d08540000120114012session 13 and 14_review 1 and 2

7/28/2019 D08540000120114012Session 13 and 14_Review 1 and 2

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Session 07Production Planning and Control

Production flows for discrete-part manufacturing and

their documentation.

D 0 8 5 4Supply Chain : Manufacturing and Warehousing


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Production Flow and Discrete Manufacturing

Business Process Flow

Create planned independent requirements

Run MRP at plant level

Purchase (convert purchase requisition to purchase order, then post goods receipt)

Release production orders for sub-assembly production

Confirm and withdraw raw material

Create production order for final assembly

Assign batch number in production order

Check capacity for the final assembly

Option1:

If final assembly is done internally

Release assembly orders

Pick Components

Confrim assebly activities


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Production Flow and Discrete Manufacturing

Option 2:

If final assembly is done externallyCreate subcontracting purchase order (external process)

Transfer stock to subcontractor storage

Release Assembly Orders

Post goods receipt for subcontracting order

Complete the production order for final assembly technically


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OwnCustomer

MRP - Run

Release Assembly OrdersCreate Subcontracting

PO (External Process)

SAP R/3Planned ind. Requirements

(6-month rolling plan)

Purchasing(Converting PR to PO,GR)

Is there enough capacity

for the final assemblyY

N

Convert Planned Order to

Production Order(In-House Production

of Assemblies / Parts Production)

Release Production Order

Confirmation & Withdrawal of Raw Material

Create Production

Order for Final Assembly & Assign Batch

Pick Components

Confrim Assebly Activities

Trasfer Stock to

subcontractor storage

Release Assembly Orders

GR to Subcontracting Order

Tecnical complete the

Production Order for

Final Assembly


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C10150

Canned Beans,Labeled

HERT

PD

C40660

Beans Label

ROH

PD

C30380

Canned Beans,

Unlabeled

PCB 2L 8B 7.6

HALB

PD

C40007

Beans, Frozen

ROH

PD

C40650

Can

ROH

PD


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Topics

Production Flow in High Volume Discrete PartManufacturing

Manufacturing System Layouts

Manufacturing Flowlines and their variations Synchronous Transfer Lines

Asynchronous Flowlines and the Push vs. Pull dilemma

Asynchronous Transfer Lines KANBAN-based Lines

CONWIP-based Lines


7/26

Discrete Part Manufacturing Systems

The end product is the

assemblage of a

number of

components

and sub-assemblies,

either produced in-

house or procuredfrom outside.

Frame

Building

Frame

Machining

Frame

Painting

Engines and

Transmissions

Oil Tank

Cell

Shocks

Cell

Steering

Wheel Cell

Wheels

Cell

Doors

Cell

Seats

Cell

TESTING

Packaging


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Production Flow in

discrete part manufacturingA-1

A-2

A-3

A-4

I-1

A-5

O-1-1 O-1-2 O-1-3 O-1-4

O-2-1 O-2-2 O-2-3

O-4-1 O-4-2 O-4-3

O-5-1 O-5-2

Part 1

Process

Plan

Part 2

Process

Plan

Part 4

Process

Plann

Part 5

Process

Plan End Product

Part 3

(Procured externally)

Main Frame


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A typical Organization of the

Production Activity inHigh Volume Discrete Part Manufacturing

Raw

Material

& Comp.

Inventory

Finished

Item

Inventory

S1,2S1,1 S1,n

S2,1 S2,2 S2,m

Assembly Line 1: Product Family 1

Assembly Line 2: Product Family 2

Fabrication (or Backend Operations)

Dept. 1 Dept. 2 Dept. k

S1,i

S2,i

Dept. j


10/26

Organizing the Workflow for Backend Operations: MajorLayout Types

Workspace

Drill Mill

Grind EndProduct

StoreAssembly

PaintWeldSaw

LatheRawMaterial

Store

(a) Fixed Product Layout

Lathe

E.P.S

tore

Assem

bly

Saw Lathe Mill Drill

Saw Mill Drill PaintGrind Mill Drill Paint

Weld Grind Lathe Drill

(b) Product Layout

R.M.

Store

E.P.

Store

Saw Drill Paint

Weld Grind PaintMill

Lathe Mill

Lathe

Drill

(c) Group or Cellular Layout

R.M.

Store

E.P.

Store

Assembly

Paint

Saw

Grind

Weld

Lathe

Lathe

Mill

Mill

Drill Drill

(d) Process or Functional Layout

Adjusted

from

Francis

et. al.


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Fixed Product Layout Workpiece remains fixed and the various processes are brought to it

Used primarily in ship-building.

Sometimes can be the preferred layout when high levels of precision

are in order.

Production activity is controlled through project management relatedpractices.


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Product Layout or Flowline

Each part has its own dedicated production line.

The line for each part is organized in a way that facilitates the

corresponding production flow.

