Safety for overhead cranes

Injec­tion moulding machines are cen­tral com­po­nents on some pro­duc­tion lines at Marelli Mako and each new product run involves retooling mea­sures to some extent. Bridge cranes then trans­port the moulds that workers have dis­man­tled and bring in the tools and equip­ment required for a new series.  Over­head cranes move loads, such as tools, at high speed and deliver them pre­cisely, safely and just in time to the spec­i­fied des­ti­na­tion. Set-up changes are to happen quickly. Down­time is not an option, as it costs money. At no time must there be any danger to the oper­ating per­sonnel beneath the trans­ported loads. That’s why spe­cial safety pre­cau­tions apply to over­head or bridge cranes.

Risk analysis for a sustainable crane safety concept

When retro­fits became due back in 2024, Marelli Mako included safety aspects on its to-do list, in addi­tion to opti­mising pro­duc­tivity and reli­a­bility. Twenty over­head cranes, each with a load capacity of 16 tonnes or more, are in oper­a­tion at Marelli Mako 24/7. The task: to make all the cranes fit for as many more years as pos­sible, using modern automa­tion and safety con­cepts. The chal­lenge: oper­a­tional processes should not be restricted for any longer than nec­es­sary.

To ensure that the plant’s over­head cranes also comply with cur­rent inter­na­tional stan­dards – in par­tic­ular EN 13135–1 (Cranes – Safety – Design – Require­ments for equip­ment) and EN ISO 13849–1 (Safety of machinery – Safety-related parts of con­trol sys­tems) – the first step was to carry out a risk analysis. The result: crane oper­a­tion was safe, but in some respects not state-of-the-art. For example, a number of safety func­tions that limit and stop the crane move­ments were not mon­i­tored by a safety con­troller. Also, the safety tech­nology installed on the cranes no longer met the cur­rent require­ments in every respect. The auto­mo­tive sup­plier could not imple­ment all of this by them­selves. To make mat­ters worse, a safety update would not actu­ally have been fea­sible without low­ering the entire crane tower.

The deci­sion-makers sought advice from Pilz, a partner of Marelli Mako since 2022, and held in high regard on all mat­ters relating to Safety & Secu­rity. The respon­sible project part­ners at the automa­tive sup­plier were con­vinced by Pilz’s approach: that the upcoming mod­erni­sa­tion mea­sures could be imple­mented without low­ering the crane – and with careful plan­ning, even in par­allel with ongoing oper­a­tions. In addi­tion to con­cep­tual advice on the sys­tems in ques­tion, the Pilz ser­vice package included the replace­ment and renewal of the safety tech­nology, including engi­neering ser­vices. At the heart of the solu­tion is the automa­tion system PSS 4000.

Customised automation solution

At the heart of the automa­tion and safety solu­tion favoured by Marelli Mako is the industry-proven automa­tion system PSS 4000 from Pilz. The con­troller in the system can be cus­tomised using var­ious I/O mod­ules, pro­viding users with a solu­tion that is tai­lored pre­cisely to their spe­cific require­ment. As such, PSS 4000 is a future-proof system – including simple pro­gram­ming based on the Pilz soft­ware plat­form PAS4000 and web-based, intu­itive diag­nos­tics and visu­al­i­sa­tion based on the visu­al­i­sa­tion soft­ware PASvisu. Building on this con­cept, safety tech­nology such as limit switches, emer­gency stop push­but­tons, drives and the con­trol cab­inet were replaced.

At the same time, Pilz experts inte­grated series drives in the over­head crane. In future, these will con­trol the move­ments of the crane car­riage, trolley drive and hoist and guar­antee safe shut­down processes. In order to mon­itor loads in real-time and diag­nose faults quickly and easily, the Pilz oper­ator ter­minal Pilz Human Machine Inter­face (PMI) was inte­grated in addi­tion to the visu­al­i­sa­tion soft­ware.

As expected, the project posed sig­nif­i­cant chal­lenges in var­ious areas. As the crane system serves a total of nine injec­tion moulding machines and the plant was not to be shut down for longer than absolutely nec­es­sary, plan­ning had to be care­fully coor­di­nated within a tight time frame. Pilz did actu­ally manage to avoid the time-con­suming and costly process of low­ering the crane tower: Pilz suc­cess­fully car­ried out the entire assembly process at great height and with only lim­ited space avail­able between the crane and ceiling.

Real-time monitoring for greater safety

The new automa­tion solu­tion, including the installed Pilz safety tech­nology, now allows crane oper­a­tion to be mon­i­tored in real-time. Fea­tures that did not exist before include an over­load con­trol system, safe speed mon­i­toring of the hook drive, safe shut­down archi­tec­ture, safety con­nec­tion archi­tec­ture in accor­dance with EN ISO 13849–1 and a diag­nostic dis­play for easy trou­bleshooting and main­te­nance. The emer­gency stop system has also been opti­mised: the EN ISO 13850-com­pliant PITestop emer­gency stop push­but­tons have been inte­grated into the crane system, allowing oper­a­tors to put the system into a safe state imme­di­ately in the event of danger. This func­tion increases human safety in the vicinity of the plant as well as the reli­a­bility of the overall system. “In the course of the project, our employees have become more aware of machinery safety and the impor­tance of safety func­tions. In addi­tion, the inte­gra­tion of modern tech­nolo­gies in our sys­tems guar­an­tees a high level of safety for everyone involved,” says Muhammet Ali İÇİN, OHS spe­cialist (Occu­pa­tional Health and Safety) at Marelli Mako, sum­marising.

Lower risk of accidents and fewer downtimes

The advan­tages for Marelli Mako and the oper­ating per­sonnel are obvious: the mod­ernised cranes guar­antee safe oper­a­tion and reduce the risk of acci­dents. For Marelli Mako, there is no sub­sti­tute for working with Pilz: Pilz is a con­sul­tant, ser­vice provider and tech­nology sup­plier – with com­pre­hen­sive exper­tise in machinery safety, stan­dards, reg­u­la­tions and global net­working. And for Muhammet Ali İÇİN, the automa­tion system PSS 4000 from Pilz is the ideal solu­tion for all safety issues. “Pilz has met our expec­ta­tions in every respect. Our col­leagues at Pilz are com­pe­tent and com­mitted. The col­lab­o­ra­tion was pro­fes­sional and on an equal basis at all times. Throughout the entire project phase, Pilz con­firmed our trust in them with a sup­portive and solu­tion-ori­en­tated approach. We worked very well together to imple­ment inno­v­a­tive solu­tions and over­come crit­ical issues, and will con­tinue to do so in future,” says Muhammet Ali İÇİN, con­vinced.