Textbook retrofit

Presses have a spe­cial status when it comes to safety require­ments. Grass GmbH, global man­u­fac­turer of move­ment sys­tems for fur­ni­ture and house­hold appli­ances, was aware of this while looking for a partner that would be able to update “slightly” older plants to the cur­rent state of the art in com­pli­ance with stan­dards. In Pilz Aus­tria, the Salzburg-based com­pany found a partner who could “com­plete the job in text­book fashion.”

“Func­tional move­ment” for fur­ni­ture means more at the Grass Group than just “open and close”. Every appli­ca­tion requires the per­fect move­ment solu­tion. Fol­lowing this approach, the Aus­trian global player has proven its inno­v­a­tive strength over the last 75 years, including with the first trolley guide or the world’s first double-walled drawer system. “With around 1 900 employees at 21 loca­tions and more than 200 dis­tri­b­u­tion part­ners in 60 coun­tries, we are the largest provider for move­ment sys­tems,” states Andreas Huber.

He is the Main­te­nance Man­ager in Grass’s Salzburg fac­tory. “With our machinery, we mainly bring plas­tics into the desired form, but thanks to two press lines we also do the same with stain­less steel prod­ucts for house­hold appli­ances,” he explains. The latter is per­formed at “sea­soned” older-model plants that were com­pletely mod­ernised and brought to the state of the art with regard to safety and con­trol under the lead of Pilz Aus­tria.

The upstream feed of the end­less belt via a reel as well as the con­nected pro­filing machine had to be taken into account during the press retrofit. © Grass GmbH / Pilz GmbH & Co. KG, Ost­fildern

Partner for standard-compliant solutions

The first round of retro­fits with Pilz took place back in 2017. The reason was the relo­ca­tion of an eccen­tric press from Höchst, the head office in the Vorarl­berg state, to Salzburg. “It had to be linked to an existing pro­filing plant and an upstream reel. This inspired us to look for a provider to not only replace the con­trol tech­nology of the auto­matic punching press, but to also per­form a close inspec­tion of the entire pro­duc­tion line, assess this with regard to com­pli­ance with stan­dards, per­form the nec­es­sary adap­ta­tions and last but not least check the func­tion of the higher-level safety con­cept,” clar­i­fies the Main­te­nance Man­ager, regarding a task that other automa­tion providers with whom he placed inquiries would not even con­sider.

“Through these two press projects our col­lab­o­ra­tion inten­si­fied immensely. We now com­mu­ni­cate with each other reg­u­larly. Should a sim­ilar con­ver­sion become nec­es­sary, we know exactly who to turn to based on our pre­vious expe­ri­ences.”

Andreas Huber, Main­te­nance Man­ager, Salzburg plant, at Grass

One reason for this is the fact that presses are listed in Annex IV of the Machinery Direc­tive in the cat­e­gory of machines that require a sep­a­rate con­for­mity assess­ment pro­ce­dure due to their dan­gerous char­ac­ter­is­tics. “As we brought our first press safety con­troller onto the market in 1995, Pilz is able to rely on more than 25 years of expe­ri­ence in this sector. We are in close con­tact with our col­leagues from the expert team at the head­quar­ters in Ost­fildern com­mitted solely to con­ver­sions and new instal­la­tions of press con­trollers, par­tic­u­larly for projects such as at Grass,” explains Ronald Kahr, Sales Engi­neer at Pilz Aus­tria. During a second retrofit in 2021, there was no ques­tion that the gen­eral over­haul of a press for the Salzburg plant should once again be car­ried out with Pilz experts.

Safety-related complete solution for high-end production

“The task con­sisted of exchanging the old con­troller in order to increase the process sta­bility during forming of low to high-alloy steels,” sum­marises Thomas Stell­berger, Man­ager of the Grass fac­tory in Salzburg. As part of this, the existing con­tactor con­trol as well as the safety cir­cuit of the entire press line were updated. They were replaced by the con­fig­urable Pilz small con­troller PNOZ­multi 2 with spe­cial mod­ules and cer­ti­fied soft­ware blocks for a safe acti­va­tion of presses. For the stan­dard automa­tion, the higher-level automa­tion system PSS 4000 from Pilz was inte­grated.

If retro­fits are nec­es­sary for safety rea­sons, safety light cur­tains PSENopt II from Pilz ensure stan­dard-com­pliant finger, hand and body pro­tec­tion. © Grass GmbH / Pilz GmbH & Co. KG, Ost­fildern

Robust and easy to assemble and operate: The PIT­gatebox push-button unit from Pilz, which can be used to flex­ibly con­trol safety gate sys­tems and acti­vate, stop and acknowl­edge sys­tems at the touch of a button.

When it comes to the pro­tec­tive fences, there is a mix of old and new after the retrofit. Wher­ever safety retro­fits had to be made, PSENopt II safety light cur­tains from Pilz now pro­vide stan­dard-com­pliant finger, hand and body pro­tec­tion.

Main­te­nance Man­ager Andreas Huber goes into detail: “This upgrade project involves a double-sided eccen­tric press for pro­gres­sive dies, year of con­struc­tion 1987, in which tele­scopic slides for ovens receive the cor­re­sponding punch-outs, imprints and inscrip­tions. Aspects to be con­sid­ered with regard to safety and con­trol included the upstream feed of the end­less belt via a reel as well as the con­nected pro­filing machine.” Addi­tion­ally, the problem of a feed that was already defec­tive was also to be solved with the retrofit.

Upgrade to and around the press

Pilz took over all the tasks as part of the safety ser­vice, from the risk assess­ment to the cre­ation of the safety con­cept and on to the val­i­da­tion and CE marking. The retrofit of the entire press line – com­prising the three machine parts reel with straight­ener, pro­filing machine and auto­matic punching press – included instal­la­tion of a com­pletely new switch cab­inet and con­trol con­sole as well as the wiring of all new safety-related com­po­nents. The safety tech­nology upgrade of the pro­filing machine addi­tion­ally included the inte­gra­tion of the safe small con­troller PNOZ­multi 2, together with new rope pull switches and the coded safety switch PSEN­code for posi­tion mon­i­toring.

“Pilz can draw on more than 25 years of expe­ri­ence in the field of press safety con­trol.”

Ronald Kahr, Sales Engi­neer at Pilz Aus­tria

Pilz also kept an eye on the plant sec­tion reel with straight­ener: Today this is pro­tected by the safety locking device PSEN­m­lock for safe inter­locking and guard locking, which can be easily man­aged via the con­trol unit PIT­gatebox. And wher­ever bar­rier-free safety had to be retro­fitted via light cur­tains, the safety light cur­tains PSENopt II for finger, hand and body pro­tec­tion from Pilz sup­ple­ment the light cur­tains already installed. Fol­lowing the con­ver­sion, Grass received a press line that was ready for pro­duc­tion.

The Main­te­nance Man­ager at the Salzburg Grass fac­tory sums it up with high praise: “Pilz prod­ucts were already in use before, but through these two press projects our col­lab­o­ra­tion inten­si­fied immensely. Keeping to the dead­line, man­u­fac­turer-neu­tral advice, the actual imple­men­ta­tion and the final con­for­mity assess­ment pro­ce­dure – every­thing really worked per­fectly.”

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