Lecture 5 & 6 Flashcards
What is lean production (generally) ?
- Lean production means doing more work with fewer resources
- Adaptation of mass production in which work is accomplished in less time, smaller space, with fewer workers and less equipment
- Based on the Toyota Production System
Illustrate the structure of the lean production system.
What are Taiichi Ohno’s seven forms of waste?
Taiichi Ohno’s seven forms of waste:
- Transportation: Unnecessary handling of materials
- Inventory: Excessive inventories
- Motion: Unnecessary movement of people
- Waiting: Workers waiting
- Overproduction: Production of more parts than needed
- Overprocessing: Unnecessary processing steps
- Defects: Production of defective parts
- Skill: Failure of making best use of workers
Extra Notes:
(He did not come up with number 8)
The different forms of waste feed into each other. Such as overproduction feeds into transport or inventory feeds into transport etc.
In a lean manufacturing: not a single defect is allowed. (conventional manufacturing they check a couple and send off the batch)
Explain pull of the product and why sometimes products need to be pushed.
- Pull the product from the system at the rate of customer demand
- Whereer practicable, pull the product through the whole system at the same rate
- But because of technical constraints it may be necessary to push product to a certain point.
- Identify the push-pull decoupling point is key.
What is Just-in-Time manufacturing (general definiton) ?
Production and delivery of exactly the required number of each component to the downstream operation in the manufacturing sequence just at the moment when the component is needed.
Minimizes:
- Work-in-process
- Manufacturing lead time
What are the two types of Kanban?
Two types of kanbans:
- Production kanban – authorizes upstream station to produce a batch of parts
- Transport kanban – authorizes transport of the parts to the downstream station
Extra notes:
Toyota’s way of implementing a pull system of production control
Kanban means “card” in Japanese
Draw and explain how set-up times are reduced (Single Minute Exchange of Dies).
What are external work elements?
- Can be accomplished while previous job is still running
- Strategy: Design the setup tooling and plan the changeover procedure to permit as much of the setup as possible to consist of external elements
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Examples:
- Retrieve tooling for next job from tool crib
- Assemble tools for next job
- Reprogram machine for next job
What are internal work elements?
- Use time & motion study and methods improvement to minimize the sum of the internal work element times
- Use two workers rather than one
- Eliminate adjustments in the setup
- Use quick-acting fasteners rather than bolts and nuts
- Use U-shaped washers instead of O-shaped washers
- Use of interrupted screw
What are some requirements for JIT?
- Production leveling
- distribute changes in product mix and quantity as evenly as possible over time
- On-time delivery of components
- Defect-free components and materials
- Reliable production equipment
- Workforce that is cooperative, committed, and crosstrained
- Dependable supplier base
What is autonomation?
- “Automation with a human touch”
- Production machines operate autonomously as long as they are functioning properly •
- When they do not function properly (e.g., they produce a defect), they are designed to stop
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Key autonomation topics
- Stop the process (Jidoka)
- Error prevention (Poka-yoke)
In autonomation what is stop the proccess?
Illustrate the simple principle of ‘zero defects’
What are the two types of poka-yoke devices?
- Prevention
- The process is designed so that it is impossible to make an error
- Removes any need to correct a error
- Detection
- Signals the user an error has been made so the user can quickly correct the problem
- Stops defects from reaching customer
Poka-yoke: what are the different levels of intervention
Explain techniques used for error prevention (“Poka-yoke”).
- Certain engine would be built, but there would be a couple of bolts left at the end and no one would know where the error was made. Re-designed so the process is made in steps with the specified number of screws for each process steps.
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Prevention in poka-yoka devices
- The process is designed so that it is impossible to make an error
- Removes any need to correct a error
- The process is designed so that it is impossible to make an error
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Detection in poka-yoka devices
- Signals the user an error has been made so the user can quickly correct the problem
- Stops defects from reaching customer
Give two examples of Poka-yoke
Explain how visual managment dictates the features of the work place.
- Principle: the status of the work situation should be evident just by looking at it
- Objects that obstruct the view are not allowed
- Build-up of WIP is limited to a specific height
- Andon boards located above the assembly line indicate the status of the workstations
- Worker training includes use of photos and diagrams to document work instructions
What is 5S?
- It is a Japaneze term.
- Method for organizing a workplace and keeping it organized
- Removes waste
- Abnormalities stand out (problems are easier to see)
- Needs to be owned by people who work in that area.
- The 5Ss can be thought of as a simple housekeeping methodology to organize work areas that focuses on visual order, organization, cleanliness and standardization. It helps to eliminate all types of waste relating to uncertainty, waiting, searching for relevant information, creating variation and so on. By eliminating what is unnecessary, and making everything clear and predictable, clutter is reduced, needed items are always in the same place, and work is made easier and faster.
Draw a diagram to illustrate the maximum available factory time lost.
Define availability rate, performance rate, quality rate.(and their equations)
What is the equation for Overall Equipment Effectiveness.
Pictures of before and after 5S approach.
What is the definiton of OEE that isn’t useful?
Explain CPS and the three systems of the Toyota Production System.
