Application of Computers in Welding Process | Metallurgy

Most important application of computer in welding is for the setting of welding parameters. Computer is used to control the welding process with regard to both static and dynamic characteristics.

A computerised welding process controller is designed to handle the various phenomena occurring during the welding process, viz., the start-up sequence, continuous welding-including parameter setting, and the termination sequence.

Start Up:

The pressing of the gun switch is sensed and it gives a start reference for the welding current. The arc voltage is also measured. Before the wire has reached the workpiece, open circuit voltage is sensed. When a number of subsequent arc voltage readouts show values below a correspondingly adapted minimum level, the processor concludes that the wire is in contact with the workpiece and it emits a maximum current reference to ensure instant striking of the arc.

Continuous Welding:

The different settings set by operator are: the desired wire feed speed, the desired arc voltage, and the desired arc trim (i.e. dynamic response of current on measured arc voltage variations). From these settings and measured arc voltage, the process controller continuously calculates the new reference values for the welding current. Any change in the preset arc voltage value implies a parallel offset of the static characteristics of the machine, and a change of the arc trim setting changes the dynamic characteristics of the machine.

During start up the welding process controller starts operating with an increased voltage reference and a decreased arc trim value. These start up parameters remain in force until such time as the power source has completed three subsequent short-circuiting. From then on the process control is carried out by way of the normal values as set by the welder.

Termination:

When computer has sensed the release of gun switch, it emits a current pulse at a value considerably higher than the latest momentary value as calculated by the computer and with doubled voltage reference value.

Automation of Electron Beam Process:

Electron beam machine generates, controls and directs a flow of highly charged electrons towards a target with a view to melt, drill, transform surface, welding etc. Electron beam welding is a high energy fusion process, achieved by bombarding the joint to be welded with a focused beam of electrons.

The electrons are produced from thermionic emission of a tungsten emitter and accelerated to two-third the speed of light by application of very high potential between the source electrodes. The accelerated beam of electrons in the evacuated enclosure, can be aligned, focused and deflected towards its target. Generation and control of beam intensity is achieved by electrical means and the positioning of the beam by electro-magnetic influences.

Control of following sub systems is required:

(i) High voltage supplies

(ii) Electromagnetic supplies

(iii) Evacuation systems, including vacuum measurement

(iv) Remote manipulation controls

(v) Remote optical viewing

(vi) Inter-locking between above systems from safety consideration.

Fig. 44.1 shows a block diagram to achieve such controls and automation.

Such a machine will respond to manual controls from the operator. Manual initiation will trigger the machine to perform a complex logic array, for example, evacuation of the work chamber requiring control of several pumps, valves and vacuum sensors.

Visual operator guidance provides guidance to the operator to control by displaying a series of options on screen. Provision for text/graphic information relating to the equipment is available. Faults are indicated from the sensors located around the machine. Diagnostic routines, allowing the testing of system are also available.

Weld quality is achieved by incorporating pre-programmable weld data unique to a particular component. When workpiece geometry data is fed, then program contains all necessary movements required to bring the weld joint line under the beam’s axis.

Computerised numerical control is necessary when the process requires two or more dimensional axes to be controlled simultaneously and/or multiple electrical parameters require high speed changes independently from each other.

Weld quality is affected by the integrity of weld parameters. On line monitoring of parameters which can influence the desired fusion geometry is made and compared to pre-determined levels. Deviations from these tolerance bands trigger audible and visual alarms alerting the operator.

Industrial Robots for Manufacturing Material Removal Processes:

While robots have been successfully used in non- contact manufacturing applications (like painting, welding, glueing, etc.) and achieved increased productivity and quality; attempts are now being made to exploit their capabilities in contact type manufacturing applications (like grinding, milling, deburring, polishing, etc.)

The former tasks required only the position control of the robot manipulator with limited requirements of robot positioning accuracy and repeatability. However, in latter application, new understanding and insights into position/force control system is required.

The industrial robots in use of material removal differ from conventional machine tools in the geometrical rigidity and motion axes. Conventional tools are structurally very stiff because of use of massive structural support members (of the order of 2 x 10⁸ N/m).

