Industry News

Specify a granulation single screw in this order: feedstock, required melt preparation, venting load, mixing duty, filtration resistance and pelletizing method. State whether the feed is clean pellet, powder, agglomerate, washed flake or a variable recycled stream. Provide resin grade, MFR test condition, moisture, contamination, filler, target output, motor, rpm, vacuum arrangement and current symptoms. The screw can then be designed around a real material window instead of a nominal diameter.

Choose a film-blowing screw in this order: resin and formulation, finished film and layer structure, line duty, then screw geometry and surface system. Ask for the exact resin grade and melt flow test condition, not only “LDPE,” “LLDPE” or “HDPE.” Record the blend ratio, additives, recycled content, output, screw speed, motor, die, film width and thickness range. Only then decide diameter, L/D, feed depth, melting profile, metering section and whether a barrier or mixing section is justified.

Measure wear as a location-based pair, not as one screw diameter. Mark axial stations through the feed, compression and metering zones. At each station, record the screw flight outside diameter and the barrel inside diameter in multiple angular directions. Then calculate diametral and radial clearance separately. Compare the map with the original approved drawing or a clearly agreed design reference. If you have only the worn parts, label the results as condition data. Do not present them as original dimensions.

Replace only the screw when measured barrel bore, roundness, surface condition and alignment remain suitable for the proposed new screw. Replace both parts when the barrel is enlarged, oval, locally washed out, scored or corroded enough that the new screw would still run with excessive or uneven clearance. If you do not have bore measurements, do not guess. Our factory position is simple: a screw-only quotation should not be treated as a complete technical recommendation until the barrel condition has been checked.

Choose a conventional screw for a stable, uniform pellet feed and moderate output when simple operation is the priority. Choose a barrier screw when the line needs more complete melting and stable output at higher rates, especially for PE and PP. Choose a mixing screw when melt-temperature uniformity, color distribution or additive dispersion is the main problem. Barrier and mixing functions are not mutually exclusive. Nanhaiya’s aluminum-plastic panel single screw, for example, uses a barrier-type mixing section to support melting, melt-temperature uniformity and the distribution of colorants and flame retardants.

A single screw extruder surges when material flow through the line stops being steady. Common sources include inconsistent feeding, screw-speed variation, unstable barrel temperature, incomplete or unstable melting, a changing screen or die restriction, screw-and-barrel wear, and downstream speed variation. Record melt pressure, motor current, screw speed, zone temperatures, feed rate and downstream speed on the same timeline before changing settings. If pressure and output move together, investigate the extruder and flow path. If the extruder trends stay stable while the product changes, start with the die, cooling, vacuum, haul-off or winder.