7 1 Layout and Flow Nigel Slack Stuart

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7. 1 Layout and Flow © Nigel Slack, Stuart Chambers & Robert Johnston, 2004

7. 1 Layout and Flow © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 2 Chapter coverage • Basic layout types • Selecting a layout type •

7. 2 Chapter coverage • Basic layout types • Selecting a layout type • Detailed design of a layout © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 3 Layout: The layout of an operation is concerned with the physical location

7. 3 Layout: The layout of an operation is concerned with the physical location of its transforming resources, that is deciding where to put the facilities, machines, equipment and staff in the operation. Layout types: 1) Fixed position layout 2) Process layout 3) Cell layout 4) Product layout © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 4 Fixed position layout 1) In a fixed position layout, the transformed resource

7. 4 Fixed position layout 1) In a fixed position layout, the transformed resource does not move between its transforming resources. 2) Equipment, machinery, plant and people who do the processing move as necessary because the product or customer is either: i. Too large ii. Too delicate or iii. Objects being moved © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 5 Process layout 1) In a process layout, similar processes or processes with

7. 5 Process layout 1) In a process layout, similar processes or processes with similar needs are located together because: i. ii. It is convenient to group them together or The utilization of the transforming resource is improved 2) Different products of customer have different requirements therefore they may take different routes within the process. 3) The flow in a process layout can be very complex. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 6 An example of a process layout in a library showing the path

7. 6 An example of a process layout in a library showing the path of just one customer Loan books in subject order On-line and CD-ROM access room Study desks Enquiries Company reports To journal sack Current journals Reference section Reserve collection Store room Counter staff Entrance © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Copying area Exit Operations Management, 4 E: Chapter 7

7. 7 Cell layout 1) In a cell layout, the transformed resources entering the

7. 7 Cell layout 1) In a cell layout, the transformed resources entering the operation move into a cell in which all the transforming resources it requires in located. 2) After being processed in the cell, the transformed resource may move to a different cell in the operation or it may be a finished product or service. 3) Each cell may be arranged in either a process or product layout. 4) The cell type layout attempts to bring order to the complex flow seen in a process layout. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 8 The ground floor plan of a department store showing the sports goods

7. 8 The ground floor plan of a department store showing the sports goods shop-within-a-shop retail ‘cell’ Books and videos Footwear Sports shop Menswear Entrance Perfume & jewellery Elevators Confectionery, newspaper, magazines and stationery Women’s clothes Luggage and gifts Entrance © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 9 Product layout 1) In a product layout, the transformed resource flow a

7. 9 Product layout 1) In a product layout, the transformed resource flow a long a line of processes that has been prearranged. 2) Flow is clear, predictable and easy to control. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 10 An army induction centre with uses product layout Waiting area Lecture theatre

7. 10 An army induction centre with uses product layout Waiting area Lecture theatre Doctor Waiting area Doctor Blood test X-ray Uniform issuing area Doctor Blood test Record personal history and medical details X-ray Uniform store Doctor © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Doctor Blood test X-ray Operations Management, 4 E: Chapter 7

7. 11 A restaurant complex with all four basic layout types Line layout cafeteria

7. 11 A restaurant complex with all four basic layout types Line layout cafeteria Cell layout buffet Starter buffet Desert buffet Fixed-position layout service restaurant Main course buffet Service line Oven Preparation Process layout kitchen Cool room Freezer © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Vegetable prep Grill Operations Management, 4 E: Chapter 7

Volume-variety relationship High Flow is intermittent Low High Volume Fixed-position layout Variety Process layout

Volume-variety relationship High Flow is intermittent Low High Volume Fixed-position layout Variety Process layout Cell layout Low Product layout Regular flow more important © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Regular flow more feasible 7. 12 Flow becomes continuous Operations Management, 4 E: Chapter 7

7. 13 Volume and variety Layout selection steps Decision 1 Process type Strategic performance

7. 13 Volume and variety Layout selection steps Decision 1 Process type Strategic performance objectives Decision 2 Basic layout type Decision 3 Detailed design of layout Project process Professional services Jobbing process Service shops Batch process Mass services Mass process Continuous process Fixed position layout Process layout Cell layout Product layout The physical position of all transforming resources The flow of the operation’s transformed resources © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 14 Selecting a layout type © Nigel Slack, Stuart Chambers & Robert Johnston,

7. 14 Selecting a layout type © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 15 1) The nature of the basic layout types Manufacturing process types Basic

7. 15 1) The nature of the basic layout types Manufacturing process types Basic layout types Service process types Project processes Project Fixed position layout Professional services Jobbing processes Process layout Service shops Batch processes Cell layout Mass processes Product layout Mass services Continuous processes © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 16 2) Advantages and disadvantages Fixed Advantages Process Product - Very high mix