On the other hand industrial robots have structural and control stiffness of the order of 2 x 10⁵ N/m. Thus vibrations and chattering have to be tackled very carefully in the design of robot system. The conventional machine tools are designed with translational orthogonal motion axes but robot may use combinations of rectangular, cylindrical, spherical and revolute movements.

In order to avoid the passing of impulsive nature of the tool cutting action to the robot structure, the active end- effector device is designed to isolate high impulsive forces from the industrial robot arm by filtering them into a quasi-constant force. A tool guiding mechanism as a bracing structure has also been used to increase the robot stiffness, but the arm motion has been constrained.

In order to make robots successful in material removal applications, lot of work is being done in:

(i) Force and motion control,

(ii) Robot structural behaviour,

(iii) Material removal characteristics,

(iv) Workpiece fixturing,

(v) Programming.

Artificial Intelligence (AI) Techniques in Production:

AI systems are finding more and more application in production techniques. These concern knowledge based systems and expert system. Knowledge base contains information together with relevant rules which are executed by an inference engine. Expert system has four modules-knowledge base, knowledge acquisition, inference engine, and explanatory interface.

Expert system applies rules based on human expertise so as to use the information in the knowledge base to solve real world problem. Such a system can be integrated into larger systems to alter real advantages to CAD/CAM system. The success of system depends on ability to elicit knowledge in the form of specific codifiable rules.

Further such systems have self-learning capability so that they can modify rules and knowledge as the system is used over a period of time. Standard packages can also be integrated into these systems to obtain overall best advantages.

Virtual Manufacturing:

A virtual manufacturing system can be built within a computer and carry out machining in this virtual factory (Refer Fig. 44.10)

A product is described using design features. NC data generation system calculates cutter paths based on tools and machining features.

Machining data consists of machine control programs. The accuracy of machining data depends on consideration of all constraints. It is necessary to consider machining environment data, i.e., machine specification and the dynamic condition data generated by simulation.

In virtual manufacturing system, first machining features are extracted through preliminary operation of the appropriate virtual manufacturing device (VMD). Next machining is simulated by precise operation of VMD.

Then the machining data is evaluated and verified using the results of simulation (VMD is a computer model which represents the specification, function and behaviour of a physical manufacturing device and thus VMD is a controlled object in the virtual factory).

Virtual manufacturing factory thus acts as a mechanism to generate optimum machining data.

Virtual Reality—A logical Evolution of Existing Human-Computer Interfaces:

The techniques of interacting with computer have changed from time to time, starting from punch cards to terminal and keyboard to windows operating environment. Virtual reality techniques provide unique way of interacting with computer data and images.

These remove the barriers of keyboard, monitor and mouse and allow user to experience the reality of a computer-generated scene. This would open up new opportunities to expand the use of computer technology for engineers in areas of design, prototyping, maintenance and assembly, factory layout and planning, etc.

The graphic models in virtual reality technique appear to occupy three-dimensional space within the viewing area. The natural motions of human (hand and head movement) act as interface to system. A person can look under, around, walk into the computer image of a design.

This technology provides immersive, interactive, multi-sensory, viewer-centred, three- dimensional computer generated environments and user gets a feeling of moving around inside and occupying a position in the computer-created world.

Objects in the computer environment occupy space and the user navigates through the space as if it were the real environment. The images in the environment change positions as the user moves in the space such as they would change positions in the real world.

Sensory inputs are supplied that support the illusion that the user is a part of the computer environment. Thus virtual reality technique offers a new and innovative way to interact with the complex data and designs and presents the opportunity to design in a 3-D environment.

Sense of immersion can be created using high-end computers, virtual reality software, visual displays, tracking devices, interaction devices, audio devices, and haptic devices. Head mounted display (helmet) is very commonly used visual display. The helmet contains LCD or CRT screens, one for each eye.

Position trackers (ultrasonic or electromagnetic receivers/transmitters) on helmet provide spatial coordinates to the computer as the user moves around in the space. The spatial coordinates change the image presented in the helmet based on the orientation and location of the user’s head. 3-D mouse has also been developed. Instrumented gloves (having sensors for position of hand) are also used to interact in the virtual environment.

