Scheduling Process

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Slide 1:

BASIC OPERATIONS SCHEDULING PROCESS 1/11/2011

GROUP 7:

GROUP 7 Ketki Pitale (7) Sajna V Koya (17) Mayuri Pawar (27) Sagnik Mukhopadhyay (37) Shruti Singh (47) Swati Verma (57) 1/11/2011 2

DEFINITION:

DEFINITION Operations scheduling uses a defined framework to address issues associated with the use of available resources and the delivery of products and services as promised to customers. Scheduling is an important tool for manufacturing and engineering, where it can have a major impact on the productivity of a process. Purpose of scheduling : To minimize the production time and costs, by telling a production facility when to make, with which staff, and on which equipment. Aims to maximize the efficiency of the operation and reduce costs. 1/11/2011

WHY SCHEDULING PROCESS?:

WHY SCHEDULING PROCESS? Process change-over reduction Inventory reduction, leveling Reduced scheduling effort Increased production efficiency Labor load leveling Accurate delivery date quotes Real time information 1/11/2011 4

TERMINOLOGY:

TERMINOLOGY LOADING Planning methodology used to assign an adequate number of jobs to the resources in an operating system SCHEDULING Process of rank ordering in front of each resource to maximize some chosen performance measure 1/11/2011 5

Cntd…:

Cntd… ROUTING Order in which the resources are used by jobs for processing SEQUENCING Is the order of the operations of the jobs in the operating system 1/11/2011 6

Cntd…:

Cntd… DISPATCHING Administrative process of authorizing processing of jobs EXPEDITING Administrative process of reviewing the progress of the job in the operating system 1/11/2011 7

CONTEXT OF SCHEDULING:

CONTEXT OF SCHEDULING Parameters for Scheduling: Number of machines Number of jobs Shop configuration 1/11/2011 8

SCHEDULING RULES:

SCHEDULING RULES Shortest Processing Time(SPT) Longest Processing Time(LPT) Earliest Due Date(EDD) Critical Ratio(CR) First-Come-First-Served(FCFS) Random Order(RAN) 1/11/2011 9

Illustration of rules:

Illustration of rules Job No. Processing Time (minutes) Order of arrival Due By CR Random Number SPT LPT EDD CR FCFS RAN 1 12 1 23 1.92 0.233 3 2 2 3 1 1 2 9 2 24 2.67 0.857 1 4 3 4 2 3 3 22 3 30 1.36 0.518 4 1 4 1 3 2 4 11 4 20 1.82 0.951 2 3 1 2 4 4 1/11/2011 10

PERFORMANCE CRITERIA:

PERFORMANCE CRITERIA Mainly three types of performance criteria are considered: Completion-Based Measures Due Date-Based Measures Inventory/Utilization-Based Measures 1/11/2011 11

Completion-Based Measures :

Completion-Based Measures Flow Time Release time of the job : Ri Completion time of the job : Ci Flow time of the job, Fi : Ri – Ci Make Span Cmax = max {Ci} 1/11/2011 12

DUE DATE-Based Measures :

DUE DATE-Based Measures Lateness Of The Job Li = Ci – Di Tardiness Of The Job Ti = max(0 , Li) 1/11/2011 13

INVENTORY/UTILIZATION-Based Measures :

INVENTORY/UTILIZATION-Based Measures Includes mean number of : Jobs waiting Finished jobs Unfinished jobs Mean utilization of resources 1/11/2011 14

SCHEDULING OF FLOW SHOPS:

SCHEDULING OF FLOW SHOPS The resources are organized one after the other in the order in which jobs are going to be processed. The number of combinations grows non-linearly. 1/11/2011 15

JOHNSON’S RULE :

JOHNSON’S RULE 1. Select the shortest processing time in either work center. 2. If the shortest time is at the first work center, put the job in the first unassigned slot in the schedule. If the shortest time is at the second work center, put the job in the last unassigned slot in the schedule. 3. Eliminate the job assigned in step 2. 4. Repeat steps 1-3, filling the schedule from the front and back, until all jobs have been assigned a slot. 1/11/2011 16

MINIMIZING TOTAL PRODUCTION TIME:

MINIMIZING TOTAL PRODUCTION TIME It is early Saturday morning and The Finest Detail has five automobiles waiting for detailing service. Each vehicle goes through a thorough exterior wash/wax process and then an interior vacuum/shampoo/polish process. The entire detailing crew must stay until the last vehicle is completed. If the five vehicles are sequenced so that the total processing time is minimized, when can the crew go home. They will start the first vehicle at 7:30 a.m. Time estimates are shown on the next slide. 1/11/2011 17

CNTD…:

CNTD… Exterior Interior Job Time (Hrs.) Time (Hrs.) Cadillac 2.0 2.5 Bentley 2.1 2.4 Lexus 1.9 2.2 Porsche 1.8 1.6 Infiniti 1.5 1.4 1/11/2011 18

CNTD…:

CNTD… Least Time Job Work Center Schedule Slot 1.4 Infiniti Interior 5 th 1.6 Porsche Interior 4 th 1.9 Lexus Exterior 1 st 2.0 Cadillac Exterior 2 nd 2.1 Bentley Exterior 3 rd 1/11/2011 19

CNTD…:

Exterior Interior 0 1.9 3.9 6.0 7.8 9.3 12.0 0 1.9 4.1 6.6 9.0 10.6 12.0 L C B L P I Idle C B P I Idle CNTD… It will take from 7:30 a.m. until 7:30 p.m. (not allowing for breaks) to complete the five vehicles 1/11/2011 20

SCHEDULING OF JOB SHOPS:

SCHEDULING OF JOB SHOPS Job shop scheduling is an optimization problem in which ideal jobs are assigned to resources at particular times. Use of graphical method such as Gantt Chart is very useful. 1/11/2011 21

CNTD…:

CNTD… Jobs 1 2 3 Due by Job-1 3(2) 7(4) 3(5) 10 Job-2 6(1) 3(2) 7(5) 12 Job-3 7(2) 3(4) 4(3) 9 Job-4 5(1) 4(3) 5(4) 14 Processing Time (Machine visited in the sequence) 1/11/2011 22

GANTT CHART FOR SPT RULE:

GANTT CHART FOR SPT RULE 1 1 1 2 2 2 2 2 2 2 1 1 1 1 1 1 1 3 3 3 4 4 4 4 4 4 4 4 4 3 3 3 3 1 1 1 3 3 3 3 3 3 3 2 2 2 4 4 4 4 4 2 2 2 2 2 2 5 4 3 2 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 1/11/2011 23

INPUT-OUTPUT CONTROL:

INPUT-OUTPUT CONTROL Identifies problems such as insufficient or excessive capacity, bottlenecks or any issues that prevents the order from being completed on time. Planned input should never exceed planned output. Input Output Work Center 1/11/2011 24

Slide 25:

Capacity requirements planning Routings and work centers Shop- floor dispatching Work- in-process control Input/ output analysis Prioritized queue lists Standard production costs Labor and equipment requirements Work orders Work order scheduling Work order tracking Hewlett-Packard’s Shop-Floor Control System 1/11/2011 25

Slide 26:

1/11/2011

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