Lean Production II
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What are Standard Operating Procedure Sheets used for and why?
show detailed necessary activities and provide a uniform training method for employee qualifications
- - training document
- - captures key qualifications which are necessary to process standard operating steps
- - identifies special tools, quality, safety aspects
- - leads to collective understanding of processes
name the seven steps to create a standardized work chart
- 1) record sequence of job
- 2) determine material, tools, equipment/machines to do the job
- 3) diagram work movement
- 4) identify waste
- 5) determine improving actions to achieve desired results (eg takt time)
- 6) create flow, define standard inventory
- 7) document method
explain the work element combination chart
- first row: manual work
- second row: automatic work
- third row: transportation/walking
it is not acceptable to make operator wait for machine
- together with Standard Work Chart:
- - shows combination of automatic and manual work
- - allows analysis of man machine relationship
What do standards mean for Associates and Leaders?
- Workers must be:
- - capable of keeping defined standards
- - willing to keep them
- Leaders must:
- - support people to deliver right results
- - train and qualify people
- - be present on shop floor/Gemba
- - implement simple controls (visualisation, KPIs, ANDON, Takt time...)
- - check controls, understand abnormalities and react
- - support problem solving process, improve and standardize again
explain the "degree of maturity of standards"
- diagram: x: right behaviour, y: maturity
- down left: no standard defined
- -standard defined but not known&trained
- -standard defined, visualized&known but no called for
- - standard defined, known, called for, followed
- up right: standard continuously challenged&improved = KAIZEN, standard work
what do you have to look at when auditing standardized work?
- - does a standard exist?
- - is the standard up to date?
- - do employees know the standard?
- - is work performed according to the standard?
--> only if all questions are answered with yes, it very likely is standard work
For KAIZEN there must be system to highlight abnormalities and learn form them
name the five indicators of stability
- variability (product families, exotics are isolated)
- work task repeatability (work not defined/only few if..then rules)
- equipment reliability (line and equipment must be reliable, downtime should be minimal)
- technical process stability (quality issues must be minimal, right process parameters deliver stable result)
- material availability (no interruption, searching)
what is the objective of 5S?
- long term creation of corporate culture, in which order and cleanliness are matter of courses
- stability of all processes, esp. in areas with many employees and little space av.
- safety and health at work
- toll to prepare flow
Name the steps of 5S and explain them
- get rid of everything that avoids better process, create space for better arrangement
- cleaning is inspecting!cleaning/inspection plans
- reduce waste, improve ergonomics, create flow
- clear and simple instructions
- Observation, Challenge and continuous improvement of standards (review by audits and checklists)
Name the japanese words of 5S
what are the goals of visual management?
- immediate identification of deviations without further tools
- realize just by walking through an area whether standards are kept and the process is in order
explain how standards support adherence to correct methods
- standard -> make standard visible -> able to verify adherence to standard -> discover deviation -> report deviation -> correct deviation -> standard
- => clear and understandable
what are visual controls?
- every kind of signals, displays or sounds, which deliver...
- .. what we need to know
- ... when we need to know it
- ... where we need to know it
- in a form that is CLEARLY UNDERSTOOD
What is visual management?
improvement process addressing abnormalities highlighted by visual controls
Abnormality -> visualisation ->process improvement
What are the three major rules of visulisation?
- only visualize, if
- 1) there is a standard
- 2) the standard is controlled
- 3) deviation leads to defined reaction
In which five categories can visual information system be devided?
- identity and location (keep basic order&flow)
- work documents(ensure standard work practices)
- process state (detect normal from abnormal)
- performance(adequately react to performance gaps on all levels)
- improvement processes (support teams&install a self propelled process)
what is the goal of performance management? name 3 tools
- support target deployment process, give teams opportunity to monitor and improve their own processes
- - team charts with current vs. target performance, supplemented by other KPI's (quality, cost time)
- - control charts for process stability (in target area with minimal deviation)
- - safety information (nr. of accidents and their causes)
name four examples for the improvement processes (part of visual information system)
- Problem solving workflow
- Action Plan (PDCA)
- Pareto diagram
- cause and effect diagram (fishbone)
which three problems arise, when we build to order?
- muda - waste
- mura - unevenness
- muri - overburden
what are the three edges of the standard work triangle?
how do you calculate the customer takt?
- total available time (min/day)
- total customer demand (products/day)
- = customer takt (min/product)
what are the consequences for "build to levelled schedule and ship to order"?
- finished goods inventory held (expensive)
- low WIP inventory
- smoothened capacity utilisation
- high degree of stability
- foundation to process improvement
Explain the revolving production schedule
a revolving production schedule distributes work evenly among the process steps of the production sequence at all times
what are the four planning steps you have to run through to reach leveled production?