A unique virtual reality environment is provided by Care Automatic Virtual Environment in which stereo computer images are projected on three walls and the floor of a room. Multiple users may be present in the room but only one person controls the view with a position tracker.

Users wear stereo shutter glasses that convert the images on the walls and floors into stereo images. Haptic devices provide the user with information about touching virtual objects. Stereo head-phones mounted in helmets provide 3-D sound.

Virtual prototypes can be developed using these techniques and studies like whether a part fills properly, whether the knob or dial is accessible, assessment of visibility, rechangeability, accessibility, clearances, comfort, aesthetics can be performed. In this way, need of developing several prototypes is eliminated and significant savings can be realised in design of any machine tool.

Virtual Enterprise:

In virtual enterprise, different functions such as product development, engineering, part production, assembly etc. may be geographically spread and be done in different parts of the world to avail of the international market competition and thus attain high productivity and competitiveness. Performance can be measured as judging effectiveness, efficiency and preparedness of companies to handle changes.

Different methods can be used to measure the productivity and competitiveness of different companies to decide whom to consider.

These methods are:

i. Self-Audit,

ii. Extended audit,

iii. Self-Assessment,

iv. Benchmarking.

One can focus on total productivity by judging time to market, quality, flexibility and total cost. It is important to be able to evolve a suitable methodology to measure the productivity and competitiveness of various enterprises.

In virtual enterprise several entities are distributed in different environments, and completely integrated from the design of the product to its delivery. Management of such global system, its control, and measurement of global performances are the new tasks and only elaborate methods with associated computerised tools can answer to such situation.

Lean Production:

Today market is shifting to more diversified product characteristics and shorter product life cycles. Manufacturing firms have to equip themselves to adapt to these market trends. Streamlined production systems with integrated design and production, utmost simplicity, and slim facility management is necessary to achieve lean production in smaller lots at lower costs.

In future there will be needed exceptionally diversified products more closely tailored to the characteristics of individuals i.e. the era of mass customisation. To meet requirement of lean production, we will need agile system capable of manufacturing greater assortments of products in short time.

To meet such situations we need product planning that is precisely geared to meet diversified demands and attain significantly shorter product development lead time. This calls for practice of concurrent engineering (parallel execution of increasingly sophisticated and complicated engineering activities through divisional cooperation).

There is need to standardise engineering activities in response to product diversification and to pursue a global policy of component sharing to achieves low-cost, high quality designs. Efficient production with minimum lead-time, man hours spent, equipment investment, inventories along with quality work are necessary.

Reverse Engineering:

It concerns producing a part based on an original or physical model without the use of engineering drawing. It uses sophisticated software and modern measuring instrument for this purpose and a CAD model is created.

3D CAD model is used in rapid prototyping environment to drive sintering, layering, depositing or sculpturing equipment to create a usable prototype. CAD files are interpreted as NC machining codes according to which the part is finally manufactured. In addition, the robot movement programs and coordinate measuring machine automatic inspection program can be developed with CAD model.

Data acquisition is possible using digitiser (Non-contact scanner and touch probe). Non-contact scanners use laser, optics and CCD cameras, etc. which can produce large amounts of point data and can digitise an unknown surface automatically.

Reverse engineering is playing an important role in rapid prototyping and CIM. Reverse engineering includes three main phases, viz. data acquisition, reconstruction of surface, and data transfer.

Quality Assurance and Quality Control in Casting Process:

Adequate quality assurance and quality control programmes need to be carried out during and after casting process, because of occurrence of shrinkage, porosity and inclusions associated with casting process, to ensure satisfactory service performance of castings.

The quality assurance programme ensures that all actions have been taken by a casting shop so that the castings not only meet the established quality requirements, but these are also produced in agreement with the customer’s requirements. A customer audit is necessary part of such programmes.

Quality assurance programmes are written in detail and it is ensured that these are necessarily complied with. A complete quality assurance system is involved with all aspects of part manufacture, including final inspection and testing.

