effect of temperature and time on the properties of AISI420/SAF2507 dissimilar joint produced by transient liquid phase bonding process was investigated. A BNi-2 interlayer with 25 μm thickness was inserted between two dissimilar steel samples. The bonding process was performed at 1050 oC and 1100 oC for different bonding times. The microstructures of the joints were studied using optical microscope, scanning electron microscope and energy dispersive X-ray spectroscopy. Microhardness and tensile shear strength of bonded samples were investigated. Isothermal solidification was completed for the joints bonded at 1050 oC and 1100 oC for 45 min and 30 min, respectively. ASZ and ISZ areas of the bonding zone at the bonding temperature of 1050 oC indicated the highest (520 HV) and the lowest (300 HV) microhardness values, respectively. Sample bonded at 1050 oC for 1 min indicated the lowest tensile strength (196 MPa) and sample bonded at 1100 oC for 60 min indicated the highest tensile strength (517 MPa).
