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TPM for lean manufacturingChap３． Kobetsu-kaizen for production efficiency

Quote From ：TPM Deployment program

TPM encyclopedia Keyword Book

（Japan Institute of Plant Maintenance)

Created by Japanese Gemba Kaizen Web

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３． Kobetsu-kaizen for production

efficiency3.1 ・・・ Improvement of zero failure ・・・・・P38

3.2 ・・・ Improvement of the setup ・・・・・P43

3.3 ･･･ Improvement of cutting blade change loss・・・47

3.4・・・ Improvement of start up ・・・・・P50

3.5・・・ Improvement of Minor stoppage ・・・・・P52

3.6・・・ Improvement of Speed losses ・・・・・P56

3.7・・・ Improvement of Yield losses・・P58

3.8・・・ Principle of improvement ・・・・・・P60

“Kobetsu-Kaizen" refers to the “individual

improvement for further efficient

production systems." It means efforts to

select model equipment or a model line

and to challenge the target of zero losses

through project team

activities according to improvement

themes.

“Kobetsu-Kaizen" takes the form of

activities through project teams composed

of managerial staff members and through

small workshop

groups.

The procedures for the implementation of

“Kobetsu-Kaizen" by managerial stall

members are as follows:

[1] Selection of model equipment

Model equipment or a model line should be

chosen.

[2] Organization of a project team

A team of several members should be

organized, with the line manager in

charge of the model equipment serving as its

leader.

[3] Grasping and confirmation of 16 major

losses

[4] Decision on the theme and preparation of a

promotion program

[5] “Kobetsu-Kaizen" project activities

For these activities, failure analysis methods

and IE methods should be

utilized. For chronic losses, PM analysis should

be applied.

[6] Standardization and horizontal evolution

should be completed for enhancement of OEE

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３．１ Improvement of zero failure ３・１・１ Common challenges related to failure

(1) No interest production Section

・ The worker is not anything other than work

・ For safety reasons, worker does not touch the equipment

・ There is no provision

(2) Failure analysis is poor

・They have not drawn broken parts

・ They dose not have to disassemble the defective part

・They only exchange parts

・No relapse prevention

Workers just do not know how to Maintenance

If Teach Maintenance to Wokers ,They can .

Maintenance personnel does not understand the function of the parts

They does not understand Why-Why analysis

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(3) Maintenance system is incomplete

・Judgment standard ,method of inspection , inspection points is incomplete

・Defective Maintenance schedule

・ Record system of failure

(4) Predictive maintenance is poor

・Periodically measuring equipment to determine the abnormality

・ Precision diagnosis ・・・Measure vibration, current load, timing, operating time, sound, etc and then understand the change point

If there is no data management can not be right!

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３・１・２ Thinking reduction of failure(1) Classification of failure・failure Classified simple and complex then Give priority to simple failure

・ Method of stratified ・・・Mode causes / line/Occurrence location

(2) Failure analysis

・Stress on the equipment

→ Electric or mechanical stress, temperature, humidity, dust, vibration,

Cause failure ：· deficiencies basic conditions

· Do not keep the terms and conditions

· Degraded without Restore

· lowering skill

· Lack of design

Intensity <Stress

Failure occurrence

To educate and Change the way of thinking

and Change their behavior

３･1・３ Four phases to achieve zero failures

Four phases to achieve zero failures

A short-term and simultaneous implementation

of the five measures for zero breakdowns is

unlikely to progress smoothly. It is more effective

to divide enforcement of the measures into four

phases and implement them one by one under a

plan. Through these steps, steady approach to

zero failures will become possible.

The four phases and principal themes of

individual themes are as follows:

~ Phase 1: To reduce dispersion of MTBF —

mean time between failures.

Repair of previous uncovered but unamended

degradation to restore the original conditions,

preparation of basic conditions, and

prevention of artificial machine deterioration

through observance of usage conditions.

- Phase 2: To extend inherent service life.

Improvement of design shortcomings (corrective

maintenance),prevention of random failure

occurrences due to operation or repair errors,

and restoration by fixing external appearance

deterioration.

- Phase 3: To periodically repair deterioration to

restore original conditions.

Regular deterioration repair to restore the

original conditions

periodic maintenance: TBM), and grasping of

abnormal symptoms

of internal deterioration based on the five senses.

- Phase 4: To foresee the service life.

Prediction of the service life based on condition

diagnosis

techniques (predictive maintenance: CBM), and

technological

analysis of catastrophic failures.

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３･1・４ Five measures to achieve zero failuresFailures represent only the tip of the iceberg, so

to speak. The leaving of

latent defects below the “water surface" causes

failures.

