dft reference materials 3

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DFT for OperatorsDFT for OperatorsBox Build ExampleBox Build Example

SJOP1


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Demand FlowDemand Flow

TechnologyTechnology

Basic PrinciplesBasic Principles


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Training the Operator to work

w ith DFT

This workbook has been written to help the operator understand theroduction strategy that Flextronics uses to m anufacture products. A

current or new operator or production lead, may have questions about the

way lines are set up and what the need for having the TQ C sheets, Kanbans

and color coded areas are. The goal of this training section is to answer all of

these question and hopefully, any that m ay come up as they work through

it.

he following paragraphs establish Flextronics needs to embark on efficientmanufacturing methods, and provide a brief description of the currently used

Demand Flow Technology. Throughout this chapter, the intent is to maintain an

interactive approach to the operators training. In a step by step format, the operator is

explained the DFT basic concepts first, and then tested with questions and situations that

will help him understand what was explained. In an effort to create more familiarity and

personalize the documents in this chapter, the word we will be used to signify

Flextronics, and you will refer to the operator.

Flext ronics and DFT

As you may already know, Flextronics is a manufacturing contractor. This means that

Flextronics does not design or build its own products. In fact Flextronics has no

products at all. The company business is to manufacture products for other companies.

If a company like IBM has an old or new product but does not want to build it, it

comes to Flextronics. We (Flextronics) buy all the materials, build the product and

deliver it to IBM or to whomever they choose.

Since all we do is manufacture for someone else, it is very important that we do

it well. Customers (other companies) will only work with us if we can produce theirproducts with the best quality possible, on time and at low cost. For this reason,

Flextronics engineering continuously looks for ways to meet these customer demands,

and still remain profitable. To make sure that we succeed in producing with quality,

speed and low cost, we have chosen to use DFT for our manufacturing activities.

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What is DFT?What is DFT?What is DFT?What is DFT?

DFT stands for Demand Flow Technology. The Demand part means that

when a customer needs to have more of their product, we start building. We

do not want to build product so that it stays some place until needed. Wewant to build only when it is needed. The Flow Technology part simply

means that we will assemble and test product in little pieces at a time. One

piece will be used to build the next one. The chain will continue until the

whole product has been put together.

Why DFT?Why DFT?Why DFT?Why DFT?

Many companies still use what is called batch production. This means thatquantities of the different parts that make up a product will be scheduled to

be assembled and stored for later use. When there is a need for sub-assemblies,

to complete the product, they are obtained from stock. In DFT, all

subassemblies are completed and routed to the final assembly in a continuous

manner. There are no schedules for build and accumulation of sub-assemblies

ahead of the product build schedule.

The following pages take through an interactive learning session which will

clarify the batch and flow manufacturing methods. This session will also

explain the need, type and content of the tools used in DFT.

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We just go t a new cus tom er !

and he w ants us to bu i ld 112 com puter c hassis a day

Let's look at the major internal chassis parts

Chassis Power Supply

Wire Set

Speaker

Working 7 hours a day we could...

2x7x4=56

Build 56

Power Supplies a

day w/ 4 people

4x7x2=56

Build 56

Wire Sets a

day w/ 2 people

Takes 30min or 2/hr

Takes 15 min or 4/ hr

4x7x4=112

Build 112

Chassis a dayw/ 4 people

Takes 15 min or 4/hr

Pack

Looks OK?

Build Power Supplies &

Wire Sets 2 days ahead !

How do w e bui ld 112 Chass is a day ?

Stock

Good new s

3

The Chassis can be of 5 different colors,

but the internal parts are always the same


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Build Power Supplies

Build Wire Sets

Build Chassis Pack

Warning Label

Pem Nuts

The first few days of production were going well

until Final Assembly found some Power Suppliesthat could not be mounted to the chassis. These

Power Supplies were missing Pem Nuts. Operatorsalso found a few Power Supplies without the

Warning Label.

Where would we find more defective Power Supplies?How many could be defective?

Who would have to help find the defective Power Supplies?

What would happen to production?

Whose fault is it?

How would our customer feel?

Stock

Bad new s

Using t he d iagram below ca n you t h ink o f :

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Build Chassis Pack

Here we find a

few more & they

all have to be

returned to stock

Pack Out only inspects theoutside of the Chassis, so theywill have to open a few to make

sure the Power Supplies have

the Warning Labels

Stock always has 112 ready

for use. We'll have to check

all of them to make sure

they are OK. There could

be up to 112 defectives,

depending on how many

operators caused the problem

Stock

Let 's see...

What w ould happen to product ion?After checking all the power supplies in the stock room and the Final

Chassis assembly, those found OK will be used to complete the assy.

There may be quite a few bad ones, however, since the operator building

them had been working for 2 days before the problem was found.

Production has been affected by having to look for

defective Power Supplies and because there is no

longer enough materials to complete the order

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Build Wire Sets

Here we can only

hope that all the

Wire Sets are OK

Build Power Supplies

Here, we'll

probably find

some finished unitswith problems

Defect ive un i ts c ou ld range f rom on ly those a l ready

found to a l l 112 in s tock and a few w i th in the Pow er

Supply and Final assem bly areas


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Whose faul t is i t ?THE PROCESS!

