Meat sector benefits from significant developments in multihead … · 2016-12-20 · weighed portion, transfer it to a tray, style it and then place the tray onto a belt which takes

International Meat Topics • Volume 7 Number 116

The impact and influence thatmultihead weighing systemshave had on all areas of the

food industry has been well docu-mented over the years. Thanks to the superb accuracy of

the technology, giveaway, whichusing other systems could be asmuch as 15%, has typically beenreduced to well under 1%. Accurate filling has also enabled

packs to be designed smaller, reduc-ing the cost of packaging, storageand transport, whilst meetingdemands for smaller packs due todecreasing average household sizesin western Europe.

by Torsten Giese, MarketingManager, Ishida Europe.

ishidaeurope.com

For food manufacturers, the bene-fits have been enormous, particu-larly in terms of the increasedproductivity that accurate weighingbrings. Product that was previouslywasted in overfill is now beingpacked into extra bags or trays.Output has therefore beenincreased without additional input.The multihead weighing con-

cept – where individual weigh hop-pers weigh product simultaneouslyand a computer calculates all possi-ble weight combinations and selectsthe one that comes closest to thetarget weight – was revolutionarywhen it was first introduced. Nevertheless there have been

many further equally notable

enhancements and innovationssince then which have enabled themultihead weighers to deliver evenfaster speeds and greater weighingaccuracy. For example, the introduction of

stepper motors made a significantcontribution to increased speeds.Accuracy levels were enhancedthrough the use of booster hoppers.These are an additional set of hop-pers, located beneath the weighhoppers. Product weighed but not selected

for the pack is discharged into thebooster hoppers, thus freeing upthe weigh hoppers to receive moreproduct and further increasing theavailable weight combinations toboost weighing speed and effi-ciency.More recently Digital Signal

Processing (DSP) and Anti-FloorVibration (AFV) features have setnew standards for speed and accu-racy. Both technologies recognise that

in most instances the weighing ofproduct does not take place underideal conditions. For example, vibration such as fork

lift trucks, vibrator feeders, bagmak-ers and even the footsteps of fac-tory workers can lead to inaccurateweight readings and thus reducespeed and accuracy.AFV senses the level of floor

vibration and compensates for it.This is then combined with DSP, sothat weigh heads that remainunused for one weighing cycle havetheir signals significantly filtered,while those that have just been

used benefit from the application ofAFV. The result in both cases ismore accurate weighing. AFV and DSP technologies have

continued to be enhanced and havebeen joined by Pulse WidthModulation (PWM) technology, anelectronic drive system which helpsto maintain a consistent productflow to the pool hoppers. Multihead weighers have also

helped companies meet demand todeliver sustainability in all areas oftheir business. Accurate weighing leads to

smaller packaging which in turnminimises material consumptionand reduces transport costs, whilemodern weighers are highly energyefficient.

Application features

Another important development formultihead weighing – and onewhich has had particular signifi-cance for the meat industry – hasbeen the introduction of applica-tion-specific features that can dealwith products with special handlingcharacteristics. This has enabledprocessors to respond to thegrowth in popularity of value addedpre-packed fresh meat and poultry.One of the challenges of handling

fresh meat in any type of auto-

mated system is its sticky naturewhich makes it difficult for theproduct to flow freely. This has been met through a vari-

ety of innovative solutions, withfeatures including anti-stick contactsurfaces, specially adapted disper-sion feeder tables, using rotatingscrews instead of radial feeders,plastic hoppers with scraper gatesand belt feeders that keep productmoving easily. These have now beencombined with designs specificallycreated for meat and poultry appli-cations.One example retains the combina-

tion weighing principle, but incor-porates it in a linear layout wherean operator feeds product to a setof belt feeders, who in turn deliverthe product to plastic or metalscraper (pool) hoppers. The belt feeders act not only as a

feed buffer but they also cope eas-ily with the most sticky productssuch as marinated meat or poultry,ensuring a consistent product deliv-ery to the pool and weigh hoppers,which then operate in the same wayas the circular multihead models. The Ishida Fresh Food Weigher

(FFW) can now handle the output ofup to five operators and togetherwith its higher accuracy and consis-tency – with product giveaway typ-ically less than 1% of the targetweight – payback periods for this

Meat sector benefits fromsignificant developmentsin multihead weighing

A linear layout and the use of rotating corkscrews to move product aretwo examples of how multihead weighing technology is able to handlefresh meat.

