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Optimally Adjusting Filling Processes

How Checkweighers Increase Profit

WhiteP

aper

Contents

1 Actively develop solutions

2 Underestimated! Checkweighers, a critical control lever

3 Neglected! Sources of error that matter

3.1 Production

3.2 Rules and regulations

3.3 The consumer and brand quality

3.4 The product quality

4 Checked! Checkweighers that are as accurate as you need

5 Characterised! Checkweighers in filling processes

5.1 Avoid commercial damage

5.2 Maintain an overview

6 Counted! Every gram counts, in particular for filling processes

6.1 The overfilling/underfilling problem

7 Focused! Limit values are the pointers on the checkweighers

7.1 Adjustment is everything

7.2 Fine tuning thanks to the latest technology

8 Detailed! The particular application determines the control method

8.1 Standard feedback control

8.2 Extended feedback control

8.3 What can be done about environmental weight variations?

9 Future-oriented! It is the integrated process that matters

9.1 What you should do

10 Tracking solutions

11. References


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No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photo-

copying and recording, for any purpose without the express written permission of Mettler-Toledo Garvens GmbH.

This documentation is furnished with restricted rights.

Mettler-Toledo Garvens GmbH does not warrant the accuracy or applicability of the information contained herein and as such is specifi-

cally not responsible for property damage and/or personal injury, directly or indirectly for damages and/or failures which may be caused

as a result of using the information provided.


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rocesses 1 Actively develop solutions

Value creation demands integrated solutions. Global competition, the variety of technological development, and

short product life cycles are amongst the driving forces behind changes that make continuous optimisation of the

production environment essential. Quality that contributes to value creation only comes into being when every part

of the production process is tuned to every other, allowing them to mesh seamlessly together.

Companies need partners who can think for them. For company managers and those responsible for production,

this means that their own production depends significantly on others' solutions. It is the skilful solutions developed

by partners that contribute in large measure to the development of one's own solutions, ensuring survival in the

market.

Dynamic weight control must be integrated into the manufacturing process.Again and again it can be seen

that far too little attention is paid to checkweighing as part of the manufacturing process. Companies that employ

it appropriately with the entire production process in mind and so consciously avoid weak links in the overall

production chain, can make an additional contribution to their own value creation.

2 Underestimated!Checkweighers, a critical control lever in the production process

Within complex production processes, some of which comprise many hundred production steps, it is always pos-

sible that one small step does not receive the necessary attention. This can have a negative effect on the overall

result.

Quality assurance within manufacturing processes is becoming more and more important. The importance of

modern checkweighers is growing rapidly. Through their ability to weigh 100% of products, even within a rapidly

operating, round-the-clock production process, they make an important contribution to successful production.The days are long gone in which the only purpose of a checkweigher was to determine the weight deviation of a

product. On the contrary, a checkweighing programme matched to the production process now has a compre-

hensive protection and safety function and therefore huge commercial significance.

Checkweighers perform a wide range of tasks. Modern checkweighing programmes are able to employ statisti-

cal evaluations of their measurements in order to control filling systems in such a way that production automati-

cally remains within very tight tolerances. In this way, the optimum utilisation of product and resources is achieved

and secured in a systematic weighing process. Expensive reworking resulting from incorrect filling, or even recall

actions that damage a brands image, can now be avoided through an integrated checkweighing programme.

Effective programmes for checkweighing also secure:

the compliance with official regulations (e.g. national and international food safety laws)

the observation of industrial standards (e.g. national ISO 9001, international ISO 2200, GMP, HACCP)

the observation of codes of conduct (e.g. trade organisations such as FDA, BRC, IFS)

the provision of customer benefits (e.g. avoiding recall actions, encouragement of trust, due diligence etc.)

3 Neglected!Sources of error and stumbling blocks that matter

Only a checkweighing system that satisfies the demands of modern production lines is able to contribute to cost

reduction and optimising product quality. Companies often only have the observation of statutory regulations

and standards in mind when they purchase a checkweigher. However, there is a wide range of other important

aspects that can be overlooked all too easily. Not infrequently these have a significant influence on the design and


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configuration of the new checkweigher, and as a result the design can have a critical impact on survival against

global competition.

3.1 Production

It is by no means certain that a production process that runs without interruption is working optimally and

economically. Only production processes that are able to operate within closely specified tolerances can fully

utilise their expensive resources. Even very small savings can often lead to cost reductions that are crucial to

survival against global competition.

Recall actions or halted production are the nightmare of every production manager. If you can only take

random samples, there is always a risk that the production process will have to be halted for correction, or, in

the worst case, that product must be recalled from suppliers or from the marketplace. The consequences range

from changes to the production timetable and unexpected additional costs, right up to cancelled contracts and a

damaged reputation.

