OFFSET · PASTE INK · TRIPLE ROLLER
Offset inks are high-viscosity pastes, not pumpable liquids, so the process does not use bead milling. Dispersion happens in the gap between rollers, and mixing is done by high-torque agitators that move the whole mass.
Offset ink is a paste process: triple roller mills provide the dispersion and three-shaft or high-viscosity mixers handle the mass. Viscosity is too high for bead mills, so equipment selection starts from torque and roller gap control.
Three rollers running at different speeds create high shear in a thin film. That film is what wets pigment in a paste system; a bead mill cannot pump the same material, and a disperser alone cannot reach the required fineness.
The gap between rollers and the speed ratio set the fineness. Cooling water through the rollers is part of the process, because a hot paste behaves differently and the film becomes unstable.
Before and after milling, the paste is moved by high-torque agitators. Three-shaft agitators combine planetary motion with dispersion for heavy pastes; hydraulic discharge then empties the vessel without manual handling.
Because the material does not flow on its own, discharge design is a real constraint on batch size and on how quickly the vessel can be turned around.
| Stage | Equipment | What it decides |
|---|---|---|
| Pre-mixing | Three-shaft agitator / high-viscosity mixer | Uniform wetting of a paste |
| Dispersion | Triple roller mill (hydraulic or PTM) | Fineness and colour strength |
| Discharge | Hydraulic discharging machine | Batch turnaround |
| Packing | Filling machine for paste products | Pack accuracy |
No. The viscosity is far too high for pumping. Offset ink is dispersed on a triple roller mill, where the shear happens in the film between rollers.
Roller gap and the speed ratio between rollers. Both are set per product, and the setting is confirmed by fineness gauge rather than by time.
Because the milling energy heats the paste, and hot paste changes viscosity and film behaviour. Cooling keeps the process inside the validated window.
Triple roller mills in the range of 0.5 to 1,000 L depending on configuration, with mixing vessels up to 12,000 L for paste handling.
Send the ink type, the pigment system, the target fineness, the batch size and whether the line must run solvent or water-based products. POLYC MACHINE engineers will confirm the configuration and state where a trial is required before performance is guaranteed.