Interactive Multiobjective Optimization in Lot Sizing with Safety Stock and Safety Lead Time

2021 ◽  
pp. 208-221
Author(s):  
Adhe Kania ◽  
Juha Sipilä ◽  
Bekir Afsar ◽  
Kaisa Miettinen
Keyword(s):  
Multiobjective Optimization ◽  
Lead Time ◽  
Lot Sizing ◽  
Safety Stock

scholarly journals SUPPLY LEAD TIME UNCERTAINTY IN A SUSTAINABLE ORDER QUANTITY INVENTORY MODEL

2013 ◽  
Vol 4 (4) ◽  
pp. 15-27 ◽  
Author(s):  
Salvatore Digiesi ◽  
Giorgio Mossa ◽  
Giovanni Mummolo
Keyword(s):  
Inventory Management ◽  
Lead Time ◽  
Expected Value ◽  
Air Pollutant ◽  
Pollutant Emission ◽  
Optimal Order ◽  
Inventory Level ◽  
Order Quantity ◽  
Industrial Case Study ◽  
Safety Stock

Abstract Transport plays a key role in inventory management since it affects logistic costs as well as environmental performance of the supply chain. Expected value and variability of supply lead time depend on the transportation means adopted, and influence the optimal values of order quantity, reorder level, and safety stock to be adopted. Fast transportation means allow reducing expected value of the lead time; they are characterized by the highest costs of externalities (i.e. air pollutant emission, noise, congestion, accidents). On the contrary, slow transportation means require high inventory level due to large order quantity; in this case costs of externalities tend to decrease. The Sustainable Order Quantity (SOQ) [1] allows identifying optimal order quantity, reorder level, safety stock as well as transportation means which minimize the sum of the logistic and environmental costs in case of stochastic variability of product demand. In this paper, the authors propose a new SOQ analytical model considering stochastic variability of supply lead time (LT). A solution procedure is suggested for solving the proposed model. The approach is applied to a real industrial case study in order to evaluate the benefits of applying it if compared with the traditional one.

A novel approach to safety stock management in an integrated supply chain with controllable lead time and ordering cost reduction using present value

2020 ◽  
Vol 54 (5) ◽  
pp. 1327-1346 ◽  
Author(s):  
S. Tharani ◽  
R. Uthayakumar
Keyword(s):  
Supply Chain ◽  
Cost Reduction ◽  
Lead Time ◽  
Cumulative Distribution ◽  
Stock Management ◽  
Present Value ◽  
Safety Stock ◽  
Novel Approach ◽  
Cost Reductions ◽  
Ordering Cost Reduction

This paper presents a novel approach to safety stock management and investigates the impact of lead time reduction within an integrated vendor–buyer supply chain framework using present value where lead time and ordering cost reductions act dependently. In particular, the cost of the safety stock is determined by adopting a logistic approximation to the standard normal cumulative distribution. The service level is formulated in relation to the dimension of the single shipment, to the average demand of the buyer and to the number of admissible stockouts. We first discuss the case where the lead time and ordering cost reductions with linear function, and then consider the logarithmic functional relationship. Numerical examples including the sensitivity analysis with some managerial insights of system parameters is provided to validate the results of the supply chain models. The main contribution of this paper is introducing various types of ordering cost reduction in Braglia et al. (Appl. Stoc. Mod. Bus. Ind. 32 (2016) 99–112) by handling a new approach.

scholarly journals LEAD-TIME, INVENTORY, AND SAFETY STOCK CALCULATION IN JOB-SHOP MANUFACTURING

2018 ◽  
Vol 58 (6) ◽  
pp. 395-401 ◽  
Author(s):  
Miguel Afonso Sellitto
Keyword(s):  
Lead Time ◽  
Job Shop ◽  
Lead Times ◽  
Lot Size ◽  
Safety Stock ◽  
Safety Stocks ◽  
Body Of Knowledge ◽  
Manufacturing Management ◽  
Workload Control ◽  
Control Body

The purpose of this article is to present a method for calculating the lead-time, the inventory, and the safety stock or buffer in job shop manufacturing, which are essentially stochastic variables. The research method is quantitative modelling. The theoretical foundation of the method relies on the techniques belonging to the WLC (workload control) body of knowledge on the manufacturing management. The study includes an application of the method in a manufacturing plant of the furniture industry, whose operation strategy requires high dependability. The company operates in a supply chain and must have high a reliability in deliveries. Adequate safety stocks, lead times, and inventory levels provide the protection against the lack of reliability in the deliveries. The inventory should remain within a certain range, being as small as possible to maintain low lead times, but not too small that it could provoke a starvation, configuring an optimization problem. The study offers guidelines for a complete application in industries. Further research shall include the influence of the variability of the lot size in the stochastic variables.

scholarly journals Lead time considerations for the multi-level capacitated lot-sizing problem

2015 ◽  
Vol 241 (3) ◽  
pp. 727-738 ◽  
Author(s):  
Christian Almeder ◽  
Diego Klabjan ◽  
Renate Traxler ◽  
Bernardo Almada-Lobo
Keyword(s):  
Lead Time ◽  
Lot Sizing ◽  
Lot Sizing Problem ◽  
Capacitated Lot Sizing ◽  
Multi Level

scholarly journals Workload Control and Order Dispatching Rules

2021 ◽  
Author(s):  
Bruna Strapazzon do Couto ◽  
Miguel Afonso Sellitto
Keyword(s):  
Lead Time ◽  
Queuing Theory ◽  
Shop Floor ◽  
Due Date ◽  
Safety Stock ◽  
Strategic Issues ◽  
Planning And Control ◽  
Work In Process ◽  
Graphical Tool ◽  
Workload Control

The purpose of this study is to choose an order dispatching rule and measure the work-in-process and lead-time in the production process of a conveyor chain manufacturer. The main strategic issue for the manufacturer is dependability, which requires meeting deadlines and managing internal lead-times. The study integrates two techniques, workload control (WLC) and an analytical hierarchy process (AHP), respectively systems for production planning and control, and multi-criteria decision support, both widely used in handling manufacturing strategic issues. The research method is a field experiment. Supported by the AHP and according to strategic criteria, practitioners selected the early due date rule (the order with the closest due date comes first) to release 231 orders. Then, employing a methodology designed to support WLC applications, the study measured key parameters that provide information regarding the overall performance of the manufacturer, the input rate, work-in-process, lead-time, throughput performance, and the level of safety stock. Using the model and a graphical tool derived from queuing theory, the throughput diagram, the study provides evidence that, although the manufacturing process is satisfactorily balanced and achieves acceptable performance, the level of safety stock is small and should be increased to prevent starvation on the shop floor.

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