Teardrop-Shaped Profiles for Rake Bar Screens in Wastewater Treatment
Rake bar screens are filtration systems used in wastewater treatment to remove solid refuse and debris before the water reaches downstream pumps and pipelines. The cross-section geometry of the rake bars has a direct effect on hydrodynamic throughput: a rectangular bar creates turbulence, traps debris, and interrupts continuous water flow. A teardrop-shaped profile with a smooth, burr-free head allows water to pass around the bar without resistance, maximising filtration efficiency and reducing jamming. Montanstahl has developed over 30 different profile designs for bar screens, available from stock in stainless steel 304 and 316 and carbon steel S235JR, with custom shapes produced to client drawings and JIT supply agreements available throughout the year.
Why Bar Screen Profile Geometry Affects Filtration Performance
The bars in a rake bar screen are regularly spaced to allow water through while blocking solids above a certain size. In continuous operation, the profile shape determines how water moves around each bar, how debris accumulates, and how effectively the rake clears the screen. A rectangular bar presents a flat face to the flow, creating a wake zone behind it where fine debris settles and compacts, increasing resistance over time. A teardrop profile with a smooth rounded head and a tapered trailing edge guides water around the section without generating significant turbulence, reducing debris accumulation between cleaning cycles and maintaining throughput capacity throughout the operating period. The head geometry also needs to be free of rolling burrs that would catch debris and disrupt the rake mechanism.
60×8×5 mm Teardrop Profile: Tight Tolerances and Ra 4 µm Surface
The bestseller profile in Montanstahl’s bar screen range is the 60×8×5 mm teardrop section, available from stock in stainless steel 304 and 316 and carbon steel S235JR. Thickness tolerance is held to ±0.2 mm maximum and width to ±0.5 mm maximum, ensuring consistent bar spacing across the full screen assembly. Surface roughness is controlled to Ra 4 µm maximum, and the head is produced smooth and burr-free to avoid debris catch points. Profiles are supplied in custom lengths from 3 to 8 metres. Where the standard range does not cover the required geometry, Montanstahl produces custom shapes to client drawings, and JIT supply agreements can be arranged for customers running continuous screen replacement programmes throughout the year.
Application Context
Rake bar screen profiles sit within Montanstahl’s Wastewater Treatment segment, where hot rolled and extruded special profiles are supplied to screen manufacturers and water treatment plant operators worldwide. Teardrop and hydrodynamic profiles are a product class where section geometry, surface quality, and dimensional consistency directly affect equipment performance rather than just structural function. Montanstahl holds a stock programme across its standard bar screen profile range for short lead time supply, and produces custom profiles for screen manufacturers requiring geometry specific to their equipment design.