The name SPAX has stood for 'chipboard screws with X-slot' and quality 'Made in Germany' for over 50 years. Manufacturer SPAX International, based in Ennepetal, North Rhine-Westphalia, employs around 500 people and produces up to 50 million screws every day.

The manufacturing process of a SPAX screw begins with cutting the original material to length from a rolled wire coil. The head of the screw is then formed by upsetting and pressing in a press, whereby the so-called force application (e.g. the cross recess) is also determined. The thread and the tip are then rolled onto the so-called press nail in a roller. Finally, the screw is hardened and finished.

Production with proven machines

SPAX uses a large number of identical or similar machines for screw production - presses and rollers that often date back to the 1970s and 1980s. However, as their machine bodies are so robust and solid, they are regularly overhauled mechanically and electronically in order to keep them up to date with the latest technology. The company has its own mechanical engineering department for this purpose, which carries out the retrofit with its own personnel and overhauls between eight and twelve machines every year.

As the presses and rollers are machines that can pose a risk to the employees working on them, the issue of machine safety is immensely important. However, while two-hand relays were still used in the 1970s and 1980s, for example, safety requirements have changed considerably in the meantime. For this reason, SPAX was already looking for a solution over ten years ago to solve the safety technology in such a way that it meets modern requirements, is future-proof and expandable and takes up as little space as possible. With around 70 to 80 presses and the associated control cabinets, space alone is a decisive criterion. SPAX found what it was looking for at Bihl+Wiedemann, a provider of automation solutions with AS-Interface and ASi Safety at Work.

Safety first - a solution for many machines

Process and diagnostic data from IO-Link sensors for pressure, temperature and flow can be used for predictive maintenance via ASi-5.

© Bihl+Wiedemann

Safety technology plays a decisive role at various points on SPAX machines: directly on the machine, it is important that the operating personnel can only open safety doors and covers when there is no more dangerous movement. This is ensured on the one hand by the active distributor ASi Safety (BWU3565) in IP67 from Bihl+Wiedemann, which is mounted directly on the machine and with which the safe door switch can be integrated into the ASi network via the profile cable. On the other hand, safe monitoring of standstills takes place. This is implemented either via a Safety Basis Monitor installed in the control cabinet or a Safety Gateway from the company. Other safety-related tasks that are also solved via the ASi Safety Gateway are the two-hand operation of the presses and rollers and the connection of emergency stop buttons.

For SPAX, safety technology via ASi Safety at Work has several advantages - apart from the simple and flexible wiring technology. As the majority of the presses and rollers are almost identical and only differ in terms of special equipment, which can be activated separately, the solution can be transferred from one machine to another. As a rule, the same products with the same functionality can be used in the same place for all machines. In addition, control cabinets can be fully assembled and tested in advance and therefore stored in a functional condition. Once a machine has been mechanically and electronically overhauled, the control cabinet can be connected directly, which saves a lot of time. And the safety program for a machine, once created in the 'Asimon360' software suite from Bihl+Wiedemann, can also be easily copied for other machines without the need for major changes. All of this makes the maintenance and modernization of the machines much easier for SPAX employees.

In addition to the safety technology, the monitoring of pressure, temperature and flow was a second issue that was solved via AS-Interface. These parameters need to be constantly monitored to ensure that the presses and rollers are always sufficiently lubricated to function efficiently and prevent damage. For this purpose, ASi digital modules from Bihl+Wiedemann were initially used, which could be used in parallel with the safety technology on the same ASi line and monitored via the same ASi gateway.