Lecture 5 & 6 Flashcards
(27 cards)
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.
Roof = customer focus
Pillars = JIT and Autonomation
Middle = Worker involvement
Base = Elimination of waste
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)
What is Just-in-Time production
The production and delivery of the required number of each component to the downstream process in a manufacturing sequence, the moment it is needed.
What determines the rate of a pull system, and why is this sometimes impossible?
- 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 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).
Step 1: Analyse the set up process
Step 2: Classify setup operations
(waste, internal, external)
Step 3: Eliminate waste
Step 4: Convert as many internal setups to external setups
Step 5: Improve internal setups to save time
Step 6: Improve external setups
Step 7: Develop SOP
Step 8: Evaluate performance and continuously improve
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
-
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
-
Key autonomation topics
- Stop the process (Jidoka)
- Error prevention (Poka-yoke)
In autonomation what is stop the proccess?
Machines are designed to stop automatically when something goes wrong, or required quantity is produced.
Illustrate the simple principle of ‘zero defects’
Do not accept, make or transfer defects
Describe Poka-yoke
Prevention of errors using low cost devices to prevent or detect them.
Common mistakes in manufacturing:
- Omitting processing steps
- Incorrectly locating a part in a fixture
- Using the wrong tool
- Neglecting to add part to assembly
What are the two types of poka-yoke?
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
Indicator
Signal
Control
Guarantee
Give two examples of Poka-yoke
Explain what Kaizen is.
- “Kaizen” – Japanese word meaning continuous improvement of production operations
- Train workers in necessary skills
- Motivate workers to improve
- Usually implemented by worker teams, sometimes called “quality circles”
- Encourages worker sense of responsibility
- Allows workers to gain recognition among colleagues
- Improves worker’s technical skills
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 Japanese 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
SORT
STRAIGHTEN
SHINE
STANDARDISE
SUSTAIN
What is total productive maintenance?
- TPM = integration of preventive and predictive maintenance to avoid emergency maintenance.
- Emergency maintenance = repair equipment that breaks down.
- Preventive maintenance = routine repairs to avoid breakdowns
- Predictive maintenance = anticipating malfunctions before they occur
- Operators do preventive maintenance and maintenance department must be just a back up, zero break downs goal.
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.
Availability losses - unplanned, set ups, breakdowns
AR = actual running time / scheduled running time
Speed losses - slow running equipment, idle equipment
PR = actual parts produced / parts that could’ve been
Quality losses
QR = Number of good parts/ total number of parts
OEE = AR * PR * QR
Pictures of before and after 5S approach.
