Unit 1 Industrial Automation

Transcription

1 Unit 1 Industrial Automation Assigned Core Text Reading for this Unit: Groover, M. P. (2008), Automation, Production Systems, and Computer- Integrated Manufacturing, 3 rd ed., Chapter Unit Introduction 1.2 Unit Learning Objectives 1.3 Production Systems 1.4 Automation in Production Systems 1.5 Manual Labour in Production Systems 1.6 Automation Principles and Strategies 1.7 Unit Review 1.8 Self-Assessment 1.9 Self-Assessment Answers Section 1.1 Unit Introduction Automation technology such as robotics, machine tools, handling systems, controllers and computers are one of the most important industries in the world and provide manufacturing industry with the means to improve quality, reduce errors, increase productivity and reduce cycles times. Manufacturing has had a long history, ranging from the initial creation of simple, hand-crafted items, to the development of large complex factories that include a host of factory-related production and fabrication techniques. The study of the systems of manufacturing and production has evolved into a complex field of research in its own right. Manufacturing and production in the contemporary world faces the following challenges: BULLETLIST Globalisation countries from all over the world are now major players in the field of manufacturing. Indeed, the manufacturing base has been seen to widen in the last twenty years or so, with the emergence of major manufacturing centres in Asia (China, India, South Korea), and in Latin America (Mexico, Brazil, Peru) International outsourcing traditional manufacturing once saw much production work done locally, or in one country; recently, however, there has been a move towards sourcing parts and products from offshore manufacturers Local outsourcing a further outsourcing trend has seen manufacturing work traditionally done inside the firm, being outsourced to local suppliers, with benefits being derived from: use of specialist suppliers, thus reducing costs; lower labour costs in smaller companies; and overcoming in-house technology limitations

2 Contract manufacturing under contract to other companies, firms that specialise in specific manufacturing techniques produce whole products or parts, as per the specifications given them by the contracting company. Contract manufacturers specialise in efficient production techniques, and let the contracting firm focus upon other business elements such as design and marketing Services there has been a move towards the service sector and away from manufacturing, best seen in the decline of manufacturing-related jobs, and the growth in service-sector jobs Quality there is a growing demand for perfect quality products every time, all the time, from both corporate customers and end consumers Efficiency manufacturing labour costs are not the same on a global basis; and so, to be competitive, companies in high-labour cost areas must find other ways, such as operational efficiency, typically using automation, to offset labour costs ENDLIST Each of these challenges creates a complex environment for manufacturing. The latter challenges summarise the growing demand for automation by firms located in high cost economic areas such as north America and Western Europe. Automation provides a mechanism to increase quality and reduce costs of production. In this unit the concept of a production system is defined, with sections on the use of automation in production systems, and the deployment of manual labour. Sections are included that describe the key principles that underlie automation adoption, and the fundamental strategies used to implement automation in a production system. Section 1.2 Unit Learning Objectives After completing this unit you will be able to: BULLET LIST Recognise the concept and elements of a production system Describe the key functions of manufacturing support systems Recognise the three basic types of automation Define computer-integrated manufacturing Describe how manual labour is deployed in production systems Determine when to use automation in manufacturing systems

3 Outline key automation principles and strategies ENDLIST Section 1.3 Production Systems A production system is a collection of people, equipment, and procedures organised to perform the manufacturing operations of an organisation. There are two levels within a production system: NUMLIST Facilities the factory, the equipment in the factory, and the way the equipment is organised around the shop floor Manufacturing support systems the set of procedures used to manage production and to solve technical and logistics problems met in manufacturing processes. These systems include product design, planning and control, logistics and other business functions. ENDLIST A production system consists of facilities and manufacturing support systems. END A manufacturing system is a logical grouping of equipment in the factory and the workers who operate it. Examples include worker-machine systems, production lines, and machine cells. A production system is a larger system that includes a collection of manufacturing systems and the support systems used to manage them. A manufacturing system is a subset of the production system. Portions of production systems tend to be automated and/or computerised, while other parts may be operated by manual labour (see Figure 1.1). The overall operation of the production system is controlled by people, including direct labour staff for facility operation, and professional staff with responsibilities over the manufacturing support systems.

