Repetitive Manufacturing Framework

1
Repetitive ManufacturingFramework Capacity
Analysis

• Factory Automation Lab. SNU.
• May. 21. 1999
• Min, Dai ki

2
Contents

• Introduction
• What is Repetitive Manufacturing ?
• Framework
• Characteristics
• REM in SAP R/3
• Capacity Analysis Model

3
Introduction

• Repetitive Manufacturing(REM) greatly differ from
  those of intermittent manufacturing.
• One of the most common problem was the use of MRP
  software packages for REM(Hall, 1982)
• There are still very few researches for the
  production planning in REM environment.
• Review the REM framework and Consider the
  production planning factors in the REM environment

4
What is REM ?The definitions

• Repetitive manufacturing(REM) is a form of
  manufacturing where various items with similar
  routings are made across the same process
  whenever production occurs. Products may be made
  in separate batches or continuously. Production
  in a repetitive environment is not a function of
  speed or volume. (APICS Repetitive Manufacturing
  SIG)
• Repetitive Manufacturing is the production of
  discrete units in a highly volume concentration
  of available capacity using fixed routings.
  Products may be standard or assembled from
  standard modules. Production management is
  usually based on the production rate.
• (M.S. Spencer J.F.Cox III)

5
What are the characteristics of REM ?

• Production tends to be continuous, rather than in
  discrete lots. (lot identity does not exist)
• Items flow through the production process on a
  relatively fixed routing. (focus on the
  production line)
• Production may be to a schedule rather than to
  specific manufacturing orders.
• Planners control production by volume produced
  over time.
• Internal lead time tend to be relatively short,
  once the basic production line has been set up.

6
What are the characteristics of REM ?

• In-line processing is common. (production is
  performed simultaneously)
• Shop floor progress can be reported at some
  points only.
• Work-in-Process tends to be smaller.
• These parameters require a different approach
  to Manufacturing Planning and Control.

7
What is the differencebetween REM Job Shop ?

• Comparison of job shop and repetitive shop
• (Handbook of Material Capacity Requirement
  Planning p.272)

8
What techniques are used by REM ?

• Backflushing for material
• Rate-based scheduling
• Flattening bill of materials
• Visual manufacturing techniques
• ( ex) planning table in R/3)

9
What are the steps to repetitive scheduling?

• Verify production line model mix
• Synchronize schedule with flow rate of production
  line
• Create repetitive schedule for specified period
• Use repetitive transfer pick_list
• Report at milestones
• Maintain and close orders.
• (APICS Repetitive Manufacturing SIG)

10
Repetitive Manufacturing Model
MPS CAPACITY
LINE RATE VOLUME COCENTRATION

• MRP is the framework necessary to provide the
  communications link from the planning function to
  the supplier base.
• ( The role of MRP in repetitive manufacturing,
  M.S. Spencer J.F. Cox, IJPR., 1995, vol. 33,
  p.1891 )

PLANNING
PRIORITY PLANNING METHODS
MRP JIT TOC
SHOP FLOOR CONTROL
PRIORITY CAPACITY CONTROL
11
REM in SAP R/3

• Process

Demand
Scheduling Agreement (SD)
Post Goods Issue
Create Delivery
Create Transfer Order
Billing
Planning Table for REM
Carry out dependent MRP
Sales Plan
Create REM
Backflush
Work Result
Create Transfer Order for Production
12
REM in SAP R/3

• Structure
• Production Version data relevant to the
  production process.
• Run Schedule Header general information for the
  production of a product.
• Run Schedule Quantity planning quantities.

Material Mater
Production Version1
Production Version2
RS header for VS3
Production Version3 Describes the production proce
dure
Product Version Validity Period storage location
Assign
copied
Run Schedule Quantities
Routings BOMs Work Centers
13
REM in SAP R/3

• Orderless production using run schedule
  quantities
• Period-based planning based on production-rate
• Assigning run schedule quantities to production
  lines
• Simplified capacity planning
• Available capacity display
• Quantity changes with interactive calculation of
  the capacity load smooth over/under loads by
  user
• Backflushing based on quantities

14
Capacity analysis in repetitiveassemble-to-order
manufacturing systems

• F. Fumero, C. Vercellis
• Dipartmento di Economia e Produczione,
• Politecnico di Milano, Italy
• EJOR Vol. 78, 1994. pp. 204-215.

