Waste Elimination Flashcards
What is 5s?
tool for workplace organization and standardization
sort
straighten
shine
standardize
sustain
What does each S mean?
sort - remove unneeded
straighten - arrange for ease of use
shine - cleanup campaign
standardize - maintain the system
sustain - make 5s the culture
What is a pull system?
a system for managing scheduling and material flow so that overproduction and excess inventory are eliminated
How does a pull system work?
- synchronizes production with customer demand
- replenishes product as it is consumed by a subsequent processing step
- seeks to produce only the exact products needed, in the exact quantity needed, in shortest lead time possible
- used when you want to reduce overproduction and inventory costs
What are the characteristics of push systems?
- bases production on forecast or other mechanisms not directly linked to consumption
- creates products that are sent when made and stored where needed
What are the characteristics of a pull system?
- limits production to only what has been consumed
- begins production with a pull signal
- products are stored where they are made and pulled when needed
What are the consequences of a push system?
- risks mismatch between supply and consumption and, consequently a shortage or excess stock (excess is more common)
- requires less planning and guesswork to determine production plans
What are the consequences of a pull system?
- results in match between supply and consumption
- material shortages are very visible
- delivers/produces in small quantities
- makes regular review of consumption levels (correct pull levels) essential
What are the primary elements of a pull system?
1) Trigger
2) Flow
3) Upstream - ready process
4) Downstream - in-use process
What are types of pull systems?
replenishment (supermarket)
sequential
mixed pull
What is a replenishment (supermarket) pull system?
- each process has a “store” that holds a specific amount of product it produces
- consumption triggers replenishment
- system carries inventory for all products
What is a sequential pull system?
- used if holding inventory isn’t feasible
- production is queued to control inventory
- kanaban cards signal production
What is a mixed pull system?
- uses replenishment (supermarket) for high volume
- uses sequential for low volume
What is kanban?
a system that ensures that material and information move into and out of a process in a timely manner
GOAL: materials do not arrive before they are needed
When is kanban used?
- in pull systems
- to reduce overproduction
- reduce work-in-progress inventory costs
What is standard work?
a method of documenting the current best practice for effectively and efficiently completing a process
What does standard work documentation create?
- clear standards
- consistency
- efficiency
- reduces variation
- minimizes waste
Standard work documents the ______________ best practice but it is intended to be _________________.
current
improved
What are the benefits of standard work?
there can be no improvement where there are no standards
What are the different time elements for measuring standard work?
cycle or process time = time for each step in process
lead time = total time including wait time
takt time = net time available to meet customer demand
What is the takt time formula?
T = Ta/D
T = product assembly time required to meet demand
Ta = net time available to work
D = customer demand
What is the formula for cycle time?
=net production time/number of units produced
What is the lead time formula?
= order delivered - order received
Standard Work In Progress (SWIP) tells us…
- if we are meeting SWIP target, process is flowing
- if # of products > SWIP, there is a bottleneck
- if # of products < SWIP, process is performing better than expected, insufficient products scheduled, or market demand has decreased
What is a standard work chart?
a graphical view of the work cell, the path of the operator and the amount of standard WIP required to keep the process running smoothly
What is the standard work combination table?
shows what the takt time is in comparison with the cycle time of the process
What is the production capacity worksheet?
takes each step and breaks it down into manual time and automated time to define the total time per unit
helps identify bottlenecks
What is the standardized work chart?
a consolidated document that addresses:
- takt time
- work sequence
- standard work in process (SWIP)
What is poka-yoke?
mistake proofing
a means of preventing errors from occurring through the use of physical, procedural, visual, or other forms of devices that prevent improper execution of a process step
What is the difference between an error and a defect?
error = deviation from standard process
defect = product does not meet specifications or customer expectations
What is the relationship between errors and defects?
defects are caused by errors but not all errors will become defects
What are sources of error? (7)
1) forgetting
2) dexterity limitations
3) fatigue
4) outside distractions
5) variation in component parts
6) ineffective maintenance
7) insufficient work instructions
What are types of error? (9)
1) misunderstanding
2) misidentification
3) lack of training
4) willful
5) inadvertent (fatigue or distraction)
6) slowness (delay in judgment)
7) lack of standards
8) surprise (malfunction)
9) intentional (sabotage)
What are defects caused by errors? (6)
- missed steps
- set-up errors
- missing parts
- wrong part assembled
- wrong part worked on
- adjustment, measurement, or dimensional errors
Remember: Everyone makes ____________. The goal is to design better _________, ______________, ____________, etc. to facilitate the ___________ or ____________ of mistakes and errors.
mistakes
systems, procedures, environments
reduction, elimination
What are the characteristics of defects?
- attributes by nature
- can’t be measured; no “degree of goodness”
- either works or doesn’t; right or wrong
- requires functional test or visual inspection
What are the three components of a poka-yoke device?
- 100% inspection
- rapid feedback
- low cost and simple
What are the two types of poka-yoke devices?
- prevention devices
- detection devices
What are the 5 principles of mistake proofing?
Elimination - remove defect causes
Replacement - substitute a different process
Facilitation - put something in place to facilitate the process of producing a good end result
Detection - identify defect when it occurs
Mitigation - reduce consequences of defect
How do you standardize?
1) Approach - establish a standardized approach
2) Flow - what needs to be done regularly
3) Frequency - determine how often
4) Checklists - create standard 5s checklist
5) Responsible Parties - decide who is responsible for what
6) Combine - incorporate checklist into standard work instructions
Standards should be… (7)
- concise
- easy to understand
- simple language (no technical jargon)
- as visual as possible
- comprehensive
- reviewed and updated
- communicated throughout