4 Figure 1.1: View of manufacturing cells within a production system Facilities include the factory, production machines and tooling, material handling equipment, inspection equipment, and computer systems that control the manufacturing operations. Facilities can also include the plant layout that is, the physical arrangement of the equipment in the factory, which is usually organised into logical groupings called manufacturing systems. The facilities of a production system includes the factory, production machines and tooling, material handling equipment, inspection equipment, and computer systems that control the manufacturing operations. END Manufacturing systems consist of groups of machines and associated workers. Typically, the manufacturing system comes in direct physical contact with the product or parts to be made. Three types may be identified, as outlined in Table 1.1. Category Manual Work System Worker-Machine Systems Table 1.1: Three categories of manufacturing systems Description One (or more) workers performing one (or more) tasks without powered tools. Typical example is the material handling task. In production tasks the use of hand tools is pre-dominant, sometimes with optional work-holder. Examples include: filing milled parts; checking quality of parts with micrometer; moving cartons using a dolly; and, assembling machinery using hand tools. A human worker operates powered equipment, in various combinations of one (or more) workers, and one (or more) pieces of equipment. Relative strengths of humans and machines are

5 Automated Systems combined. Examples include: machinist operating engine lathe; a fitter working with an industrial robot; a crew of workers operating a rolling mill; and personnel performing work on a mechanised conveyor. Process is performed by machine without the direct participation of a human worker. Automation uses a programme of instructions and a control system for implementation; there are two sub-categories: semi-automated, and fully automated. Semi-automation implies only part of the work cycle is completely automated, with other work done by a human worker. A fully automated machine, on the other hand, has the capacity to operate for extended periods of time (longer than one work cycle) with no human interaction. However, although fully automated, human monitoring may still be used. Examples include: injection moulding machines; and automated processes in oil refineries and nuclear power plants. Manufacturing systems consist of groups of machines and associated workers. There are three types: manual work systems; worker-machine systems; and automated systems. Automated systems may be fully automated or semiautomated, depending on their operating characteristics. END Manufacturing Support Systems are used by a company to manage its production operations. Most support systems do not directly contact the product, but they plan and control its progress through the factory. Manufacturing Support Systems use a four-function information-processing cycle that is explained in Table 1.2. This list of functions is activated by customers orders, which propels the system into action, and operates by deploying the facilities detailed above. Table 1.2: Information-processing cycle for Manufacturing Support Systems Function Business Function Product Design Manufacturing Planning Description First and last phase. The principle means of communicating with the customer, includes sales and marketing, sales forecasting, order entry, cost accounting, and customer billing. Product originates from customer order, and after sales and marketing, proceeds to become a production order. Production order is in the form of one of the following: a manufacturing order against customer specifications; a customer order to buy one or more of manufacturer s proprietary products; or, an internal company order based on future-demand forecasts. Second phase. If product is manufactured by customer design, then design supplied by customer. If there are customer specifications, then manufacturer s design department may be contracted to create a design on this basis, as well as to manufacture the product also. For a proprietary product, the manufacturing firm is responsible for its development and design. Third phase. Upon completion of product design, the associated information is given to the manufacturing planning function. Process planning, master scheduling, requirements planning, and capacity planning are performed here. Process planning determines the process and assembly steps, and the order of the steps, needed to

