Sharif Digital Repository

In the domain of manufacturing, computer numerically controllers (CNC) technology is a major contributor to the production capacity of the enterprises. The advances in CNC technology coupled with enhancements in computing systems have provided the basis to re-examine the way in which computer-aided systems (CAx) can be used to enable global manufacturing. Interoperability of the various components of the CAx chain is therefore a major prerequisite for manufacturing enterprises for becoming strategically agile and consequently globally competitive. Being interoperable, resources can be utilized interchangeably in a plug-and-produce manner. Over the last 8years the eminence of a STEP... 

In competitive environment of quick market changes, developing an interoperable manufacturing system is a necessity. Process planning as a connection link between design and manufacturing, has never been able to integrate these up/down stream activities and in spite of employing computer systems, CAPP’s information has been managed in an isolated manner. To realize interoperability, the exchange of part and product data must be independent of their platforms. There are two basic approaches for this purpose: i) Utilizing interface and ii) Utilizing neutral formats. STEP (Standard for the Exchange of Product data) plays a significant role as a neutral data model to integrate design,... 

CIM includes major components with different performances, although in last decades any researchers starting a way to high level of integration in these functions. Process planning and scheduling are two tasks of manufacturing that searches have not paid attention to them. In the other word there is a good environment for integration studies but researchers didn’t find best approach for integrating these two tasks.The proposed approach can quickly integrate these two functions and be implemented in a company without working process planning and scheduling departments separately. This methodology consists of four main modules that introduced in detail in this study. They are Integrated... 

Ferritic stainless steels, despite having a good combination of mechanical properties and corrosion properties and low price, are less used than austenitic stainless steels due to their low weldability. The main challenges of welding ferritic stainless steels are coarse grain formation in the molten area as well as grain growth in the heat affected zone. In this research, in the first phase, an attempt is made to change the shape and size of the grains in the melted zone by changing the GTAW fusion welding parameters, including welding current and welding speed. In the second phase, an attempt is made to prevent the formation of columnar grains by adding micron particles to the molten pool... 

Lean management is an approach to running an organization that supports the concept of continuous improvement, a long-term approach to work that systematically seeks to achieve small, incremental changes in processes in order to improve efficiency and quality. In this research, design and implementation of Lean Management concept in a production company was addressed. The method for implementing lean management is based on Jackson & Jones Method in implementing a lean management system. This method starts with the business renewal process. The output of this process is company’s vision and a development plan. After that, the first strategic improvement cycle starts for a period. There are... 

Product knowledge is the most precious asset of any manufacturing company, particularly for OKP companies. High level of customization is one characteristic of OKP which means more customer involvements in OKPPD activities, and customer requirements and expectations may be changing at any activity in PD, e.g., at designing stage. As SMEs, OKP companies always have limitation in resources such as machines tools, human resources, cutters, clamps, so managing the limitations is one of the major challenges that must be faced for maximizing the efficiently and productivity. The part of design that involves fuzzy problems and a lot of product knowledge, it is a critical part for the entire PD. In... 

Lean manufacturing, was published as a research work named “the machine that changed the world” by James Womack and his assistants in MIT in 1990. Lean thinking can be presented in five principles: specifying what creates value, identifying value stream, creating value flow, make only what is pulled by the customer, and strive for perfection. In contrast with what is generally believed that lean manufacturing can only be used in production systems, lean tools and methods can be used in administrative departments of a factory or in a service firm. In such processes, not only hardware, but also service added values should be considered using information and the software service tools. In this... 

The present research is aimed at providing solutions for the implementation of the concept of lean production in manufacturing companies. As with increasing production, customer orientation, removal of waste and more arrangements, it can be used in the various equipment manufacturing industries (custom). It can be implemented in accordance with the conditions of each company, in order to help the production sector of the country and in order to develop appropriate strategies to improve performance, especially in the field of production, in line with the principles of pure production. Understanding the principles of pure production helps companies while familiarizing themselves with these... 

This research aims to explore the effectiveness of past tariff evolutions in shaping firms' response to current input prices. Additionally, it investigates how asymmetric fuel pricing across different industries influences overall industry efficiency and prosperity. Furthermore, the study examines the impact of fuel subsidies on the equilibrium distribution of companies independent of welfare decline. In Chapter 1, utilizing microdata from Iranian industrial workshops between 1386-1396 (2007-2017) A key finding is that new firms exhibit a significant and stronger reaction to energy price variations compared to other firms when it comes to technology choices.Chapter 2 presents a structural... 

In the process of industrial and economic development and in the competitive environment in the world, reducing the cost of industrial products is an important factor for more customers' satisfaction, more revenue acquisition, and stability and success in the business. Cost engineering is the area of engineering practice concerned with the application of scientific principles and techniques to problems of cost estimating, cost control, business planning, management science, profitability analysis, project management, planning and scheduling. In this research through the studying the structures and models of cost engineering, in addition to consider this dimensions of cost engineering, the... 