The world of modern production needs predictive checking systems. Ideally the active feedback control built into

the checkweigher is used to control filling processes. Thanks to continuous analysis of the measured weights, it

is able to automatically adjust the filling head of a filling installation, resulting in comprehensive regulation along

the production chain. The efficient production not only yields optimised levels of manufactured goods, but also

minimises the cost of the control process.

3.2 Rules and regulations

A major feature of global trade is the expanding range of specifications and statutory regulations that must

be observed in the manufacture of products. The enormous pressure to produce quickly and to overcome the

competition demands systems that are flexible and reliable. One of the requirements of modern checkweighing

systems is that their operators can quickly make the specified adjustments, and can change them when needed.

It is also necessary to prepare and archive documentation relating to the tests for Weights and Measures authori-

ties and for other administrative offices. In addition to its reliability, a checkweighing system must be simple and

secure in operation, particularly bearing in mind that it will have different operators.

3.3 The consumer and brand quality

Often the little things are the most annoying and this also applies to filling processes. Products that are

short on content have already done lasting damage to consumer attitudes to more than a few manufacturers and

brands. The loss of a commercial relationship can af fect the company just as badly as the loss of brand image that

stops new customer contacts. Companies must here emphasise the need for a degree of care that has precisely

the opposite effect to what has just been described: that is to say an optimisation of product quality from the end

consumer's point of view, generated through reliability that characterises the brand quality. Consumer protection,

and the protection of the company's market reputation and its customer relationships, are the result.

3.4 The product quality

Checkweighing has a crucial role to play in the control of quality and methods provided it covers 100% of

production. Every product manufactured must be weighed. Integrated checkweighing systems are now capable of

doing this. They document the entire production, monitoring it in real-time, so that accurate control of the amount

of product dispensed by filling installations is therefore possible at any time.

But the checkweigher can do more than just weigh. It is increasingly becoming the central point of quality assur-

ance, as a result of the option of interlinking with other testing procedures. By connecting sensors, scanners or

identification systems, barcodes can be applied, for instance, or products with missing or incorrectly positionedparts can be rejected. With just one central user interface for all the components employed, quality assurance

gets a significant boost. Multilingual operator guidance not only reduces costs, but also saves valuable personnel

resources.


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4 Checked!Checkweighers that are as accurate as you need

Programmes must satisfy clear criteria. The analysis of practical operation can clearly demonstrate that quite

specific factors are responsible for the success of a checkweighing programme. These include the unchanging

accuracy of the checkweigher, the ability to make necessary adjustments quickly and easily when the produced

items change, and the reliable rejection of products that do not meet specification.

Accuracy pays! When purchasing a new checkweigher system it is therefore crucial to bring the requirements

of the particular application into a proper relationship with these factors. Greater precision of measurement can,

for instance, initially entail a higher investment cost; fewer instances of under- or overfilling, savings in rework or

minimisation of product wastage, can over time lead to a reduction in costs and in a long term consideration of

profitability can justify the initially high investment. This always demands comprehensive knowledge of the par-

ticular application. In the tug-of-war between costs and benefits, it is necessary to discover the right compromise

for the required precision of the checkweigher.

5 Characterised!Checkweighers in filling processes

Anyone who invests wants to be sure that the capital used will pay out. That is also true when evaluating and

purchasing a checkweigher system. Reliability, efficiency and the proper design are the key parameters. Very often,

only the observation of specifications and statutory regulations receives full attention, since failure here can result

in sanctions. But there is a whole range of important aspects that can have a significant effect on reducing costs

and increasing product quality. These should also be included in the purchase calculation.

5.1 Avoid commercial damage!

Only if 100% of the products coming off the production line can be weighed can the company be certainthat they are good enough for market requirements and up to modern production standards. It also avoids

infringing the wide range of standards and regulations applying to both national and international trade. An effec-

tive checkweigher programme therefore automatically supports the good name of a product brand or a company.

Faulty products that get into the distribution system and reach the end customer have already put an end to a few

business relationships.

Accuracy is also a question of costs. Checkweighers that operate within a quality assurance process are capable

of working within very close tolerance bands. As a result, numbers of incorrect rejections and cases of wrong sort-

ing are reduced! On the one hand this improves the quality of the manufacturing process, and on the other hand it

reduces product wastage and the need for rework. A point that clearly weighs on the side of cost reduction.

A vital argument in favour of a checkweigher system is feedback control for filling heads. Intelligent weighing

technology provides predictive monitoring of the filling heads in the filling installation. Accurate control adjustments

then ensure that overfilling or underfilling are avoided. Feedback control ensures seamless regulat ion that can lead

to enormous savings (cf. Page 5 / calculation example).