The monitoring of all the process steps during the manufacture of castings is established in the process control programme. This plan includes the chemical analysis and weighing of charge material, control of pattern and mould materials, preparation of moulds, measurement of metal temperature, tapping, and pouring.

Surveillance of the process steps is needed to maintain quality consistency. A variety of analytical equipment spectrometers, optical pyrometers, etc. is needed to determine chemical composition.

Inspection of castings needs to be done to determine if it conforms to the relevant engineering drawing, specification, and standard requirements. Testing is done for dimensions, presence of surface and internal defects, and other mechanical properties. Castings intended to withstand pressures are leak tested.

The specifications precisely state a minimum set, or in some cases the range, of requirements like chemical composition, hardness, grain size, mechanical properties to be satisfied by the casting. Procedure used to repair defective parts, if permitted, are also specified.

Aerospace Material Specifications (AMS) have developed a comprehensive document to include casting process, properties, chemical analysis, testing, quality, sampling, conditions, identification and approval conditions related to the manufacturing process.

Quality assurance provisions cover the responsibility for inspection, classification of tests (acceptance, periodic, preproduction, etc.) sampling, approval reports, resampling and retesting provisions in detail.

Computer Integrated Manufacturing (CIM):

Industry is today facing challenge to be able to produce a constantly changing range of products. For this propose, manufacturing flexibility and a minimal product lead time are necessary. Better and more reliable communications and data transfer between departments within an organisation is essential.

Computer exchange and manipulation of data held in different database is ideal way to transfer knowledge among all users concerned.

Computers are currently providing an important service to many industrial functions, from non-manufacturing sectors such as market and sales analysis, and accounting and financial control through to manufacturing activities of production control and numerical control of machine tools. The integration of all these sub-systems is referred to as CIM.

CIM includes complete integration of following activities:

(i) Group technology

(ii) Computer aided process planning

(iii) Material requirement planning and manufactur­ing resource planning

(iv) Production planning, control and scheduling

(v) Material handling

(vi) Robots and robotics

(vii) Computer-aided design

(viii) Computer-aided manufacturing

(ix) Customer interface

(x) Financial and accounting activities

(xi) Generation of reports for top management.

Thus the most important aspects of CIM are:

(i) Capture and collection of relevant data

(ii) Intelligent consideration and decisions made based on this information

(iii) Flow of appropriate data to the sub-system.

Micromachining:

Micromachining refers to the miniaturised shaping of objects by both conventional and nonconventional methods of machining. Material removed rate is small than several micrometers. Improvement of the equipment precision is main aim.

Micromachining applications are found for extremely compact electrical circuits, miniaturised integrated circuit packages, fuel injection nozzels, micro-effectors to handle biological cells and genes, miniaturised tools for surgery, etc.

In conventional methods, vibration is imparted to cutting tool to remove material without imparting cutting force on tool. Diamond and hard ceramics are used for abrasives.

Diamond micromachining is used in optical and electronic industries to accuracy of 0.01 µm and good surface finish, low subsurface damage in materials. Diamond micro machining at the ductile mode producers mirror like surfaces in hard and brittle materials.

Diamond micro grinding at the ductile mode is used for machining of brittle materials (ceramics) at grinding wheel speed of 30 to 60 m/s, workpiece speed of 0.1 to 1.0 m/ min and depth of cut 1 to 10 µm. Micro-grinding in ductile mode minimises sub-surface damage and micro cracking.

Magnetic abrasive micro-finishing uses magnetic abrasive brushes. These are energised electromagnetically across a small machining gap formed between the work surface and magnetic poles. Finishing abrasion action removes defects like scratches, hard spots, lay lines etc.

Abrasive micro-lapping is used for machining magnetic and electronic materials like ceramics, silicon, quartz wafers etc.

Micro-ultrasonic machining uses a micro tool vibrating at ultrasonic frequency. The submicron abrasive grains are driven to create a brittle breakage. It is used to machine brittle materials.

Non-conventional micro machining processes include thermal erosion, µEDM, laser micromachining, micro electrochemical erosion, chemical assisted mechanical polishing, mechano chemical polishing, etc.