7. 16 2) Advantages and disadvantages Fixed Advantages Process Product - Very high mix position and product layout flexibility - High mix and product flexibility layout - Good compromise between cost and layout flexibility Lo- w unit costs for high volume layout - Product/customer not moved or disturbed. - Relatively robust if in the case of disruptions - Fast throughput. - Gives Opportunities for specialization of equipment - High variety of tasks for staff - Easy supervision of equipment of plant - Group work can result in good motivation - Gives Opportunities for specialization of equipment Low utilization of resources. - Very high unit cost. Disadvantages Cell Can have very high WIP - Scheduling space and activities can be Complex flow. difficult. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Can be costly to rearrange existing layout Can need more plant and equipment Can have low mix and flexibility Not very robust to disruption Work can be very repetitive. Operations Management, 4 E: Chapter 7

7. 17 (a) The basic layout types have different fixed and variable cost characteristics

7. 17 (a) The basic layout types have different fixed and variable cost characteristics which seem to determine which one to use. (b) In practice the uncertainty about the exact fixed and variable costs of each layout means the decision can rarely be made on cost alone (b) Fixed-position Costs (a) Process Cell Product Use fixed process -position Use cell Use product Volume 3) Consider total cost © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 ? ? Volume Use product Use cell or product Use process or cell Use process Use fixed-position or process Use fixed-position Operations Management, 4 E: Chapter 7

7. 18 Detailed design of a layout © Nigel Slack, Stuart Chambers & Robert

7. 18 Detailed design of a layout © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 19 Fixed position layout design: • • The location of resources for each

7. 19 Fixed position layout design: • • The location of resources for each project is unique and it will be determined on the convenience of transforming resources themselves. Although there are techniques which held to locate resources on fixed position layouts, they are not widely used because this layout can be very complex and planned schedules do change frequently. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 20 Process layout design: • • When cost of traveling is important: –

7. 20 Process layout design: • • When cost of traveling is important: – Collecting information such as: • number of loads per day • cost per distance traveled When process relationship is important – Relationship chart © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 21 (a) Collecting information in process layout (b) LOADS/DAY If direction is not

7. 21 (a) Collecting information in process layout (b) LOADS/DAY If direction is not important, collapses to © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 22 (c) Collecting information in process layout LOADS/DAY (d) LOADS/DAY A B C

7. 22 (c) Collecting information in process layout LOADS/DAY (d) LOADS/DAY A B C Or alternatively D E © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 30 30 40 80 60 30 20 Operations Management, 4 E: Chapter 7

7. 23 (e) Collecting information in process layout (f) UNIT COST/DISTANCE TRAVELLED LOADS/DAY If

7. 23 (e) Collecting information in process layout (f) UNIT COST/DISTANCE TRAVELLED LOADS/DAY If cost of flow differs between work centers, combine with © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 24 Collecting information in process layout (g) DAILY COST/DISTANCE TRAVELLED To give ©

7. 24 Collecting information in process layout (g) DAILY COST/DISTANCE TRAVELLED To give © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 25 Collecting information in process layout (h) DAILY COST/DISTANCE TRAVELLED (i) DAILY COST/DISTANCE

7. 25 Collecting information in process layout (h) DAILY COST/DISTANCE TRAVELLED (i) DAILY COST/DISTANCE TRAVELLED If direction is not important, collapses to © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

A relationship chart 7. 26 DEPARTMENT Metrology Electronic testing Analysis Ultrasonic testing Fatigue testing

A relationship chart 7. 26 DEPARTMENT Metrology Electronic testing Analysis Ultrasonic testing Fatigue testing Impact testing E A I U I I E O U X X U O © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 27 Cell layout design 1) Cells in an operation can be created based

7. 27 Cell layout design 1) Cells in an operation can be created based on two interrelated decisions: 1) 2) What is the extent and nature of the cell i. e. the amount of direct and indirect resources the cell has as shown in Fig 7. 28 Which resources to allocate to which cell using: i. ii. Cluster analysis – which process group naturally together Parts and family coding – based on similar characteristics of parts of products OR 2) Production Flow Analysis (PFA) Examines both product requirement and process grouping (See Fig. 7. 31) © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 28 Types of cell High e. g. Specialist process manufacturing cell Internal audit

7. 28 Types of cell High e. g. Specialist process manufacturing cell Internal audit group in a bank Amount of indirect resources included in the cell e. g. Plant-within-a-plant manufacturing operation Maternity unit in a hospital Low e. g. Small multi-machine manufacturing cell Joint reference and copying room in a library e. g. Complete component manufacturing cell Proportion of the resources needed to complete the High transformation included in the cell Lunch and snack produce area in supermarket Low © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 29 (a) and (b) Using production flow analysis to allocate machines to cells

7. 29 (a) and (b) Using production flow analysis to allocate machines to cells (b) Product Machines Cell A Cell B Cell C © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 30 Product layout design 1) Product type layout is designed based on a

7. 30 Product layout design 1) Product type layout is designed based on a technique called line balancing. The technique consist of the following steps: 1) 2) 3) 4) Calculating the required cycle time. Calculating the number of stages. Producing a precedence diagram. Finally allocating activities to the stages. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 31 Cycle time: It is the time between completed products emerging from the

7. 31 Cycle time: It is the time between completed products emerging from the process. Example: Suppose the regional back-office operation of a large bank is designing an operation which will process its mortgage applications. The number of applications to be processed is 160 per week and the time available to process the applications is 40 hours per week. Cycle time = 40 = 1/4 hours = 15 minutes 160 1 product every 15 minutes © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 32 Number of stages Required no. of stages = total work content required