5.2 Maintain an overview

The requirements of a company and its manufacturing processes are the measure for an effective checkweigh-

ing programme. This requires clear operating targets to be set for the flow of production, knowledge of the metro-

logical regulations to be observed, as well as an understanding of how limit values are specified. Measuring 100%

of the products provides information about the availability of an item of equipment as well as about its performance

and quality. It affects the total effectiveness of the plant, and therefore is an important control lever for profitability.

3 Optimally Adjusted Filling ProcessesHow Checkweighers Increase Profit

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Your operating requirements also provide the measure for the selection of the right supplier.A serious supplier

will always want to know about the particularities of your operat ion. Ideally, the supplier's experience is reflected in

a wide range of products, from the entry-level model for use in a stable environment through to high-performance

systems for tough production conditions every solution calls for clearly defined pre-sales and after-sales advice

along with comprehensive service. And the rule here, as in ordinary life, is that bargain prices call for caution!

6 Counted!Every gram counts, in particular for filling processes

Precision makes itself very noticeable, above all in modern, high-performance filling installations. Every bit of

product wastage caused through overfilling, for example can turn into an expensive waste of resources when

large quantities are being produced in multi-shift operations.

The basic rule is that the greater the precision, the smaller is the loss of product. The consistency of the product is

the result of two considerations: one is the checkweigher, and the other is the filling machine. It is only if a highly

accurate checkweigher is used in combination with optimum control and filling precision in the filling machine

that the process can be guaranteed not to waste resources.

Note: Checkweighers are subject to environmental influences (e.g. air temperature), the packaging or the application

itself, and these can lead to variations in weight. A changed fill weight can, however, always be traced back to the

filling installation that controls the filling. Reasons for these variations can be found in changes in the environment or in

the properties of the product, but malfunctions in the equipment itself can also often be the cause.

6.1 The overfilling/underfilling problemCheckweighing involves both specifications and mathematics. Legal regulations require filling companies to

ensure that the mean weight of a defined production quantity is equal to or larger than the weight quoted on the

packaging. Individual products must also not weigh significantly more or less than stated on the packaging. There

are a number of influences that can affect the checkweigher and the filling installation, regularly leading to devia-

tions in the fill quantity. It is therefore necessary to take account of these deviations in the control process, i.e. in the

equipment controller. If they are random, and occur with the same probability, these deviations follow the standard

deviation pattern. This corresponds to a mathematically defined normal distribution, and can be calculated exactly.

Definition: The standard deviation is a measure of the way values are spread around a mean value in a normally distrib-

uted series of observations.

If the standard deviation is very small, all the weights are in fact very close to the target weight. If, however, it is

large, underfilling or overfilling to a degree that can not be tolerated will occur, ending in rejected product.

If the waste of resources caused by overfilling in the production process is to be restricted, and if the number of

items that have to be rejected because their weight is wrong is to be reduced, it is necessary to achieve a reduction

in the standard deviation of the filling machine.

Note: What you can do to reduce the standard deviation of your filling machine: Use a filling machine that is appropriate for your product.

Make sure your filling machine is in optimum condition.

Make sure that there is a steady flow of product to your filling machine.




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rocesses The example below shows how small variations in weight can give rise to large effects.

What's a gram worth?

If the overfilling of product packages is reduced by 1 gram per pack through the application of 100% weight control,

or by replacing an existing and less accurate checkweigher by a more accurate and more capable weighing solution,

remarkable savings can be made. A simple example for a product that is worth just 0.1 cents per gram is shown below.

Packing and production

Nominal product weight = 450 g

Material costs = 0.1 cent per gram

Throughput = 200 packs/minute

Production line utilisation = 65%Working shift = 8 hours

Shifts per day = 2

Production days per year = 230

Saving resulting from 1 g waste reduction per pack

0.1 cent saving per pack

20 cent saving per minute

12.00 saving per hour

124.80 saving per day

28,704.00 annual saving

IN ADDITION TO WHICH there are 60,000 further product packs (with the associated profit) that could have been

produced from the material saved.

7 Focused!Limit values are the pointers on the checkweigher for quality and productivity

"What it says on the package must be what is inside." This, in simple terms, is what the law says about content

fill levels of packages. There are, of course, tolerances and limit values that are clearly defined in the relevant

regulations. Companies must implement this consumer protection, which is, at the same time, a mark of quality.

For any given product setup there are upper and lower weight limits, defined as the tolerance limits on what each

individual product must contain. These tolerance limits, which are also known as classification limits in the context

of checkweighers, are preset in the checkweigher for when particular specifications are to be followed. They canalso be individually adjusted by each operator.

The classification limits define the range of weights which, when the product is weighed, will be considered "good",

meaning the item will remain in the production process. Modern checkweighers normally have 3 or 5 weight zones.

Products that fall within the outer two zones are rejected, as their weight is no longer acceptable.