6 Manufacturing Control produce the product. The master production schedule lists products to be made, when they are to be made, and the quantities of each to be produced. Based upon the master production schedule, requirements planning is performed that is, the individual components, sub-assemblies, raw materials etc. required are purchased, created, and scheduled to be available when needed. Capacity planning is concerned with planning the manpower and machine resources to carry out the manufacturing function. Fourth phase. Concerned with managing and controlling the physical operations in the factory to implement the manufacturing plans. Shop floor control, inventory control, and quality control are performed here. Shop floor control monitors the product as it moves about the shop floor; as the product is a work-in-process inventory as it proceeds across the shop floor, shop-floor control is related to inventory control also. Inventory control tries to maintain the correct amount of inventory in the manufacturing system, and avoid overloading or starving the system. Quality control tries to ensure correct product and component quality, as per the specified design. It uses inspection activities on the shop-floor, and at the point of entry of outsourced components, to do this. Manufacturing Support Systems are used by a company to manage its production operations. It uses an information-processing cycle consisting of the following functions: Business Function; Product Design; Manufacturing Planning; and Manufacturing Control. END PROFESSIONAL TRANSFERABLE SKILLS [CRIT] [PROB] [WCOMM] LEARNING ACTIVITY 1.1 Use the internet or a company with which you are familiar to investigate what systems have been put in place for the information-processing cycle: business function, product design, manufacturing planning, and manufacturing control. Focus on images (e.g. Google Images), software products that are available (e.g. SAP or BAAN). Write a short report outlining details of the manufacturing support systems that you have found. END LEARNING ACTIVITY 1.1 Section 1.4 Automation in Production Systems There are two types of production system automation: automation of the manufacturing systems, and computerisation of the manufacturing support systems. Since automation of the manufacturing systems consists of some computerisation for control and operational purposes, the two types tend to overlap. The term computer-integrated manufacturing is used to indicate this extensive use of computers in production systems (see Figure 1.2).

7 Figure 1.2: Computer equipment, sensors and actuators used in production Computer-Integrated Manufacturing is the term used to indicate the extensive use of computers in production systems, through the automation of manufacturing systems, and the computerisation of manufacturing support systems. END Automated manufacturing systems operate in the factory on the physical product. Typical processes performed under this system of operation include processing, assembly, inspection, and material handling; often some of these are performed simultaneously. There are three basic types of automated manufacturing system, which are outlined in Table 1.3. They generally operate in fully-automated mode, although, with programmable systems, semi-automated systems may be favoured in certain instances. Type Fixed Automation Table 1.3: Typology of Automated Manufacturing Systems Description Sequence of processing or assembly operations fixed, as equipment configuration is fixed. Each operation in sequence is typically simple in nature, usually using combinations of plain linear or rotational motions to achieve results. Characteristics of fixed automation include: high initial investment in customised equipment; high production rates; and relative inflexibility to accommodate product varieties. Examples include transfer

8 Programmable Automation Flexible Automation lines, and automated assembly machines. Sequence of operations can be changed to accommodate different product configurations. This is done by use of a programme, a set of coded instructions, which is read and interpreted by the system; by using different programmes, the system can be configured as required. Regularly used in low- to medium-volume production, but requires physical setup change-overs from one part style to the next. Characteristics of programmable automation include: high investment in general-purpose equipment; lower production rates than fixed automation; greater flexibility to deal with variations and product change-overs; and high suitability for batch production. Examples include numericallycontrolled machine tools, industrial robots, and programmable logic controllers. Capable of producing a variety of parts with virtually no time lost for change-overs from one part style to the next. The system can produce various mixes and schedules of parts or products instead of requiring batch production. This system takes advantage of part or product similarities, so that the amount of change-over required is minimised. Characteristics of flexible automation include: high-investment in customised system; continuous production of variable mixtures of products; medium production rates; and flexibility to deal with product design variations. Examples include flexible manufacturing systems. There are three types of automation: fixed automation; programmable automation; and flexible automation. END PROFESSIONAL TRANSFERABLE SKILLS [CRIT] [PROB] [WCOMM] LEARNING ACTIVITY 1.2 Use the internet or a company with which you are familiar to investigate what automation systems have been put in place for machine processing (e.g. CNC machines), material handling (e.g. Robotics), transportation and storage (e.g. AS/RS) and inspection (e.g. CMM). Focus on images (e.g. Google Images), and available products (e.g. KUKA Robotics). Write a short report outlining details of the automation that you have found. END LEARNING ACTIVITY 1.2 The relative product varieties handled, and the production quantities enabled by the three types of automation are compared in Figure 1.3. As can be seen for greater production quantities fixed automation is ideal, although this sacrifices significant product variety; alternatively, greater product variety is ensured in the programmable automation model, although the quantities produced are not comparable with fixed automation.

