Title: Order Review/Release in a Job Shop
1Order Review/Release in a Job Shop
- 1998? 9? 10?
- ????? ????????
- ? ? ?
2Order review and release strategies in a job shop
environment a review and a classification
- Bergamaschi, D., Cigolini, R., Perona, M.
and Portioli, A., - IJPR, 1997, 35(2), 399-420.
- Former student of Politecnico di Milano, Milano,
Italy - Dipartimento di Economia e Produzione,
Politecnico di Milano, Milano, Italy
3Contents
- Objectives of this paper
- Order Review/Release System? ??
- Order Review/Release System? ??
- Literature Review
- Analysis and Classification
- Conclusion and Further Research Paths
4Objectives of this paper
- A review and a classification framework of the
main research work carried out to date - A better understanding of ORR strategies and the
most promising research paths
5Order Review/Release System? ??
- Planning ???? ??? ?? ????? shop floor? ?? ????
??? ?? - Decision which order, at what time, under what
conditions to release - WIP control? workload balance? ?? shop?
utilization? ???, ????? ?? delivery performance?
????? ?? ???? ? - both filtering mechanism and capacity management
tool
6Order Review/Release System? ??
- Order Entry Phase
- Routing Check, Pick List Check, Due/Delivery Date
Assignment - Pre Shop Pool Management Phase
- Sequencing orders according to their priority
- EDD, ERD, CR, Capacity slack based rule
- Order Release Phase
- ?? order? ?? shop? release? ???? ??(triggering or
input control mechanism) - employ three types of information current
pre-shop pool status, current shop status,
planned shop performance (manufacturing lead
time, delivery timeliness)
7Position of ORR within PPC
8Literature Review (1/6)
- Wight(1970)
- first to understand and describe the importance
of controlled release - The interactions between ORR and dispatching
rules - Nicholson et al.(1971), Bechte(1988) if job
release is carefully controlled, sophisticated
dispatching rules might be replaced by a simple
FCFS - Bertrand(1983) even with an effective order
release procedure, such rules as tSPT can yield
to better shop performance than FCFS - Ragatz et al.(1988) the greatest advantage from
the use of ORR appears to be achieved with non
due date related sequencing rules - Ahmed et al.(1992) an interaction does exist
among three activities of a job scheduling policy
(due-date assignment, ORR and dispatching) - Perona et al.(1996) the impact of an ORR
procedure should be evaluated while considering
all the relevant scheduling decisions
9Literature Review (2/6)
- The relationship between WIP, MLT and throughput
rate - Little (1961) from a theoretical point of view
- Shimoyashiro (1984) simulation approach
- A strong indication towards the existence of a
critical level of WIP inventory that should be
kept in the system. - These conclusions led researchers to look for an
effective way of controlling both lead time and
WIP inventory through the control of work input
to the shop
Utilization
MLT
Desired WIP level
WIP
10Literature Review (3/6)
- Basic mechanisms to control the shop's workload
- the limitations of load released to the shop
- Wiendahl (1995), Bechte(1988, 1994), Ragatz et
al. (1988), Bobrowski (1989), Philipoom et al.
(1993) - the balancing of workload among different work
centers of the shop - Irastorza and Deane (1974) MILP
- LIMITE by Portioli (1991) loosening the rigid
limitation of workload for improving overall
workload balance
11Literature Review (4/6)
- Application of workload control
- Input control
- A feedback tool to control and reduce lead times
through shop load limitations and balancing - Output control
- The regulation of the shop production capacity
with a feed-forward approach - Hendry and Kingsman (1991) input? output? ???
control - Onur and Fabrycky (1987) an combined
feed-forward/back control procedure - To prevent specific work center from being idle
- Glassey and Resende (1988) Starvation Avoidance
- Melnyk and Ragatz (1989) WCEDD, AGGWNQ
- may prove ineffective whenever multiple
bottleneck work centers are dynamically changing
over time, subject to the particular order mix
processed
12Literature Review (5/6)
- Broadening ORR time-wise workload smoothing
- Melnyk Ragatz (1991)
- the effects of broadening the range of ORR
functions, by smoothing workload over time - Fredendall and Melnyk (1995)
- ORRs potential is greatly improved by providing
for a time-wise workload balancing with an
extended schedule visibility - Contributions to OE and PSP phases
- Bobrowski (1989) loading exchange heuristics in
OE phase - Philipoom and Fry (1992) consider rejecting
customer orders - Philipoom et al. (1993) demonstrated the choice
of an appropriate PSP priority rule plays a
leading role in a ORR procedure effectiveness and
thus has a significant impact on overall shop
performance
13Literature Review (6/6)
- Order Review/Release? ?? ??? ??
- Positive view reduced stock carrying cost, shop
congestion and flow times - Negative view
- Bertrand(1983), Baker(1984), Kanet (1988), Melnyk
and Ragatz(1988), Melnyk et al.(1994) long delay
in the pool, overall MLT may increase - Bechte(1988), Perona and Portioli(1996)
- above authors might have undervalued the
possibility offered by an appropriate ORR
strategy to better balance workloads both over
time and among the work centers of the shop, thus
achieving better utilization and throughput rate,
together with improved MLTs and delivery
performance.