For example: tolerance limits on a checkweigher with 5 weight zones:

130g120g110g100g0g Max Load

Zone 1

OK-Under

Zone 4

Over

Zone 3

OK-Over

Zone 2

OK

Zone 0

Under

Target Weight

Note: Checkweighers are normally preset: The programming already takes into account the permitted variations in the

weight in accordance with the OIML guidelines, NIST manual or local packaging regulations. The statutory tolerance

limits are thus shown automatically.




7.1 Adjustment is everything

The process of adjusting the tolerance limits is oriented around the precision of the checkweigher and the

variations in weight that are acceptable for the particular product. Practical experience shows that products

tend to be wrongly classified when narrower tolerance bands are set. Improved measuring techniques can help

in these cases. They have the effect of optimising the process control of the filling, and therefore improve quality,

since the filled weight of the products has less variation.

Step 1:The first step required to control the filling process is to define the nominal weight and the tolerances. In

practice, the quantity dispensed by filling machines is a little bit higher than the weight indicated on the package.

This usually ensures that the mean value of the weight dispensed by the overall production process is not below

the indicated weight the manufacturer is then "on the safe side".

Step 2: The legal regime applying in the particular region specifies the maximum permitted deviation from

the nominal weight upwards and downwards. This is used in the second step to specify the tolerance

bands. In Germany, for instance, it is the "Fertigpackungsverordnung" (FPVO / Finished Packaging Ordinance

http://www.bundesrecht.juris.de/fertigpackv_1981/index.html) that specifies the maximum permitted deviation

for various products. In addition, the OIML guidelines (Organisation Internationale de Mtrologie Lgale) regulate

the weight variations permissible in Germany. The "slight inaccuracies in weighing" caused by environmental

influences, to which every checkweigher is subject, can be compensated for by specifying the tolerance in such

a way that the limiting value for the "good" weight class is made "tighter" by the precision of the checkweigher.

7.2 Fine tuning thanks to the latest technology

The potential of modern checkweighers is far from being exhausted. They can do far more than merely weigh-

ing and indicating tolerance limits. Using special software and additional options they can contribute to improving

production processes, and can increase productivity.

The documentation and recording of production processes, to provide evidence to government offices or to trad-

ing partners, is enormously important for modern production companies. Nowadays, software programs cannot

only join together different checkweighers and control them, but also offer versatile options for documenting their

results. Preset adjustments for different items can be stored, and country-specific versions can be recalled. Certi-

fication obligations can be satisfied easily and reliably.

The performance of the filling head is the crucial point for filling processes. So is the rule of thumb. Environ-

mental effects and the condition of the filling installation contribute to unavoidable variations in the weight. In the

worst case this ends in tolerance ranges being exceeded, to rejected product and to the machine being stopped

potentially a commercial disaster.

Checkweigher systems with special software

are capable of monitoring the performance

of the filling head, and readjusting the filling

machine in such a way that filling proceeds

within the specified tolerances. By analysing

the changes in the weight distribution, they can

detect the trends in filling the product, and can

correct the filling behaviour appropriately. This

"feedback control" supports optimum process

control.

The more accurate and more

consistent the filling process,

the less resources are wasted

through overfilling.




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rocesses 8 Detailed!

The particular application determines the control method

One effective way of optimising filling processes is to maintain closer tolerance limits. This brings a reduction in

scrap product and requires less rework, since the filled products should already be within the specified weight

range. An accurately operating checkweigher with its control possibilities thus performs an important task. Control

systems that permit rapid and accurate fine-tuning of the filling head make this process possible.

8.1 The standard feedback control

The filling heads are automatically adjusted when necessary. The checkweigher directly controls the filling in-

stallation to which it is connected. A figure for the mean weight is continuously calculated in a continuous process.

As soon as this varies from the set weight, a correction signal is sent to the filling installation, and this adjusts the

filling quantity.

Feedback control in brief:

100.5Filler

X X

CheckweigherController

Monitor product

weights

1

102.1Filler

Checkweigher

Controller

Monitor product

weight and signalfiller as

necessary

4

100.7Filler

X XX X

Checkweigher

Controller

Do not analyse

filler while previousfills run through

the system(Continue to

classify)

3

100.3Filler

X XXX

Checkweigher

ControllerSignal filler

to adjust fill

2

If you would like more detailed information about feedback control visit:

www.mt.com/garvens-app and request application note 04

Feedback

ControlFunction

Feedback Control FunctionOverfilling Does Not Pay

Customerbenefits:

