DAR 4 & 5 — Edge Crack Detection System
The DAR 4 and DAR 5 systems from TECHPAP are designed to detect edge cracks in paper and board production lines. They prevent costly process interruptions and material waste by identifying and localizing cracks in real time.
Overview
Edge cracks can cause significant problems in paper machines, calenders, winders, coaters, and printers. The DAR 4 sensor uses reliable optoelectronic components to detect cracks and folded edges on moving webs of various thicknesses, colors, and types — even at very high speeds (up to 3000 m/min).
Construction and Design
Built in a solid aluminum block, the DAR 4 detection head includes two parallel tubes forming a 36 mm wide detection area. As long as the web passes through this zone, any crack — as small as 2 × 0.4 mm — is detected.
Detection Head and Electronics
The detection head and electronic unit are connected by a 2-meter cable. The lightweight head can be mounted on trimmer-knife assemblies or in tight spaces. The electronic control unit features a display panel with eight positioning LEDs and four status LEDs for operation and crack detection. A counter records the total number of cracks since the last reset.
DAR 5 Motorized Bracket
The DAR 5 is a motorized bracket designed to automatically position or retract the DAR 4 head. In case of web break, the head moves to a standby position. The compact 60 × 60 mm design can be customized in length.
Electrical and Control Features
The electronic unit includes multiple outputs for connecting markers or transferring complete information — including running status, web breaks, and crack detection — to a central control system. The sensor starts immediately upon power connection. Tests have demonstrated superior detection performance compared to most camera-based systems.
Key Advantages
- No radiation or laser beam
- No complex optics or settings
- No moving or wear parts
- Not affected by external light or sunlight
- Simple installation and maintenance
- High performance and reliability
Applications
The DAR 4 can be used on a wide range of web materials — cigarette paper, newsprint, coated base papers, translucent papers, corrugated boards, and liners. It is also suitable for carrier rope control and fraying detection. When mounted on trimmers, the DAR 4 ensures reel production without cracks.
In Summary
The DAR 4 & 5 systems offer a robust, maintenance-free, and highly sensitive solution for edge crack detection. They integrate easily into any paper or board production line, providing precise, real-time monitoring and improved process reliability.