Safety as a strategic process – METAV Safety Day provides insights into machine tool safety concepts

Farank­furt am Main, the 27th Jan­u­ary 2020 — The Euro­pean Machin­ery Direc­tive is prob­a­bly the most impor­tant set of machine safe­ty reg­u­la­tions; it is cur­rent­ly being reviewed. The EU Com­mis­sion is plan­ning a new ver­sion. How­ev­er, the mes­sages emerg­ing from the Com­mis­sion are caus­ing unease among com­pa­nies and asso­ci­a­tions alike. The under­ly­ing objec­tives of the review, such as adapt­ing to tech­ni­cal progress, may find broad agree­ment, yet the dev­il, as so often, lies in the detail. This applies in par­tic­u­lar to machine tools. How the safe­ty design of machines can be fur­ther improved in the face of chang­ing mar­ket con­di­tions is the main focus of the Safe­ty Day, which the VDW (Ger­man Machine Tool Builders’ Asso­ci­a­tion) is stag­ing on 10 March at the Düs­sel­dorf Exhi­bi­tion Cen­tre as part of the METAV trade fair (9 to 11 March 2020).

safety engineering on cutting machine tools Photo: Fotolia
safe­ty engi­neer­ing on cut­ting machine tools Pho­to: Fotolia

The cur­rent­ly valid Machin­ery Direc­tive from 2006 is com­mon­ly reck­oned to have had a pos­i­tive effect on the indus­try. It has made a sig­nif­i­cant con­tri­bu­tion to har­mon­is­ing secu­ri­ty stan­dards and thus to gen­er­at­ing added val­ue with­in the Euro­pean Union. For Eber­hard Beck, Head of Con­trol Tech­nol­o­gy at the machine tool man­u­fac­tur­er Index-Werke and mem­ber of VDW Work­ing Group 3, “Safe­ty Tech­nol­o­gy”, it is clear that it is only pos­si­ble to devel­op effec­tive and pro­duc­tive machines if man­u­fac­tur­ers are aware of and can doc­u­ment all tech­ni­cal prop­er­ties and func­tions through mea­sure­ments and analy­ses. This also includes machine safe­ty. Dis­tinc­tive sell­ing fea­tures can then be devel­oped for the mar­ket and suc­cess­ful­ly com­mu­ni­cat­ed. Beck’s posi­tion is clear: “I take a pos­i­tive over­all view of high safe­ty lev­els and do not regard them as a dis­ad­van­tage for the Ger­man machine tool industry.”

Con­tin­u­ous increas­es in safety

The VDW is the lob­by­ing body for the Ger­man machine tool indus­try. It has devel­oped a strat­e­gy for pro­mot­ing under­stand­ing of stan­dard­i­s­a­tion process­es regard­ing the prac­ti­cal aspects spe­cif­ic to machine tools. This is not always an easy task, as experts are now dis­cov­er­ing with regard to the revised ver­sion of the Machin­ery Direc­tive. A fur­ther aim is to address key machine tool safe­ty issues togeth­er with experts from mem­ber com­pa­nies, sup­pli­ers and cus­tomers and thus con­tin­u­ous­ly raise indus­try stan­dards – includ­ing through stan­dard­i­s­a­tion. “Safe­ty is not a char­ac­ter­is­tic, but a process,” points out Dr. Alexan­der Broos, head of the Research and Tech­nol­o­gy Depart­ment at the VDW.

Con­stant counter-check­ing, rethink­ing and think­ing ahead,” are need­ed in order to achieve high (per­son­al) safe­ty lev­els in the han­dling of machines, con­firms Eber­hard Beck. Any machine-relat­ed acci­dent or near-acci­dent that is report­ed must be scru­ti­nised and assessed in a safe­ty-con­scious man­ner in order to make any nec­es­sary improve­ments. Only then is it pos­si­ble to steadi­ly increase machine safe­ty and ensure “that the simul­ta­ne­ous occur­rence of mul­ti­ple unfore­seen haz­ardous sit­u­a­tions can be con­trolled from a per­son­al safe­ty view­point.” This prompt­ed Eber­hard Beck to com­mit him­self to the field of safe­ty tech­nol­o­gy with­in the VDW. Con­tribut­ing to the work­ing group enables the par­tic­i­pants to pool their expe­ri­ence and for the group to serve as a cat­a­lyst, he claims.

