Browsing by Subject "Tool management"

Now showing 1 - 6 of 6

Open Access
Due date and cost-based FMS loading, scheduling and tool management
(Taylor & Francis, 2007) Turkcan, A.; Akturk, M. S.; Storer, R. H.
In this study, we consider flexible manufacturing system loading, scheduling and tool management problems simultaneously. Our aim is to determine relevant tool management decisions, which are machining conditions selection and tool allocation, and to load and schedule parts on non-identical parallel CNC machines. The dual objectives are minimization of the manufacturing cost and total weighted tardiness. The manufacturing cost is comprised of machining and tooling costs (which are affected by machining conditions) and non-machining cost (which is affected by tool replacement decisions). We used both sequential and simultaneous approaches to solve our problem to show the superiority of the simultaneous approach. The proposed heuristics are used in a problem space genetic algorithm in order to generate a series of approximately efficient solutions.
Open Access
Dynamic lot sizing and tool management in automated manufacturing systems
(Elsevier, 2002) Aktürk, M. S.; Önen, S.
The overall aim of this study is to show that there is a critical interface between the lot sizing and tool management decisions, and these two problems cannot be viewed in isolation. We propose "ve alternative algorithms to solve lot sizing, tool allocation and machining conditions optimization problems simultaneously. The "rst algorithm is an exact algorithm which "nds the global optimum solution, and the others are heuristics equipped with a look-ahead mechanism to guarantee at least local optimality. The computational results indicate that the amount of improvement is statistically signi"cant for a set of randomly generated problems. The magnitude of cost savings is dependent on the system parameters.
Open Access
Essays on scheduling with controllable processing times in flexible manufacturing systems
(2003) Türkcan, Ayten
In this study, we consider FMS loading, scheduling and tool management problems simultaneously. Our aim is to determine the machining conditions, to load and schedule parts on the nonidentical parallel CNC machines and to determine tool allocation and replacement decisions. We consider due date and cost based objectives. The due date related objectives are minimization of weighted tardiness, and weighted earliness/tardiness. The cost related objective is the minimization of the manufacturing cost, which is the sum of machining, tooling and nonmachining costs. An important issue in flexible manufacturing systems is that the processing times can be controlled by changing the machining conditions. In this study, we consider controllable processing times because of the flexibility they provide for finding alternative solutions in predictive and reactive scheduling.
Open Access
Integrated lot sizing and tool management in automated manufacturing systems
(IIE, 1997) Aktürk, Mehmet Selim; Önen, Siraceddin
We propose a new algorithm to solve lot sizing, tool allocation and machining conditions optimization problems simultaneously to minimize total production cost in a CNC environment. Most of the existing lot sizing and tool management methods solve these problems independently using a two-level optimization approach. Thus, we not only improve the overall solution by exploiting the interactions, but also prevent any infeasibility that might occur for the tool management problem due to decisions made at the lot sizing level. We showed that in a set of randomly generated problems 22.5% of solutions found by the two-level approach were infeasible and we improved the solution on the average by 6.79% for the remaining cases with an average computation time of 63.4 seconds.
Open Access
Joint lot sizing and tool management in a CNC environment
(Elsevier, 1999) Aktuük, M. S.; Önen, S.
We propose a new algorithm to solve lot sizing, tool allocation and machining conditions optimization problems simultaneously to minimize total production cost in a CNC environment. Most of the existing lot sizing and tool management methods solve these problems independently using a two-level optimization approach. Thus, we not only improve the overall solution by exploiting the interactions among these decision making problems, but also prevent any infeasibility that might occur for the tool management problem due to decisions made at the lot sizing level. The computational experiments showed that in a set of randomly generated problems 22.5% of solutions found by the two-level approach were infeasible and the proposed joint approach improved the solution on the average by 6.79% for the remaining cases.
Open Access
Single CNC machine scheduling with controllable processing times to minimize total weighted tardiness
(Elsevier, 2011) Akturk, M. S.; Ilhan, T.
Advanced manufacturing technologies, such as CNC machines, require significant investments, but also offer new capabilities to the manufacturers. One of the important capabilities of a CNC machine is the controllable processing times. By using this capability, the due date requirements of customers can be satisfied much more effectively. Processing times of the jobs on a CNC machine can be easily controlled via machining conditions such that they can be increased or decreased at the expense of tooling cost. Since scheduling decisions are very sensitive to the processing times, we solve the process planning and scheduling problems simultaneously. In this study, we consider the problem of scheduling a set of jobs on a single CNC machine to minimize the sum of total weighted tardiness, tooling and machining costs. We formulated the joint problem, which is NP-hard since the total weighted tardiness problem (with fixed processing times) is strongly NP-hard alone, as a nonlinear mixed integer program. We proposed a DP-based heuristic to solve the problem for a given sequence and designed a local search algorithm that uses it as a base heuristic.