Machine tool automation has become the prime necessity of the manufacturing industry. India Inc needs to comprehend the significance of automation technology to stay competent, says Pravin Mehta With the advent of civilisation, human needs have grown more complex and diverse. Today, there is a tremendous demand for sophisticated goods and services in almost all parts of the world, owing to rising levels of awareness and affluence, easy access to a globalised economy and brilliant advances in science and technology. Such patterns in global consumerism have resulted in the progressive evolution of a manufacturing industry with diverse operations and tooling needs. The methods of tooling have evolved greatly over time as well. To match the scale and scope of complex manufacturing, machine tools were developed in the 19th century. These eventually took over hand tools and became an integral part of key manufacturing operations like drilling, hobbing, grinding, broaching, milling, etc. Machine tools play an immense role in the overall efficiency of a manufacturing facility and the quality of its end products. Considering the importance of machine tools, several innovations have been developed to enhance their performance, including the development of electricallypowered machine tools, nonconventional machine tools and multi-purpose machining centres, etc. The generation of electricallypowered machine tools ensures higher productivity and greater accuracy. Due to their benefits, such machine tools have largely been deployed across all large manufacturing hubs and facilities in India. Recent data by the Indian Machine Tool Manufacturers’ Association (IMTMA) reveals that Indian metalworking machine tool industry, which is worth Rs 17,525 million, registered a growth of 5 per cent during the period from January 2007 to December 2007. The industry’s growth was largely driven by demands from the automotive sector, auto ancillary industry, defense, railways sector, and smallscale industry units.  However, conventional machine tools have their own drawbacks—inconsistent quality, the continuous need for manual monitoring and control, and increased maintenance and downtime, which ultimately has cost implications and impacts overall plant efficiency. According to Sagar Nagpure, Director, Dran Engineers Pvt Ltd, “The development of electricallypowered machine tools such as the conventional lathe machine have definitely revolutionised machining technology. However, their inherent drawbacks like continuous monitoring and manual operation have been major liabilities in terms of quality consistency and costs.” To resolve such issues, hybrid machine tools have been developed in the last few decades. These are basically an improvisation on electricallypowered machine tools. Commonly known as automated machine tools, these hybrid systems consist of electronic and electrical components integrated with the mechanical components (mainly the machining components and tools). Such automated systems have gained immense importance in the current scenario due to their capability to perform operations ‘intelligently’, and with 100 per cent quality consistency. “Machine tool automation has gained considerable significance as it improves the overall workflow, smartens condition monitoring and minimises manual intervention, which enhances quality consistency and productivity,” says Juzar Gandhi, Proprietor, Raj Overseas, a company which manufactures an extensive range of automation systems. However, despite the advantages of automated machine tools over their mechanised counterparts, their large-scale implementation has yet to become a reality in India. This is largely due to the lack of awareness, shortage of initial investment capital, severe power shortage in large parts of the country, and lack of competitive drive. Thus, to ensure full-fledged implementation of automated systems in manufacturing domain, it is of utmost importance to spread awareness in the industry. Machine Tool Automation It is the integration of automation system with machine tool components to automate their motion and the governing process. Modern automation systems consist of control system elements—numerical control (NC) and programmable logic control (PLC)—integrated with IT elements such as computer-aided technologies. These are used to control industrial machinery and processes, and, thus, reduce human intervention, specifically at the operators’ level. This whole setup is commonly referred as computer numerical control (CNC) machine. “Modern CNC machines are based on the concept of an integrated architecture platform with software embedded hardware chips. Such systems enable automated machining with a high degree of motion control and process repeatability,” says Avinash Malviya, Technical Director, Solpro Automation. Modern CNC machines are programmable systems with limited intelligence, which are fed with instruction sets to execute precise control over tool motion in strict accordance with the manufacturing process. These can also be retrofitted with sensors for automated condition monitoring to assess tool wear on a real-time basis, which helps tool replacement well before failure. “Due to their inherent intelligent features and level of automation, modern machine tools, such as CNC machines can perform both machine along with predictive maintenance. This helps minimise machine downtime and also optimises the maintenance costs,” adds Mr Malviya. For example, SmartSlaves, an automation solution by Omron, monitors the status of connected devices along the production line and helps establish an effective preventive maintenance system. The automation system monitors both the operating status of the connected devices and the On/Off status of control bits, indicating the need for maintenance much before actual failure of the tool or equipment. Control Systems for Machine Tool Automation Due to the growing number of industrial variables, like tool position, pressure and temperature, control systems have also been developed to execute greater control over various processes. These also have a great role in achieving maximum automation and minimising human intervention. A few control systems which are mainly used in manufacturing processes, especially to control tool motion, are discussed below. CNC CNC is a type of control mechanism which controls machine tool motion in accordance with preprogrammed commands that are fed into the CNC system as instruction sets. It is an immensely powerful automation tool, and can automate both design and manufacturing processes using programmemes based on CAD/CAM, C and Automatically Programmed Tool (APT). Such programmes then produce a computer file consisting of instruction sets to operate and control the motion of various machine tools used in any particular manufacturing process. Modern CNC interpreters are built in with parametric programming capabilities, which enable them to include both device commands for multiple tool automation and a high-level control programming language like BASIC. This widens the range of programming functionality like inclusion of if/then/else statements, loops, subprogramme calls, and inclusion of arithmetical functions and manipulation of variables.