9 Variety Programmable Automation Flexible Automation Fixed Automation Quantity Figure 1.3: Product variety against Production quantity Computerised manufacturing support systems aim at reducing the clerical- and human-effort required to run the production operations of the firm. Nearly all modern manufacturing support systems are implemented using computers. As noted above, the term computer-integrated manufacturing (CIM) is used to indicate this extensive use of computers in production systems; whereby computer systems are used to design the products, plan the production, control the operations, and perform the various information-processing functions needed in a manufacturing firm. These functions, when combined together, form the CIM system. Various parts of the CIM system have individual names; these include the computer-aided design (CAD) system the computer system for supporting the product design function; and the computer-aided manufacturing (CAM) system the computer system used to perform manufacturing engineering functions. In some CIM applications CAD and CAM functionalities are combined to produce the integrated CAD/CAM system. Other computerised systems include customer relationship management (CRM), computer aided process planning (CAPP) and computer aided inspection (CAI) and so on. Computerised manufacturing support systems aim at reducing the clerical- and human-effort required to run the production operations of the firm. END Section 1.5 Manual Labour in Production Systems Although automation in production systems is more predominant now than it has ever been, there is still a significant place for manual labour. Manual labour is required to manage and maintain the plant, and can be examined across two criteria: manual labour in factory operations; and labour in manufacturing support systems.

10 For manual labour in factory operations, there are a number of parameters to be considered: manual labour cost; manual labour tasks; manual labour flexibility; manual labour demand; and manual labour requirements. These parameters are briefly discussed in Table 1.4. Task Manual labour cost Manual labour tasks Manual labour flexibility Manual labour demand Table 1.4: Manual labour in factory operations Description The cost of labour can differ as we move from location to location; for example, from one country to another. In places where the average hourly rate paid to manual labour is extremely low, automation projects are hard to justify. Outsourcing work to areas where manual labour is relatively inexpensive is also an option that inhibits automation take-up. Certain tasks are difficult, or impossible, to automate. These tasks must be performed by manual labour. Reasons for automation difficulties include: problems of physical access; adjustments required in the task; manual dexterity requirements; and demands on handeye co-ordination. Manual labour can be more flexible than its automated counterpart. In situations where a product is expected to have a short product lifecycle, and hence a fast product launch, manual labour may be favoured, as tooling costs are lower than for automation. Similarly, if a one-of-a-kind product is to be produced, manual labour may be chosen for its versatility and adaptability. Demand patterns in some industries can go up and down, or be seasonal. Manual labour can be hired and laid-off as necessary, while automation requires an investment in equipment, which is a fixed cost. Equipment has a fixed upper limit to its production rate, while manual labour, since can be increased or decreased, has no such limits. There are a number of issues that affects the use of manual labour in factory operations: manual labour costs; the tasks manual labour are expected to do; the flexibility of using manual labour; and the demand patterns under which we use manual labour. END For manufacturing support systems, labour is primarily office based and used in a number of specific ways, often to aid the work of automated systems. A number of tasks that were once in the domain of manual labour have been automated using computer systems. These include material requirements planning (MRP), which generates order releases for component parts and raw materials, based upon the master production schedule. MRP requires huge amounts of data processing, and so has become automated; however, humaninteraction is still used to monitor and to check periodically the results that the MRP system is producing.

11 Figure 1.4: Human labour in manufacturing systems In general, the computer is used as an aid in performing virtually all manufacturing support activities; however, humans will continue to be needed in manufacturing support systems, even as the level of automation increases. People will be required to do the decision-making, learning, engineering, evaluating, managing, and other functions that make these automated systems operable. Specific tasks that remain in the domain of the human include: BULLETLIST Equipment maintenance automated systems must be maintained and repair by skill technicians, as necessary Programming and computer operation software upgrades and programme execution for automated equipment must be performed by people, if the automated systems are to remain up-to-date Engineering project work it is likely that there will be a continual need to upgrade production machines, design tooling, solve technical problems, and undertake continuous improvement projects. All of these tasks must be performed by human engineers

