Machinery safety for new 3D printer - managing risks from lasers

Behind the tinted glass pane of the Sintratec S1 3D laser printer, a class-four laser operates in the visible light spectrum. When the laser beam hits the pre-heated polymer material, the material melts and bonds with previously completed cross-sections. This produces, layer-by-layer, a three-dimensional polymer model with a maximum edge length of eleven centimetres.

The S1 3D laser printer is the flagship product of Sintratec AG, a start-up with its registered office in Brugg, Switzerland. Joscha Zeltner, one of the heads of the company, says: "The Sintratec S1 provides entry into the world of additive manufacturing and is particularly suitable for the production of functional prototypes. The printer can be integrated into every production environment and is easy to operate."

Risks associated with lasers

During the development of the Sintratec 3D laser printer, a series of far-reaching and consequential entrepreneurial decisions had to be taken - also with regard to the safety of the plant. Joscha Zeltner states: "All the devices delivered thus far obviously have sufficient safety features. However, a thorough risk analysis as well as a safety concept derived from this according to the Machinery Directive 2006/42/EC were still missing until recently."

Comprehensive machinery safety service

Sintratec contracted Pilz to perform a risk analysis with safety concept for the final CE marking. The first consulting meeting made it clear which tasks still had to be solved on the way to providing a declaration of compliance according to Machinery Directive 2006/42/EC. Pilz determined the valid, harmonised standards, regulations and potential sources of risks as part of the risk assessment. This was the basis for the actual risk estimation and the actions recommended for reducing the risk. Risks for the operator are primarily due to the class-four laser of the Sintratec 3D printer, as Joscha Zeltner explains: "The accessible and diffuse laser radiation poses a risk to the eyes and skin. Laser radiation also has the potential to ignite fires."

Guard switches

Pilz created the safety concept based on the risks determined. The concept describes the technical measures for eliminating or minimising the risks and ensures the safety of the machine in compliance with the nationally and internationally harmonised standards. It had to be ensured that upon opening the safety gate of the Sintratec 3D laser printer during operation, the laser is immediately switched off and all moving components are stopped. This task is handled by a Pilz PSENmag non-contact, magnetic safety switch, which is used for status monitoring of guards according to EN 60947-5-3 as well as for position monitoring.

The required performance level (PLr) or the safety integrity level (SIL) according to EN ISO 13849-1 / EN IEC 62061 were determined and verified using the Pilz PAScal Safety Calculator before the appropriate components were selected.

Essential steps

A critical follow-up at the end of a project is essential: were the protective measures correctly designed and implemented with regard to machine control? This necessarily includes the performance of a function test and a fault simulation of the safety system. All safety-related work as well as the unavoidable residual risks were also reliably documented. The presence and completeness of the instructions were checked according to the requirements of the Machinery Directive - which affects liability issues and is therefore essential.

CE marking

By attaching the CE mark to the product, Sintratec confirms that its 3D printer meets all the legal requirements of the European Machinery Directive 2006/42/EC in terms of its assured properties when used in accordance with its intended purpose. Joscha Zeltner concludes: "Its service package for comprehensive safety makes Pilz the perfect partner."

Follow the link for more information about machinery safety services from Pilz.