Thus, a large degree of freedom is enabled within a single programme, which makes it capable of controlling machine tool(s) motion for an entire range of components that can be scaled as per the requirements. Moreover, in the increasingly complex manufacturing environment, wherein a wide range of machine tools are being employed in tandem or simultaneously, CNC machines can perform tool motion control either through external controllers or in a single unit. While, in the case of a single unit, multiple tool changers or machining heads are used, external controller employs robots or manual operator to change machine tools. In either of the cases, the complete manufacturing process and process parameters are fully automated and produce components in exact dimensions as specified in CADgenerated designs.  Programmable Logic Controller
A programmable logic controller (PLC) is basically a digital computer which automates manufacturing processes such as controlling the motion of machine tools used in manufacturing processes. However, unlike digital computers, PLCs have a more robust design with multiple input and output capability, higher working temperature ranges and resistance to vibrations and electrical noise. Modern PLCs are programmed using standardsbased programming languages, wherein the programmes can also be downloaded to the desktop machine as ladder-style logic through Ethernet connecting it to the PLC. This way the programme can also be edited, which helps debug and troubleshoot the programme.
As per the IEC 61131-3, five programming languages have been specified for PLCs for machine tool automation—these include Function Block Diagram (FBD), Ladder Diagram (LD), Structured Text (ST), Instruction List (IL), and Sequential Function Chart (SFC). In the last few years, the scope of PLCs in manufacturing industry has widened to include vital control operations like sequential relay control, motion control, process control and networking, etc. Moreover, these have gained considerable popularity over desktop-based logic controllers due to their suitability of application in heavy industries. “PLCs have greater tolerance to tough shop floor work conditions, and, also, these are extremely consistent in terms of the response time corresponding to variations in input logic states, which has gained them an edge over conventional desktop-based logic controllers”, adds Mr Gandhi. In turn, desktopbased logic controllers, which work in Windows environment, have lower responding capability to logic execution, thus, resulting in occasional ‘system hangover’. In a machine tool automation setup, PLC is connected to sensors (optionally machine vision system) and actuators on either of its ends. The sensors provide PLC with data on process variables like temperature, pressure and tool position, which is processed and analysed by the PLC to actuate required output through actuation systems like pneumatic or hydraulic cylinders and electric motors. Thus, automating machine tool motion and manufacturing processes, various standalone machines and consoles can also be networked. Communication among PLCs can be established using protocols like Modbus, BACnet over modern fieldbuses such as DeviceNet or Profibus. Moreover, modern PLCs also have peer-to-peer (P2P) communication capability, which enables different parts of a complex process to have individual controls, while allowing the subsystems to co-ordinate over the communication link. Distributed Control System (DCS) It is another major control system which is used to control parameters in manufacturing processes. In DCS, the controller elements are not located at any particular central location but are distributed through the entire system, wherein individual sub-systems are controlled by individual controllers. According to Prof AK Sinha, HOD, Electrical Engineering Department, IIT Kharagpur, “In DCS, the controller elements are distributed throughout as sub-stations with individual workstations. These are configured locally and can be interconnected over a network to perform remote communication, process monitoring and control.” Communication over the networked machines is performed by a control network which transmits information over twisted pair, coaxial, or fiber optic cables. Further, to enhance the computing, data acquisition and reporting capabilities, DCS can be provided with server and/or applications processor. A distributed control system is either directly connected to machine tools and equipment like switches, pumps and valves or communicates through intermediaries like SCADA. Typically, a modern DCS consists of custom-designed digital controllers which can execute a vast number of regulatory control loops, in the range of 1 to 256, in a single box. The input/output (I/O) devices in DCS can either be integrated with the controller or situated remotely through a field network. Today, DCS have found wide-spread continuous and batch-oriented applications in industries like power generation, manufacturing, steelmaking and oil refining etc.