12 Plant management someone must be responsible for running the factory. Management, at all levels, is likely to remain to cover necessities such as plant operation, and administrative and personnel issues. All of these functions can only be carried-out by humans ENDLIST Human labour will continue to be required to do the decision-making, learning, engineering, evaluating, managing, and other functions that make automated systems operable. END Section 1.6 Automation Principles and Strategies Automation may not always the right answer for a given production situation. A certain caution and respect must be observed in applying automation technologies. Three approaches for dealing with automation projects are outlined in Table 1.5. Automation may not always be the right answer and various approaches (principles and strategies) are needed to assess each particular situation. END Approach The USA Principle Ten Strategies for Automation and Process Improvement Table 1.5: Automation principles and strategies Description General approach that consists of three steps: 1. understand the existing process; 2. simplify the process; and 3. automate the process. In the first step all details of the process must be comprehended, including the inputs, outputs, the process sequence, the value added by the process etc. Traditional engineering tools, such as flow charts, may be used here to capture the relevant information; while mathematical models may be deployed to obtain input and output variables. In the second step we must search for ways to simplify what we have mapped in the first step. Tools used here include checklists on existing processes that question their usefulness, and whether they can be replaced or not. In the third step automation is considered. Possible forms of automation are listed and discussed, often using the next approach. An automation migration strategy might also be considered. After the USA principle has been used, and automation has been found as a feasible solution, we can implement the following ten strategies, in a checklist format, to search for improvements; they are in no particular order. NUMLIST Specialisation of operations use special-purpose equipment designed to perform one operation with the greatest possible efficiency. Combined operations reduce the number of distinct production machines

13 or workstations, and perform more than one operation at a given machine, thereby reducing the overall number of machines used. This saves on setup times, material handling effort, waiting times, and manufacturing lead time. Simultaneous operations simultaneously perform the operations that are combined at one workstation. This reduces total processing time. Integration of operations link several workstations together to form a single integrated mechanism, and use automated work handling devices to transfer parts between the linked stations. Reduces the number of separate work centres, and as several parts may be processed simultaneously, overall output of the system increased. Increased flexibility use flexible automation to achieve maximum utilisation of equipment for job shop and medium-volume situations. This means using the same equipment for a variety of parts or products. This leads to reduced set-up times, programming times, less work-in-process, and lower manufacturing lead times. Improved material handling and storage improve non-productive time by using automated material handling and storage systems. This can reduce both work-in-process, and manufacturing lead times. On-line inspection incorporate inspection into the manufacturing process, and correct the process as the product is being made. Reduces scrap and rework, and improves quality of products at the end of the process. Process control and optimisation implement a wide range of control schemes with the intent of operating the individual processes and associated equipment more efficiently. Process times can be reduced, and product quality can be improved. Plant operations control improve the aggregated operations in the plant by implementing a high level of computer integration and networking within the factory. Automation Migration Strategy Computer-integrated manufacturing (CIM) integrate factory operations with engineering design and the business functions of the firm. ENDLIST Often successful products, manufactured using methods of manual labour, become candidates for automation. An automation migration strategy, or a formalised plan for evolving the manufacturing system from one based on manual labour, to one based on automation, may be deployed. It has the advantage of being graduated, as automation is introduced step-by-step, and not all at once. Typically it contains the follow steps: NUMLIST Manual production in single-station manned cells, that operate independently, is used upon product introduction; this allows us to use quick and low-cost tooling. Automated production, using single-station automated cells operating independently, follows. As product demand grows, automation costs can be justified; single stations are automated and the production rate increases. Manual transfer of parts remains though.

14 Automated integrated production the final step follows. This uses a multistation automated system with serial operations, and the automated transfer of work units between stations. This occurs when the firm is confident that they can produce the product in mass quantities over several years, for a willing market. It justifies further automation expenses, and the phased reduction of manual labour, while the production rate rises to meet demand. ENDLIST A strategy for automation implementation should consider the following elements: Examine the existing system; Assess various strategies for automation; Implement a graduated migration strategy from manual labour to automation. END Section 1.7 Unit Review The following points summarize the various concepts presented in this unit: BULLETLIST A production system consists of facilities and manufacturing support systems. The facilities of a production system includes the factory, production machines and tooling, material handling equipment, inspection equipment, and computer systems that control the manufacturing operations. It can also include the plant layout. Manufacturing systems consist of groups of machines and associated workers. There are three types: manual work systems; worker-machine systems; and automated systems. Automated systems may be fully automated or semiautomated, depending on their operating characteristics. Manufacturing Support Systems are used by a company to manage its production operations. It uses an information-processing cycle consisting of the following functions: Business Function; Product Design; Manufacturing Planning; and Manufacturing Control. There are two types of production system automation: automation of the manufacturing systems, and computerisation of the manufacturing support systems. Computer-Integrated Manufacturing is the term used to indicate the extensive use of computers in production systems, through the automation of manufacturing systems, and the computerisation of manufacturing support systems. Automated manufacturing systems operate in the factory on the physical product. There are three types: fixed automation where the sequence of potential

