Facility Design вЂ“ An Introduction R. Lindeke, Ph. D. IE 3265 Sp. 2006 Facility Layouts: пЃ¬ A Decision that Encompasses: вЂ“ вЂ“ вЂ“ вЂ“ Placement of вЂ�DepartmentsвЂ™ Placement of Workstations/Machines Placement of Stockholding points within Factory or Warehouse Development of Controlled Traffic Patterns to generate smooth workflow throughout Decision Makers: пЃ¬ пЃ¬ пЃ¬ What is the desired flexibility and required output? What is the forecast product demand and its growth? What are the processing requirements? пЃ¬ пЃ¬ пЃ¬ пЃ¬ Number of operators Level of flow between work stations and between work areas How can the design balance requirements on Workstation loading Facility Space Available Signs of a Successful Layout 1. Directed Flow Patterns: 1. 2. 2. 3. 4. 5. 6. Straight line or other smooth patterns of movement Backtracking kept to a minimum Predictable Processing Time Little WIP in Facility Open Floors: allow communication and easy tracking of work & employees Bottleneck operations under control Work Stations close together Signs of a Successful Layout, cont: 7. 8. 9. Orderly Handling & Storage of Raw Materials and Finished products No extra handling or unnecessary handling of materials Can easily adapt to changing conditions 1. 2. 3. Considers demand growth or decline Considers product change over Considers technological change Workstation Layouts Within a cell: Standard Layouts IMPROVED LAYOUTS: End to End Front to Front I/O Back to Back (poor) Circular or U Flow Considering Circular or U-Flow: пЃ¬ Advantages: пЃ¬ пЃ¬ пЃ¬ пЃ¬ One operator can tend several machines Common I/O station simplifies material transfer to/from cell to the rest of the facility Automation can be tried for several machines Disadvantages: пЃ¬ пЃ¬ Limited Queuing space or WIP storage within cell Requires excellent balance and high quality to keep flow active between workstations in the cell Flow Patterns within Process Departments (Job Shops) Aisle Aisle Aisle A. Parallel Flow B. Perpendicular Flow Aisle C. Diagonal Flow Aisle Some Job Shop Ideas: пЃ¬ пЃ¬ пЃ¬ Flow is in-out of the department not between machines Traffic patterns must support movement from and to aisles Diagonal designs often save floor space in 1 way aisle shops Overall вЂ“ Flow is a Function of Aisles пЃ¬ пЃ¬ As a designer, aisle placement is of primary interest and often marks successful or failed designs! Aisle Size is a function of Load Size! Set Aside is controlled by Largest Load Area (Rules of Thumb) Load Area < 6 ft2 6 вЂ“ 12 ft2 12 вЂ“ 18 ft2 > 18 ft2 Aisle Set Aside 5 -10% of calc. size 10 - 20% of calc. size 20 - 30% of calc. size 30 - 40% of calc. size Aisle Consideration, cont. Aisle width is controlled by the traffic that flows on it Type of Traffic Min. Aisle Width Large Wheeled Indoor/outdoor Tractors 12вЂ™* Large Forktrucks 11вЂ™ Small Forktrucks 9вЂ™ Narrow Aisle trucks/AGVвЂ™s 6вЂ™ Manual Platform Trucks 5вЂ™ Personnel 3вЂ™ Personnel w/doors 1 side 6вЂ™ Personnel w/doors both sides 8вЂ™ NOTE: Consider turning radiuses at intersections! General Aisle Issues: пЃ¬ Good Aisle Designs вЂ¦ вЂ“ вЂ“ вЂ“ вЂ“ Avoid curves/jogs/non 90п‚° intersections Avoid outside wall paths (these are used for utilities so machine/workstations should back to walls if possible Are straight and lead to door ways Allow Flow to be controlled by entrances and exits (as it should) Facility Designs Seeks: пЃ¬ To maximize directed (forward) flow вЂ“ пЃ¬ пЃ¬ пЃ¬ Materials move directly from sources to destination without jogging around and by paths that donвЂ™t intersect other flows* Minimize total flow (volume) of all products Distances minimized, too Minimize cost of flow вЂ“ expensive flows should be short while lighter or less critical flows can be longer *No Backtracks! An Example: A 50вЂ™ D 50вЂ™ B пЃ¬ пЃ¬ пЃ¬ 50вЂ™ C 75вЂ™ 25вЂ™ Flow Straight Thru: A-B-C-D is 250вЂ™ Flow w/Backtracking: A-B-C-A-D is 550вЂ™ Backtracking is an Economic decision! пЃ¬ пЃ¬ Cost of Added Equipment (replication of A) VS. Cost of added flow movement and traffic patterns (aisle set aside) for each product that flows along backtrack The Technical Jobs of Facilities Design: пЃ¬ Determination of Space requirements: вЂ“ Workstation space for: пЃ¬ Equipment вЂ“ пЃ¬ Materials вЂ“ вЂ“ пЃ¬ Footprint + machine travel + access (load/maintenance) + shop services (air/electrical/water, etc) consider unit load size + tooling/scrap etc Personnel вЂ“ вЂ“ ingress & egress 30 вЂ“ 42вЂќ for passage between stationary or operating machines The Technical Jobs of Facilities Design: пЃ¬ Determination of Space requirements (cont.): вЂ“ Departmental (Cell) Requirements: пЃ¬ пЃ“(WSreqr + G.Service + M.Handlingreqr) пЃ¬ G. Service areas вЂ“ пЃ¬ offices, records, data, inspection/QC, etc. Material Handling вЂ“ inside traffic set asides to move product, tools, raw materials, etc The Technical Jobs of Facilities Design: пЃ¬ Determination of Space requirements (cont.): вЂ“ Specifics for Work Centers: пЃ¬ пЃ¬ пЃ¬ пЃ¬ вЂ“ Use a Worksheet (see handout) Lists various resources and their requirements considering services, physical loading (special needs?) List and sum all areas required Add in Aisle Allowance See handout (one for each work center or assembly line) The Technical Jobs of Facilities Design: пЃ¬ пЃ¬ The second job is to effectively provide for minimum flow and cost of flow Here the designer performs studies of the space requirements and desired travel patterns вЂ“ Using Qualitative Tools: пЃ¬ пЃ¬ вЂ“ SLP (systematic layout planning) based on activity relationship charts to suggest appropriate layouts Software to optimize the relationships Using Quantitative tools: пЃ¬ пЃ¬ пЃ¬ Mileage Charts: area to area distance matrices From -To Charts: Move/Volume/Cost Matrices Appropriate software to compute and optimize the arrangements Typical Activity Relationship Chart: These charts are often called an AEIOUX chart вЂ“ the letters used to explain relationships that are learned during our facility studies: Completing the Activities Relationship Chart: пЃ¬ пЃ¬ пЃ¬ After listing all departments on chart, Conduct Surveys to assess relationships with each departmentвЂ™s staff Interpret results of surveys as closeness needs вЂ“ itemize and record closeness requirements to support assessed relationship Establish the relationships: пЃ¬ пЃ¬ пЃ¬ пЃ¬ пЃ¬ пЃ¬ пЃ¬ A вЂ“ absolutely necessary E вЂ“ Especially Important I вЂ“ Important O вЂ“ вЂњordinaryвЂќ closeness okay U вЂ“ Unimportant X вЂ“ Undesirable Allow all concerned parties to review proposed chart for accuracy of closeness settings Using Activity Relationship Chart to build Designs: пЃ¬ Using Pure SLP ideas we develop a вЂњMeatballвЂќ diagram and move departments around to shorten A & E lines while increasing length of X lines Using Activity Relationship Chart to build Designs Using Activity Relationship Chart to build Designs пЃ¬ An alternative approach begins with looking at each department as equal sized rectangles listing letter relationship with all departments in the Facility Receiving: A -; X-; E-B; I-D; O-C,E; U- F,G Plating: A -E; X-; E-G; I-B; O-C; U- A,D Milling: A -; X-; E-A,D; I-E,F; O-; U- C,G Shipping: A -; X-; E-F; I-E; O-; U- A, B, C,D Press: A -; X-; E-; I-; O-A,F; U- B,D,E,G Sc. Machine: A -; X-; E-B; I-A,E; O-; U-C,F,G Assembly: A -F; X-; E-; I-B,D,G; O-A; U- C Using Activity Relationship Chart to build Designs пЃ¬ Select template with highest number of A relationships; tied templates selected subject to hierarchy: most EвЂ™s, Most IвЂ™s, fewest XвЂ™s пЃ¬ пЃ¬ Next template chosen should have A relationship w/ 1st chosen вЂ“ any ties broken as above пЃ¬ пЃ¬ Here Assembly, department E Next template chosen should have the highest joint relationship with first two chosen пЃ¬ пЃ¬ Here select Plating department (F) Here is Shipping вЂ“ G This continues until all departments are chosen In doing the Design: F By This Order: E G Place F in Center. Then follow in order keeping Ideas (AEIOUX) of arrangements: A B C D B D A C E F G A Final Step: now we consider actual departmental areas: Code Function Area Ft2 # Units (2000 per) A B C Receiving Milling Press 12,000 8,000 6,000 6 4 3 12,000 6 8,000 4 12,000 12,000 6 6 E Sc. Machines Assembly F G Plating Shipping D Leads to the following Proposed Layout: пЃ¬ пЃ¬ пЃ¬ When equal sizes are replaced with scaled sizes we develop these layouts: Obviously, many variants would be possible (no XвЂ™s and few A and EвЂ™s) We determine appropriate layout only after quantitative analysis is applied to the proposed arrangements Addressing the Quantitative Approaches: пЃ¬ Mileage Charts: showing Distances