Nano-Manufacturing:

Nano structures are formed by Nano factrication processes like photon and electron beam lithography to produce patterns and/or layers of material. Non-conventional processes like polymer replication processing by hot embossing or imprinting, injection moulding, laser ablation, soft lithography and X-ray photo lithography are quite popular.

Processes like electron beam machining, focused ion beam, reactive ion etching and pulsed laser ablation are swarf-free and virtually zero force processes. Future trend is to use optical lithography to produce fine widths below 100 nm.

In Nano-Manufacturing, every atom and molecule is positioned in the correct position and Nano-structures that follow the laws of physics and chemistry. It is possible to generate ultra-precision surfaces with roughness value less than 1 nm.

Energy beam processes are used for material removal, accretion and chemical surface modification transformation on a molecular scale. Chemical surface modification is possible with depositing of low surface energy polymerised fluro-carbon film in the field free zone of plasma reactors.

Electron beam and ion beam techniques being electro thermal processes can produce high density energy to remove material in atomic-bit processing mode. Focused ion beam process is used for cutting and repairing of individual tracks in prototype integrated circuits.

Nanometer level surface roughness can be achieved with plasma chemical vaporisation machining process. In this process plasma is generated between an electrode (in the shape of hollow cylinder or rotating disk) and the sample in the presence of a gas.

Electron beam lithography technique, popular for Nano imprint fabrication, uses an electron beam to expose an electron sensitive resist. The electron beam gun is a part of a scanning electron microscope. The beam control and pattern generation are achieved through a computer interface. The electron scattering in the resist limits the attainable resolution of 10 nm.

Electron beam lithography can be used to fabricate various nanostructures in conjunction with processes like life off, etching and electro deposition. Quantum wells, super lattices, quantum wire and dots etc. can be fabricated by subsequent steps such as etching and selective growth.

Molecular Nano-manufacturing enables self-assembly without using organic monolayers, Self-assembly is a nanofabrication technique involving aggregation of colloidal Nano-particles into the final desired structure. Atoms, molecules, molecular aggregates organise and arrange themselves into ordered functioning entities. Interfacing of molecules is possible by chemical activation of probe and substrate to be built up or modified.

Scanning tunneling (STM) and atomic force microscopes are used to fabricate surface structures at atomic dimensions. The scanning tunnelling micro-scoping (STM) utilises an evanescent wave with an intrinsic wavelength of about 1 nm, which extends beyond the surface of a sharp metal tip. If a conducting surface is brought to within 1 nm of the tip and a potential difference is applied between them, then a tunnelling current will flow.

The scanning probes enable to manipulate matter down to the atomic level to form structures. The forces between STM tip and an absorbed atom are used to move atom to a new location on the surface. Individual surface atoms can be removed and/or deposited by direct tip sample contact, high tunnelling currents or voltage pulses.

Atomic force microscope has a sharp tip less than 100 Å in diameter and a few microns long. It probes the surface of a sample with sharp tip which is located at the free end of cantilever. Forces between the tip and the sample surface cause the cantilever to bend or deflect and a detector measuring the deflection of cantilever. The measured cantilever deflections, as it is scanned over the sample, allow a computer to generate a map of surface topography.

The force associated with atomic force microscopy is inter-atomic force called the van der Waals force.

Manufacturing in Space:

The manufacturing in space offers advantages of zero gravity and perfectly clean and pressure-less environment.

This environment will be helpful in:

(i) Growing crystal chips used in electronic products,

(ii) Making pure metals by refining due to absence of dust and pollutants,

(iii) Mixing liquids that do not easily mix together on earth due to gravity,

(iv) Enable making alloys of any combination of metals, for instance, alloy of lead and aluminium can be made and this alloy has a nearly zero coefficient of friction due to long- lasting, self-lubricating properties,

(v) Making perfect spheres i.e. round ball-like objects,

(vi) It will be possible to manufacture nearly 400 super-alloys which will greatly improve the strength, cost, weight, wear characteristics, conductivity and several other properties,

(vii) Production of super-pure glass in space will enable manufacturing fibres for improved fibre-optics communication technology.

