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Manufacturing Process by Jacobs 5e Chapter 6 2019 edit
- 1. 1 1- Chapter 6 Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. McGraw-Hill Education / Jacobs MANUFACTURING PROCESSES
- 2. 2 1- LEARNING OBJECTIVES 1. Understand what a manufacturing process is. 2. Understand production process mapping and Littleās law. 3. Explain how manufacturing processes are organized. 4. Understand how to design and analyze an assembly line. Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 3. 3 1- PRODUCTION PROCESS TERMS ā¢ Lead time ā the time needed to respond to a customer order ā¢ Customer order decoupling point ā where inventory is positioned to allow entities in the supply chain to operate independently ā¢ Lean manufacturing ā a means of achieving high levels of customer service with minimal inventory investment Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 4. 4 1- TYPES OF FIRMS Make-to-Stock ā¢ A production environment where the customer is served āon-demandā from finished goods inventory Assemble-to-Order ā¢ Preassembled components, subassemblies, and modules are put together in response to a specific customer order Make-to-Order ā¢ The product is built directly from raw materials and components in response to a specific customer order Engineer-to-Order ā¢ Firm works with the customer to design and then make the product Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 5. 5 1- MAKE-TO-STOCK ā¢ Examples of products ā Televisions ā Clothing ā Packaged food products ā¢ Essential issue in satisfying customers is to balance the level of inventory against the level of customer service ā Easy with unlimited inventory, but inventory costs money ā Trade-off between the costs of inventory and level of customer service must be made ā¢ Use lean manufacturing to achieve higher service levels for a given inventory investment Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 6. 6 1- ASSEMBLE-TO-ORDER ā¢ A primary task is to define a customerās order in terms of alternative components, since these are carried in inventory ā An example is the way Dell Computer makes their desktop computers ā¢ One capability required is a design that enables as much flexibility as possible in combining components ā¢ There are significant advantages from moving the customer order decoupling point from finished goods to components ā¢ Wide variety of finished goods combinations can be built from a set of components Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 7. 7 1- MAKE-TO-ORDER/ENGINEER-TO-ORDER ā¢ Boeingās process for making commercial aircraft is an example ā¢ Customer order decoupling point could be in either raw materials at the manufacturing site or the supplier inventory ā¢ Depending on how similar the products are it might not even be possible to pre-order parts Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 8. 8 1- PRODUCTION PROCESSES ā¢ Production processes are used to make any manufactured item ā Step 1 ā Source the parts needed ā Step 2 ā Make the product ā Step 3 ā Deliver the product Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Positioning inventory in the supply chain Exhibit 6.1
- 9. 9 1- PRODUCTION PROCESS MAPPING ā¢ Develop a high-level map of a supply chain process ā¢ Useful to understand how material flows and where inventory is held ā¢ First step in analyzing the flow of material through a production process Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Exhibit 6.2
- 10. 10 1- INVENTORY MEASURES ā¢ Total average value of inventory ā The total investment in inventory at the firm ā Raw materials ā Work-in-process ā Finished goods ā¢ Inventory turn ā An efficiency measure where the cost of goods sold is divided by the total average value of inventory ā¢ Days-of-supply ā A measure of the number of days of supply of an item (the inverse of inventory turn scaled to days) Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent
- 11. 11 1- LITTLEāS LAW ā¢ The flow of items through a production process can be described using Littleās Law ā¢ Work in Process Inventory (WIP) = Throughput rate Ć Flow time ā Inventory ā materials held by the firm for future use ā Throughput ā long-term average rate that items are flowing through the process ā Flow time ā time for a single unit to to completely flow through the entire process Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 12. 12 1- ORGANIZATION OF PRODUCTION PROCESSES Project ā the product remains in a fixed location, equipment is moved to the product Workcenter (job shop) - similar equipment or functions are grouped together Manufacturing cell - a dedicated area where products that are similar in processing requirements are produced Assembly line - work processes are arranged according to the progressive steps by which the product is made Continuous process ā (assembly line only) the flow is continuous, such as with liquids Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 13. 13 1- PRODUCT-PROCESS MATRIX Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Exhibit 6.3
