Facility Layout Technical Note 6

Facility Layout Defined Facility layout can be defined as the process by which the placement of departments, workgroups within departments, workstations, machines, and stock-holding points within a facility are determined. This process requires the following inputs: Specification of objectives of the system in terms of output and flexibility. Estimation of product or service demand on the system. Processing requirements in terms of number of operations and amount of flow between departments and work centers. Space requirements for the elements in the layout. Space availability within the facility itself. 3

Basic Production Layout Formats Process Layout Product Layout Group Technology (Cellular) Layout Fixed-Position Layout 4

Basic Production Layouts Product Layout Layout that uses standardized processing operations to achieve smooth, rapid, high volume flow. Process Layout Layout that can handle varied processing requirements. Fixed-Position Layout Layout in which the product or project remains stationary, and workers, materials, and equipment are moved as needed. 4

Basic Production Layouts Cellular Manufacturing (Layout) Layout in which machines are grouped into a cell that can process items that have similar processing requirements Group Technology The grouping into part families of items with similar design or manufacturing characteristics

Layout Structures Job shop Batch Assembly line Continuous flow

Process Layout (Job Shop) Product 3 Product 2 Product 1 A B C Product 1 Product 2 D E F Product 3

Process Layout – Position of equipment is dominant consideration

Process-Focused Strategy Facilities are organized by process Similar processes are together Example: All drill presses are together Low volume, high variety products ‘Jumbled’ flow Other names Intermittent process Job shop 11

Process Layout: Interdepartmental Flow Given The flow (number of moves) to and from all departments The cost of moving from one department to another The existing or planned physical layout of the plant Determine The “best” locations for each department, where best means interdepartmental transportation, or flow, costs 6

Process Layout: CRAFT Approach [COMPUTERIZED RELATIVE ALLOCATION OF FACILITIES TECHNIQUE] Omit Slide It is a heuristic program; it uses a simple rule of thumb in making evaluations: "Compare two departments at a time and exchange them if it reduces the total cost of the layout." It does not guarantee an optimal solution. CRAFT assumes the existence of variable path material handling equipment such as forklift trucks. 8

Process Layout: Systematic Layout Planning Numerical flow of items between departments Can be impractical to obtain Does not account for the qualitative factors that may be crucial to the placement decision Systematic Layout Planning Accounts for the importance of having each department located next to every other department Is also guided by trial and error Switching departments then checking the results of the “closeness” score Omit Slide 9

Example of Systematic Layout Planning: Reasons for Closeness Omit Slide Code 1 2 3 4 5 6 Reason Type of customer Ease of supervision Common personnel Contact necessary Share same price Psychology 10

Example of Systematic Layout Planning:Importance of Closeness Omit Slide Value Closeness Line code Numerical weights A Absolutely necessary 16 E Especially important 8 I Important 4 O Ordinary closeness OK 2 U Unimportant X Undesirable -80 11

Example of Systematic Layout Planning: Relating Reasons and Importance Omit Slide From To Area (sq. ft.) 2 3 4 5 1. Credit department 6 I -- U 4 E 100 2. Toy department U I A 400 -- 1 1,6 3. Wine department U X 300 -- 1 4. Camera department X 100 1 5. Candy department 100 Letter Closeness rating Number Reason for rating 12

Example of Systematic Layout Planning:Initial Relationship Diagram Omit Slide 1 E 3 I 4 U U 2 5 A 13

Example of Systematic Layout Planning: Initial and Final Layouts Omit Slide 2 5 1 4 3 50 ft 20 ft Final Layout Adjusted by square footage and building size 1 2 4 3 5 Initial Layout Ignoring space and building constraints 14

Process Focused Strategy - Pros & Cons Advantages greater process flexibility more general purpose equipment lower initial capital investment Disadvantages more “specialist” trained personnel required more difficult production planning and control 13

Product Layout (Flow Shop) B C Product 2 Product 2 D E F Product 3 Product 3 D E F

Product Layout – Flow of product is dominant consideration

Product-Focused Strategy Facilities are organized by product High volume, low variety products Where found Discrete unit manufacturing Continuous process manufacturing Other names Line flow production (flow shop) Continuous production 17

Product-Focused Strategy Pros & Cons Advantages lower labor skills easier production planning and control higher equipment utilization Disadvantages lower product flexibility more specialized equipment usually higher capital investment 18

