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Due to emerging concepts like globalisation and liberalisation, customers have to change their demands frequently as they have a variety of products with improved quality and lower price

MACHINE RETROFIT & RECONDITION Economical analysis of existing machine tools through retrofitting

Nov 26, 2018

With concepts like globalisation providing options to customers and decrease in the life of products, old machines cannot be totally discarded to replace new ones. This case study provides a solution in the form of retrofitting and discusses how it helps the industries.

Due to emerging concepts like globalisation and liberalisation, customers have to change their demands frequently as they have a variety of products with improved quality and lower price. Such demands cannot be met by conventional manufacturing of machine tools because of their limited capability and flexibility. Hence, market life of the product reduces. Conventional manufacturing of machine tools cannot meet these requirements.

Long-term competitive edge

To sustain competition and exist in the global market, Indian manufacturing industries need to upgrade their technology for their survival and sharpen their long-term competitive edge. Due to the prevalence of capital constraints, upgradation of existing machine tools through re-conditioning and retrofitting is the best possible answer to them. Retrofitting leads to cost effective modernisation of existing workshops.

Reconditioning and oiling of old equipment plays a significant role in developing countries like India due to prohibitive costs of new equipment, lack of adequate foreign exchange resource for machinery imports, and scarcity of capital. Once the life span of a machine is over, its reliability decreases and planning of spare parts becomes a difficult task. The components have a low residual life and could fail without a warning. To bring CNC operations into working, it is not necessary to purchase a new CNC machine. It can be achieved by incorporating CNC features like DRO CNC system.

Idea of renovation

Since Sunbeam Auto has been incepted, they have complied many machine tools and plants. Of these, many machine tools and plants have gone old. Though there are a lot of advantages of using new CNC machines, the old ones cannot be discarded and replaced. For any industry, 1:1 replacement of machine tools by new CNC machines is not possible due to the issue of replacement versus renovation of senescent machine tools. In this context, the 4R’s approach (Retire, Relegate, Renovation and Replacement) has been thought of.

CNC retrofitting

Today’s urgent need to modernise conventional machine tools and acute difficulties regarding availability of large capital contradict each other. High prices for new large and medium size CNC machines make it difficult for the user to reap the benefits of CNC technology. In this context, introduction of CNC technology is through retrofitting.

The process involves addition of new systems or modules to enhance the capability of existing machines. The purpose is to upgrade the conventional senescent machine tools. CNC retrofitting will find a place today in the industry due to:

• Cost effective monetisation

• Large-size senescent machine tools that cannot be discarded

Reconditioning and its need

Reconditioning may be defined as a planned systematic engineering, actively designed to restore the equipment to its original sound performance condition. It is a practical exercise intended to bring back the equipment used for a long time to its original reliability and performance state. This involves repairs to certain problematic areas in the machine, to remove slackness due to wear and replacement of certain parts depending upon the intended performance of the machine.

Reconditioning does not make a machine a totally new one but upgrades it to a certain extent. In developing countries like India, where procuring capital is a challenge, reconditioning seems to be a very feasible solution.

Cost justification for high cost automation

Every conventional senescent machine tool is not recommended for renovation. Features of automation that add value to retrofit machines like robots, AGVs, etc, are not justifiable until they are cost effective. They are only recommended for certain machines with high initial cost that can ably support such automated features.

One example is Kolb’s multi-spindle drilling machine, which has 8 spindles for simultaneous drilling of holes on baffle plates of HCM division. Due to the continuous use, the productivity had reduced. Thus, it has been upgraded with a state-of-the-art CNC controller, having the latest features and integrating the ASI bus concept with a high-rating AC spindle, servo motors and drives for high reliability and fast diagnostics. It has been completely reconditioned and upgraded for use of high-speed delta drills resulting in increased productivity, flexible automation, cycle time reduction, etc.

Results

During upgradation, defective parts are either repaired or replaced to bring back original accuracy. This leads to lesser downtime, higher machine accuracy and increasing availability from 78% to 96%. By introducing automatic tool turret, hydraulically operated tall stock, modified numeric CNC controller and servo drives, selection of tool, speed and feed are performed automatically, according to instructions given in the program. These things lead to dramatic decrease in cycle time, reduction in worker’s fatigue and his duty is limited to loading, unloading and entering program.

Further, AC servo motors, drives induced higher speed upto 1000 rpm without drop torque. Accurate positioning, precision feed attained through PLC controlled turret gave higher accuracies, better repeatability, hence lesser rejection, bringing the cost of production down. Chip conveyors, machine enclosure attached for safety of worker enhanced time saving. Centralised automatic lubrication system improved tool life and facilitated extended operations.

By incorporating power tool in the turret for drilling, grinding, hydraulic chuck and automatic job handling, we can further improve productivity. C-axis arrangement will improve capability of upgraded machines. With the help of computer program, it is very easy to decide the feasibility of a machine for upgradation. The cost effectiveness of upgraded machines is at par with CNC as well as conventional machines can be analysed.

Enhancing productivity

The obtained results have proved that retrofitting is very cost effective for enhancing productivity, availability and improving performance level. With suitable and economical application of automation, value addition takes place and takes performance of retrofitted machine to a better level. Customised retrofit makes maximum re-use of existing equipment and is therefore, more economical than a complete new installation. With the possibility to sequence the retrofit installation, service interruptions can be minimised. At the same time, our clients’ power systems are upgraded to the latest available breaker, protection and control technology, thus increasing functionality and improving reliability and safety.

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