15 operations is fixed; programmable automation where a programme is coded into the system to allow for changes in the operational sequence; and flexible automation which extends programmable automation techniques by taking advantage of product similarities to reduce product changeover times, and boost production rates. Computerised manufacturing support systems aim at reducing the clerical- and human-effort required to run the production operations of the firm. Computerised manufacturing support systems are part of the computer-integrated manufacturing (CIM) system, which covers the extensive use made of computers in production systems. Individual parts of the CIM system have their own names, such as the CAD and CAM systems. There are a number of issues that affects the use of manual labour in factory operations. These include: manual labour costs; the tasks manual labour are expected to do; the flexibility of using manual labour; and the demand patterns under which we use manual labour. For manufacturing support systems, labour is also used in a number of specific ways, often to aid the work of automated systems. Labour will be required to do the decision-making, learning, engineering, evaluating, managing, and other functions that make automated systems operable. Automation may not always be the right answer for a given production situation. Principles and strategies of automation, which assess the need for automation, how it should be implemented, and to what depth (i.e. fully- or semi-automated), should be used where possible. A strategy for automation implementation should consider the following elements: 1. examine the existing system, and determine whether or not automation should be applied; 2. assess various strategies for automation and process improvement across the existing system, and determine which to implement; and 3. implement a graduated migration strategy from manual labour to automation, as product demand increases. END LIST Section 1.8 Self-Assessment Questions NUMLIST What is meant by a production system, and what categories of production system are generally specified? Manufacturing systems depend for their operation on the interaction of manual labour and automation. What are the categories of manual labour / automation

16 that can be identified? What mode of automation do these categories usually operate in? Define briefly computer-integrated manufacturing. When is automation used in a manufacturing system? Describe the three types of automation that can be used in a manufacturing system. Manual labour is used alongside automation in production systems. Name a number of the issues that affect the use of manual labour in production systems. What elements should a strategy for automation implementation consider? ENDLIST Section 1.9 Answers to Self-Assessment Questions NUMLIST A production system is a collection of people, equipment, and procedures organized to perform the manufacturing operations of a company (or other organization). Two categories recognised in production systems are facilities consisting of the factory, factory equipment, and equipment configuration; and manufacturing support systems consisting of the procedures used by the company to manage production and to solve the technical and logistics problems faced in production. The three categories of manufacturing system manual labour / automation interaction are: manual work systems; worker-machine systems; and automated systems. Automated systems may be fully automated or semi-automated, depending on their operating characteristics. Computer-Integrated Manufacturing is the term used to indicate the extensive use of computers in production systems, through the automation of manufacturing systems, and the computerisation of manufacturing support systems. Automated manufacturing systems operate in the factory on the physical product. There are three types: fixed automation where the sequence of potential operations is fixed; programmable automation where a programme is coded into the system to allow for changes in the operational sequence; and flexible automation which extends programmable automation techniques by taking advantage of product similarities to reduce product changeover times, and boost production rates. There are a number of issues that affects the use of manual labour in factory operations. These include: manual labour costs; the tasks manual labour are

17 expected to do; the flexibility of using manual labour; and the demand patterns under which we use manual labour. There are three specific areas that come into consideration for a strategy for automation implementation; these are: first, to examine the existing system, and determine whether or not automation should be applied; second, to assess various strategies for automation and process improvement across the existing system, and then to determine which to implement; and finally, to implement a graduated migration strategy from manual labour to automation, as product demand increases. END LIST