- 1) stabilisation
- 2) leveling by volume
- 3) leveling by type
- 4) sequencing
What does the first step to leveled production "stabilisation" include?
- stable processes and plant availability,
- stable suppliers,
- clear understanding of capacity available
What does the second step to leveled production "leveling by volume" include?
- leveling by volume:
- clear understanding of customer demand, stable
- production volume over planning period, understanding customer takt
What does the third step to leveled production "leveling by type" include?
- leveling by type:
- understanding changeover,
- adjusting customer takt,
- definition of runners&exotics,
- definition of pitch size,
- building a daily leveled schedule,
- operating at heijunka box
What does the fourth step to leveled production "sequencing" include?
- sequencing :
- stabilise planning process,
- improve availability of material and
- reduce and stabilise changeover,
- reduce pitch size,
- reduce EPEI
explain the importance of changeover times for planning perspective
if changeover times are irrelevant --> basis for planning is customer takt
if changeover times are >>0 --> production must index faster than customer takt to fulfill customer demand
how do you calculate the adjusted customer takt? (adjusted to changeover times)
- planned production time - changeover timeloss /
- customer demand = adjusted customer takt
what are the definitions for runners and exotics?
- runners: will be produced every day following a constant volume and cyclic schedule
- exotics: will be produced once a week at free time slots
number of runners depends on largest number of possible changeovers per week
calculate the largest number of changeovers
= changeover time provision (min/week) / changeover time (min/changeover)
calculate the planned changeovers and name the rule how to fix number for runners and exotics
- nplanning days x nrunners + nexotics
- with nrunners + nexotics = ntypes
- rule: choose split between runners and exotics so that
- 1. planned <= largest no. of changeovers
- 2. planned changeovers --> max
- 3 runners/day x 5 days + 8 ex = 23
- 4 runners/day x 5 days + 7 ex = 27
- 5 runners/day x 5 days + 6 ex = 31
largest no of changeovers = 28 --> choose 27 combination
what does "pitch" mean?
- standardised planning increment
- pitch = n x box size x customer takt
- - is multiple of customer takt
- - is the time increment of work released at the pacemaker process
- - equals or is a multiple of standardised material quantity moved between processes
- the higher leveling maturity, the smaller the pitch
what is heijunka box?
- heijunka box is a tool to level mix and volume of production using kanban within a facility at fixed intervals (also called: leveling box)
- - each horizontal row is for one type of product
- - each vertical column represents identical time intervals for paced withdrawal of kanban
- - slots represent material and information flow timing
- - kanban in the slots each represents one pitch of production for one product type
why is the pacemaker process streamlined?
- it synchronizes the whole production process with the customer takt
- it controls processes which are located upstream via pull
- it receives production plan as the only process
what is the functionality of the pacemaker process?
- 1) customer sends orders to company
- 2) orders are translated in kanban-cards and sorted into heijunka board
- 3) material supplier picks up removal-kanban of every pitch and takes it to pacemaker
- 4) upstream processes are initiated via removal-kanban
name the three meanings of heijunka
- idealistic: tool to level production by volume and type with ideal of producing every part every day
- stability: leveling for internal benefit of standardised and stabilised value stream with aligned resources (equipment, materials, people, methods)
- improvement: improvement approach to push process to higher degrees of flexibility and responsiveness to changing customer demand
what does EPEI stand for?
- Every Part Every Interval = No. of types/largest no. of changeovers
- shortest possible time interval to produce a product program whilst achieving required quantity
explain the approach on heijunka production planning
- understanding customer demand
- understanding customer takt
- understanding changeover
- largest number of changeovers
- definition of runners and exotics
- definition of pitch size
- definition of leveled weekly schedue
- definition of pitch cycles for replenishment
- implementation of daily heijunka schedule
- stabilisation and reduction of EPEI
Expalin Just in Time
- to produce and transport within the entire value stream
- - what is needed
- - when it is needed
- - where it is needed
- - in the quantity and quality, which is needed
- also know as 5R (right product, quality, time, quantity and place)
goal: reduce production costs, increase flexibility
approach: provides steady, stable processes in order to achieve continuous flow production with minimal stocks
which parts does Just in Time include?
- takttime planning
- continuous flow
- pull system
- quick changeover
- integrated logistics
what does Just in Time Production and delivery mean?
- - product is delivered form finished goods supermarket
- - production process is synchronized with customer demand and procedures only with presence of production order
- - system efficiency has priority - not machine load factor
why do you need a production flow?
