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Kunststoffe international 6/2009

HANNES FRITZ

FRANZ STARZER

If a crisis becomes the dominating is-sue for wide sectors of the economy,it is not necessarily bad in every re-

spect. On the contrary, crises often act ascatalysts for the launch of new ways ofthinking. Of course, cost reduction meth-ods are top of the list. In terms of injec-tion molding production, that means re-viving automation options that have beenavailable for around 25 years, but not ful-ly utilized. By this means, set-up work canbe shortened to less than three minutes.The Austrian injection molding machinemanufacturer Engel has picked up on thistrend again and is extending its set-uprange for mold exchanging equipment,particularly in combination with the En-

gel duo line of medium-sized and largemachines.

The Number of Long-runningJobs is Declining

Though a production plant’s goal shouldbe to use its resources efficiently, the pic-ture is often different in reality. Produc-tion generally takes top priority and theefficiency here is being improved contin-ually, however, much of the efficiencygained is squandered again because of thepoor efficiency for set-up.With long-run-ning jobs and large orders, this does notresult in significant cost disadvantages.However, the number of long-runningjobs is declining steadily. It is only in thepackaging industry and parts of medicaltechnology that long-term productionwithout the need for set-up is still the rule.In all other industries, the trend towardsindividualization has resulted in smallerbatches with a greater diversity. As a re-

sult, unless appropriate countermeasuresare taken, set-up takes up an increasingamount of the time, and productivity fallsproportionally.

At Engel, a statistical analysis of thetechnical delivery specifications of medi-um-sized and large machines showed thatonly 5 to 10 % of the machines in theclamping force range between 5,000 and40,000 kN are ordered with equipment tospeed up mold and material exchange exfactory. Although the necessary ancillary

Tapping Hidden Reserves

Mold Exchange. The

large number of cooling

circuits, hydraulic con-

nections, sensors and

heating connections

makes conventional set-

ting up of large molds a

complex and time con-

suming undertaking, with

many sources of error. Short set-up times offer hitherto untapped potential for

improving efficiency, and the conditions for highly flexible production. New set-up

packages make it easy to automate mold exchange.

An alternative to conventional set-up is offeredby semiautomatic mold exchange with cart andclamping system, and the grouping of the fluidconnectors in a few main connections (photo: EAS Europe B.V.)

Engel Austria GmbHLudwig-Engel-Strasse 1A-4311 SchwertbergAustriaTel. +43 50 620-0Fax +43 50 620-3009www.engelglobal.com

Manufactureri

Translated from Kunststoffe 6/2009, pp. 38–41Article as PDF-File at www.kunststoffe-international.com; Document Number: PE110135

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© Carl Hanser Verlag, Munich Kunststoffe international 6/2009

modules, such as mold clamping systems,quick-action media couplings, preheat-ing stations or mold transport systemshave been available for around 25 years,a comparison performed over severalyears shows that the amount of ancillaryequipment ordered to automate produc-tion changeover remains persistently at alow level.

The search for the causes revealedsome surprising facts. One of the mainreasons is still the fact that many plantsstill do not have an integrated approachto investment in modernization. They of-ten only focus on the production capac-ities of machines. Systematic improve-ments in material flow, mold infrastruc-ture or ancillary equipment are oftenneglected. This focus is the reason whyequipment for streamlining the set-upprocess, e.g. quick-action clamping sys-tems, are left out of the machine budget.Retrofitting the equipment or acceptingthe reduced efficiency are the only alter-natives.

The profitability of investing in reduc-ing set-up time is documented by empir-ical projects gained from implementedprojects.A savings potential of 70 to 90 %

over mold exchange by traditional, com-pletely manual methods is realistic – forevery machine and every mold exchangein a production shop.

Menu-guided Mold Exchange with EnormousSavings Potential

Engel has been developing a comprehen-sive program of set-up modules for its en-tire machine range for around 25 years.In extending its Engel duo large-machinerange to the medium-size range, Engel al-so overhauled and improved its moldchanging equipment.

