Manufacturing Systems: A Transfer Line

INTRODUCTION

Manufacturing plays an important part in making a product come to life. It is the process where the actual design comes to life as several different materials are processed and worked upon to bring a particular product into existence and at a state at which they are ready to be sold. This manufacturing process can be achieved in several different ways depending on key factors such as type of product, the quantity of the product and how complex it is to build said product. Choosing a manufacturing process is an essential task and must be done with absolute care as the wrong process could cause heavy financial loss and how the product is ultimately built (the finish of the product). One of the method that is used to manufacture products is called transfer line.

A transfer line is a method that is employed to manufacture products that are large in quantity and have a small family of parts. (Liberopoulos, 2003) The process involves organizing a chain of work stations in a sort of a line that have products flowed through them. Each workstation has a machine which performs a specific task or process to manufacture part of the product and after doing its specific task it is passed further down the line to complete its manufacturing process. (Liberopoulos, 2003). With this method and sequence, the material handling time is greatly reduced.

However, the overall design and the unpredictability of the work environment can greatly influence how efficient this system is. In addition, the overall design and the unpredictability of the work environment can greatly influence how efficient a manufacturing plant is and can be the major factor in deciding how costly the whole operation is. Investing in a transfer line manufacturing system is expensive enough to begin with, therefore it is necessary to make use of the expensive equipment to the fullest. Unpractical layout of such a system can cause low utilization thus resulting in low profits or even loss. Problem solving techniques such as transfer line balancing can greatly reduce this cost. This involves the process of bringing and bundling process together that have similar operations. (Dolgui A, Ihnatsenka I). this method has been known to increase cycle time, output of the plant and the utilization. (Syed Masood, (2006)).

More over installation of buffer between work station also increases line efficiency. The paper done by (Chomnawung and Prombanpong, 2018) on buffer analysis on a production line highlights the key findings on this matter. Therefore this report aims to analyse a particular transfer line based on PET bottle production. PET bottles are the standard recyclable bottles that are used to sell standard beverages. This manufacturing plant produces two types of products, i. e. two types of beverages that are fairly similar in nature and it is done in two eight hour shifts with standard breaks. It will report findings such as parameters that affect the output of the factory. To name some of the areas of interests, the efficiency, production rate, downtime, output speed and wastage are being researched on. After these areas have been successfully looked into, further research and investigation will be done as to how to improve such a setup. The aim is to maximize the factory output and ultimately to save costs.

LITERATURE REVIEW

Transfer line is widely dedicated to manufacturing industry in which the production is much more centred on mass production of some unique products or family of similar parts [1]. The manufacturing system is design in such a way that it consists of sequence of machines that is operated by an automated controlled system. Along the production lines are processing machines called work stations. As the raw part enters the transfers line it passes a number of workstations through which several of operation were taken place until the work piece exits the automated transfer line at the final Worked-station. There are some check-up setups such as the inspections being installed throughout the production line to take care of the work-part quality and also some manually operated workstations to perform some of the tasks that cannot be performed by automation. In designing such production lines can be quite complex at the first initiation as it requires much consideration to account for the designing and manufacturing limitations. In most cases the engineers and designers have to be in good terms with their customers, to responding interactively on the design specifications and the part modifications in which their customer may wish to provide on the started design.

This figure shows the general automated transfer line system. It consist of a sequence of workstations that involved in transferring of parts from one workstation to the next. In this configuration, the setup consist of a straight line arrangement of work stations. The workpiece can transfers from one station to the next work station. Processing takes place in each station as the workpart is being transferred. This following figure shows this type of configuration. The arrangement can be made up of two or more than one straight-line set up which can be in perpendicular or designed in a U-shape.

In Rotary, the configuration is made in such a way that workpiece is transferred through a circular path. In this arrangement the work-stations has to be stationary and they are outside of the periphery of a circular table or dial.

Two Mechanisms in Work part Transfer

Linear Transfer Systems

In this type the system, a number of mechanism were involved such as the belt conveyors, rollers, track conveyors and chains drives as a means of transferring the workpart from one station to the next station. The way in which the work part is transferred can be through continuous motion, synchronous motion (all parts move at the same time) and asynchronous motion in which workparts move through the line independently.

As in the figure above, the attached to the conveyor are the work carries that ensure that the workpart is transferred through the line in a synchronous manner. The belt design (‘under’ and ‘over’) conveyers are place to ensure that there is a supply of carriers in continues means. Friction can be applied to the conveyor belt to transfer parts by means of an asynchronous fashion. The figure below shows the walking beam system which is one of the forms of a linear transfer line. This system allows workpart to be transferred in a synchronous fashion in which a transfer beams lift the parts from the initial location and move them a distance ahead. The work parts can be lowered into a nest, at which they can be placed in for the next processing workstation and the transfers beam then retracts itself for the next set of workpart transfer cycle.

Rotary indexing Mechanism

The other work part transfer mechanism is a Rotary indexing Mechanism. In rotary mechanism, two types are used mainly to generate the type of rotary transferred power that is required and they are the Geneva and the Cam drive mechanisms. Geneva mechanism pictured below, uses a specially- design rotating driver incorporated to achieved partial rotation. It is a gear mechanism that translate continues movement into index intermediate movement. Cam drivers can be most preferred to Geneva mechanism as they provide more velocity in indexing a rotary dial table. However, in spite of providing more accurate and reliability in index intermediate movement, it can be expensive to initiate such mechanism in a production line.

Storage Buffers

Storage buffers are temporary storage place along the production line to be used for parts that are transversing the line. They are place to stabilize the production line and to avoid fluctuation and provide a constant supply of the workparts flow in progress. Also it can be used to provide high efficiency in production in terms of avoiding blockages and starvation. Buffers can be operated manually or automated.

Analysis of Transfer Lines

In most of the production lines there are some problems that affects the reliability, efficiency and productivity of a production line, in these cases, there are some method used in analyzing the problems that might be experienced on the production line. This become known as transfer line analysis. Considering transfer line analysis, there are three key areas involved, they are process technology, line balancing and system reliability.

In Line balancing, there has to be evenly distributed total processing work among all the stations that a production line may have consist of. Process technology is another method, and it based mainly on the knowledge on the theory and the principles that governs that particular manufacturing process. Based on good knowledge and machining principles, such problems encountered can be solved. System reliability is another form of transfer line analysis, and it involves analysis the overall reliability of the system. By examining the integrated system, a failure of one component can result in the failure of the whole system.