SNV Story No. 10: What an extra two minutes mean for safety

In simple terms, what is electrical discharge machining?
Electrical discharge machining (EDM) is used to precisely cut or shape material. To do this, electrical charges or sparks are used to erode the material. Pulses of direct current are applied in order to shape electrically conductive materials such as steel, aluminium, copper or tungsten. One practical application is creating a highly precise mould for producing water bottles out of plastic.

What is the content of the ISO 28881:2022 standard?
This ISO standard is a safety standard. With ISO there are three different levels for which standards are drafted: A) general standards B) standards for a broad product family and C) standards for a specific product category. The ISO 28881:2022 standard falls in the last category, as it explicitly deals with safety aspects for EDM machines.

ISO standard versus ISO safety standard
The main difference is that ISO standards primarily describe the quality, performance and efficiency of products and processes, while safety standards aim to minimize the hazards and risks for the health and safety of human beings.

What was the main reason for the 2022 revision?
Ten years after its initial publication, the standard was thoroughly revised and brought completely up to date. User feedback had uncovered weak points that were rectified. One example is the amount of time that the machine can be operated while its protective guards are open (with additional safety measures in place to ensure that the user stays outside the hazardous area). This mode is primarily used for positioning the wire on the piece being worked on. Before the revision, this was limited to three minutes. However, many users required more time to complete the positioning process. Previously, the only safe alternative was switching off the function and then starting it up again. But this wasn’t optimal in terms of ergonomics. “In the revised standard, the time was increased to five minutes. These two additional minutes improved the efficiency of the positioning process and increased the protection afforded to employees,” explained Sargenti.

Innovative and well considered: the service mode
Since the standard’s initial publication in 2013, a new operating mode has been introduced: the service mode. This is intended for service technicians who need to take safety precautions during commissioning, maintenance or repair. In service mode the machines are slower and can only be moved along one axis. This is intended to prevent machines from being used in service mode during production.

Why was the safety standard launched in 2013?
EU law, and more precisely the “EU Machinery Directive”, was decisive here. This is a strict guideline for manufacturers of machines and tools relating to safety and health requirements. The goal is to only allow safe products to leave the factory in order to guarantee the protection of users. In most countries, employers must ensure that the machines and tools being used are not harmful to the health of their employees. Japan is the only country that recognizes responsibilities similar to those of the EU.

Switzerland and Japan at the forefront
A Swiss producer and four Japanese companies cover 60-70% of the global market for EDM machines. They all contributed to developing the standard.

How are safety standards developed?
Based on the regulations of the EU, you start with a risk assessment. This analyzes all potential hazardous situations for the users of the machines. In the next step, safety measures are described and implemented to provide protection from these dangers. Then, tests are run to see whether these precautions work within the prescribed tolerance limits. “In 2013 we developed an extensive table with standards for all of the cases that were evaluated. This table makes it easier for manufacturers to implement EU regulations, and helps make machines safer,” Sargenti reported proudly. In addition to drawing up the standard, compatibility with EU law was a priority. The EU specifies a harmonization process for this.

How does harmonization work?
The process is complex and usually slows down the work as several committees are involved. “What would be optimal in our case is if Marcel Schulze, the standards manager assigned by the SNV, were to also participate in other relevant commissions and in turn be able to easily and quickly introduce our initiative to the correct bodies, and take part in the decision-making,” reinforced Sargenti. The EU delegates the harmonization to external advisors who monitor and ensure EU regulations. In order for the revision of the standard to be completed, the advisors must give their approval. This means that they as individuals play a decisive role. The first proposal from the working group was rejected by the advisors. After the input for the “Safety” and “Noise” categories had been taken on board and coordination with the advisors was taken up a notch, all systems were go for the second attempt. “One important thing we realized is that it is worth including the harmonization advisors from the very beginning. That way, you can avoid time-consuming feedback loops and you can work together in the most efficient manner,” added Sargenti.

Who are the chief participants working on ISO 28881?
Worldwide, there are only a few notable manufacturers of EDM machines. Currently, a Swiss company and four Japanese manufacturers share 60-70% of the entire market. Representatives from both manufacturing countries have taken the lead, working together and engaging in a constructive dialogue to modernize the standard. What was helpful here was that Japan has legislation that is just as strict as that of the EU. “The input from our Asian colleagues was very valuable and important. The ISO offers a neutral framework within which goal-oriented work is fostered, including among competitors, to the benefit of all the participants,” affirmed Sargenti. Representatives from Germany, the UK and Italy were also involved.

Who benefits most from the standard?
The users themselves enjoy the greatest benefit. They can rest assured that they are working with safe machines, and they are not putting their safety at risk. The manufacturer benefits indirectly. All market participants have a clear idea of what a safe machine looks like. However, that means that there is less room for interpretation when it comes to development, production and sales. In practice, the following is a striking example when it comes to product development: five to ten people stand around a new machine, and it is subjected to various internal safety and quality tests. If it satisfies the requirements, the machine goes for beta testing on site with the customer. It is here that weaknesses in terms of practical use and the user’s perspective are always quickly recognized and reported directly to the manufacturer. Sargenti can reflect on many years of experience: “Even if we’ve worked out all of the use cases down to the last detail, beta tests always turn up something new. Users often operate the machines differently than expected, and they have a completely different perspective on processes based on their practical experience.”

Is the working group already planning the next revision?
The EU published a new version of the “EU Machinery Directive” in July 2023, which will go into force in January 2027. That means there are 3.5 years left to further develop or revise the corresponding standards. “Besides adapting to safety standards that are becoming more and more modern, cybersecurity and artificial intelligence will also become important points of discussion,” Sargenti said, looking to the future. “This modernization will, however, be guided by my successor. We are currently on the hunt for my replacement. Due to ISO term limits, I am stepping down as Chairperson at the end of 2026.”

Orio Sargenti

Sargenti has been Chairperson of the “ISO TC 39 – Machine Tools” and “ISO/TC 39/SC 10 – Safety” committees for five years. As far back as the late 1990s, he was already being entrusted with ISO work in various roles that he held. Sargenti is a qualified engineer and has more than 30 years of experience in the machine tools industry. He has been with the Georg Fischer Group since 2009, and is currently Head of Standards and Conformity at GF Machining Solutions.