A new feature is the menu-guidedmold exchange. It is a software modulefor interactive user guidance during semi-automatic mold exchange. The operatoris guided through the sequence, and theprogram steps are performed automati-cally where possible; manual steps mustbe acknowledged in the control unit. Thesequence itself can be planned offline onthe PC on a virtual machine before theactual set-up process, and then trans-ferred to the production machine. Themenu-guided mold exchange eliminatesprocedure errors. Compared to the con-ventional personnel-dependent se-quence, set-up can be reduced to about60 %. In many cases, the time compari-son was performed on an appropriatelyset-up machine in combination withmatched injection molds with standard-ized interfaces for mold mounting andfluid couplings.

The “mold exchange” program mod-ule is also suitable for combination withan automatic mold changing station –either a cart with docking station or afixed station with one or more mold po-

Example of an injection molding machine adapted for rapid mold exchange: Mold clamping takesplace via hydraulically operated clamping elements. The fluid connections are grouped together oncoupling terminals (photo: EAS)

Specific programmodules are avail-able for programmingmold exchange. Itcan either be per-formed online on themachine or offline onthe PC (photo: Engel)

The preheating of theinjection molds to op-erating temperatureis a key prerequisitefor rapid productionchangeover. Ma-chine-software pro-gram modules areavailable for actuat-ing the temperature-control units and hot-runner heaters (graphic: Engel)

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sitions. In this case, the program runs au-tomatically without intermediate ac-knowledgement of individual programsteps and synchronizes with the necessaryset-up movements of the machine.A ded-icated PLC is used for internal control ofthe mold station.

Reducing Plant Complexity,Minimizing Downtimes

To minimize the machine downtime be-tween two production orders and rapid-ly exchange the molds, it is necessary forthe new mold to be heated ready for pro-duction start. That means it must be pre-heated. That applies for both the hot run-

ners and the cavities themselves. Engelsupplies a new control concept for thepreheating station, with an appearanceand control logic similar to the machinecontrol. The mold parameters can be im-ported from the machine from the oper-ating terminal via data storage media.The settings of the heating zones and er-ror connection codes are identical to themachine. The Engel preheating stationcan be expanded with machine-specificoptions, e.g. heat flux monitoring, inte-gration of temperature-control equip-ment and integration into the e-factorynetwork.

To improve ease of operation and atthe same time reduce the complexity of

a production cell with integrated moldexchange equipment, Engel will soon beintegrating the movement control forthe mold exchange station completelyinto the machine control. The advantageof integration is to integrate all the ex-ternal plant modules – from mold ex-change cart through preheating stationfor the hot-runner heaters, to the cou-pling station for the fluid temperaturecontrol, including the temperature-con-trol equipment – in a control unit of themachine control, and to manage it all inone program file. The same applies to ac-tuating stand-alone mold exchange sys-tems for several machines, except thatthe plant control is performed by a sin-gle control unit.

Another innovation is the introductionof an intelligent transponder in the ma-chine’s clamping unit for mold identifi-cation. This unit allows information suchas the mold identification number, keydata, operating hours and service inter-vals to be exchanged between the machineand mold, and stored in the mold.

High Value-creation Potential

Reduction of the set-up time increases theuseful potential of a system. Short set-uptimes make even small production batch-es increasingly economic and make it eas-ier for the processor to adapt to changingmarket circumstances requiring maxi-mum flexibility. The challenge now is touse the crisis as an opportunity and ori-ent production to it. ■

THE AUTHORS

ING. HANNES FRITZ, born in 1967, is head of con-trol technology software at Engel Austria GmbH’s St.Valentin large machine factory; hannes.fritz@engel.at

ING. FRANZ STARZER, born in 1952, is technicalmanager the St. Valentin large machine factory atEngel; franz.starzer@engel.at

The operating dialog ofthe preheating-stationcontrol terminal has thesame operating logic asthe machine control (photo: Engel)

Example of a production line for alternating production of components of a subgroup in small,matched batch sizes. This presupposes frequent mold exchanges (photo: Engel)

Collections of articles about specific topics (construction, automotive, electri-cal/electronics, packaging, medical, temperature control) can be found atwww.kunststoffe-international.com/dossiers

Kunststoffe-international.com

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