Group Technology: Transition from Process Layout 1. Grouping parts into families that follow a common sequence of steps. 2. Identifying dominant flow patterns of parts families as a basis for location or relocation of processes. 3. Physically grouping machines and processes into cells. 35

Batch/Lot Thinking Departmental (Batch Process) Specialization Saw Saw Grinder Grinder Corrected Heat Treat Lathe Lathe Lathe Press Press Press 8

Single-Piece Flow Thinking Group Technology Cells Grinder 1 2 Lathe Press Saw Lathe Heat Treat Grinder A B Lathe Press Saw Lathe 9

Group Technology Assembly Line Cells

Benefits of Group Technology Changeover setup time reduced for tooling and equipment Automation may be possible Operator may be specially trained with improved expertise Quality of output improved In-process inventory reduced Productivity improved Lead time reduced Improved human relations

Fixed Position Layout Question: What are our primary considerations for a fixed position layout? Answer: Arranging materials and equipment concentrically around the production point in their order of use. 36

Volume and Variety of Products Low Volume High Repetitive High Volume Variety of Variety Process Process Low Variety Products (Intermittent) (Modular) Process (Continuous) One or very few Projects Poor Strategy (Fixed costs and cost changing to other products are high) units per lot Very small runs, high Job Shops Aluminum part variety Modest runs, modest Disconnected variety Cell Assembly Repetitive Long runs, modest Poor Strategy (High variable costs) Connected variations Repetitive Motor Assembly Very long runs, Continuous Changes in Part Molding attributes 24

Assembly Lines Balancing Concepts Question: Suppose you load work into the three work stations below such that each will take the corresponding number of minutes as shown. What is the cycle time of this line? Station 1 Minutes per Unit 6 Station 2 7 Station 3 3 Answer: The cycle time of the line is always determined by the work station taking the longest time. In this problem, the cycle time of the line is 7 minutes. There is also going to be idle time at the other two work stations. 15

Main Points of Line Balancing An analysis of production lines Nearly equally divides work between workstations while meeting required output Has objectives to Maximize efficiency Minimize number of work stations 51

Example of Line Balancing You’ve just been assigned the job a setting up an electric fan assembly line with the following tasks: 16

Example of Line Balancing: Structuring the Precedence Diagram Task Predecessors Task Predecessors A None E D B A F E C None G B D A, C H F, G A B G H C D E F 17

Example of Line Balancing: Precedence Diagram Question: Which process step defines the maximum rate of production? A C B D E F G H 2 3.25 1 1.2 .5 1.4 Answer: Task C is the cycle time of the line and therefore, the maximum rate of production. 17

Example of Line Balancing: The Bottleneck Total 11.35 Minutes 18

Example of Line Balancing: Determine Cycle Time Question: Suppose we want to assemble 100 fans per day. What would our cycle time have to be? Answer: Question: What else can the 4.2 min time be called other than cycle time? 19

Example of Line Balancing: Determine Theoretical Minimum Number of Workstations Question: What is the theoretical minimum number of workstations for this problem? Answer: 19

Example of Line Balancing: Rules To Follow for Loading Workstations Primary: Assign tasks in order of the largest number of following tasks. Secondary (tie-breaking): Assign tasks in order of the longest operating time 21

Station 1 Station 2 Station 3 Task Followers Time (Mins) 6 4 3 0.5 A C B D E F G H 2 3.25 1 1.2 .5 1.4 Station 1 Station 2 Station 3 Task Followers Time (Mins) 6 4 3 0.5 23

Station 1 Station 2 Station 3 A (4.2-2=2.2) Task Followers Time (Mins) C B D E F G H 2 3.25 1 1.2 .5 1.4 Station 1 Station 2 Station 3 A (4.2-2=2.2) Task Followers Time (Mins) 6 4 3 0.5 24

A (4.2-2=2.2) B (2.2-1=1.2) Station 1 Station 2 Station 3 Task C B D E F G H 2 3.25 1 1.2 .5 1.4 A (4.2-2=2.2) B (2.2-1=1.2) Task Followers Time (Mins) 6 4 3 0.5 Station 1 Station 2 Station 3 25

A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Station 1 Station 2 C B D E F G H 2 3.25 1 1.2 .5 1.4 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Task Followers Time (Mins) 6 4 3 0.5 Station 1 Station 2 Station 3 26