Easy to manage and supervise

However, a capital-intensive proposition

Production volumes must be sufficiently large


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Process Layout or Job Shop

Facility is organized into departments supporting different functions

Production lots are visiting these departments according to theirprocessing needs (process plans)

Can result in high equipment utilization and operational flexibility

But it also incurs extensive material handling and long productiontimes

Necessitates involved production planning and scheduling

Appropriate for low-volume production of a large, volatile portfolio ofparts


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Group or Cellular Layout

Parts are grouped into families based on the similarity of theirprocessing requirements.

Each family gets a dedicated production facility, known as productioncell.

Typically cells operate as switching flowlines, with switching taking

place between the production of batches of different part types. Frequently switching can involve substantial effort and time, known as

setup time.

Provide a middle ground between a product and a process layout, interms of operational efficiency and investment


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Re-entrant Lines

Flowlines in which certain processing stages share the same type of

equipment, and therefore, they present re-entrance.

The motivation for re-entrance and the resulting operational

complexities are similar to those underlying the deployment and

operation of a cellular layout. Re-entrant lines is a typical layout for semiconductor manufacturing.


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The product-process matrix

Production

volume

& mix

Jumbled

flow (job

Shop)

Disconnectedline flow

(cellular)

Connected

line flow

(assemblyLine)

Continuous

flow

(chemical

plants)

Processtype

Low volume,

low standardi-zation

Multiple products,

low volume

Few major products,

high volume

High volume, high

standardization,commodities

Commercial

printer

Heavy

Equipment

Auto

assembly

Sugar

refinery

Void

Void

(Figure borrowed from Hayes and Wheelright)


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Manufacturing Flowlines:

A working abstraction

Flow line: A sequence of workstations supporting the production of a singlepart type.

Each workstation consists of one or more identical servers executing oneparticular stage of the entire production process.

processing time at each workstation variable due to inherent processvariability but also due to operational detractors, like

machine downtime,

operator unavailability,

experienced set-up times,

preventive maintenance, etc.


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Flowline Performance Measures

Production rate or throughput, i.e., the number of parts produced per unittime

Line capacity, i.e., the maximum sustainable production rate

Line (expected) cycle time, i.e., the average time that is spend by any partinto the line (this quantity includes both, processing and waiting time).

Average Work-In-Porcess (WIP) accumulated at different stations

Expected utilization of the station servers.

Remark:The above performance measures provide a link between the directly quantifiable and manageable aspects and attributes ofthe line and the primary strategic concerns of the company, especially those ofresponsiveness and cost efficiency.


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A flowline classificationFlowline

Synchronous Asynchronous

Pushe.g.,

Asynchronous

TransferLine

Pulle.g.,

KANBAN or

CONWIP lines


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Synchronous Transfer Lines

Production is paced by an

interconnecting conveyor system

No WIP accumulation at the

different stations

Production control logic is

hardwired in the supportingconveyor system

Line expensive and inflexible

Typically used for high-

throughput final assembly

c.f. the module on scheduling

for further coverage of these lines


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Asynchronous Flowlines and the Push vs. Pull

dilemma

Part advancement between the different stations is not synchronized. Need for buffering capacity at the different stations to accommodate

the resulting WIP.

Two primary control mechanisms

Push:

Lots are released into the line according to an externallyspecified production plan.

A lot that has completed processing at its current station willimmediately advance to the next one.

Pull:

Target WIP levels are specified for different line segments.

Lot advancements that can cause the exceeding of some targetWIP levels are blocked.

A drop from the target WIP level is a signal for replenishment.


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Asynchronous Flowlines and the Push vs. Pulldilemma (cont.)

Push properties

Directly connected to production planning

Can easily accommodate changes in target production

(In its basic definition), it lacks a feedback mechanism that canfacilitate reaction to operational contingencies

As a result, congestion is possible


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Asynchronous Flowlines and the Push vs. Pulldilemma (cont.)

Pull properties

Main control variable is WIP

The enforced WIP caps make the line reactive to contingencies andprevent congestion

Need for some (analytical) machinery to translate target productionplans to target WIP levels

Need considerable stability of the production plans, since frequent

changes of the target WIP levels can lead to chaotic behavior.


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Asynchronous Transfer Lines

W1 W2 W3

TH THTH THB1 B2 B3M1 M2 M3

Some important issues:

What is the maximum throughput that is sustainable through this

line?

What is the expected cycle time through the line?

What is the expected WIP at the different stations of the line?

What is the expected utilization of the different machines? How does the adopted batch size affect the performance of the

line?

How do different detractors, like machine breakdowns, setups,

and maintenance, affect the performance of the line?


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KANBAN-based production lines

Station 1 Station 2 Station 3


What is the throughput attainable by a certain selection of

KANBAN levels?

What is the resulting cycle time?

How do we select the KANBAN levels that will attain a desiredproduction rate?

How do we introduce the various operational detractors into the

model?


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CONWIP-based production lines

Station 1 Station 2 Station 3 FGI


Same as those for the KANBAN model, plus

How can we compare the performance of such a system to that

of an asynchronous transfer line and/or a KANBAN-based

system?

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