Optimisationoffillingprocesses

Reductionofoverandunderfilling

Reductionofunnecessaryproductgiveaway

Reductionofrejectsandproductscrap

Compliancewithnetcontentlawsandregulations

Higherandmoreconsistentproductquality

Thefeedbackcontrol function minimisesproduct weight errorsand product giveawaythrough

proactivefeedback,keepingfillerheadsproperlyadjusted.Checkweigherscan beintegrated

directlywith thefillercontrol or networked to existing factoryfloorautomation systemsfor

completeand seamlessfeedbackcontrol.Feedbackcontrol froma checkweighercan minimise

productweighterrorsand productgiveawayintroduced byfillerdrift.Thedrift maybecaused by

slow changesin theenvironment,theproduct characteristicsora fillerproblem.Theaccuracyof

thecheckweigherwith thefeedbackfunction compensatesforthesechanges,butdoes not

improvethefillerperformance.Thefollowing statementsarethebaseforthisfunction:

Aim 1:Net content lawsdefine thatthe mean of the

totalproduction runmust beequalorabove

the labelled weight protect yourbrand and

fulfil Weightsand Measuresguidelines

Aim 2: Every gram overfilling should be avoided to

saveraw materialsand thereforereduce

product giveaway profitscan beincreased

bymoreefficient useof raw materials

Thefillerfeedbackcontrol function isbased on

the calculationof a mean weight value of a

preset numberof weighingsduring a set

period.If a deviation is detected between the

target weight and thismean valuethen the

deviation value is translated into a control

signal which issent to thefillerto adjust thefill

levels. This mean weight calculation,

comparison with thetarget weight and

feedbacktothefilleris a continuousprocess.

Standard feedback control:Advantages at a glance: It optimises filling processes and leads to a reduction in rejects.

It results in less overfilling and underfilling.

It generates cost savings, through lower unnecessary product wastage.

It ensures that statutory specifications regarding the net package contents are observed.

Step 1: The checkweigher detects a down-wards deviation. If this trend continues, the

deviation in the filling weight will increase,

leading to under filling.

Step 2: The checkweigher sends a signal to

the filling system to regulate the fill level. A

pause then follows, during which the check-

weigher does not send any signal to the

filling system.

Step 3: This pause corresponds to the time

required for weighing the packages that were

filled before the change in the fill weight was

signalled.

Step 4: The downward trend in filling weight

has been corrected automatically by the

feedback control.

The greater the distance between the filling

system and the checkweigher, the more

incorrectly filled packages there will be

between them. In the ideal case, the filling

machine and the checkweigher are immedi-

ately next to one another, in order to permit

the fastest possible reaction to changes in

the fill weight.




8.2 Extended feedback control

The best way to avoid errors is to see them coming and take the right measures to avoid them. This proactive

approach becomes a reality with extended feedback control. The statistical interpretation of the weight distribution

as the product is filled permits automatic adjustment of the filling head so quickly that products with the wrong

weight and material wastage are reduced to a minimum.

The adjustment is even more accurate than it is with standard feedback control. The approximation between

the target weight of the feedback control and the nominal weight is even closer, therefore reducing both underfilling

and overfilling more quickly and more effectively. In addition, the behaviour of the control system can be adjusted

in such a way as to be more closely in tune with the particular product and its properties.

In model A "overfilling" is corrected significantly more quickly than "under filling". In this case, emphasis is placed

on the fastest possible reduction of overfilling with the aim of reducing rejects. This model would be suitable

when product that is rejected through being underfilled is not lost, but can be reused or returned to the process.

In model B "underfilling" is corrected significantly more quickly than "overfilling". In this case the emphasis is

placed on the fastest possible reduction of underfilling. This model is appropriate when product that has been

rejected once as a result of underfilling cannot be reused, as would for instance be the case when processing

frozen food.

Target weight

Upward trend is corrected faster

than a downward trend.

Downward trend is corrected faster

than a upward trend.

Fill qty. corrected Fill qty. corrected

Model A: Model B:

Extended feedback control:Advantages at a glance:

It ensures a perfect match between the control behaviour and filling process. As a result, product wastage is

minimised. It is directly linked into the statistics program, and ensures continuous monitoring of the mean value from the

production system as a whole.

It causes the actual weight (product) to automatically come closer to the indicated weight.

It makes it even easier to maintain statutory regulations regarding the net pack content.

It does not require the fill level to be readjusted manually at the end of the production run.

It contributes to extremely high, consistent product quality.