C (4.2-3.25)=.95 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 F G H 2 3.25 1 1.2 .5 1.4 C (4.2-3.25)=.95 Task Followers Time (Mins) 6 4 3 0.5 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Station 1 Station 2 Station 3 27

C (4.2-3.25)=.95 Idle = .95 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) F G H 2 3.25 1 1.2 .5 1.4 Task Followers Time (Mins) 6 4 3 0.5 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Station 1 Station 2 Station 3 28

D (4.2-1.2)=3 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 C B D E F G H 2 3.25 1 1.2 .5 1.4 D (4.2-1.2)=3 Task Followers Time (Mins) 6 4 3 0.5 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Station 1 Station 2 Station 3 C (4.2-3.25)=.95 Idle = .95 29

C (4.2-3.25)=.95 Idle = .95 D (4.2-1.2)=3 E (3-.5)=2.5 A (4.2-2=2.2) B D E F G H 2 3.25 1 1.2 .5 1.4 C (4.2-3.25)=.95 Idle = .95 D (4.2-1.2)=3 E (3-.5)=2.5 Task Followers Time (Mins) 6 4 3 0.5 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Station 1 Station 2 Station 3 30

C (4.2-3.25)=.95 Idle = .95 D (4.2-1.2)=3 E (3-.5)=2.5 F (2.5-1)=1.5 A C B D E F G H 2 3.25 1 1.2 .5 1.4 C (4.2-3.25)=.95 Idle = .95 D (4.2-1.2)=3 E (3-.5)=2.5 F (2.5-1)=1.5 Task Followers Time (Mins) 6 4 3 0.5 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Station 1 Station 2 Station 3 31

C (4.2-3.25)=.95 Idle = .95 D (4.2-1.2)=3 E (3-.5)=2.5 F (2.5-1)=1.5 A C B D E F G H 2 3.25 1 1.2 .5 1.4 C (4.2-3.25)=.95 Idle = .95 D (4.2-1.2)=3 E (3-.5)=2.5 F (2.5-1)=1.5 H (1.5-1.4)=.1 Idle = .1 Task Followers Time (Mins) 6 4 3 0.5 A (4.2-2=2.2) B (2.2-1=1.2) G (1.2-1= .2) Idle= .2 Station 1 Station 2 Station 3 Which station is the bottleneck? What is the effective cycle time? 32

Example of Line Balancing: Determine the Efficiency of the Assembly Line 33

Assembly Line Balancing The General Procedure Determine cycle time by taking the demand (or production rate) per day and dividing it into the productive time available per day Calculate the theoretical minimum number of work stations by dividing total task time by cycle time Perform the line balance and assign specific assembly tasks to each work station 50

Assembly Line Balancing Steps 1. Determine tasks (operations) 2. Determine sequence 3. Draw precedence diagram 4. Estimate task times 5. Calculate cycle time 6. Calculate number of work stations 7. Assign tasks (load workstations) 8. Calculate efficiency 52

Mixed-Model Processing Short cycle-interval (time) Production of a variety of types, sizes, or models of a product family on the same line or within the same cell.

Example – The Fresh Bakery: Cakes Daily sales for: 24 Product L (Lemon Pound) 12 Product M (Chocolate Mud) 3 Product N (Nine Layer Carrot) What is the best schedule for these products? What are we assuming for this schedule to work?

Example Daily sales for: 24 Product L 12 Product M 3 Product N Step 1 - find minimum ratio 8 L -- 4 M – 1 N Step 2- determine number of cycles 39/13 = 3

Example In order to meet daily demand, this cycle will have to repeat 3 times Step 3 - find the mix of the units that is most repetitive. LLM LLM N LLM LLM What are we assuming for this schedule to work? Demand is uniform and our objective is to avoid inventory.

Summary - Comparison Process Focus Product Focus Bank 1. Product: Small 1. Product: Large quantity, large quantities, small variety variety 2. Equipment: 2. Equipment: General purpose Special-purpose 3. Operators broadly 3. Operators less skilled broadly skilled 4. Many job 4. Few work orders instructions and job instructions; standardization 20

Process/Product Continuum Process Focused (intermittent process) Product Focused (continuous process) Group Technology Continuum High variety, low volume Low utilization General-purpose equipment Low variety, high volume High utilization Specialized equipment 23