Methods for uncovering such latent defects and

preventing failures are the

"five measures to achieve zero failures, "and

they are as follows:

[1] Put basic conditions in place:

Keeping of basic conditions for equipment, i.e.,

enforcement of cleaning,oiling, and retightening

(of bolts and nuts).

l2] Abide by operational conditions:

Observance of the specified operational

conditions of the equipment, such

as pressure, temperature, speed, and flow rate.

[3] Restore original functions by fixing

deterioration:

The prevention of forced deterioration of

quipment is possible by preparing basic

conditions and abiding by usage conditions.

Even so,natural deterioration, such as wear,

corrosion, fatigue, and declining insulation,

inevitably occurs. Therefore, such deterioration

should not be left unattended but corrected to

restore the original conditions.

l4] Improve design weaknesses:

Only repeating correction of deterioration cannot

lead to progress. To begin with, deterioration

may be accelerated due to material selection

errors or structural defects during design stage.

Such design shortcomings must be rectified

(this is corrective maintenance).

' l5] "Improve skills:

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Ask to

the machine

cleaning,oiling, and retightening is Important

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３．２ Improvement of the setupThis is one of the seven major losses that

impede equipment operations and refers to the time lost from the termination of the production of a present item until the good-quality manufacturing of the next item subsequent to setup and adjustment.

The setup here means a series of work:

removal of jigs/tools upon the completion of the on-going production, clearing up, cleaning; preparation,attachment, adjustment, and measurement of jigs/tools required for the next item and manufacturing of non-defective products.

There remain many issues to be addressed to shorten the time spent on ‘internal setup’ (setup during machine stoppage) and ‘external setup’ (setup without machine stoppage) based on IE approach.

Adjustment means the following:

[1] Measures to be taken to seek the optimum solutions or values to attain some purpose; for instance, the procedures to put quality within

designed values

[2] What is achieved through ther e p e t i t i o n o f t r i a l a n d e r r o r s

Understand the setup, to quantify ！

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(1) Organize and tidy

・ Management position of tooling

・ Do not search, do not move

(2) Clarification External setup and Inter setup

・ Study Elimination of work-

・ Review of work procedures

(3)Study External setup to Inter setup

・Preset(Pre-assembled)

・ Sharing of jig and Exchange one-touch

・ Changes the adjustment to External setup

・Using the auxiliary jig・・・The elimination of adjustment

(4) Study procedures of Inter setup

・Study on method of fixation Screw fixing → Hydraulic

・ One worker → Two worker Time savings

(5) The elimination of adjustment

· The purpose of the adjustment

① positioning

② centering

③ the correct dimensions

④ timing

⑤ balance

-Cause of the adjustment

① cumulative error

② shortage standardization

③ shortage rigidity

Analysis of adjustment

Study the one-touch setup

Study eliminating waste of External setup and Inter setup

３・２・２ Improvement of the setup

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Viewpoint Improvement of setup

5S, preset, standardization, into fixture, no adjustment

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One-touch attachment and Analysis of adjustment

The elimination of adjustment

→ One-touch attachment

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３．３ Improvement of cutting blade change loss

３．３．１－ Problem of cutting blade

（１）The life of the cutting tool

・Shape and material of the cutting tool

· Cutting conditions (cutting speed)

・Material, hardness

・requirements of Quality product

(Dimensional accuracy, surface roughness)

・Rigidity of the equipment

Look the cutting edge！

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（２）Exchange conditions

Reason:

・Unclear Exchange standards

・Failure occurs,

Exchange without permission

（３）Inhibiting unattended operation

Reason:

・varies Quality ・Short-cutting tool life

・Occurs Minor Stoppage

（４） Reduction of cutting tool’s cost

・Storing the old chip

・ No management objectives of cost cutting tool

・ Many kinds of cutting tool

・Management chip is loose

・ No historical record use of a chip

・ No Management abrasion of the chip

(Can be use but exchange can not use but No exchange)

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Detection parameters of the cutting tool life

Quantify sound, vibration, AE, resistance, current, heat

Start-up losses denotes the time losses and

volume losses (from defects and remark)

until product quality stabilizes to

manufacture non-defective products even in

accordance with the specified cycle time

without mechanic troubles, such as minor

stoppages, small troubles, and breakage of

cutting blades, during

[1] start-up after periodic overhaul

[shutdown maintenance]

[2] start-up after downtime (long-term line

stoppage)

[3] start-up after holidays

[4] start-up after the lunch break.

At a machining shop dimension dispersions

are likely to occur during the morning setup,

causing frequent adjustments, rework due to

failure to

adjustment, and breakdown of cutting

blades. To prevent these, warm-up and

idling operations are conducted early in the

morning. The target of

start-up losses is “minimization.”

