WaCo Gerätetechnik GmbH, Dresden, a manufacturer ofcustom sheet metal parts, assemblies and equipment,has reduced its handling operations and increased its pro-ductivity by investing in an automatic STOPA COMPACTsheet metal storage system. Thanks to automation, utili-sation of the processing machines linked to the systemhas risen by up to 30 percent. Delays that were previouslycaused by additional time-intensive manual work have be-en eliminated. Another benefit is provided by the veryshort access times to the sheet metal storage system.

The system is roughly 67.5 metres long and consists of 40blocks arranged in double rows. It has space for 804 sto-rage locations, not counting the stations, and can be ex-tended as needed. The system’s flat pallets are designedfor medium-sized (1,250 x 2,500 mm) and small (1,000 x2,000 mm) sheets and for material weighing up to 3,000kg. The storage system is very flexible. It can work withloading heights of 130, 355, 580 and 805 mm, as well as1,030 mm when wire mesh boxes are placed on pallets.Sheet stops prevent shifting and make it easier to load thepallets. STOPA also achieves a high degree of space utili-sation through close spacing of the shelf dividers. Theoperator benefits from detailed real-time overviews ofstock levels, especially since the control system weighseach pallet that comes in. The same applies to materialthat is returned to storage.

Much better machine utilisation

WaCo opted for STOPA Anlagenbau GmbH because of itsexperience working with TRUMPF, which manufacturersthe processing machines linked to the system. In view ofthe complex connections between the controllers for themachines and the storage facility, a mastery of the interfa-ces is essential.

WaCo’s decision for the STOPA COMPACT system cameat the time when it wasbuilding a new plant. Thesystem solved the compa-ny’s space problem, whichhad arisen because thepallet racks in the old buil-ding were unable to holdall of the raw material. Infact, many sheets werebeing stored in the hallway.Moreover, transporting thesheets to the machinesand loading and unloadingthem had become too la-borious.XXXXXXXXX

Handling capacity of800 metric tons

The storage system, whichhandles 800 metric tons ofsheets per year, suppliesfour processing machines:a punching machine, a la-ser-cutting system withautomatic loading, and

two combined laser-cutting and stamping machines withautomatic loading and unloading. In addition, there arethree outgoing goods stations through which the compa-ny sends sheets for deburring and dressing. Semi-finishedparts are sent to laser-cutting facilities in a separate buil-ding.

WaCo stores 140 kinds of sheet metal, differing in quality,thickness and material. They include sheet steel, hot-tipgalvanised and electroplated steel, nickel-chromium steel,copper sheets and brass sheets. The thicknesses rangefrom 0.3 to 8 millimetres; one to two millimetres are mostcommon. Plastic sheets are also stored.

The process at WaCo begins at the unpacking table,

STOPA COMPACT sheet metal storagesystem reduces handling and raises

productivity

The storage and retrieval unit achieves speeds of up to 150 metres per minutewhen travelling, 23 when lifting and 20 when pulling or pushing

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where stacks of sheets are removedfrom the pallets. The table has mova-ble plungers that can be adjusted tothe dimensions of the wooden pallets.A forklift truck fetches the stacks andtakes them to the incoming/outgoinggoods station. Here scissor lift tablesand transport carts supply and remo-ve sheets during machining time andwithout personnel. This boosts pro-ductivity. Pneumatic centring of theflat pallets on the carts and scissor lifttables is also automatic. Photoelectricsensors make sure that the specifiedloading heights are not exceeded.STOPA has also provided spreadermagnet units on the scissor lift tablesat the three stations that supply thedual-function machines and the lasercutting system. The magnets ensurereliable separation of the sheets. Inaddition, the last sheet is detectedautomatically at each loading station and the unloadingcarts of the dual-function machines have rotary encoderswhich ensure that the punched and laser-cut parts are ex-actly positioned.

A storage and retrieval unit handles the load carriers

A robust two-mast storage and retrieval unit handles theload carriers. It travels between theshelf towers with its push/pull deviceand wear-resistant, easy-maintenancechain lifting gear. A digital travel mea-suring system ensures exact longitu-dinal positioning. An additionalload-independent digital measuringsystem permits precise positioning wi-thout having to move to a referencepoint.

Data are transmitted to the storageand retrieval unit via a photoelectrictransceiver without any physical con-tact. Power is supplied via an over-head bus bar, ensuring quiet,low-wear operation. To prevent collisi-ons during storage operations, the storage and retrievalunit automatically monitors the loading height at the stora-ge locations above and below the selected location. Thecontrol unit, which monitors the functions of the storageand retrieval unit to ensure reliable operation, also checksthe contours of each stack for sheets that protrude overthe side. The storage and retrieval unit achieves speeds ofup to 150 metres per minute when travelling, 23 when lif-ting and 20 when pulling or pushing. The weighing unit of

the lifting beam determines the weights of the pallets andtheir loads when they are stored and retrieved, which ma-kes it useful for efficient incoming goods inspection. Easy-to-understand function keys ensure simple operation ofthe system. A 12-inch TFT screen in the ergonomicallydesigned control panel continuously shows the status ofthe storage and retrieval unit in a plain text format. Thesoftware also graphically displays the storage towers and

the SRU.

Current stocks in real time

A real-time soft PLC, integrated in anindustrial PC, controls the com-ponents of the storage system. Itcommunicates with the TRUMPF TC-Cell warehouse management com-puter via an interface supplied bySTOPA. The software assigns storagelocations dynamically, keeps track ofthe stocks and manages sheet metaldata, thus providing a clear picture ofthe stocks at all times.

There are four available operatingmodes for the storage system. In online mode a higher-level host controls the system. If automatic mode is selec-ted, the system processes individual orders by itself oncethe operator has entered the start and finish coordinates.The system will continue to run even if a fault occurs in thehost. Other options are an interlock-free service mode inwhich employees enter commands directly at the storageand retrieval unit, and a manual mode with active safetyinterlocks.

Autor: Jürgen WarmboldPressekontakt:STOPA Anlagenbau GmbHIndustriestraße 12D-77855 Achern-GamshurstTel. +49 7841 704-0E-Mail: presse@stopa.com

The system is roughly 67.5 metres long and consists of 40 blocksarranged in double rows. It has space for 804 storage locations, not

counting the stations

As

of:

2011

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Dipl.-Ing. Dieter Bohnig, production

engineer at WaCo