A recent example is of National Thermal Power Corporation Ltd (NTPC) which has awarded Yokogawa Electric Corporation with the contract to supply automation and control system for its new supercritical coal fired power plant in Bihar. Yokogawa has provided CENTUM CS 3000 R3 Distributed Control System and various other instrumentation systems to automate operations at NTPC thermal power plants. Benefits Machine tool automation, if done judiciously and under appropriate expertise, provides great advantages. The foremost benefit of automation is productivity enhancement. “Due to preprogrammed processes and machine tool motion, minimal time is spent on non-productive activities, and, it also minimises human intervention, thus, improving the production rate”, says Premprakash, Business Partner, Concept Engineers. Another advantage is improved quality consistency, which is again due to minimal human intervention, and close monitoring and control of manufacturing processes. Moreover, automated machine tools like robots and CNC machines with in-built intelligent functionality can work in hazardous environments without engaging the operator. This minimises risk and makes even hazardous work environments safer for the operator. Furthermore, CNC machines can make a remarkable improvement in the machining capabilities of a facility. “CNC machines enable high-speed machining of complex 3-D structures and contours with utmost precision, thus, adding to process versatility, quality and application scope”, adds Mr Chandavarkar. Moreover, this is achieved alongside minimising the number of stages with human engagement. Automation Tips Despite the apparent benefits of machine tool automation, their optimal application on shop floor needs considerable technical expertise and a sound evaluation of the existing machine floor setup. Moreover, considering the steep initial investments associated with installation of automation systems, manufacturers need to make a careful assessment of intrinsic parameters like targeted production, operator expertise, investment capacity and desired quality, etc. One of the vital aspects of machine tool automation is the capital investment which largely depends upon the level of automation. In this regard, there are two major points that manufacturers should consider prior to automation, namely investment in new machines or retrofitting of existing machines. In fact, in a manufacturing cell, replacement of machine tools with job-shop controls is not always required. For example, conventional machine tools like lathe or milling machines usually have a highstrength machine bed with considerable stiffness. Thus, instead of scrapping them, manufacturers can retrofit such machines with linear rules and digital read-out (DRO) to enhance this quality and tolerances. Another improvement in conventional machine tools can be done by retrofitting them with a NCprogramme interpreter, PLC, actuators and sensors. Moreover, frequency converters can also be fitted on conventional machines to control the motion of the main spindle drive. Another aspect of automation is partial retrofitting, in which a few conventional machining features of the machine are maintained. For example, mobilising work table and saddle with hand wheels in addition to the numerically controlled servo drives facilitates manufacturing of simple jobs prior to the use of CNC-control to machine geometrically complex jobs. This enables machine tool to switch from manual processing to NC support in an intelligent manner, which enhances shop-floor productivity. Another important aspect of machine tool automation is operator expertise; depending on the type of automation, the skill and knowledge of the operator also needs to be upgraded. However, operator skill also has two aspects, namely machine programming and operating, which have separate cost factors. Manufacturers can save costs and avoid unnecessary organisational efforts by using operative systems like Windows NT which can be integrated with enterprise network and connected through internet. This makes machine programming easier and also facilitates storage and sharing of these at a remote location, thus, imparting flexible manufacturing capabilities. Thus manufacturers should look forward to installing PC-enabled automation systems to upgrade the functionality of traditional CNC technology in terms of interoperability and tool data management. Such automation systems, commonly referred to as open-system CNC, have very high degree of logical integration, which implies that integration between the CNC and the PC is enabled even at remote locations. This enables exchange of extensive data volumes on real-time basis, thus, improving operator interface, central tracking and analysis of statistical process control (SPC) data, ultimately leading to superior control over machine tools. The modern machine tool automation technology is highly efficient but it still has a long way to go in terms of intelligent features like pattern recognition and language recognition. Advanced simulation is another aspect in which there is considerable scope of evolution for automation technology. With the increasingly dynamic workpiece specifications in contemporary manufacturing environments, automation systems are evolving to become dynamically reconfigurable. In this concern, simulation tools have an important role to visualise machining processes prior to the execution of actual process to get a desired job profile. An accurate simulation of machine tools can be performed using machine tool data obtained through the official website of the supplier. The operators can document the simulation data thus obtained, which can also be used for future reference. Virtual machining functionality along with skilled workforce will enable manufacturers to schedule complex manufacturing processes in a short-time with optimisation. CIMPLICITY Station by GE Fanuc Automation is an example in this category. It is basically a compact, panel-mounted industrial computer that provides advanced computing architecture needed for complex control applications. Bundled with the CIMPLICITY Machine Edition, it is suitable for use as an operator panel in an embedded Human-Machine Interface (HMI) system or as a secure platform for PC-based machine control and HMI. Unlike traditional PCs, CIMPLICITY Station uses built-in systems access keys along with a virtual keyboard to enter changes, which obviates the need of awkward peripheral devices. Moreover, the product helps establish a scalable infrastructure which extends from the factory floor to the business enterprise. Intel Virtualization Technology (VT) makes another apt example in the category of virtualisation tools for industrial automation. The technology employs Intel’s multicore processors to integrate two or more autonomous applications that are handled by a general purpose operating system (GPOS) in industrial automation. Conventionally, in such applications, the user needs to integrate individual machines for real time control based on a realtime operating system (RTOS) and operator interface based on a GPOS. This doubles both upfront and operating costs, and increases the hardware space consumed. Intel VT enables virtualisation using multi-core technology, in which both the OS run on the same platform. This optimises costs, hardware space, and power, and also maintains integrated performance equal to that of the individual systems. Machine Tool Industry: The Current Scenario A report by United Nations Industrial Development Organization (UNIDO) says that the contemporary machine tool industry in India can be divided into two main categories, namely, the metal cutting sector and the metal forming sector. In turn, both the metal cutting and the metal forming sectors can further be categorised into conventional machines and CNC machines. A few commonly used and manufactured metal cutting machines in India include electrical discharge machine (EDM), machining centres, lathes, boring machine, milling machine, drilling and grinding machines etc. The metal forming machines include bending machines, straightening machines, flattening machines, punching and shearing machines, and die casting machines. The report further says that to keep up with the global trends and meet the diverse customer demands, developments in CNC machine tool segment needs to be focussed upon specifically. This is because CNC machine tools have fast emerged as key growth drivers for the overall machine tool industry in India. Currently, indigenous machine tools have the greatest impact on capital output, and though the sector consumes around Rs 2,500 crore of capital, it largely supports the nation’s engineering sector which is worth around Rs 1,50,000 crore.  The Export-Import Scenario A report by IMTMA reveals that Indian machine tool manufacturers have steadily found their way into the overseas markets. Around 395 machine tools valued at Rs 1,475 million were exported from India during the period from January 2007 to December 2007, which increased the exports by 98 per cent. Export of CNC machines in financial year 2007–2008 also registered a 100 per cent growth over the previous financial year.
Currently, indigenously manufactured machine tools are being exported to over 55 countries such as the United States, Italy, Brazil,Germany, the Middle East, etc. The majority of machine tools that are being exported from India include lathes and automats, presses, EDM, and machining centres. Despite this presence in diverse export markets, the nation’s machine tools export business is still waiting for exponential growth. However, bigger machine tool manufacturers have targeted to achieve the annual gross exports revenue of over Rs 300 million in the next few years. The IMTMA report further states that the growing machine tool demands in Indian market resulted in a zoom-phase for importers. In financial year 2007–08, the import of machine tools increased by 47 per cent and reached a total value of Rs 55,640 million. Currently, the bulk of machine tool imports, which is around 75 per cent of the Indian market share, is accounted by metal cutting machine tools such as machining centres, grinding centres,turning centres, etc. Government Initiatives Recognising the role of machine tool industry in the development of core engineering sectors in India, and in order to support its growth in both the domestic and export markets, the government has made certain provisions. Earlier, the government removed quantitative restrictions from all categories of machine tools, and the duty on machine tools was also reduced from 110 per cent to 20 per cent, and was later completely done away with. The industry is licensefree, which permits any domestic or foreign firm to set up establishments in urban limits with 100 per cent equity and managerial control without the need for prior permission. The government also provides export incentives to support domestic firms for competing in the export market. These incentives include provision of duty-free import of capital goods, raw materials and components to export-oriented firms. The government also passed the Indian Patents Act which fully conforms to trade-related aspects of intellectual property rights (TRIPS) of WTO. Thus, the overall policy environment in India became positive for the industry.
Looking to the Future To tap the growing demand for in-house manufactured products in both the domestic and overseas markets, Indian manufacturers need to emphasise key aspects like productivity and quality consistency. In this regard, the implementation of machine-tool automation has become a necessity to acquire the desired level of competence and optimise profits. In the last few decades, control systems like CNC, DCS and PLC have been developed to control tool motion and other process parameters in the manufacturing industry. Sensorbased condition monitoring is useful to perform predictive maintenance and stay ahead of unnecessary maintenance costs and machine downtimes. Though a multitude of automation systems have been developed for the manufacturing industry, players in the domain need to assess critical factors like their requirements, expectations and investment capacity prior to implement a particular type of automation. With all their proven benefits and despite ongoing speculations, automation systems are there to stay and evolve.
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