Accurate weighing brings improved productivity.

machine have been shown to be aslow as just six months.Another bespoke design for meat

products retains the more familiarcircular multihead weigher layoutbut incorporates unique rotatingstainless steel screws to replace thetraditionally used radial feedtroughs. The use of these screwsprovides a powerful, controlled andfully automatic product feed to thehoppers.This technology is able to double

packing speeds for the stickiestproducts, while again using thecombination weighing principle tosignificantly reduce giveaway. Of course, when it comes to con-

venience products, fast and accu-rate weighing is only half the battle.Attractive presentation is also

essential for retail markets. Theautomatic weighing of the productcan therefore be combined with amanual batching operation toensure that the meat or poultry ineach tray is appropriately placedand styled in each tray.For example, the screw feeder

weigher can be combined with a lin-ear or rotary batching table contain-ing individual stations, whereoperators receive an accuratelyweighed portion, transfer it to atray, style it and then place the trayonto a belt which takes it for seal-ing, labelling and quality control. The station automatically informs

the system once the filled andstyled tray has left, triggering thesending of another weighed portionto be packed.A typical system featuring eight

operators, can deliver speeds of 55trays per minute with an averagegiveaway of only 1% of the targetweight.

Grading by weight

Multihead weighing technology isalso used to grade meat and poultrycutups by piece weight, count orminimum weight. The central idea

of using a multihead weigher forgrading is to use many weigh headsto individually classify incomingpieces of cutups and, depending onexact piece weights, to releasethem into either the graded productstream or into one or more ‘out ofspec’ streams which can then be putto other, non-premium uses.How it works is that a rotating

infeed chute distributes successive(poultry) cutups (such as wings orthighs) into a set of pool hoppers.These pool hoppers feed a set of

weigh hoppers, which can releasetheir contents in either of two dif-ferent directions depending onwhether their piece weight isappropriate to go into the gradedproduct stream or into the bulkstream for further processing. The multihead grader grades with

great accuracy (with an error of just±0.1g) and can easily handle the 240pieces per minute needed to keeppace with the cut-up machinery. Intests under typical industry condi-tions and without intensive trainingit has consistently demonstratedefficiency levels of 90-98%. Given the immense versatility of

multihead weighers and their abilityto deliver effective qualitycontrol in terms of bothpack weight and productconsistency, the check-weigher might at first glance

be considered as some-what redundant.However, just as multi-

head weighing technology hasevolved, so too have the capa-bilities of checkweighers.Today, instead of merely act-

ing as the ‘policeman’ at the endof the line to ensure packweights are correct, check-

weighers are able to monitor,assess and provide detailed infor-mation on weight data by batch,shift, product or machine to pro-duce fully customised reports –both real time and historical –which depict such crucial parame-

ters as downtime, OEE (OverallEquipment Efficiency) of the pro-duction line, and product giveaway. These reports are fully customised

to meet an individual manufac-turer’s needs and can be instrumen-tal in identifying cost savingopportunities, minimising productgiveaway and improving productionefficiencies.In addition, specialist software is

now available that enables suchinformation to be gathered from upto 100 individual checkweighers andcompiled into a single secure data-base, so that the overall perfor-mance of the factory can beassessed. The information can also be

accessed remotely, allowing pro-duction managers to monitor theiroperations from anywhere in theworld from a laptop or mobilephone.

Central control

All these developments in weighingtechnology are significant in theirown right but they have also beentaking place against a background ofincreased integration with the abil-ity of all equipment on the produc-tion and packing line to interface

with each other to provide a com-plete single system.As a result, we are seeing the

increasing use of project manage-ment in the development of pack-ing lines. Instead of sourcing individual

pieces of equipment from differentcompanies, meat and poultryprocessors are using one supplier todevise and install the entire line,linking together all the differentmachines into one centrally con-trolled operation in order to ensurethat throughput is maximised andall parts of the line are working tothe greatest efficiency. Having one supplier take full

responsibility in this way means cus-tomers also benefit from a singlepoint of contact.At the same time, many suppliers

are also extending their productranges to include all the major ele-ments of the packing line fromweighers and tray sealers to inspec-tion systems and end of line pack-ing.

Conclusion

Multihead weighing technologycaused a revolution on its firstintroduction to the food sector andit has continued to make an impactsince then. For the meat sector it has deliv-

ered levels of automation that onlya few years ago were not thoughtpossible and it has allowed theindustry to take full advantage ofconsumer demand for conveniencepacks. Given what has already been

achieved, it is safe to say that theremay yet be more significant devel-opments to come in the future. n

International Meat Topics • Volume 7 Number 1 17

Weighers can be combined with a batching operation for effectivestyling and presentation in trays and accuracy.

The latest weighers incorporate featuressuch as AFV and DSP, which have set newstandards for speed and accuracy.

Checkweighers are able to monitor, assess and provide detailed informationfor enhanced OEE.