Cloud Manufacturing (CMfg) which is one of the newest and important business models, can have a great effect in enterprises' success by sharing information and production resources among them. Due to the semi-made products which should be transferred between distributed production centers, Logistics and Transportation concept in CMfg are very important. Reverse Logistics (RL) that is the flow of used products from customer to manufacturer, by its role in recycling and proper disposal of components, has a great impact on industry effect on environment and helps enteprises to make better profit. Despite this importance, working on RL in CMfg has not been paid attention to in former researches.... 

Selective laser sintering is an additive manufacturing technique based on fusion of powder bed, wherein after spreading a powder layer, a focused laser beam directs onto selected points of powder bed to fuse powder particles together. This process is repeated layer by layer until the final part is created. Although utilization of blade as a conventional powder spreading (CPS) mechanism has a good compression ability, the fixed contact line between blade and powder bed surface results in improper powder flowability and increasing shear forces applied on underneath layer. In this study, in order to obtain the basis for conducting practical experiments, discrete element simulation of powder... 

Selective Laser Melting (SLM) process is a powder-based metal Additive Manufacturing (AM) technique. This developing industry has many advantages like generation of geometrically complex shapes with high density. High Cost, production and characterization of powders, limited material choices and process parameters optimization are some of the challenges associated with SLM. Stainless steel 316L due to its unique properties, like corrosion resistance, high strength, biocompatibility, availability and cost is indeed a commonly used material in SLM. In this research, the characterization of the powder produced by the flame spraying device, which is a new method, was discussed. Wire with 3mm... 

In this research, we present a new method for solving layout problems in the cellular manufacturing system. We also analyze the transportation systems using automated guided vehicles (AGVs) and its cost affecting the performance of cellular manufacturing system. For elimination of inter current and traffic problems, we use a new idea of dividing workstations to some non-overlapping closed zones to which independent automated guided vehicles (AGVs) are allocated for internal transfers in each zone. In this research, a combinational mathematical model has been developed for minimizing the cost of material flow intra and inter-loops and minimization of procurement of AGVs for each zone while... 

The electrohydrodynamic (EHD) 3D printing technology is an Additive Manufacturing (AM) method that can be used in the manufacture of submicron-size structures. Due to the multiphysics dynamics and the multiphase nature of the microdroplet formation in the EHD printers, modeling of this phenomenon is complicated. In this thesis, the formation of a droplet in an EHD printer—under a pulsed electrical field—is simulated using a new numerical model which couples the fluid flow, the electric field distribution and the movement of the electric charges under dynamic and transient conditions. The level-set method is applied to the entire multiphysics domain in order to study the formation of the... 

Selective laser sintering is a technique which uses a laser as the power source to sintering some selected points at a bed of powder in order to create a solid structure. In this research the SLS mechanisms of powder deposition is simulated and surface smoothness and layer density created by each mechanism is computed. For this purpose roller, blade and hopper mechanisms are simulated. For this simulation, polyamide 12 (PA2200) which is a common material is used. In this simulation at first powder specifications are extracted according to the references and for particle shape instead of using the spherical particle shape we use a certain shape that is more close to reality which created by... 

Millions of people due to factors such as osteoporosis, aging, sports incidents, and accidents face complications from bone fracture injuries every year. Nitinol shape memory alloy and Gyroid metamaterial have attracted researchers to use them as suitable replacements to fill empty areas of broken bones. In this research, numerical modeling and additive manufacturing were used to take advantage of the special properties of both nitinol and gyroid structures. In the modeling section, finite element modeling of the superelastic effect and the one-way shape memory effect of sheet and solid gyroids in cubic and cylindrical geometries with different porosities were done. As a result of the... 

Along with globalization of competition and economy, and development of Internet and Ethernet infrastructures, IoT, artificial intelligence, etc., to modify the impact of changes and volatility, active organizations and product chains have faced with an advanced service-oriented manufacturing model based on complicated networks of operation and logistics service providers. On the other hand, appearing of individualized and customized orders have leaded to more complicated manufacturing procedure and manufacturing industries have been more restricted to satisfy varied demands. In the context of physical products and cyberspace convergence, the novel generation of advanced manufacturing... 

Additive manufacturing enables fabricating lattice structures with tailored mechanical responses based on lattice materials. Full exploitation of such a possibility requires reliable and efficient mechanical analysis tools to be explored by topology optimization algorithms for designing the interior architecture of the structures to meet the desired mechanical behavior. However, detailed mechanical analysis of lattice-based structures using the conventional finite element approach is prohibitively expensive due to lattices’ complex and fine features that demand adopting very fine space discretization. As an alternative, equivalent models based on the homogenization principle have widely been... 

Increasing competition in global market and different requirements of customers persuade manufacturers to improve the efficiency of their manufacturing activities. For this end cellular manufacturing systems can be introduced as an innovative and compromising practice for companies. Among the necessary decisions for a successful cellular manufacturing design and implementation, production routing selection (PRS), cell formation (CF), group layout (GL) and group scheduling (GS) are the four most important ones. This research investigates these decisions and proposes a new approach to integrate them. We use important production factors such as production volume, operation sequence, operational...