Globally Competitiveness:

To become globally competitive, industries are doing all that is possible to excel in quality, productivity, safety, delivery and cost. People, who are assets of company have to be innovative in all areas of operation, may it be customer satisfaction, supply chain integration, or human resource management.

Practice of waste removal by critically examining every cost element of an operation/product and taking appropriate actions to reduce them. In attempt to reduce cost we should not cut down technology or compromise with quality. Manufacturing technology being adopted should be of fool proof design, i.e. zero defect. Automation should be adopted where-ever necessary.

Best systems, best materials can produce best products only if best people support them. It is necessary that we enable humans to secure their intrinsic abilities by securing, organising and treating people at work properly by imparting suitable training and education at all levels, abilities for effective communication and awarding talents.

It is important to understand the psychology of local people and align ourselves with the prevailing culture aspects. Human resource management is important for success of an industry and it is both science and art. Ability to grow own people through training and education and creating environment to enable people to contribute their best is important part to be truly world class.

Fast retrieval of correct and appropriate information is essential for increased manufacturing flexibility, reduced lead times, enhanced product and process quality, increased productivity and healthy bottom line. Globalisation has made manufacturing industries to wake up to bigger challenges and greater opportunities.

Industry is today conscious of issues like time, cost, quality, safety, product innovation and optimisation, waste management and implementation of appropriate information technology (IT) solutions to provide intelligent solutions and increase productivity.

In the present competitive scenario, IT is playing a decisive role to increase effectiveness of manufacturing processes and activities. In fact IT is today affordable and accessible and it has come a long way in offering easy operation and solutions in conceptualisation, economic selection of materials and resources, decision making, monitoring automation of the machines and business processes, analysis and trouble shorting, marketing, distribution and sales, business solution, etc.

IT has rightly penetrated in all areas of manufacturing and increased business value. Accordingly, database management systems, enterprise resource planning systems, simulation and computer aided design and analysis tools have become indispensable in manufacturing industries.

Resource Efficiency—Reduce Waste, Reuse, and Recycle (Three R’s):

Wasted resources are lost profits. Resource efficiency promotes the reduction of waste, the reuse of materials, and recycling. Resource efficiency is thus concerned with obtaining the maximum benefit from every resource, i.e. adopting best practices to improve operations and create an organizational culture that values resource efficiency.

It is important to follow the policy of buying ‘green’ products, i.e., prioritize the selection of materials and products with the following characteristics:

(i) Products that efficiently use energy, water, and other resources to reduce both consumption and waste and materials found locally or regionally.

(ii) Products with identifiable post-industrial and post- consumer recycled content and salvaged, refur­bished, or remanufactured materials.

(iii) Products made from natural, plentiful, or renewable materials and preferable labeled low VOC’ (volatile organic compounds).

(iv) Products manufactured using resource-efficient processes, and certified by an independent third- party source.

(v) Products that can be easily dismantled and reused or recycled at the end of their useful life, and recycled or recyclable product packaging.

(vi) Successful goal achievement requires consistent effort. Set goals to reduce waste, reuse materials, and recycle. Provide on-going training on conservation and recycling. Use signs and placards that promote conservation and recycling habits.

(vii) Incorporate the ‘three R’s’ expectations across company job descriptions and policies, and start a suggestion and incentive system to recognize and encourage three R’s behaviours.

Prevention of Waste:

Waste can be prevented by extending the useful life of equipment with preventive maintenance, turning off lights and computers when not in use, reducing paper use by printing less and by making double-sided copies, organising meetings by teleconferencing and webinars instead of traveling to meetings, borrowing instead of buying-share power tools and other items that are not frequently used, using durable, reusable products rather than single-use materials, order supplies to exact requirement, offer incentives to employees to bike, walk, use public transportation, or carpool.

Recycle (collecting recyclable materials that would otherwise be considered waste) and reduce e-waste. Recycling reduces the need for landfill waste, reduces pollution, saves energy, decreases greenhouse gas emissions, conserves natural resource and helps sustain the environment.

Future Trends in Intelligent Machine Tools:

(i) Be able to model the skills and expertise of experts so as to be able to make small be tools of parts without human intervention.

(ii) Use of light weight, height strength alloys.