There is no real time quality checks built into the process for building

any of the parts that go in the Chassis

How w ou ld the cus t omer fee l?VERY UPSET!

The customer might even decide to take his businesss somewhere else

Could t h is problem ha ppen again?YES!

This is one of the most common problems in batch manufacturing

This w ould be an even b igger prob lem i f w e had to

produce t housands of uni ts inst ead of hundreds

How do w e change the process so t hat

potent ia l defec t s have min imum ef fec t

on product ion

In this process, inspection happens once the assembly of the lot has beencompleted. Even if the inspectors were to find the defective units, therewould still be many to rework. No significant improvement can be made

to this proces, as designed, to build in quality.

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More answ ers

STOP


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Now that we have seen the advantages of manufacturing with DFT, let'slook at the tools required to develop a good DFT process.

The TQC Met hod Sheet is the first tool. This document is an instructionsheet that explains visually the work activity details within a station. Thegoals of the TQC method sheet are to:

Provide continuous referenence during and after training

Describe and show the parts to be usedShow how to assemble the partsPoint to what parts or work should be inspected and how

DFT Too ls

TQC OPERATIONAL METHOD SHEET

ASSEMBLY P/N PROCESS I.D. DOC. REV. ORIGINATOR

2 of 2

PAGESEQUENCE#

ST 3 Power Supply Top Cover Assy 25-32 A RR

WORK CONTENT

Item# Part No Description Qty

1. 36-298 Top Cover 1

2. 36-228 Screws 9

3. 36-268 Warning Label 1

4. 36-200 Jumpers TBD

TQC

1. Insure that all mounting holes have a

Pem Nut2. Insure that PCB is secured properly

VERIFY

1. Verify that jumper setting follows

TABLE 1

2. Inspect Top Cover for cosmetic

defects

A

B

C

D

Product Jumper

Model Setting

1

4

TABLE 1

3

2

1

2

1

2


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ASSEMBLY P/N PROCESS I.D. DOC. REV. ORIGINATOR2 of 2PAGESEQUENCE#


WORK CONTENT


1. 36-298 Top Cover 1

2. 36-228 Screws 9



TQC

1. Insure that all mounting holes have a

Pem Nut

2. Insure that PCB is secured properly

VERIFY

1. Verify that Jumper setting follows

TABLE 1

2. Inspect top cover for cosmetic

defects

A

B

C

D

Product Jumper

Model Setting

1

1

TABLE 1

3

2

TQC Met hod Sheet e lem ent s

There must be a 1 of 2 page

describing other required work

The numbers matching theones in the work content area

point to all the parts to be used

in this assembly. Parts are

described and shown their

location within the assembly

These items insure that the previous

operator performed his Verify steps.

Station number for this

operation or Assy P/N

this operation belongs to

4

1

2

These items require special attention;

extensive rework may happen if not

observed. They also help to verify the

correct assembly of parts that could

be installed in more than one way.

This area is a reference of how to

assemble the product once proper

training has been completed.

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There are 4 problems w i th t h is TQC met hod sheet .

Can you f ind t hem?


ASSEMBLY P/N PROCESS I.D. DOC. REV. ORIGINATOR

2 of 2

PAGESEQUENCE#


WORK CONTENT


1. 36-298 Top Cover 1

2. 36-298 Screws 9



TQC

1. Insure that all mounting holes have aPem Nut

2. Insure that PCB is secured properly

VERIFY

1. Verify that jumper setting follows

TABLE 1

2. Inspect Top Cover for cosmetic

defects

A

B

C

D

Product JumperModel Setting

2

TABLE 1

3

2

1

Let 's Review and prac t ic e

1-Items1and2,intheworkcontentarea,havethesamepartnumber.Everypartusedinaproductneedstohaveitsownpartnumber

2-Parts4and2withintheyellowsquaresseemtobereversed.Part4ispointingtoascrewwhilepart2showsthejumpers

3-TQCandverifypointsnumber1,withintheassemblydesriptionarea,seemtobereversed.Verify1askstoverifythejumpersetting

butpointstoapemnut.

4-Part3,withintheassemblydescriptionarea,pointstoalabelthatisnotshown

A TQC met hod Sheet has t o mak e sense

t o you to be useful

4

1

1

2


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1- Items 1 and 2, in the work content area, have the same part

number. Every part used in a product needs to have its own

part number

2- Parts 4 and 2 within the yellow squares seem to be reversed.

Part 4 is pointing to a screw while part 2 shows the jumpers

3- TQC and verify points number 1, within the assembly

desription area, seem to be reversed.

Verify 1 asks to verify the jumper setting but pointsto a pem nut.

4- Part 3, within the assembly description area,

oints to a label that is not shown


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DFT

Basics

Training

You are now o f f ic ia l l y t ra ined in

basic c oncep ts o f m anu fac t u r ing w i t h DFT

Improvement means c hange

Flextronics will continue to improve its manufacturing processesThis means that current tools and process designs may change andnew ones will be developed

Remember. . .

dft reference materials 3

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