7. 32 Number of stages Required no. of stages = total work content required cycle time Where the total work content is the total quantity of work involved in producing the product given in time. Example: Suppose that the bank in the previous example calculated that the average total work content of processing a mortgage application is 60 minutes. The number of stages needed to produce a processed application every 15 minutes can be calculated Required no. of stages = 60 minutes = 4 stages 15 minutes If you get a fraction round it up to the higher whole number. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 33 Precedence diagram This is a diagram representing the ordering of the elements

7. 33 Precedence diagram This is a diagram representing the ordering of the elements which comprise the total work content of the product or service. Two rules when constructing the diagram: 1. The circles which represent the elements are drawn as far to the left as possible. 2. None of the arrows which shows the precedence of the elements should be vertical. 0. 17 mins e 0. 25 mins 0. 30 mins a 0. 12 mins b c d 0. 36 mins 0. 05 mins f 0. 25 mins g i 0. 10 mins h 0. 08 mins © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 34 Allocating activities to the stages The general approach is to allocate elements

7. 34 Allocating activities to the stages The general approach is to allocate elements from the precedence diagram to the first stage, starting from the left, until the work allocated to the stage is as close to, but less than, the cycle time. When the stage is full of work without exceeding the cycle time, move to the next stage. Two rules help to decide which activities to allocate to a stage: 1. 2. Choose the largest that will fit into the time remaining at the stage Choose the element with the most ‘followers’. © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 35 Balancing loss The effectiveness of the line balancing activity is measured by

7. 35 Balancing loss The effectiveness of the line balancing activity is measured by the balancing loss. This is the time wasted through the unequal allocation of work as a percentage of the total time invested in processing the product or service. Balancing loss = Total idle time No. of stages x Cycle time © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

7. 36 Balancing loss is that proportion of the time invested in processing the

7. 36 Balancing loss is that proportion of the time invested in processing the product or service which is not used productively But if work is not equally allocated the cycle time will increase and ‘balancing losses’ will occur An ideal ‘balance’ where work is allocated equally between the stages Cycle time = 3. 0 mins Cycle time = 2. 5 mins Load 3. 0 Stage Work allocated to stage Idle time © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 2. 5 2. 3 2. 2 Stage Calculating balancing loss: Idle time every cycle =(3. 0 - 2. 3) + (3. 0 - 2. 5) + (3. 0 - 2. 2) = 2. 0 mins Balancing loss = 2 4 x 3. 0 = 0. 1667 = 16. 67% Operations Management, 4 E: Chapter 7

7. 37 Worked Example Consider Karlstad Kakes, a manufacturer of specialty cakes, which has

7. 37 Worked Example Consider Karlstad Kakes, a manufacturer of specialty cakes, which has recently obtained contract to supply a major supermarket chain with a specialty cake in the shape of a space rocket. It has been decided that the volumes required by the supermarket warrant a special production line to perform the finishing, decorating and packing of the cake. This line would have to carry out the elements shown in the next slide, which also shows the precedence diagram for the total job. The initial order from the supermarket is for 5000 cakes a week and the number of hours worked by the factory is 40 per week. From this: The required cycle time = 40 hrs x 60 mins = 0. 48 mins 5000 The required number of stages = 1. 68 mins (total work content) 0. 48 mins (required cycle time) = 3. 5 stages © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

Element listing and precedence diagram for Karlstad Kates 7. 38 Element Element Element ab

Element listing and precedence diagram for Karlstad Kates 7. 38 Element Element Element ab - De-tin and trim 0. 12 mins - Reshape with off-cuts 0. 30 mins c d - Clad in almond fondant 0. 36 mins - Clad in white fondant 0. 25 mins - Decorate, red icing 0. 17 mins - Decorate, green icing 0. 05 mins - Decorate, blue icing 0. 10 mins - Affix transfers 0. 08 mins - Transfer to base and pack 0. 25 mins e f g h i Total work content = 1. 68 mins 0. 17 mins e 0. 25 mins 0. 30 mins a 0. 12 mins b c d 0. 05 mins f 0. 36 mins 0. 25 mins g i 0. 10 mins h 0. 08 mins © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7

Allocation of elements to stages and balancing loss for Karlstad Kates 7. 39 Stage

Allocation of elements to stages and balancing loss for Karlstad Kates 7. 39 Stage 1 Stage 2 Stage 3 0. 17 mins Stage 4 e 0. 25 mins 0. 30 mins a b 0. 12 mins c d 0. 36 mins 0. 05 mins f 0. 25 mins g i 0. 10 mins h 0. 08 mins Cycle time = 0. 48 mins Idle time every cycle = (0. 48 - 0. 42) + (0. 48 - 0. 36) + (0. 48 - 0. 42) = 0. 24 mins Proportion of idle time per cycle = 0. 24 = 12. 5% 4 x 0. 48 © Nigel Slack, Stuart Chambers & Robert Johnston, 2004 Operations Management, 4 E: Chapter 7