(iii) Greater use of easy to machine composite materials.

(iv) Higher spindle speeds and faster table feeds, informed feedback deuch laser scales, with etc.

(v) More accurate and stable machines with machine sensors to maintain thermal and vibrational stability.

(vi) Faster setup, keener and exacting quality control methods.

(vii) Ability to get “a good first part right the first time”.

(viii) Unattended manufacturing with knowledge rich controllers, rugged vision and other sensors and feedback methods, comprehensive diagnostic pack­age to monitor and successfully react to emergen­cies.

(ix) Composite/granite structures of machine tools and high speed spindles.

(x) Accurate and automated loading and fixturing— Tool changers will be faster and more selective, enhanced by tool-wear sensing and replacement devices.

(xi) Chip control and disposal to suit unattended manu­facturing.

(xii) Machine tools to have heavy tables close to the ground for maximum support and vibration resist­ance (instead of having table at waist height on knee support for a person to intervene).

(xiii) Use of composite materials to improve vibration damping, resistance to warping and thermal sta­bility of machine tool tables.

(xiv) Laser and ion beam technologies for manufactur­ing will be used to take care of problems of wear of cutting tools.

(xv) With advancement in photonics devices, it will be possible to run millions of virtual computers through the same optical mechanisms all operating at different frequencies.

(xvi) Generic tooling inventories will be minimised.

(xvii) Inventory of several parts will be reduced as parts will be produced by pressing and sintering the powder.

(xviii) Self diagnostics, contingency planning, and creative use of resources will deserve greater attention.

(xix) Expert system technology to be a built-in component of a machine tool with provision of encoding some heuristics by experts and some automatically deducted by controllers.

(xx) Feedback techniques—(both hard ware and software) will enable to make approach to manufacturing more vigorous.

This will enable to reliably change parameters and control the effects on the manufacturing process with full assurance and confidence

(i) New manufacturing techniques will be developed to manufacture small components which will be required to build sophisticated arrays of sensors (e.g. robot skin), output/devices (e.g. flat display panels), and actuators (e.g. muscle like motors from fibres) etc.

(ii) Quality control will be part of manufacturing process plan to guarantee that parts emerging from the intelligent machine tool are accurately produced.

(iii) Growth in both knowledge and sensors will lead to the automated self-correcting machines.

Present Trends in Production Technology:

Various obvious trends in manufacturing world today are clear indicators of the factories and workshops of future. The overall aim of these trends is as a result of achieving higher efficiency, productivity, and competitiveness.

Various trends to be seen are:

(i) Greater Emphasis on Quality and Reliability:

Techniques to achieve higher quality at competitive prices are well recognised and being adopted. There is a clear trend to adopt ISO 9000 standard in order to be recognised in the world. The advantages of quality and reliability, viz. higher consumer acceptance, increased sales volume, lower unit costs, less problems in field service, etc. are well appreciated. It is clearly understood that there are no options but to strive for quality and reliability in the manufactured products.

(ii) Shorter Product Life Cycle:

Due to greater competition and survival of fittest, there is technological rat- race which has resulted in shorter product life cycles. The products become obsolete very fast. The moment a new model is released, the design and research activities start for advanced version.

The industry is thus faced with task of development and production of new products of increased complexity in less time. Fortunately this task is achieved by parallel developments which have taken place in the field of computers, computer aided design and manufacturing field.

(iii) Greater Usage of Microprocessors:

More and more consumer products, business products and industrial products are incorporating microprocessors (computers on chips) for data processing, control and communication purposes. Chips have set in a great industrial revolution. Applications are infinite.

Automation has become essential. Control of units producing microelectronics is beyond human slow capabilities and limitations. Robots are going to find more and more applications. Day is not far when total production, assembly, and testing may be done by robots and human beings may be required only for overall supervision.

(iv) Manufacturing in Small Batches due to Demand of More Customised Products:

Every customer dictates special features to suit his own requirements and limitations. The manufactured products are thus becoming more individualised and custom-engineered. There are thus more special options and features to meet customised needs.