between Departments вЂ“ вЂ“ Distances measures вЂњEuclidian-wiseвЂќ using computed straight lines between department centroids Distances measure вЂњRecti-linearвЂќ were department to department distances are computed by moving horizontally and vertically along expected aisle routes Mileage Chart Format A B C D E A XXX 100 200 300 400 B 100(?) XXX 100 200 300 C 200 100 XXX 100 200 D 300 200 100 XXX 100 E 400 300 200 100 XXX BackTracks: From-To Charts пЃ¬ пЃ¬ пЃ¬ Charts, based on Routings, that show each relevant partвЂ™s movement through the proposed facility Format is similar to Mileage chart but are rarely symmetrical or fully populated More expensive travel can be handled with increased Volumes or have other special handling costs attached Examining Quantitative Design пЃ¬ пЃ¬ We begin with a Qualitatively designed facility (one that meets perceived activity relationships) To keep it simple, lets look at a FlowвЂ“thru facility: A B C D General Flow Direction E Consider that each of the departments (A to E) are 100 units square Representative Products are selected for study: пЃ¬ пЃ¬ These might be вЂњgroup seedsвЂќ or вЂњlarge volumeвЂќ products or in other ways represent how the product will move thru the facility Lets explore 3: (Pr 1, Pr 2 and Pr 3) Product Pr1 Prod. Quantity 30 Routing A-C-B-D-E Pr2 Pr3 12 7 A-B-D-E A-C-D-B-E Mileage Chart: A B C D E A XXX 100 200 300 400 B 100 XXX 100 200 300 C 200 100 XXX 100 200 D 300 200 100 XXX 100 E 400 300 200 100 XXX From To Chart (based on Routing) A B C D E 0 0 A XXX Pr2 12 Pr 1 30 + Pr 3 2*7 = 30 +14 = 44 B 0 XXX 0 Pr 1 30 + Pr2 12 = 42 Pr 3 2*7 = 14 C 0 Pr 1 30 XXX Pr 3 2*7 = 14 0 D 0 Pr 3 2*7 = 14 0 XXX Pr 1 30 + Pr2 12 = 42 E 0 0 0 0 XXX Pr 3 is heavier and costlier to move вЂ“ we double volume to make it equivalent to Pr 1 & Pr 2 From To Issues пЃ¬ пЃ¬ пЃ¬ The filled cells below the diagonal represent moves against the general directed flow of the original facility design (пЃњ they вЂ“ may (should) вЂ“ cost more than moves above the line for the same distances) Cells Close to the diagonal are short distance moves while cells remote from the diagonal are long distance moves The number of moves (not filled cells!) must equal the total of each move in the routing sheets for the products Costing Transport in the Layout: пЃ¬ For comparison: пЃ¬ пЃ¬ all forward moves cost $1/unit vol/unit distance All Backtrack move cost $1.25/unit vol/unit distance Costs A A xxx B 1 C 1 D 1 E 1 B C D 1.25 1.25 1.25 xxx 1.25 1.25 1 xxx 1.25 1 1 xxx 1 1 1 E 1.25 1.25 1.25 1.25 xxx Layout Total Transport Cost пЃ¬ пЃ¬ Form: M*F*C вЂњcell productsвЂќ Sum each cell of resultant matrix пѓ it is the facility transportation cost (for comparison) Can we do Better? пЃ¬ Lets Swap Departments B & C A C B D E General Flow Direction пЃ¬ This will change our Mileage and Cost Matrices as well as arrangements in From/To Matrix New Mileage Chart: A C B D E A XXX 100 200 300 400 C 100 XXX 100 200 300 B 200 100 XXX 100 200 D 300 200 100 XXX 100 E 400 300 200 100 XXX New From-To Chart A C B D E A XXX Pr 1 30 + Pr 3 2*7 = 30 +14 = 44 Pr2 12 0 0 C 0 XXX Pr 1 30 Pr 3 2*7 = 14 0 B 0 0 XXX Pr 1 30 + Pr2 12 = 42 Pr 3 2*7 = 14 D 0 0 Pr 3 2*7 = 14 XXX Pr 1 30 + Pr2 12 = 42 E 0 0 0 0 XXX New Cost Matrix: Costs A C B D E A xxx 1 1 1 1 C 1.25 xxx 1 1 1 B 1.25 1.25 xxx 1 1 D 1.25 1.25 1.25 xxx 1 E 1.25 1.25 1.25 1.25 xxx New Transportation Costs: Examining these results: пЃ¬ Swapping 2 departments lead to a reduction in cost of: вЂ“ пЃ¬ $9900 or about 28% of the original cost Can we improve further? вЂ“ вЂ“ вЂ“ Not with this fundamental design Can we redesign the general footprint? Then we can keep looking! New Fundamental Design: пЃ¬ And applying a Euclidean Concept of distances! A пЃ¬ пЃ¬ пЃ¬ C D B E Distance from A to B is: (1002+1002).5 = 142 units Distance A to E is: (2002+1002).5 = 224 units Typically, with Euclidean distances, were would not consider transport cost differences in either direction вЂ“ this facility shape doesnвЂ™t favor general directions of flow! Mileage Chart (now) A C B D E A XXX 100 142 200 224 C 100 XXX 100 100 142 B 142 100 XXX 142 100 D 200 100 142 XXX 100 E 224 142 100 100 XXX Transportation Cost Picture: A further savings of $1000 вЂ“ as manager we decide if the new configuration design is worth the savings gained!