If you would like more detailed information about extended feedback control visit:


Extended

Feedbac

k

ControlFunction

Extended Feedback Control FunctionFlexible, Powerful, Adjustable

Customerbenefits:

R educ tionofoverandunder filling

Reductionof unnecessaryproduct giveaway

R educ tionofr ejec ts andproduc ts c r ap

P erm anentcontr olofm eanw eightv alues for acom pleteproductionrun

A utom atic adjus tmentoftar getw eightnearer tolabelledw eight

Compliancewith netcontent laws andregulation s

A voidsm anualadjus tmentsoffilllevels attheendofaproduc tionrun

Higherandm orecons is tentpr oduc tquality

Thestandard feedbackcontrol function minimisesproduct weight errorsand productgiveaway

through proactivefeedback, keeping fillerheads properlyadjusted.T headditionalfunction

Extended FeedbackControl can substantiallyimprovethe filling processand saveextra money

while complying with Weightsand Measure regulations.The Extended Feedback Control Function

isan add-on to theexisting feedback control programmeand givespowerful new flexibilityand

adjustment capabilitiesto thefilling process.Thefollowing statementsarethebaseforthis function:

Aim 1: Much greatercontrol of filllevelsin conjunction with statistical mean weight valuesto

automatically ensureregulatorycompliance

Aim 2: Automatic correctionof the target weight to bring it closerto the labelled weight to reduce

product giveaway

Aim 3: Taking full advantageof legal packaging regulation filllevel limitsto reduce product

giveaway to anabsolute minimum

Aim 4: Much greatercontrol of fill level correction speed to reducescrap and getfilling processes

in tunefaster

A good comparison forthedifference between thestandard feedbackprogrammeand theextended

feedbackcontrol isthetechnical advancesin musicsystems.Thestandardfeedbackprogramme

can be compared to a radio with dials forjustBass and Treble adjustment whereas the extended

feedbackfunction can becompared to a stereo systemwith a graphicequaliserto finetunethe

musicforan excellent and perfect sound.




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rocesses 8.3 What can be done about environmentally triggered weight variations?

There are also solutions for creeping weight variations. It can sometimes happen that product properties change

quite slowly as production continues. In the case, for instance, of paper tissue, the external temperature and hu-

midity can cause variations in weight as they affect moisture content. Special software is needed if this change is

to be taken into account by the checkweigher. This software for gliding limits looks at the measured trends in both

short-term and long-term mean values, and it deduces from them how the preset nominal weight value and the

tolerance limits must be moved in order to compensate for this change.

If you would like more detailed information about gliding limits visit:


FeedbackControlFunction

Gliding LimitsKeeping Control of Unstable Products

Customerbenefits:

Compensatesfor changesin environmentalcondit ions

Compensatesfor changesin productcharacteristics

Compensateswhere large butacceptable productweightf luctuations

occurorcan be expected

GlidingLimitsprovidesthe capability

toadjust thetolerancelimitsin direct

relationshiptothe runningaverage of

theproduct.Thisfunctionalityis often

u sed w h en p a cka gesa r e so l d b y

count and the item count perpackage

must remain constant,however the

weight of theindividual itemswithin

the package or the tara (package

material) mayvary overtimedueto

environmentalor otherfactors. For

example,when thehigh humidityof

the ambientaircausesthe productor packaging material toaccumulatemoisture.Gliding

Limitswillguardagainstthefalserejectionof productproducedwiththecorrectitem count,by

adjustingthe zone limits to compensateforlong termchanges in the meanvalueof the product

beingweighed.GlidingLimitswill automaticallyraiseorlower thepreset zonetoleranceswithin

limits predetermined by the operatorduring product set-up.

Howdoes Gliding Limitswork?

GlidingLimitsisbasedonthe principlesof a5 zonecheckweigherwhereanestablishedtarget

weight islocatedwithinadefined Acceptzoneaccompaniedby adjacentOverAccept and

UnderAccept.These innertolerancezonesare bordered byOver andUnderreject zones.

Seeillustrationonpage3.

When using Gliding Limits the Target Weight is a constantlyrecalculated Mean Value with the

centerAccept ZonecontinuouslytrackingthemovingMeanValueat tolerancerangedefined

as Offset Plusand Offset Minus.

GlidingLimits

9 Future-oriented!It is the integrated process that matters

A continuous improvement in manufacturing processes is indispensable for survival against global competition.

It is becoming increasingly important to simplify process steps and to combine them. Against the background of

rising staff costs and foreseeable shortage of skilled workers, it becomes important to organise more functions

through a workstation.

Modern checkweigher systems can be combined with a large number of further inspection options, that can com-

municate through one user interface that allows the parameters to be adjusted together. Multi-language systems

make instruction and operation easy. They lower both costs and failure rates. The work required to maintain and

clean combination systems is relatively low in comparison with multiple pieces of separate equipment. In this way,

modern checkweigher systems are increasingly turning into a central control point.

9.1 What you should do

Nowadays checkweighers are a crucial instrument for profitable filling. They weigh, provide statistics, and

automatically control other systems. This functions only as well, of course, as the rest of the elements involved.