15
Contents

• The ATO production environment
• Capacity planning and Multi Layered Modeling
• Capacity planning model for ATO environment
• Model decomposition algorithm

16
The ATO environment

• ATO a hybrid between MTS and MTO
• new problems arise concerning the integration
  between two stages regulated by different rules.
• In the ATO environment the capacity planning
  models should allow to evaluate the various
  performances.
• service level
• flexibility
• productivity
• with focus on control levels which are
  responsible of the lead times.

17
Capacity planning andMulti Layered Modeling

• Analytic approach based on queuing theory
  excessively restrictive assumptions which are
  rarely fulfilled in practice
• Simulation models become too complex and
  impractical
• Optimization models provide more active support
  to decision makers.

18
Capacity planning andMulti Layered Modeling

• Aggregate planning may be regarded as a way to
  overcome the practical limitations divide and
  conquer approach
• Hierarchical Production Planning(HPP) approach
  suffers from the drawback of missing the bottom
  up links.
• Multi Layered Modeling(MLM) based on Lagrangean
  relaxation techniques, bi-directional information
  flow among the hierarchical levels.

19
Capacity planning model for ATO
Transportation (1)
Backordering (2)
Inventory of Subassemblies (3)
Extra-quantities of the different production
resources and equipment (4)
20
Capacity planning model for ATO
Aggregated production volume (5)
Transportation Quantities (6)
Inventory level (7)
Aggregated component quantities (8)
21
Capacity planning model for ATO
(9)
(10)
(11)
(12)
(13)
(14)
22
Capacity planning model for ATO
(15)
(16)
(17)
(18)
(19)
(20)
(21)
23
Capacity planning model for ATO
(22)
(23)
(24)
24
Lagrangean decomposition algorithm
(25)

• Lagrangean multipliers to the consistency
  conditions (5), (6), (7), (8), (25),
  respectively
• We obtain a dual problem in the form

(26)
25
Lagrangean decomposition algorithm

• F1 interplant planning splitting of the
  end-items production among the different plants,
  according to the available resources and with an
  aggregate check of demand fulfillment.
• Balance equations at an aggregate level

(27)
(28)
(29)
(30)
26
Lagrangean decomposition algorithm
(31)
Subject to (15), (27), (28), (29) and (30)

• F2 Families disaggregation. demand fulfillment
  is verified more carefully
• considering the specific end-items, instead of
  their families.

(32)
Subject to (9), (10), (11), (12) and (16)
27
Lagrangean decomposition algorithm

• F3 Subassemblies planning. fulfillment of
  internal and external demand and verifying
  general resources availability and inventory
  bounds

(33)
Subject to (13), (14), (17) and (22)
F4 Routing Choice. split the production volume
among the different types of machines, verifying
the availability of resources.
(34)
Subject to (18)
28
Lagrangean decomposition algorithm

• F5 Lot-sizing the weekly production plan is
  arranged by fixing the lot-size for each
  subassembly.

(35)
Subject to (19), (20), (21), (23) and (24)
29
References

• Capacity analysis in repetitive assemble-to-order
  manufacturing systems, F.Fumero, C. Vercellis,
  EJOR. vol. 78(1994), pp204-215
• Repetitive manufacturing planning and control
  systems a framework for analysis, Alberto de
  toni and Roberto panizzolo, PPC. Vol. 8(1997),
  pp500-508
• The role of MRP in repetitive manufacturing, M.
  S. Spencer and J.F.Cox III, IJPR. Vol.33(1995)
  pp.1881-1899
• Handbook of MCRP, Howard W. Oden, McGraw-Hill
• http//www.apics.org
• http//www.nissi.co.kr