03 Lean Production Flashcards
Production System (Definition)
A production system is a framework for all employees of the company consisting of mission statements, visions, principles and methods with the aim of establishing and living a culture of improvement and manifests itself in improvement projects, training, communication and leadership.
Principles of Lean Production
“Lean Thinking” has to be lived beyond the manufacturing process, in all indirect areas as well as in the entire value-creation network.
- Customer Value
“Lean Thinking” means understanding what the customer is willing to pay for, the value of the product is defined by the end user
->Focus on service scopes that increase the value of a product or avoid processes that do not lead to any product added value - Value Stream
All value-adding processes must be aligned with customer value and waste must be eliminated
-> Detect waste, Supplier processes should be considered beyond the boundaries of the company Makes production more transparent and frees up resources that can be used to support value-adding steps - Flow
The goal is to synchronize all value-adding processes and create a continuous flow
-> Using methods like inventories, capacity transitions, gaps or forms of product provision - Pull
Performance is only provided if there is a customer need
-> Possible due to a significant reduction in throughput times; Waste due to overproduction is avoided and fast delivery is made possible - Perfection
By constantly repeating these steps, further improvement measures are taken and the process chain is continuously improved
-> Iterative improvement potentials are identified and realized
Method and Tools of Lean Production
- Demand Smoothing
- Process Synchronization
- Kanban
- Empowerment and Group Work
- Autonomation
- Pokal Yoke
- Muda
- Visual Management
- 6S
- SMED
- Value Stream Design
Demand Smoothing
Demand smoothing as the basis for stable processes
a. Demand within a production phase is artificially smoothed to create stable, constant working conditions in production -> Designed to reduce the variation of quantities in production as much as possible
-> Demand smoothing allows the daily production volume to remain constant due to a combination of temporal smoothing and smoothing by mix
Process Synchronization
Process synchronization as the basis for capacity utilization
a. The cycle time is defined as the total time of production divided by the total customer demand in a period
-> Synchronizing production speed with the demand rate eliminates the risk of overproduction (worst form of waste in lean production)
b. Each process has exactly one bottleneck (pacemaker), which controls the entire process: upstream as pull and downstream as FIFO push
c. All work contents are adjusted to an approximately equal cycle time
d. Due to the considerable fluctuations in customer demand within the periods, companies must recalculate the cycle time in each period in order to be able to process the relevant customer demand
-> Matching the processes synchronizes the capacity requirements and optimizes utilization
Kanban
Kanban for autonomous material control according to the pull principle
a. Push System: Parts are processed and then transferred to the downstream workstation.
i. There is no explicit limit for work in process (WIP) in a push system
ii. Although a low level of inventory is theoretically possible, in push systems a high work in progress level and long lead times often occur
b. Pull System: Suction effect of the upstream stations
i. Trigger for pull production is always the customer Demand-based triggering creates an information flow that runs in the opposite direction to material flow
ii. WIP is set in advance. Inventory levels are limited, therefore allowing shorter lead times, smaller batch sizes and self-controlling manufacturing processes
-> Difference between pull and push: The stock is limited in a pull system
Empowerment and group work
Empowerment and group work
a. Classic System: Efficiency through formalization and standardization
i. Tayloristic division of labor
ii. Central Planning and Organisation
iii. Separation of execution and control
b. Autonomous working groups: Efficiency through incentives and involvement
i. Integration of environmental activities
ii. Job Rotation
iii. Capacitive levelling in the group
iv. Standards as “Temporary Best Practice”
-> Attempt to reduce great coordination effort (due to necessary interaction between several employees and with the inclusion of different qualifications) by forming working groups which can fulfil a closed work task in a self-organised manner.
Autonomation
a. The autonomy has been developed to give workers the possibility to quickly identify and solve problems that occur in production with regard to quality, quantity, work processes and equipment. Processes are to be stopped automatically when faults occur.
b. Autonomy consists of three elements:
i. Detect and stop:
Most effective method of detecting fault or source of interference Responsibility is transferred to employee of the process
ii. Alerting:
As soon as a problem is detected, the employee must immediately notify hos superior or competent person (verbally, alarm or Andon display)
iii. Error tracking:
If error cannot be identified immediately, appropriate measures have to be taken and production may only restart afterwards (e.g. Additional checks on all components until source of temporary fault has been identified)
c. Components
- Design operations efficiently
- Easier and cheaper equipment
- Match machines to the flow
- Simplify retooling
- Error autonomy
Pokal Yoke
Poka Yoke for failsafe working
a. Poka-Yoke is the use of so-called fail-safe or fool-proof facilities in the production process. Poka-yokes are a simple way of protecting the machine operator from unintentional errors.
b. It is to be prevented that a product defect can arise from a misconduct, such as inattention, mixing up, misinterpretation or stress, which can be intensified by adverse environmental influences or poor working conditions.
c. Important elements of Poka-Yoke
i. Basic elements of initialization or triggering mechanism
ii. Regulation mechanism
iii. Group work (quality circle)
d. To exclude the possibility of repeating errors source inspections are carried out in conjunction with Poka Yoke
Muda - Levels of Waste
- Hiragana Muda -> Unavoidable waste
- Bringing back to start position
- Cleaning of supply areas
- Holding keys and switches
- Manual operation of machines - Kanji Muda -> Equipment and machine related waste
- Idle return paths of tools
- Too long feed paths
- Oversized machines - Katakana Muda -> Directly eliminable waste
- Stacking of Parts
- Removing of packing material
- Removing chippings
- Part acquiring paths
Muda - Types of Waste
- Overproduction
- Idle time
- Transport
- Production of bad parts
- Processing
- Storage
- Movement
Worst type of waste: Overproduction, storage and production of bad parts
Visual Management
Visual management as a control and management instrument
a. Visual management is the communication basis of the Lean Production System.
b. Three essential aspects of visual management:
i. Information transfer: Visualisation of the information directly or indirectly affecting the employees or their work, with the aim of encouraging the employees to “think along”
ii. Communication of working standards and procedures: Explicit knowledge documentation of information relevant to work
iii. Visual design of workplaces and processes: Creation of a clarity that allows any form of deviation from the target state to be identified
c. Examples:
- Status displays and Andon-Board
- Displays for the elimination of errors
- Advice and warning signs
- Area marking
- Standardized worksheets
6S
6S: Problems that nobody sees are not disturbing
a. The 6S are a basis for the introduction of a synchronous production system, as well as standardization and visualization.
b. Steps of implementation:
i. Step 1:
-> Seiri: Separation of required and not required units and immediate removal of not required ones “Sorting”
-> Seiton: The necessary units have to be put on comprehensively defined places to which everyone has access “Arranging”
-> Seiso: Thorough cleaning “Cleaning”
ii. Step 2:
-> Seiketsu: Keep the condition created before “Standardization”
iii. Step 3:
-> Shitsuke: Accomplish the work in the correct way “Discipline”
SMED
SMED: Separation of “Internal” and “External” activities
a. SMED is an abbreviation for Single Minute Exchange of Die and stands for a method to reduce downtime during changeover processes.
b. The method can be sensibly applied wherever time-critical, standardizable activities must be carried out. (e.g. changeover procedures, maintenance work, material loading)
c. Proceeding:
i. Group of people revises the expiration of an activity according to pictures A-D
ii. Examination of the result
iii. Adaption or extension of existing standards
Process Innovation (Definition)
Process innovations are radical improvements of organizational procedures, production processes or the use of technology with the aim of increasing efficiency or agility, for example by changing the sequence of activities or using modern technologies for autonomous production and logistics processes.