Only checkweighers that are regularly serviced can truly measure accurately, and even the best system will not

function adequately without regular training of the operating staff. Powerful software programs that can carry out

statistical analysis and feedback control are a hallmark of suppliers who continuously develop their systems further

and update them. This demands expert knowledge together with experience over multiple industrial sectors and

countries suppliers who continually offer solutions, even after years, that not only meet statutory requirements

but often even exceed them.

10 Tracking solutions

Increasing market requirements, new statutory specifications and changes to the commercial environment demand

both continuous performance and continuous performance increase.

It is critical here to make a comparison with previous production runs. The analyses and statistics from the check-

weigher are of key significance to this task. Many companies make use of overall equipment effectiveness (OEE) as

a yardstick of their efficiency. A factor is calculated on the basis of availability, performance and quality, providing

a clear indication of performance on the production line. The OEE also therefore shows how well a solution works

in the company. If the overall equipment effectiveness is greater than 85 %, your production line is world-class!




An example of an OEE calculation:

(2736 pcs.)

Total Products produced (2880 pcs.)

Actual Throughput (2880 pcs.)

Specified Throughput (10 pcs. per Min. = 3600)

Actual Production Time (360 Minutes)

Planned Production Time (480 Minutes)

Underfills

Overfills

Re-workF

43% LOSS!!E

Quality

Lack of or

Poor

MaintenanceD

C

Unexpected

halts in

ProductionB

A

Good Products - 2736pcs.

Total Products Produced - 2880 pcs.

Actual Throughput - 2880 pcs.

Specified Throughput - 10pcs.per min. = 3600 pcs.

Actual Production Time - 360 minutes

Planned Production Time - 480 minutes

Underfills

Overfills

Re-workF

43% LOSS

E

Lack of or

Poor

MaintenanceD

C

Performan

ce

Unexpected

Halts in

ProductionB

A

Availability

OEE = 75% x 80% x 95% = 57%

Availability = B/A = 360/480 = 75%

Performance = D/C = 2880/3600 = 80%

Quality = F/E = 2736/2880 = 95%

If you would like more detailed information about OEE (Overall Equipment Effectiveness),

a white paper is available for you to download www.mt.com/garvens-OEEWhitePaper

A Guide to OEE

Overall Equipment Effectiveness

GARVENSCheckweighing




OptimallyA

djustedFillingP

rocesses 11 References

Further information, application examples and white papers relating to check-weighing can be found at

www.mt.com/garvens

The Organization for Machine Automation and Control (OMAC) www.omac.org

Organisation Internationale de Mtrologie Lgale (OIML) www.oiml.org

Fertigpackungsverordnung (FPVO) http://bundesrecht.juris.de/bundesrecht/fertigpackv_1981/gesamt.pdf

German Federal Institute of Physics and Technology (PTB) www.ptb.de

International Food Standard (IFS) www.food-care.info

EHEDG www.ehedg.org




Checkweighing Guide

The Garvens Principles of Checkweighing Guide

serves as a denitive reference work providing an

insight into all aspects of checkweighing from basic

principles to implementation of a comprehensive

programme.

This FREE 70 page guide has been written to assist

manufacturers in the setting up of such a checkweighing

programme and is essential reading for everyone

concerned with checkweighing.

www.mt.com/cwguide

White Papers

WhitePaper

A Guide to OEE

Overall Equipment Effectiveness

GARVENSCheckweighing Overall Equipment Effectiveness

This white paper describes OEE in

detail and shows, using the simple

calculation, how you can improve

productivity whilst also reducing costs.

www.mt.com/garvens-oee

WhitePaper

A Guide to Pharmaceutical Serialisation

Choosing the Right Equipment Supplier

GARVENSCheckweighing

TrustGarvensto

show you the way

Pharmaceutical Serialisation

This white paper addresses in detail

the questions that must be asked when

choosing a serialisation equipment

supplier.

www.mt.com/garvens-serialisation

PrinciplesofHygienic Design

Food Production in SanitaryEnvironments

WhitePaper

Contents

1 Why isSanitaryDesign Critical?

2 Who SetstheStandards?

2.1 EHEDG

2.2 FDA

2.3 A-3

2.4 NSF

3 Cleaning Processes

4 SanitaryDesign Criteria

4.1 Cleanability

4.2 Construction Materials

4.3 Accessibility

4.4 No Liquid Collection

4.5 HermeticSealing

4.6 No Niches

4.7 Operational Performance

4.8 MaintenanceEnclosures

4.9 HygienicCompatibility

4.10 Cleaning Validation andSanitising Protocols

5 SanitaryDesign Assessment

Principles of Hygienic Design

This white paper covers all aspects of

checkweighersanitarydesign.Thenal

chapter includes a tool for assessing

your sanitary design requirements.

www.mt.com/garvens-hygiene

Calculators

Calculating Checkweigher ROI

This calculator enables you to calculate

how much you can save by reducing

overllingandscrap.IncludinganROI

calculation.www.mt.com/garvens-roi

Manual vs. In-Line Weighing

This calculator enables you to

calculate how much you can save by

replacing a static scale with an in-line

checkweighing solution.

www.mt.com/garvens-dynamic

OnDemand WebinarsOnDemand webinars are available 24 hours a day to

provides viewers with fexible access.