Sci­en­tif­ic sup­port indispensable

Coop­er­a­tion with uni­ver­si­ties and research insti­tutes is also pro­mot­ed, since it is no longer sim­ply a mat­ter of mak­ing improve­ments, but also one of gaug­ing the prob­a­bil­i­ty of a crit­i­cal event occur­ring (prob­a­bilis­tic approach) and eval­u­at­ing the resid­ual risk. Pre­vi­ous stud­ies have inves­ti­gat­ed e.g. how the use of cir­cuit-break­ing pro­tec­tive devices can sig­nif­i­cant­ly reduce safe­ty risks, or iden­ti­fied which options are avail­able for min­imis­ing the risk of a grav­i­ty-loaded axle falling, for example.

The VDW ini­ti­ates and sup­ports man­u­fac­tur­er-based inves­ti­ga­tions, while the trade asso­ci­a­tions organ­ise their own research projects for cus­tomers and users. Ide­al­ly, the experts will then arrive at unan­i­mous con­clu­sions, for which they will seek inter­na­tion­al recog­ni­tion togeth­er. For exam­ple, Chris­t­ian Adler, head of the Test­ing and Cer­ti­fi­ca­tion Body for Sur­face Tech­nol­o­gy and Lift­ing Tack­le with­in the Hanover-based BGHM trade asso­ci­a­tion, trav­elled to Tokyo with VDW safe­ty expert Hein­rich Möd­den at the end of Jan­u­ary to pro­mote a pro­pos­al for the dimen­sion­ing of pro­tec­tive devices on grind­ing machines. “The basis of the prob­lem was that the pre­vi­ous inter­pre­ta­tion was total­ly overblown and scarce­ly imple­mentable,” says Adler. This led to the stan­dard sim­ply being ignored in prac­tice. The BGHM’s own study proved that the enclo­sure does not have to be par­tic­u­lar­ly stur­dy, as it can even warp with­out los­ing its pro­tec­tive effect. Chris­t­ian Adler will present the result­ing pro­pos­al at the METAV Safe­ty Day. He takes the fol­low­ing view: “It makes no sense to demand per­fect pro­tec­tive fea­tures if prac­ti­cal or eco­nom­ic fac­tors then pre­vent the machines from being built.”

Cost-effec­tive­ness as the basic premise

Of course, eco­nom­ic con­sid­er­a­tions have top pri­or­i­ty when it comes to design­ing a machine. “First and fore­most, a machine has to do what it was pur­chased for,” is how Dr. Alexan­der Broos describes the customer’s view­point, “and it has to be cost-effec­tive.” The bal­anc­ing act between mar­ket and safe­ty require­ments changes “on a dai­ly basis,” the VDW expert explains. Calls for high­er safe­ty stan­dards in Euro­pean prod­ucts are often heard fol­low­ing an acci­dent caused by an import­ed, non-stan­dard machine. The fact that the reform of the Machin­ery Direc­tive is to include cyber­se­cu­ri­ty and arti­fi­cial intel­li­gence has inject­ed new urgency into the whole debate. The aim of reflect­ing tech­ni­cal progress might be under­stand­able, yet Broos believes that aspects such as process opti­mi­sa­tion through dig­i­tal­i­sa­tion and machine safe­ty should be kept fun­da­men­tal­ly sep­a­rate. “After all, a machine does not become less safe sim­ply because the machin­ing process is opti­mised using AI meth­ods.” The terms “safe­ty” and “secu­ri­ty” are some­times dif­fi­cult for Ger­mans to dis­tin­guish between (the Ger­man word “Sicher­heit” cov­ers both aspects), but they will be clear­ly sep­a­rat­ed at METAV 2020 in two dif­fer­ent events. In a nut­shell, cyber­se­cu­ri­ty is about pro­tect­ing machines from human attacks. Safe­ty is all about pro­tect­ing peo­ple from machines – or themselves.