The batch size is accordingly smaller and mass production of products is not feasible. Numerical control machine tools, flexible manufacturing systems, and CAM systems have all the answers for meeting such requirement at competitive costs.

(v) Use of New Materials and Processes:

Conventional materials are getting replaced by new and unconventional materials. A great revolution has been brought in by plastics, ceramics, and composites. These materials call for use of newer production techniques. The newer materials offer the advantages of light weight, greater styling flexibility, and life matching the shorter product life cycles.

(vi) Just-In-Time (JIT) Production:

This technique is being adopted due to higher pressure to reduce inventories of raw-materials and bought out items in factories. The idea is to minimise idle cost in maintaining huge stocks. JIT enables factories to plan their inventories so that the supplier delivers the desired materials and components just in time (i.e. say a few hours before it is required). This reduces both the time period and investment in raw materials, components and the cost involved in stocking them.

(vii) Point-of-Use Manufacture:

This technique ensures no time delay between use and production of a part. The workstations producing the parts are located adjacent to the assembly line and without any time loss feed them to the assembly operations, thus reducing the amount of work- in-process.

In order to reduce the risk of entire assembly line coming to stop in the event of failure of any component production workstation, a small buffer of parts is typically held between the workstation and assembly station.

(viii) Focused Factories:

When attempts are made to totally automate a factory, the problems of operating and controlling it will grow significantly or its size and capacity increase. It is thus felt that the automated factory will be most successful when its activities are limited to certain products and processes rather than engage in too many different things.

This has led to the idea of focused factories which will concentrate their efforts on a limited, concise, manageable set of products, technologies, volumes and markets. Focused factory will use principles of group technology and standardisation in design, raw materials, tooling and production processes. The focused factories will thus specialise in certain activities and some of the less usable activities may have to be sublet to outside contractors.

Trends in Future Automated Factory:

Computers will find greater applications in planning, monitoring, control and management of production. This will result in computer integrated factory. Such a factory will be ideally suited for production of discrete components manufactured in small batch sizes. All the important functions of a factory, viz. processing, assembly, material handling, inspection, and control will be achieved by using computers.

The number of persons participating directly in the processing will be minimal. The level of automation, compared to continuous process plants, will be more complex because of the information processing requirements in dealing with a diverse mix of individual product.

Each product will be specified by parts list, operating specifications, assembly drawings, inspection requirements, etc. Each product in turn will have several components which have to be uniquely defined in terms of geometry, material, processing (requirement of raw material, and machines, etc.). Production schedules have to be created, materials ordered, productive resources planned, etc. The amount of information to be generated and managed in the plant will thus be substantial.

The raw materials have to be processed and manufactured, products assembled. Machining at high speed (900 to 1500 m/minutes) will be required to match advancements. This will pose a challenge on designers of machine tools. Cutting tools may be based on sintered polycrystalline diamond and other super-hard materials with coatings.

Machine tools for higher productivity with greater structural rigidity, advanced bearings for high speed, automated features, advanced sensor system for tool monitoring, continuous disposal of chips, etc. will be required.

Processes like plastic moulding, powdered metallurgy, casting, forging and other deforming processes which generate the final shape in a single step will be more popular.

The assembly processes are expected to adopt snap fits, adhesive joining techniques instead of mechanical fastening processes, and greater use of robotics is expected.

Computer controlled material handling systems for flexible routing of different parts, and for mechanical interfacing of materials handling and production system will be used.

Inspection systems are expected to become more automated and sophisticated. With developments in sensors and automation technology, 100% inspection will become inevitable. On-line inspection systems with non-contact sensors will find greater applications. Inspection process may get integrated with the production process to form closed loop feedback control system, enabling achievement of zero defects system.

The information processing requirements in automated factory will increase considerably. Distributed database arrangement and hierarchical control structure of computers will become inevitable. Considering the huge and diverse information to be handled, use of artificial intelligence capability will aid in simplifying the task of information handling and processing.

Total integration will be essential so that a change done at one place should be automatically transmitted to various databases that are affected by the change. The problem of compatibility between the diverse types of computers and programmable devices used in the plant will have to be taken care of in order to achieve total integration and communication amongst all the devices and computers.