Browsing by Subject "Tool allocation"

Now showing 1 - 4 of 4

Open Access
An integrated process planning approach for CNC machine tools
(Springer-Verlag, 1996) Aktürk, M. S.; Avcı, S.
In view of the high investment and tooling cost of a CNC machining centre, the cutting and idle times should be optimised by considering the tool consumption and the non-machining time cost components. In this paper, we propose a detailed mathematical model for the operation of a CNC machine tool which includes the system characterisation, the cutting conditions and tool life relationship, and related constraints. This new module will be a part of an overall computer-aided process planning system to improve the system effectiveness and to provide consistent process plans. A hierarchical approach is presented for finding tool-operation assignments, machining conditions, appropriate tool magazine organisation and an operations sequence which results in the minimum production cost. © 1996 Springer-Verlag London Limited.
Open Access
Integrated scheduling and tool management in flexible manufacturing systems
(Taylor & Francis, 2001) Aktürk, M. S.; Özkan, S.
A multistage algorithm is proposed that will solve the scheduling problem in a flexible manufacturing system by considering the interrelated subproblems of processing time control, tool allocation and machining conditions optimization. The main objective of the proposed algorithm is to minimize total production cost consisting of tooling, operational and tardiness costs. The proposed integrated approach recognizes an important trade-off in automated manufacturing systems that has been largely unrecognized, and which is believed can be effectively exploited to improve production efficiency and lead to substantial cost reductions.
Open Access
Scheduling with tool changes to minimize total completion time: a study of heuristics and their performance
(John Wiley & Sons, Inc., 2003) Aktürk, M. S.; Ghosh, J. B.; Güneş, E. D.
The machine scheduling literature does not consider the issue of tool change. The parallel literature on tool management addresses this issue but assumes that the change is due only to part mix. In practice, however, a tool change is caused most frequently by tool wear. That is why we consider here the problem of scheduling a set of jobs on a single CNC machine where the cutting tool is subject to wear; our objective is to minimize the total completion time. We first describe the problem and discuss its peculiarities. After briefly reviewing available theoretical results, we then go on to provide a mixed 0–1 linear programming model for the exact solution of the problem; this is useful in solving problem instances with up to 20 jobs and has been used in our computational study. As our main contribution, we next propose a number of heuristic algorithms based on simple dispatch rules and generic search. We then discuss the results of a computational study where the performance of the various heuristics is tested; we note that the well-known SPT rule remains good when the tool change time is small but deteriorates as this time increases and further that the proposed algorithms promise significant improvement over the SPT rule.
Open Access
Tool allocation and machining conditions optimization for CNC machines
(Elsevier, 1996) Aktürk, M. S.; Avcı, S.
In the literature, there exist many variations of machining economics problem in terms of modelling approaches and solution methodologies. However most of the existing studies focus on the single machining operation which is seldom in practice. On the other hand, tool management approaches at the system level fail to relate the tooling issues to the machining conditions, and ignore the tool availability and tool wear restrictions. A new solution methodology is developed to determine the optimum machining conditions and tool allocation simultaneously to minimize the production cost of a multiple operation case where there can be alternative tools for each operation. As a result, we can both improve the solution by exploiting the interaction between these two decisions, and also prevent any infeasibility that might occur for the tool allocation problem due to tool contention among the operations for a limited number of tool types by considering the tool availability and tool life limitations.