- 14. 14 1- PRODUCTION SYSTEM DESIGN Project Layout ā¢ The product remains in a fixed location ā¢ Labor, material, and equipment are moved to the product ā¢ A project layout may be developed by arranging materials according to their assembly priority Workcenter Layout ā¢ Most common approach to developing this type of layout is to arrange workcenters in a way that optimizes the movement of material ā¢ Optimal placement often means placing workcenters with high levels of interdepartmental traffic adjacent to each other ā¢ Sometimes is referred to as a job shop and is focused on a particular type of operation Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 15. 15 1- PRODUCTION SYSTEM DESIGN (2) Manufacturing Cell Layout ā¢ A dedicated area where products that are similar in process requirements are produced ā¢ Cells are designed to perform a specific set of processes ā¢ Dedicated to a limited range of products Assembly Line and Continuous Process ā¢ Area where an item is produced through a fixed sequence of workstations, designed to achieve a specific production rate ā¢ A process that converts raw materials into finished product in one contiguous process Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 16. 16 1- MANUFACTURING CELL DEVELOPMENT 1. Group parts into families that follow a common sequence of steps. 2. Identify dominant flow patterns for each part family 3. Machines and the associated processes are physically regrouped into cells Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Exhibit 6.4
- 17. 17 1- REALLOCATING MACHINES Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Manufacturing cells are formed according to part family processing requirements Exhibit 6.4
- 18. 18 1- ASSEMBLY LINE DESIGN ā¢ Workstation cycle time - a uniform time interval in which a moving conveyor passes a series of workstations āAlso the time between successive units coming off the line ā¢ Assembly-line balancing - assigning all tasks to a series of workstations so that the required cycle time is met and idle time is minimized ā¢ Precedence relationship - the order in which tasks must be performed in an assembly process Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 19. 19 1- ASSEMBLY-LINE BALANCING 1. Specify the sequential relationships among tasks using a precedence diagram. 1. Determine the required workstation cycle time (C). 2. Determine the theoretical minimum number of workstations (N). 3. Select a primary rule to assign tasks to workstations and a secondary rule to break ties. Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 20. 20 1- ASSEMBLY-LINE BALANCING (2) 5. Assign tasks (one at a time) to the first workstation until no more tasks can be added (due to cycle time or sequencing constraints). Repeat for all subsequent workstations until all tasks are assigned. 6. Evaluate the efficiency of the balance 7. If efficiency is unsatisfactory, rebalance using a different rule. Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 21. 21 1- ASSEMBLY STEPS AND TIMES ā EXAMPLE 6.2 Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Exhibit 6.5
- 22. 22 1- PRECEDENCE GRAPH ā EXAMPLE 6.2 Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Exhibit 6.5
- 23. 23 1- PRIORITIZE TASKS ā EXAMPLE 6.2 Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Prioritize tasks based on the largest number of following tasks. Prioritize tasks in order of longest task time. Exhibit 6.6
- 24. 24 1- EFFICIENCY ā EXAMPLE 6.2 Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Exhibit 6.6
- 25. 25 1- REDUCING TASK TIME POSSIBILITIES ā¢ Split the task ā Can we split the task so that complete units are processed in two workstations? ā¢ Share the task ā Can the task be shared so an adjacent workstation does part of the work? ā¢ Use parallel workstations ā¢ Use a more skilled worker ā¢ Work overtime ā¢ Redesign ā It may be possible to redesign the product to reduce the task time Copyright Ā©2020 McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education.
- 27. 27 1- Exhibit 7.7 Value Stream Map for Restaurant Order Posting and Fulfillment Process
- 28. 28 1- PROCESS ANALYSIS AND IMPROVEMENT ā¢ Strategies to improve process designs focus on: āIncreasing revenue, agility, and product and/or service quality āDecreasing costs, process flow time, and carbon footprint LO 7-5
- 29. 29 1- PROCESS ANALYSIS AND IMPROVEMENT (CONTINUED) āReengineering: Fundamental rethinking and radical redesign of business processes ā¢ Helps achieve improvements in critical and contemporary measures of performance such as cost, quality, service, and speed LO 7-5
- 31. 31 1- UTILIZATION AND OPTIMIZATION Work Activity #1 [Chef decides if order is accurate] Work Activity #2 [Chef stages raw materials] Work Activity #3 [Chef prepares side dishes] Work Activity #4 [Oven Operation] Work Activity #5 [Chef assembles order] Order arrival rate [given] D 20 orders/hr 20 orders/hr 20 orders/hr 20 orders/hr 20 orders/hr Time per order 1 minute 4 minutes 12 minutes 10 minutes 3 minutes Number of resources N 1 chef 1 chef 1 chef 1 oven 1 chef Output per time period [capacity] SR 60 orders/hr 15 orders/hr 5 orders/hr 6 orders/hr 20 orders/hr Resource Utilization 33% 20/(15 x 1) = 133% 400% 1.0 = 20/(5 x N) N = 4 333% 1.0 = 20(6 X N) N = 3.33 = 4 100% Where are the bottlenecks? How can we fix it?
- 32. 32 1- UTILIZATION AND OPTIMIZATION Work Activity #1 [Chef decides if order is accurate] SR = 60 Work Activity #2 [Chef stages raw materials] SR = 15 Work Activity #3 [Chef prepares side dishes] SR = 5 Work Activity #4 [Oven Operation] SR = 6 Work Activity #5 [Chef assembles order] SR = 20 Resource Utilization with 4 chefs and 4 oven U = 20/(60 X 4) = 8.3% 33% 100% 83.3% 25%
- 33. 33 1- UTILIZATION AND OPTIMIZATION Work Activity #1 [Chef decides if order is accurate] Work Activity #2 [Chef stages raw materials] Work Activity #3 [Chef prepares side dishes] Work Activity #4 [Oven Operation] Work Activity #5 [Chef assembles order] Order arrival rate [given] 20 orders/hr 20 orders/hr 20 orders/hr 20 orders/hr 20 orders/hr Time per order 1 minute 4 minutes 12 minutes 10 minutes 3 minutes Number of resources 4 chefs 4 chefs 4 chefs 4 ovens 4 chefs Output per time period [SR x N] 240 orders/hr 60 orders/hr 20 orders/hr 24 orders/hr 80 orders/hr Resource Utilization 8.33% 33% 100% 25% Revised utilization analysis with 4 chefs & 4 ovens What questions are you left with? Next steps?