Production planning under dynamic product environment: a multi-objective goal programming approach

Production planning is a complicated task that requires cooperation among multiple functional units in any organization. In order to design an efficient production planning system, a good understanding of the environment in terms of customers, products and manufacturing processes is a must. Although such planning exists in the company, it is often incorrectly structured due to the presence of multiple conflicting objectives. The primary difficulty in modern decision analysis is the treatment of multiple conflicting objectives. A formal decision analysis that is capable of handling multiple conflicting goals through the use of priorities may be a new frontier of management science. The objective of this study is to develop a multi objective goal programming (MOGP) model to a real-life manufacturing situation to show the trade-off between different some times conflicting goals concerning customer, product and manufacturing of production planning environment. For illustration, two independent goal priority structures have been considered. The insights gained from the experimentation with the two goal priority structures will guide and assist the decision maker for achieving the organizational goals for optimum utilization of resources in improving companies competitiveness. The MOGP results of the study are of very useful to various functional areas of the selected case organization for routine planning and scheduling. Some of the specific decision making situations in this context are: (i). the expected quality costs and production costs under identified product scenarios, (ii).under and over utilization of crucial machine at different combinations of production volumes, and (iii). the achievement of sales revenue goal at different production volume combinations. The ease of use and interpretation make the proposed MOGP model a powerful communication tool between top and bottom level managers while converting the strategic level objectives into concrete tactical and operational level plans.

Some STL file generation issues in rapid prototyping

The stereolithography (STL) file format was introduced by 3D Systems and has become the de facto industry standard. However, this is not an ideal format due to the existence of some inherent problems. Due to the non- robustness of commercial CAD systems, the choice of tolerance is a major issue when saving STL files. These tolerances will affect the file size, the number of triangular facets and the number of STL file errors. The primary focus of this paper is to outline the relationship between tolerance and these issues in the conversion of CAD models to STL files. To meet the aim of this study, the file size and the number of triangular facets were recorded after STL file generation while the number of file errors was obtained after scanning. Some interesting relationships were noticed and are documented. It is noted that the number of errors decreases with increasing tolerance and that in general there are more errors in the ASCII file format than in the binary equivalent. This paper is intended to provide to the practitioner an idea of how the different factors mentioned are affected by tolerance and allow them to choose the best values based on the finding

Synergies in the Application of Industry 4.0 and Lean Manufacturing at a Product Label Manufacturer – A Discrete Event Simulation Case Study

Industry 4.0 is a manufacturing philosophy and industry standard for the design of Cyber-Physical Production Systems. The aim of Industry 4.0 is the creation of a smart manufacturing system. A smart system which applies novel applications of developed and current technologies to simplify complex work and enable waste averse production. It is based on the concepts of data-driven decision support services, Horizontal and Vertical Information Technology-Operations Technology value-chain integration, decentralized control and flexible production. Lean Manufacturing is a value-to-customer- focused manufacturing philosophy which applies procedures designed to ingrain waste reduction and efficient, competency- building practices into workplace culture. The aim of this paper is to examine the synergistic benefits of these manufacturing philosophies on a local firm using Discrete Event Simulation. The key performance indicators of Flow Time, Waiting Time and Work in Process were used to determine the efficacy of the models investigated. The study results indicated a 52 %, 57 % and 58 % improvement in the respective metrics of the best performing proposed model when com-pared to the existing system

Effect of tool path and feed rate on the machining of coons surfaces / Boppana V. Chowdary and Anton Gittens

In this study, complex shapes are defined as the sculptured surfaces created by the blending of curves, to form surface patches. Past investigations show that non-uniform rational B-Splines (NURBS) curves are the most appropriate for the modeling of sculptured surfaces. The main objective of this research is to examine the effects of toolpath and feed rate variations on the machining of the Coons surface, which is modeled through NURBS. Based on simulation results, it is clear that toolpath and feed rate selection plays a significant role in sculptured surface machining. In particular, the toolpath selection seemed to have a greater effect on the surface finish and machining time than the feed rate. The results also show that the feed rate option has a much greater effect on roughing than finishing operations. It can also be seen in this research that the toolpath option played a more significant role than feed rate selection in determining the file size

Slicing issues in CAD translation to STL in rapid prototyping

The rapid prototyping (RP) process is being used widely with great potential for rapid manufacturing of functional parts. The RP process involves translation of the CAD file to STL format followed by slicing of the model into multiple horizontal layers, each of which is reproduced physically in making the prototype. The thickness of the resulting slices has a profound effect on the surface finish and build time of the prototype. The purpose of this paper is to show the effects of slice thickness on the surface finish, layering error, and build time of a prototype, as well as to show how an efficient STL file can be developed. Three objects were modeled and STL files were generated. One STL file for each object was sliced using different slice thicknesses, and the build times were obtained. Screenshots were used to show the slicing effect on layering error and surface finish and to demonstrate the means to a more efficient STL file. From the results, it is clear that the surface finish and build time are important factors that are affected by slice thicknes

Production planning under dynamic product environment: a multi-objective goal programming approach

Production planning is a complicated task that requires cooperation among multiple functional units in any organization. In order to design an efficient production planning system, a good understanding of the environment in terms of customers, products and manufacturing processes is a must. Although such planning exists in the company, it is often incorrectly structured due to the presence of multiple conflicting objectives. The primary difficulty in modern decision analysis is the treatment of multiple conflicting objectives. A formal decision analysis that is capable of handling multiple conflicting goals through the use of priorities may be a new frontier of management science. The objective of this study is to develop a multi objective goal programming (MOGP) model to a real-life manufacturing situation to show the trade-off between different some times conflicting goals concerning customer, product and manufacturing of production planning environment. For illustration, two independent goal priority structures have been considered. The insights gained from the experimentation with the two goal priority structures will guide and assist the decision maker for achieving the organizational goals for optimum utilization of resources in improving companies competitiveness. The MOGP results of the study are of very useful to various functional areas of the selected case organization for routine planning and scheduling. Some of the specific decision making situations in this context are: (i). the expected quality costs and production costs under identified product scenarios, (ii).under and over utilization of crucial machine at different combinations of production volumes, and (iii). the achievement of sales revenue goal at different production volume combinations. The ease of use and interpretation make the proposed MOGP model a powerful communication tool between top and bottom level managers while converting the strategic level objectives into concrete tactical and operational level plans.