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3.4 Improvement of start up

Understanding the thermal displacement!!

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3.4.2 Improvement Way of start up

(1) measure：

・Measuring temperature of the table, Main shaft, etc to stabilize.

(2) Study Material ：

・Consult the manufacturer the material to minimize thermal displacement

(3) Cooling the generator

・ Cool heat by Cooling fan

(4) Automatic correction

・Automatically adjusts to predict beforehand the amount of displacement

Study Cause,Thermal displacement curve,Time to settle

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3.5 Improvement of Minor stoppage losses

[1] In case temporary functional stoppage ensues.

[2] in case the recovery of functions is made by simple fixing (elimination of abnormal work-piece and/or resetting)

[3] ln case parts exchange or repair are not required.

[4] Recovery time lasts from 2 or 3 seconds less than 5 minutes.

Unlike failures, minor stoppage/idling losses represent a status in which the machine is subjected to either stoppage or idling due to temporary troubles; for instance, when a work-piece is clogged in the chute, idling

occurs ; or when a sensor activated

because of a quality defect to cause a temporary stoppage.

These are the conditions in which the machine will revert to normal operation, if the stuck work-piece is removed, or resetting is carried out. Therefore, they are fundamentally different from machine failures.

To reduce minor stoppages, it is important to in detail analyze phenomena [or slight defects] and to thoroughly eliminate slight defects.

Observation, analysis, stratified to investigate at the site

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3.5.2． Improvement Way of Minor stoppage losses

(1) Phenomenon analysis and motion analysis of workpiece:

Video recording the phenomenon of Minor stoppage , Viewpoint is movement

posture, angle, float, vibration

(2) Remediation of the defect:

Contact surface of the workpiece is key point

Improve the small defects of parts and jigs

（３）Compliance with the basic maintenance：Cleaning, refueling, retightening

（４） Compliance with of the basic tasks：Correct operation, setup, adjustment

（５）Study on optimum condition：Studied the optimization of processing conditions of Parts

（６）Study Weakness:

Studied the problem of the design of equipment、parts,jigs

Understand the movement of the workpiece by video shoot

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Classification of phenomenon

and Classification of causes

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３．６ Improvement of Speed losses

Into the data to understand the current status of equipment!

One of the seven major losses impeding

efficiency improvement of equipment. These

losses incurred by slow machine speed are

defined as

follows:

[1] Losses due to the difference between the

actual speed and the design

speed (or reference speed for each product

item)

[2] Losses resulting from lower design speed

compared to the present technological level or

desirable speed

(or ‘mission’ speed)

As an example of the former case, the cycle

time is 60 seconds as reference but the actual

operation cycle time is 65 seconds. There is a

speed loss of 5 seconds. As an example of the

latter case, the cycle time is set at 60 seconds

but it could be reduced to 50 seconds through

improvement based on the current

technological level. There is a speed loss of

10 seconds in this case.

Aiming at speed increase would contribute to

clarification of problems and

upgrading of technological levels. Therefore,

the target should be to make

nit the difference between the design speed

and the actual speed.

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３．６．２ How to improve the speed loses（１）Understand the causeTo speed up For the experiment.

① Changes in Cp ？② New bad item ？③ The life of the cutting tool ？④ Number of occurrences of Minor Stoppage？⑤ Percentage occurrence of defective ？

＊Examine the aggravating factors measures ahead

（２）Check the validity of the action①Reduction of air cut time

②Reduction of idle time ③Reduction of operating time ④ Reduction of working hours by two people work

＊Make improvement on equipment mechanism, component structure, timing, the cycle diagram.

Study Air cut time,Idle time,Operating time,Two person work

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３．７ Improvement of Yield losses

This refers to the volume losses resulting from differences between raw material weight and product weight, or between raw materials input and product weight.

The former represents material losses that can result from leaving too much iron cast for fear of casting shortcomings (such as sand inclusion) or from forging too thick so that it may be sufficient enough to obtain mold precision in the shaping process.

As a result of these, cutting time can be lengthened, or the service life of cutting blades shortened.

The latter represents the difference between whitewash weight, gate weight, generated burr volume and the product weight. in other words, the losses in this category result from increased burr generation due to molding precision insufficiency.

in the case of aluminum casting, this refers to the

losses representing runner weight and blur Weight.

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３．７．２ How to to reduce chronic defects

（１）Immobilization of variable factors

factors?:Impact phenomena logically

Cause？：Which have proved to have influenced the phenomenon

“Restore ,For Immobilizing the "Variation factor"!！

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３．８ Principle of improvement

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