精益生产之平滑生产 smoothing and leveling_EN

• It is simulated that the customer demand is fix over a period of time
• Within the leveling period all products are produced regularly in defined quantities
supermarket. Service classes are understood to be standardized supply processes (finished products) from production to customers based on the demands of the customers.
short-term variations in demand have an effect on production. • The decoupling will be achieved by defined service classes in connection with a finished products
• High inventories in the finished 2 products warehouse to bridge the
long replacement time
6
Schematic diagram of Production leveling - Plan
Leveled production
defined period of time.
2
What is Production smoothing and leveling used for ?
• Prevent unnecessarily high variations in production output • Shorten lead times, and therefore response times to the customer • Reduce WIP (work in progress) inventory • Increase productivity by avoiding unplanned changes to production scheduling • Reduction and/or elimination of the Bull-Whip-Effect • Ensure continuous flow, to support standardized work • Increase flexibility
Production leveling: • Leveling of the production will be achieved if the production orders are scheduled in a planned
and preferably standardized and recurrent pattern. • Small batches and minimal frozen horizons are required to represent the customer takt over a
4
Schematic diagram of Production smoothing - Plan
delivery scheduling
production scheduling
placement of demands in supermarket
supplier
prefabrication
final assembly
3
Schematic diagram of Production smoothing - Actual
∆Pcs.
Quantity demanded Production output
Quantity [Pcs.]
∆t Time [t]
• Customers order products at irregular intervals and in varying quantities ( ) • Production tries to follow the demands of the customers with the production output ( ) • Due to lag time Δt, the sequence and quantity of production have to be adjusted frequently • The system alters (Δ Pcs.)
▪ Definition of order processing ▪ Decoupling of customer demand with defined finished products warehouses ▪ Dimension of the inventories in the finished products warehouse on the basis of the
increasing variations
finished products warehouse
high inventories
customer
• Traditionally it is tried to level the demand variations by using big batches and few changeover activities (changeover optimization)
customer
decoupled production (assembly)
• Finished products supermarket after the last process decouples as a defined buffer the production from short-term variations in demand
defined inventory in a finished products supermarket for cushioning of external variations
at optimal inventory quantity
Leveling period
Production output Quantity demanded
R* A 13
13
14
RB
10
10
RC
4
4
RD
3
3
Exotics
2
*R – Runner
4 days replacement time
2
4 days
• Long replenishment timefor all Fr products
• Sequence of production is not constant
Quantity [Pcs.]
Planning period*
Time [t]
*long-term consideration: Combination with delivery forecast, determination of types, personal planning, procurement planning
Design of pacemaker
III
Pull
Control of up-stream production processes
▪ Dividing of products with ABC/XYZ-Analysis (see tool description) in the following production categories: runner products with relative regular (AX, BX, AY, BY) and exotics with alternating demands (CX, CY, CZ)
5
Schematic diagram of Production leveling - Actual
delivery scheduling
production scheduling
production scheduling
scheduling
supplier
prefabrication
final assembly
1
What is Production smoothing and leveling ?
Production smoothing: • By using standardized buffers, production is decoupled from customer demands. This avoids that
placement of leveled
demands
supplier
prefabrication
final assembly
customer
leveling also in prefabrication
leveled production (assembly)
7
Inventories represent waste (Muda)
• Within the period of leveling all
Mo Tu We Th Fr Mo Tu We Th Fr products are manufactured
RA
444 4
4 444 4
4
regularly in fix quantity
RB
2 2 2 2 2 2 2 2 2 2 • By using small batches the quantity
对于企业来说如何合理安排生产比如等批次小批量将大大减少库存减少资金的占用同时也快发现隐藏在车间和工序间的浪费
Production System
Training Materials
Principle – Demand orientated production Method – Customer takt Tool – Production smoothing and leveling
Inventories
Lead time
Inventories are approximately proportional to lead times.
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Procedure
I Smoothing
II
Adaptation of production quantity to demand
Leveling
• Consequent changeover optimization necessary
• Leveling simulates an „ideal customer“, who orders regularly in small quantities
replenishment timeminimizes the inventories in the finished products warehouse
Changeover Time
Based on: Regber, Zimmermann: Change Management in der Produktion (2001)
Inventories conceal problems and waste.
They are not the cause rather symptoms 来自f the problems.
• This is the reason why demands are alternating from manufacturing level to manufacturing level with growing batches
changeover optimized production
Mo Tu We Th Fr Mo Tu We Th
water level = inventory lever
Production
Inventory
Production- Downtime
and Losses
Quality Issues
Production - Downtime
WaitingTime
Transport
Down Time
Long Paths
RC
111
RD
111
Exotics 1 day
1 111 1 111 2 Exotics: 5 days
1 demanded is more directly 1 realized, despite constant
production program
2
• Significantly reduced