IMPLEMENTATION OF AUTOMATED MATERIAL HANDLING SYATEM IN ASSEMBLY SHOP

Abstract

ABSTRACT In general, the term automation describes the employment of automatic devices as a substitute for human physical and mental labor. In an automated manufacturing process, functions once performed by humans are replaced by automatic devices that replicate those functions. Computers are widely used for process control. Automation arose out of a need for improved efficiency, higher output greater uniformity of product and a solution to worker‟s fatigue. Thus automation has simplified the work. Initially, robots were used to perform simple tasks too dangerous for humans. But nowadays highly advanced robots can accomplish a wide variety of jobs. They can transfer, manipulate and position any kind of work piece. Though, automation is most widespread in automobile industry due to its rapid growth, widely and fast changing demands, cash richness and frantic competition between the players, its use is rapidly increasing in non manufacturing applications as well. There appears no end to technological innovations in the foreseeable future and to the application of automation to new areas. The new frontiers for automation are no longer production but the service industries. Prominent among them are health care, financial services, retail and transportation. The present work has been carried out to automate the material transfer system of a Hydraulic Cylinder assembly shop. The hydraulic cylinder assembly line under study is a assembly line in which different parts of hydraulic cylinder being transported to the assembly line. In present situation the manufactured parts are transported to the assembly line manually with the help of manually towed trolleys. This system has following drawbacks:-  Requirement of considerable manpower.  Delays in deliveries.  Interference with other material handling equipments.  Chances of damage to the products.  Noise pollution. To automate the present Material transfer system, following three alternatives are analyzed;  AGV  In floor towline conveyor.  Overhead trolley conveyor. In first alternative, an AGV is used to tow the loaded trolleys from production stations to the assembly line and taking the empty trolleys back to production stations. The system is cost effective, silent, results in manpower reduction, smooth material flow with very less chances of product damage. But at the same time, may interfere with other material handling equipments on the floor which will result in delays and chances of accidents also cannot be ruled out. It requires more maintenance and some manpower is still required for loading and unloading of parts. In second alternative, an in floor towline conveyor is considered for material handling. In this system, trolleys are pulled by a motorized chain contained in a trench cut in the floor. Loaded/unloaded trolleys required to be transported, are latched in the chain with the help of a pin. On reaching the destination, they are de-latched and used. The system is simplest with low startup cost, requires less maintenance, reduced manpower, low noise levels, less chances of product damage. But in the absence of any smart safety system (unlike AGV), it has more chances of meeting accidents and traffic on shop floor. The third alternative is of overhead trolley conveyor which not at all uses floor area. In this system, a power driven chain located overhead forms closed loop. To this chain are attached equally spaced carriers. The parts are loaded on these carriers at the production stations and unloaded at the assembly station. These carriers travel overhead in the assembly line thus ruling out even the minutest chance of its interference with other material handling equipments running on the assembly shop floor. The system gives guaranteed no accidents, timely delivery and smooth material flow, elimination of man power, silent operation low maintenance, and no damage to the product. But the system demands huge initial investments and longer installation time. These three alternatives are then evaluated by AHP technique. The overall rating of each alternative is then calculated and the one with highest rating is selected. In present case the selected alternative is overhead trolley conveyor.