- flowing reduces throughput time and shortens cost to cash cycle
- surfaces any problem immediately that would inhibit that flow
- creation of flow forces correction of problems and creates need for quality improvements
when is flow processing not (yet) possible?
- high changeover times
- shared assets are used by different value streams
- process times are much higher than customer takt
- great distance between processes
- processes are unsteady
explain the three steps of flow creation
- disconnected stability (of single operation)
- multiprocess connected stability (multiple operations)
- value stream connected stability
flow is a waste elimination tool - explain
- Waste Elimination (Philosophy)
- Create Continuous Flow(Principle) -> Reduced Lead Times (Performance Measures)
- Create independent connected processes (Strategy)
- Pull System(Method)->Kanban, Supermarkets, Defined FiFo Lanes(Tools)
- Problems are surfaced quickly&critical(reason)
- problems must be corrected quickly (effect)-->management reviews reports,adjusts standards(control method)
- Waste is reduced!(result)
what are the advantages of flow production?
- creates revolving stock of constant amount
- reduces transport,movements,space by moving processes closer together
- reduction of scrap
- illustrates waste within process(waiting time,stock)and supports continuous improvement
What are the advantages of CHAKU CHAKU(load, load) lines? (flow assembly environments)
- minimal lead times
- small stocks without intermediate buffer
- minimal land requirements
- high quality
- low investment
- requirement: high availability of plants
which three characteristics have to be in place to distinguish pull from push?
- 1) defined agreement between supplier and customer
- 2) shared items between parties clearly dedicated
- 3) simple controls in place to support adherence of above
what are the main characteristics of a pull-system?
- low coordination effort
- stocks in line with demand
- short lead times
- but:higher suscetibility to failure due to less stocks
What are the definition, goal and approach of pull systems?
- def: in pull-system production processes are controlled by their direct customer,ie what and when to produce is defined by the customer
- goal: produce exactly the quantity demanded by customer, not more!
- approach: integrate information flow and material flow between each stage of production and its direct customer
name the three types of pull systems and give a short definition
- FIFO: system in which components are handled in same order(up and downstream)
- Supermarket: characterized by defined stock between processes that include all types
- Mix-Pull:uses a FIFO system or supermarket depending on variant
explain the simplified decision matrix for pull systems
- high Supermarket Mix-Pull
- low FIFO/Supermarket FIFO
- low high
- Number of variants
supermarkets bring transparency into existing stocks - explain
- predefined spot for each variant
- labeling of storage location
- defined max and min stock
- visual control of upstream process according to principle "if one thing leaves, sth new has to come in"
- removal of parts according to principle "fist in-first out"
explain the continuum of flow
- traditional: batch&queue
- Push/Scheduled (schedule each process and push to next)
- supermarket pull (kanban)(upstream process replenishes what downstream customer took away)
- sequenced pull(broadcast)(Pull from a feeder in sequence)
- FIFO sequenced flow (defined lane with defined standard WIP between unlinked processes in FIFO sequence)
- Continuous flow(1pc flow)(physically link process steps with no inventory between)
- Ideal state of Lean
how do you calculate kanban?
no of kanbans = response time/consumption time per container
what does SMED stand for?
- Single Minute Exchange of Dies
- Def: scientific approach to set up time reduction that can be applied in any factory at any machine
- separates between internal and external procedures
- converts internal into external set up
- streamlines all aspects of set up operation
define changeover time
time between the last part of the old product manufactured at normal speed until first part of new product manufactured at normal speed
name the six phases of SMED
- analysis of changeover process
- evaluation:internal, external or waste
- convert internal to external steps
- reduce internal steps
- optimize external steps
- standardize process
- internal: during standstill
- external: before/after standstill
explain the correlation of batch size and inventory
- with short changeover times small batch production is cost effective.
- Rule of Thumb: doubled changeover frequency -> 50% less inventories
name the two basic rules of externalization
- materials, tools, fixtures, gauges need to be made available before machine stops!
- cleaning, removal of tools,equipment, filling out of forms etc is to be organized after the start of next type
name the three methods to reduce internal activities
- parallelization of steps
- additional capacity
reduce effort needed for adjustments(self aligning fixtures)
adjusted fixtures quick clamps
name four examples for quick clamping
- pear-shaped holes
- u-shaped washers
- split thread
explain the optimization of external activities
- reduction of all walking and transportation distances
- - position all tools, materials, equipment in shortest possible distance from machine
- - modify machine: switches, buttons, handles should be in one central position
- define shortest possible route for operator
- double equipment that is needed in different workplaces to eliminate loss of time caused by transportation and waiting
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