Focus on human-machine interaction

A major prob­lem remains that machine tool acci­dents only hap­pen very rarely, but when they do, they are often caused by oper­a­tor error and can lead to very seri­ous, if not fatal, injuries. The top pri­or­i­ty is there­fore pro­tect­ing the “source of error” from harm­ing him or her­self. The three-step ISO 12100 risk min­imi­sa­tion strat­e­gy says that the first con­cern here must be to pro­mote inte­grat­ed and safe machine design. The sec­ond con­cern is imple­ment­ing pro­tec­tive and com­ple­men­tary mea­sures. Only when the first and sec­ond lev­el mea­sures have been con­sis­tent­ly applied and mere­ly rel­e­vant resid­ual risks remain, can the aspects of instruc­tions and user infor­ma­tion be addressed.

The METAV Safe­ty Day will focus on the top­ic of human-machine inter­ac­tion. The great­est dan­gers arise from errors in the clamp­ing process, which can result in parts com­ing loose and fly­ing off, as well as from enter­ing the pro­tec­tive area of a machine that is still work­ing, or from tampering.

Dr. Volk­er Witt­stock, research asso­ciate in the Pro­fes­sor­ship for Machine Tool Design and Form­ing Tech­nol­o­gy at the Chem­nitz Uni­ver­si­ty of Tech­nol­o­gy, con­duct­ed safe­ty tests into the prob­lem of ver­ti­cal turn­ing in milling machines with a group of trainees. He observed the process­es, analysed assem­bly errors and cal­cu­lat­ed human error prob­a­bil­i­ty lev­els. This led to the research top­ic “Deter­mi­na­tion and com­pa­ra­bil­i­ty of human and tech­ni­cal reli­a­bil­i­ty for improved work­piece clamp­ing in ver­ti­cal / CNC turn­ing”. He applied for fund­ing from the Ger­man Fed­er­a­tion of Indus­tri­al Research Asso­ci­a­tions (AiF) via the VDW Research Insti­tute for this. Work on the project will begin at the begin­ning of March. Accord­ing to Witt­stock, the aim is to devel­op a new method for eval­u­at­ing the cause-and-effect rela­tion­ship that can arise in the event of pos­si­ble fail­ure of man­u­al work­piece clamp­ing and sub­se­quent unin­ten­tion­al release. The solu­tion is pri­mar­i­ly aimed at sup­port­ing small and medi­um-sized enter­pris­es (SMEs) involved in man­u­al or semi-auto­mat­ed production.

Accord­ing to Witt­stock, the planned user tests will involve as many com­pa­nies as pos­si­ble, and iden­ti­fy weak­ness­es in human-machine inter­ac­tion. Here he sees poten­tial for improv­ing instruc­tions or the gen­er­al aware­ness of safe­ty-rel­e­vant con­texts, for exam­ple through pri­ori­ti­sa­tion. At the METAV Safe­ty Day, it is expect­ed that Witt­stock will be asked whether it is best to con­vey this infor­ma­tion by smart­phone, via a screen on the machine or even via Vir­tu­al Real­i­ty (VR). No clear solu­tions have yet emerged, he says, espe­cial­ly since the require­ments of the new Machin­ery Direc­tive will also play a role. A dig­i­tal instruc­tion man­u­al would, how­ev­er, rep­re­sent a high­ly flex­i­ble solu­tion. An instruc­tion hand­book, either on paper or in the form of a PDF file, as cur­rent­ly pro­vid­ed for in the new ver­sion of the Machin­ery Direc­tive, is unlike­ly to pro­vide sim­i­lar lev­els of flexibility.

VDW Safe­ty Day – Machine Tool Safe­ty Tech­nol­o­gy under Chang­ing Con­di­tions, 10 March 2020, in Hall 1
10:00 Welcome
10:10 Upcom­ing revi­sion of the Machin­ery Directive
10:40 Risk assess­ment and iden­ti­fi­ca­tion of tol­er­a­ble resid­ual risk
11:30 Suc­cess­ful safe­ty principles
12:20 Lunch break
13:00 Suc­cess­ful safe­ty principles
14:40 Legal aspects

(9,779 char­ac­ters incl. blanks)
Author: Cor­nelia Gewiehs, free­lance jour­nal­ist, Roten­burg (Wümme)

Categories: 2020, January