A cell that's all-round safe

Weidplas had optimised the unloading process on an injection moulding machine, on which a six-axis robot removes parts and places them on a conveyor, and afterwards decided to optimise the safety of this process step as well. They were looking for a solution that would guarantee in every situation that there was nobody left in the robot cell after the safety light curtain had been activated and the gate locking devices acknowledged. Aim: to design the restart to be as flexible and safe as possible. A safe complete solution for monitoring the robot cell's protection zone emerged with the safe radar system PSENradar, in conjunction with the existing configurable small controller PNOZmulti 2. The current safety solution from Pilz ensures greater plant safety and minimum downtimes.

In the event of a malfunction, only a qualified service engineer could pull the robot from the injection moulding machine and then re-enable the safety light curtain between the injection moulding machine and robot cell. The availability of the service engineer dictated how long the plant was at standstill. Today it's different: three PSENradar sensors have the protection zone completely in their sights. Both installation and implementation were simple due to existing Pilz function blocks. The gates are equipped with PSENmlock safety locking devices. When they are opened, or the injection moulding machine is accessed, the robot switches to a safe stop, "as previously". "New": now the radar sensors launch into action and detect any movement within the protection zone. Only when the PSENradar registers no more movement within the cell for a defined period of time are the safeguards and the robot reactivated. It automatically goes to its start position and the production process can be continued. So lengthy plant downtimes are a thing of the past.

• Efficient set-up mode: operators can now carry out the whole reactivation process themselves
• Current protection zone monitoring with PSENradar enables a safe, flexible and reliable robot application in accordance with PL d, Cat. 3​
• The radar solution can be implemented simply, based on the existing small controller PNOZmulti 2

Weidplas is a plastics processer and part of the Techniplas Group, with its head office in the USA. At its plant in Treuen in the Vogtland region of Saxony, Weidplas manufactures car wheel arch panelling from plastic granulate. Large injection moulding machines are used in the process. The company has made a name for itself in multi-component injection moulding, primarily supplying customers in the automotive, medium and heavy goods vehicle industry. The group maintains 14 production sites as well as 16 sales and technical centres in Europe, Asia, South Africa and South, Central and North America, employing more than 3,500 people worldwide.