VIRTUAL MANUFACTURING SYSTEMSPRESENTATION BY: AJIT DAS, USN: 1AY12ME005

INTRODUCTION

•Virtual Manufacturing is defined as a computer system which is capable of generating information about the structure, states, and behavior of a manufacturing system as can be observed in a real manufacturing environment. In other words, a VM system produce no output such as materials and physical products , but it can produce information about them VM is an integrated computer-based model which represents the physical and logical schema and the behavior of a real manufacturing system.

WHAT IS VIRTUAL MANUFACTURING?

•VM can be used in the evaluation of the feasibility of a product design, validation of a production plan, and optimization of the product design and processes. These reduce the cost in product life cycle.

•VM can be used to test and validate the accuracy of the product and process designs. For example, the outlook of a product design, dynamic characteristics analysis, checking for the tool path during machining process, NC program validation, checking for the collision problems in machining and assembly etc.

•With the use of VM on the internet, it is possible to conduct training under a distributed virtual environment for the operations, technicians and management people on the use of manufacturing facilities. The costs of training and production can thus be reduced.

•As a knowledge acquisition vehicle, VM can be used to acquire continuously the manufacturing know-how, traditional manufacturing process, production data etc. This can help to upgrade the level of intelligence of a manufacturing system.

WHY IS VIRTUAL MANUFACTURING NEEDED?

•QUALITY•SHORTER CYCLE TIME•PRODUCIBILITY•FLEXIBILITY•RESPONSIVENESS•CUSTOMER RELATIONS

WHAT ARE THE BENEFITS THAT WE WILL GET OUT OF USING VIRTUAL MANUFACTURING?

A CASE STUDY

VIRTUAL MANUFACTURING SIGNIFICANTLY REDUCED FUEL COSTS FOR BOEING

Problem During the metal-forming process of aircraft skin panels, the work piece undergoes large deformations and accumulates considerable plastic strain. Upon release of the work piece, the part recovers the elastic energy stored in it. This causes the deformed part to deviate from the desired shape. Historically, empirical methods were used to determine this spring-back effect after forming the panel. In the modern era, such methods are impractical and cost prohibitive, especially because of the large number of various parts in a modern airplane. A new stretch form block shape must be designed with the inherent Spring back accounted for. Without optimized die shapes, the quality of the part suffers, leading to assembly problems that are compensated for by trimming and shims to attain a proper fit. Such difficulties can extend production schedules unpredictably. The final installed aircraft skins can become wavy, resulting in reduced fuel economy over the life of the aircraft.

SOLUTION ACHIEVED BY USING VM

By using the nonlinear finite element (FEA) software, MSC. Marc, to simulate the metal-forming process, the spring-back can be accurately predicted before the real die is built. The material often used is aluminum, which is elastic-plastic with large deformation in the plastic region. There is material, geometric,

and boundary nonlinearity involved. The software must be able to accurately predict this spring back effect. To optimize the die shape, a trial-and-error procedure is required. Instead of implementing the trial-and error procedure on the real model, FEA is used to find the optimal die shape. Using MSC.

Marc's automated contact applied to 3-D bodies required no exotic programming by the end user to converge on a solution, making it a very practical tool for this virtual manufacturing simulation. Once a Stretch Form Block shape was designed, a robotics model of the stretch press was undertaken to determine the optimal control of the sheet-forming process. Once the robotics model was optimized in the virtual environment, the data was sent to the controller on

the stretch press. Thus the operator, when forming the part, directly used the FEA information. By developing the tooling dies and the manufacturing controls in a virtual manner, the risk associated with part manufacture and assembly was reduced.

TYPES OF BASIC MANUFACTURING SIMULATIONS IN VIRTUAL MANUFACTURING

CASTING SIMULATION COMPOSITE SIMULATION

FORMING SIMULATION WELDING AND ASSEMBLY SIMULATION

CASTING SIMULATION

SOLIDIFICATION•Micro Porosity•Gas Porosity•Piping•Hot Spot

POURING•Misruns•Air Entrapment•Oxides•Surface Defects•Cold Shuts•Turbulences•Inclusions•Core Gases

STRESS

•Hot Tears•Surface Cracks•Residual Stresses•Cold Cracks•Distortion•Die Fatigue

METALLURGY SPECIFICATIONS

•Stray Grain•Freckle•Segregation•Mechanical Properties•Distortion•Dimensional Tolerances

CASTING DEFECTS THAT CAN BE SIMULATED

TYPES OF CASTING THAT CAN BE SIMULATED• GRAVITY CASTING

Sand / Permanent Mold / Tilt Pouring

• LOW PRESSURE DIE CASTING• HIGH PRESSURE DIE CASTING• INVESTMENT & SHELL

CASTING• CONTINUOUS CASTING

• CENTRIFUGAL CASTING• LOST FOAM• SEMI-SOLID MODELING• CORE BLOWING & GASSING

COMPOSITE SIMULATION

FORMING SIMULATION

WELDING SIMULATION

ADVANTAGES OF WELDING SIMULATION

Minimize the cost of prototyping,

Minimize the cost of distortion repair

work,

Develop and optimize a weld plan within the shortest

time range,

Keep welding distortion within

allowable tolerances,

Guarantee the best weld quality,

Control stresses in welded designs.

ABILITY TO VISULIZE THE VIRTUAL COMPONENTS

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