Service and Product Design: Redundancy Optimization

Transcription

1 Service Supply Chain Thought Leaders Forum, San Francisco, 1 March 2011 Service and Product Design: Redundancy Optimization Geert-Jan van Houtum Prof. of Reliability, Quality, and Maintenance Based on: Work with K. Öner and A. Scheller- Wolf (CMU) and master thesis R. Vlasblom (TU/e, now at Gordian Logistic Experts)

2 / School of Industrial Engineering 3/9/2011 PAGE 1

3 TCO for an example system 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% Acquisition costs Maintenance costs Downtime costs / School of Industrial Engineering 3/9/2011 PAGE 2

4 Life Cycle Needs and requirements Design Production Exploitation Disposal Big influence on TCO One may look at: Modular design More reliable components Building in redundancy Means to facilitate monitoring and diagnosis A large portion of the TCO is made in this phase / School of Industrial Engineering 3/9/2011 PAGE 3

5 CONTENTS Introduction Redundancy in a baggage handling system Redundancy in a serial system Concluding Remarks / School of Industrial Engineering 3/9/2011 PAGE 4

6 Redundancy in a baggage handling system Cf. master thesis of R. Vlasblom / School of Industrial Engineering 3/9/2011 PAGE 5

7 Vanderlande Industries Designs, implements and services automated material handling systems. Express Parcel Distribution Baggage Handling Service / School of Industrial Engineering 3/9/2011 PAGE 6

8 Assignment Develop a tool (calculation model) that determines the system availability and TCO of a given system design in the early sales phase of a project Focus: Baggage Handling Systems / School of Industrial Engineering 3/9/2011 PAGE 7

9 Model development Configuration of a system Transport zone Check in zone Check in area Section: Belt floorveyor Section: Weighing belt section level (building blocks) zone level area level system level / School of Industrial Engineering 3/9/2011 PAGE 8

10 Model development (cont.) Factors that affect availability via system reliability Higher equipment reliability - higher technical availability - higher equipment costs Technical availability System Reliability (MTBF) Down Time (MDT) Equipment System redundancy Inspections and Preventive Maintenance More redundancy - higher technical availability - higher equipment investment Modifications and Retrofits Constant More inspections - higher technical availability - higher maintenance costs / School of Industrial Engineering 3/9/2011 PAGE 9

11 Model development (cont.) Factors that affect availability via down time Technical availability System Reliability (MTBF) Down Time (MDT) Equipment System redundancy Inspections and Preventive Maintenance Modifications and Retrofits Response Time Spare Part Delay Time Maintenance Repair Time Constant Constant Constant Higher spare part stock levels - higher technical availability - higher investments in spare parts / School of Industrial Engineering 3/9/2011 PAGE 10

12 Model development (cont.) Factors that affect availability via down time Technical availability System Reliability (MTBF) Down Time (MDT) Production loss (Down Time Costs) forms large part of life cycle costs / School of Industrial Engineering 3/9/2011 PAGE 11

13 Case 2 design alternatives: with and without redundancy Departure Carousel Departure Carousel Departure Carousel X-ray X-ray X-ray X-ray Check in 1-12 Check in Check in Check in in / School of Industrial Engineering 3/9/2011 PAGE 12

14 Case (cont.) Design with redundancy: Investment increase of 21% Down time cost decrease of 30% Reduction in TCO 5% / School of Industrial Engineering 3/9/2011 PAGE 13

15 Redundancy in a serial system Cf. working paper with K. Öner (TU/e) and A. Scheller-Wolf (CMU) / School of Industrial Engineering 3/9/2011 PAGE 14

16 Model Production site Spare parts stock Regular replenishments Emergency supply procedure (in case of stockout) / School of Industrial Engineering 3/9/2011 PAGE 15

17 Model (cont.) Component 1 Component 2 Component 2 Component i Component m Component m Per machine: Multiple critical components Serial structure / School of Industrial Engineering 3/9/2011 PAGE 16

18 Model (cont.) Three possible policies per component 1. No redundancy 2. No redundancy, apply emergency supply procedure when on-hand stock drops to 1 3. Redundancy Optimization problem Min. TCO s.t. system availability constraint / School of Industrial Engineering 3/9/2011 PAGE 17

19 Our main contribution Modeling of the problem Method to generate the efficient frontier for TCO and system availability Method to rank candidates for redundancy Effect of policy 2 / School of Industrial Engineering 3/9/2011 PAGE 18

20 Analysis per component Costs Policy 1 Policy 2 Policy 3 Policy 1 optimal Policy 2 optimal Policy 3 optimal / School of Industrial Engineering 3/9/2011 PAGE 19

21 Efficient frontier Without policy 2 With policy 2 included Availability / School of Industrial Engineering 3/9/2011 PAGE 20

22 Concluding Remarks / School of Industrial Engineering 3/9/2011 PAGE 21

23 Redundancy can be an attractive way to reduce TCO Needed: More research on effect of redundancy on system availability and TCO Tools to support redundancy decisions / School of Industrial Engineering 3/9/2011 PAGE 22