14Analysis and Classification (1/8)
- Eight dimensions of OR methodologies
- Order release mechanism
- Timing convention
- Workload measure
- Aggregation of workload measure
- Workload accounting overtime
- Workload control
- Capacity planning
- Schedule visibility
15Analysis and Classification (2/8)
- Order release mechanism mechanism that triggers
the release of one or more orders - Load limited methodologies decide which orders
should be released based upon their distinctive
features and the existing workload in the shop - Time phased methodologies computing a release
time for each order based on information about
jobs in the pool such as due date, job work
content and job routing (MIL, CMS)
16Analysis and Classification (3/8)
- Timing convention determines when an order
release can take place - Discrete periodic interval
- Continuous MIL, SA, AGGWNQ, WCEDD, ORM, CMS
- Workload measure
- number of jobs MIL(Ragatz), MNJ, CMS
- work content (hours or percentage of the planned
capacity) - A logic which looks after more than the simple
number of jobs on the shop floor is needed at the
release stage
17Analysis and Classification (4/8)
- Aggregation of workload measure
- total shop load AGGWNQ, MNJ, MAX
- bottleneck work center load SA, ORM
- load by each work center
- In a job shop environment a workload control
methodology seems to be fully effective only if
the workload distribution among work centers is
considered (Melnyk et al. 1989)
18Analysis and Classification (5/8)
- Workload accounting over time
- load? ?? load on hand, load in transit, released
load - Attemporal (total shop load ? ?? ??? attemporal)
- Time bucketing SCOPE2, BFL, FFL
- requires a pre-processing scheduling activity
- Probabilistic LOMC, LIMITE
- a greater robustness against the typical
industrial perturbations - authors disagree the way by which workload
accounting should be accounted over time
19Analysis and Classification (6/8)
- Workload control
- Upper bound only BFL, LOMC, FFL, PBB, MNJ, ORM,
MAX - control the WIP level and therefore the
statistical distribution of MLTs result in a
reduced mean with a smaller coefficient of
variation - Upper and lower bounds JSSWC
- trying to ensure that each work center is
provided with an appropriate buffer - Lower bound only SA, AGGWNQ, WCEDD
- potential drawback the assumption of a fixed
bottleneck - Workload balancing Irastorza-Deane, SCOPE 2,
DI/OCS - selective release of orders to the shop on
condition that the sum of deviations from
aggregate balance of each machine center is
reduced - Authors disagree about the way in which workload
should be limited
20Analysis and Classification (7/8)
- Capacity planning controlling/adjusting capacity
- Passive feedback logic
- Active Irastorza-Deane, SCOPE 2, DI/OCS, JSSWC
- Onur and Fabrycky(1987) if the feedback input
control is combined with a feed-forward control
mechanism through which the amount of production
capacity available is adjusted, better shop
performances can be adjusted.
21Analysis and Classification (8/8)
- Schedule visibility
- Limited oriented at controlling the workload
level in the shop during the next closest
planning period - workload is actually smoothed over time, but only
in order to optimize the next period, regardless
how following periods could be affected - Extended (Irastorza-Deane, DI/OCS, MAX) oriented
at achieving a more general optimization of the
shop performances along a time horizon longer
than a single time horizon (look-ahead module) - In time phased release mechanism, the schedule
visibility is absent.
22(No Transcript)
23Conclusion and Further Research Paths
- Further Research Paths
- To combine an upper lower bounds approach with
a continuous timing convention - The analysis of the workload control strategy by
means of load balancing - A formalized investigation of the dimension
related to workload accounting over time - Designing new techniques for capacity and
workload planning in order to achieve good
performances, while keeping them simple enough to
be effectively implemented in a real-life
industrial context - The adjustment of production capacity and the
ability to optimize the order release over an
extended time horizon - Time bucketing approach with schedule visibility
24References (1/4)
- Ahmed, I. and Fisher, W. W., 1992, Due date
assignment, job order release and sequencing
interaction in job shop scheduling. Decision
Sciences, 23, 633-647. - Baker, K. R., 1984, The effects of input control
on the performance of a simple scheduling model.
Journal of Operations Management, 4(2), 99-112. - Bechte, W., 1988, Theory and practice of
load-oriented manufacturing control. IJPR, 26,
375-395. - Bergamaschi, D., Cigolini, R., Perona, M. and
Portioli, A., 1997, Order review and release
strategies in a job shop environment a review
and a classification. IJPR, 35(2), 399-420. - Bertrand, J. W. M., 1983, The use of workload
information to control job lateness in controlled
and uncontrolled release production systems.
Journal of Operations Management, 3, 79-92. - Bertrand, J. W. M. and van Ooijen, H. P. G.,
1996, Integrating material coordination and
capacity load smoothing in multi-product
multi-phase production systems. IJPE, 46-47,
1-12. - Bobrowski, P. M., 1989, Implementing a loading
heuristic in a discrete release job shop. IJPR,
27, 1935-1948.
25References (2/4)
- Fredendall, L. D. and Melnyk, S. A., 1995,
Assessing the impact of reducing demand variance
through improved planning on the performance of a
dual resource constrained job shop. IJPR, 27,
1935-1948. - Glassey, C. R. and Resende, M. G., 1988,
Closed-loop job release control for VLSI circuit
manufacturing. IEEE Transactions on Semiconductor
Manufacturing, 1, 36-46. - Hendry, L. and Wong, S. K., 1994, Alternative
order release mechanisms a comparison by
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L., 1991, Load smoothing by the planning and
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26References (3/4)
- Park., P. S. and Salegna, G. J., 1995, Load
smoothing with feedback in a bottleneck job shop.
IJPR, 33(6), 1549-1568. - Perona, M. and Portioli, A., 1996, An Enhanced
loading model for the probabilistic workload
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Capacity-based order review/release strategies to
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B., 1993, An evaluation of capacity sensitive
order review and release procedures in a job
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27References (4/4)
- Irastorza, J. C. and Deane, R. H., A loading and
balancing methodology for job shop control. AIIE
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Production and Inventory Management, 29, 13-17. - Onur, L. and Fabrycky, W. L., 1987, An
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