Plastics manufacturing
Drilling Unit for an Extrusion Line
Challenge
A plastics manufacturer with two sites in two countries wanted to drill extruded profiles directly in the line instead of running it as a separate step. There was neither a suitable machine on the market nor a safety and control concept for integrating one into the existing production network.
Solution
We developed the drilling unit from scratch as the fifth machine of the extrusion line: an igus linear robot with three axes, control on Phoenix Contact PLCnext in IEC 61131-3 Structured Text, an OPC UA link to a FastAPI client and a Python teach tool for drilling sequences. This was complemented by a safety concept per EN ISO 13849-1 with OT security zones and the complete EPLAN schematic.
Result
The concept was presented to management and approved. The line gains an inline drilling step with a documented safety architecture, clean network segmentation and a control system the team can maintain and extend on its own.
Starting point
The extrusion line consisted of four machines: extruder, water bath, haul-off and saw. Holes in the profiles were drilled afterwards in a separate step, costing handling, intermediate storage and setup time. The goal was a fifth machine that drills directly behind the saw without disturbing the line cycle and without compromising the existing network and safety architecture.
Mechanics and drives
The base is an igus linear robot with three axes and NEMA24 stepper motors. We calculated travel times and motion profiles in Python beforehand to verify that the unit keeps up with the line cycle. For clamping the profile we developed a stepper-driven clamp brake with ESP32 firmware. It follows a fail-safe logic: the spindle may only stop while the clamp remains engaged, so no workpiece is ever released uncontrolled.
Two control variants
The first variant was a Python sequence controller talking to the robot via the iRC/CRI protocol, with a web drilling tool for teaching drilling sequences and running them automatically. It shipped as a standalone application and served as a fast proof of feasibility.
For series operation we chose a Phoenix Contact PLCnext AXC F 1252. The sequence is programmed in IEC 61131-3 Structured Text, and communication with the operator client runs over OPC UA to a FastAPI service. Instead of a motor axis, three independent pneumatic cylinders handle the feed, which simplifies the mechanics and eases the safety assessment.
Safety and OT security
The safety concept covers functional safety per EN ISO 13849-1, electrical and mechanical safety, and the acceptance and change process. On the network side, a zone and conduit model with an industrial DMZ separates the machine from the office network so that remote access and data flows stay under control.
Electrical design and approval
The schematic was created in EPLAN Electric P8 with power supply, emergency-stop circuit and motor strings, complemented by a bill of materials, terminal diagram and a custom symbol export as a reference for the maintenance team. The concept and an in-house automation pitch were presented to management and approved.