1. Chapter 10 - Layout Layout planning involves decisions about the physical arrangement of economic activity centers within a facility. Basically, anything that consumes space: people/teams, machines, work benches, aisles, timecard rack, storage room. The goal: allow workers and equipment to operate effectively. 1.What centers should the layout include? 2.How much space and capacity does each center need? 3.How should each center’s space be configured? 4.Where should each center be located? Relative location: place of a center relative to other centers Absolute location: particular space that the center occupies

2. Layout Types (a) Layout of a job shop Foundry Milling machines LathesGrinding PaintingDrills Office Welding Forging Layout can: facilitate flow of materials and information. Increase utilization of labor and equipment Reduce hazards to workers Improve employee morale Improve communication Process layout: groups workstations according to function: most common when the same operation must intermittently produce many different products or serve many customers. Product layout: centers are arranged in a linear path; continuous flow; high volume; L, O, S U - shapes Advantages/disadvantages on page 448! Station 1Station 2Station 3Station 4 (b) Layout of a production line

3. Flexible Manufacturing Systems (FMS) were born out of the desire to make small batch production more efficient and recently to improve the company’s market performance by improving manufacturing flexibility (Chen et al, 1992). There are three key components to FMS: Several CNC machines (only one CNC would be a FM Cell not FMS) and the hierarchy of the communication and levels of control (Stecke) An automated material handling system for moving materials and parts from one machine to another (conveyor, guided carts, AGV) A host computer controlling the CNC’s FMS are designed around families of parts for mid-volume production. FMS completes a given number of operations on an item before it leaves the system. The root process is still batch. Manufacturers should consider several important implications before implementing FMS: Technological – CNC machines, CAD, Robots, AGV (auto guided vehicles). Early in FMS development, FMS technology was purchased to reduce environmental uncertainty (threats). Research by Chen et al (1992) proposed that FMT can assume an offensive role to turn threats into opportunities and firms can achieve benefits of manufacturing flexibility. Financial – capital appraisal techniques Political – management, skills, commitment Sociological – fewer jobs Layout Types

4. Hybrid Layouts One-worker, multiple-machines cell: worker operates several different machines simultaneously to achieve a line flow. Can change setups to produce different product/part Reduces inventory Machi ne 1 Machi ne 2 Machi ne 3 Machi ne 4 Machi ne 5 Materials in Finishe d goods out

5. Group Technology Product layouts with low-volume processes. Creates cells not limited to just one worker and groups parts or products with similar characteristics into families and sets aside groups of machines for production. Goal is to minimize setup or changeovers for similar processing requirements

6. Group Technology (a)Jumbled flows in a job shop without GT cells (b) Line flows in a job shop with three GT cells Cell 3 LM G G Cell 1Cell 2 Assembl y area A A L M D L L M Shipping D Receiving G First image is grouped to function (lathing, milling, drilling) After lathing, part is moved to next function where it waits until it has a higher priority than any other job competing for the machine. Second image is grouped into product families – simplified the flow.

7. Designing Process Layouts Line Balancing – assignment of work stations in a line to achieve desired output rate with the smallest number of workstations. Line is as only as fast as the slowest workstation. Work elements –smallest unit of work that can be performed independently and immediate predecessors – work elements that must be done before the next can begin. Precedence diagram – work elements are circles and time required to perform work is below the circle. Arrows lead from immediate predecessors to next work element.

8. Line Balancing ABolt leg frame to hopper40None BInsert impeller shaft30A CAttach axle50A DAttach agitator40B EAttach drive wheel6B FAttach free wheel25C GMount lower post15C HAttach controls20D, E IMount nameplate18F, G Total244 WorkTimeImmediate ElementDescription(sec)Predecessor(s) 40 6 20 50 15 18 E 30 25 40 H I D B F C A G

9. Line Balancing 40 6 20 50 15 18 E 30 25 40 H I D B F C A G Desired output rate = 2400/week Plant operates 40 hours/week r = 2400/40 = 60 units/hour c = 1/60 = 1 minute/unit = 60 seconds/unit Matching output to demand decreases inventory. After determining desired output rate for a line, calculate the line’s cycle time. This is the maximum time allowed for work on a unit at each station. If the time for work elements at a station exceeds the line’s cycle time, causes bottlenecks. Cycle time = 1/r where r is the desired output rate.

10. Line Balancing c = 60 seconds/unit TM = 5 stations Efficiency = 81.3% Desired output rate = 2400/week Plant operates 40 hours/week TM = 244 seconds/60 seconds = 4.067 or 5 stations always round up Efficiency = [244\5(60)]100 = 81.3% 40 6 20 50 15 18 E 30 25 40 H I D B F C A G Theoretical minimum: to achieve the desired output rate, use line balancing to work to a station, satisfying precedence relations and minimizing the number of workstations. Minimizing n, the number of workstations also maximizes worker productivity.

11. Line Balancing Theoretical minimum =  t / c Where  t = total time required to assemble each unit (the sum of all work element standard times) c = cycle time Idle time, efficiency, and balance delay: Minimizing n automatically ensures minimal idle time, maximum efficiency, and minimal balance delay. Idle time is the total unproductive time for all stations in the assembly of each unit: Idle time = nc –  t Efficiency – ratio of productive time to total time, as a percent:  t / nc (100) Balance delay – amount by which efficiency falls short of 100%: 100-Efficiency

12. Finding a solution Longest work-element time: assigns, as quickly as possible, those work elements most difficult to fit into a station and saves work elements having shorter times for fine tuning Largest number of followers – reduces unnecessary station idle time

13. Line Balancing c = 60 seconds/unit TM = 5 stations Efficiency = 81.3% 40 6 20 50 15 18 E 30 25 40 H I D B F C A G S1 S2 S3

14. Finding a Solution S1AA4020 S2B,CC5010 S3B,F,GB3030 E,F,GF555 CummIdle StationCandidateChoiceTimeTime S4D,E,GD4020 E,GG555 S5E,II1842 EE2436 HH4416

15. Line Balancing 40 6 20 50 15 18 E 30 25 40 H I D B F C A G c = 60 seconds/unit TM = 5 stations Efficiency = 81.3% S1 S2 S3 S5 S4