Obtain specic information about applications and

products, learn about industry trends and standards

and receive useful and informative presentations

without added sales pressure.

www.mt.com/pi-ondemand

Below are the available checkweighing webinars:

The European Directive

2004/22/EG (MID = Measuring

Instrument Directive)

Effective Checkweighing For

Challenging Times

High Performance

Checkweighing for Maximum

OEE

Pharmaceutical Serialisation

Choosing the Right Equipment

Supplier

Using weight measurement

to improve your product and

processes


15/16


16/16

www.mt.com/garvensFor more information

Mettler-Toledo Garvens GmbH

Kampstrasse 7

31180 Giesen

Germany

Telephone +49 (0) 5121 933-0

Facsimile +49 (0) 5121 933-456

e-mail [email protected]

Subject to technical modifications

Contact:For more information about checkweighing solutions please contact your local

METTLER TOLEDO representative.

Australia Mettler-Toledo Ltd., Victoria 3207

Austria Mettler-Toledo GmbH, 1230 ViennaBelgium N.V. Mettler-Toledo S.A., 1932 Zaventem

Brazil Fabrima Mquinas Automaticas Ltda., Guarulhos, SP

BulgariaRomyTech,8,PrelomSt.,1113Soa

China Mettler-Toledo International Trading Co., Ltd., Shanghai 200233

Croatia Mettler-Toledo d.o.o., HR-10000 Zagreb

Czech Republic Mettler-Toledo spol, s.r.o., 100 00 Praha

Denmark Mettler-Toledo A / S, 2600 Glostrup

Egypt Anasia-Egypt for Trading S.A.E, 11361 Cairo

Finland Oy G. W. Berg & Co. AB, 01511 Vantaa

FranceDivisionProductInspectionS.A.,78222Viroaycedex

Germany Mettler-Toledo Product Inspection, 31180 Giesen

Greece NEFTON TECHNOLOGIES SA, 15344 Gerakas, Attica

Hungary Mettler Toledo Kft., 1139 Budapest

India Mettler Toledo India Private Limited, Mumbai 400 072Indonesia PT. Mitra Pack, Jakarta, 10730

Israel Agentek (1987) Ltd., 61580 Tel-Aviv

Italy Mettler-Toledo S.p.A., 20026 Novate Milanese

Korea Mettler-Toledo (Korea) Ltd., Seoul 137-130

Malaysia Mettler-Toledo (M) Sdn.Bhd., 40150 Shah Alam, Selangor

Malta Labo Pharm Ltd, ATD 1400

Mexico Mettler-Toledo, S. A. de C. V., 11570 Mexico D.F.

Netherlands Mettler-Toledo Product Inspection BV, 5215 MLs Hertogenbosch

New Zealand J.L. Lennard Ltd., Auckland 1644

Norway Mettler-Toledo AS, 0581 Oslo

Philippine L+H Automation, INC, Mandaluyong City 1550

Poland Mett ler-Toledo Sp.z.o.o., 02-822 Warszawa

Romania O.F. Systems s.r.l., Bucharest

Russia Mettler-Toledo Vostok, 101000 MoskowSaudi-Arabia Anasia Trading Co. Ltd, Jeddah 21533

Serbia Trim d.o.o., 35000 Jagodina

Singapore Mettler-Toledo (S) Pte. Ltd., Singapore 139959

Slovakia Mettler-Toledo spol, s.r.o., 83103 Bratislava

Slovenia Mett ler-Toledo d.o.o., 1261 Ljubljana Dobrunje

South Africa Microsep (PTY) LTD., 2018 South Africa

Spain Mettler-Toledo S.A.E., 08908 Barcelona

Sweden Mettler-Toledo AB, 12008 Stockholm

Switzerland Mettler-Toledo GmbH, 8606 Greifensee

Taiwan Mettler-Toledo Pac Rim AG, Taipei 114

Thailand Mett ler-Toledo (Thailand) Ltd., Bangkok 10320

Turkey Mert Teknik Mhendislik Ve, 34235 Esenler, Istanbul

United Arabian Emirates Himatrix ME LLC, 119396 Dubai

United Kingdom Mettler-Toledo Ltd., Leicester, LE4 1AWUnited States Mettler-Toledo Hi-Speed Inc., Ithaca, NY 14850

Vietnam Mettler-Toledo (Thailand) Ltd., Ho Chi Minh City

white paper optimally adjusting filling processes-en

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