Gradual-Type Single Screw

This gradual-type single screw is made from 38CrMoAla steel. Raw material is crucial to screw performance, and we select high-strength and wear-resistant steel from renowned Chinese steel producers that meets national standards (GB/T 3077).

Nanhaiya's tgradual-type single screw extruders are divided into three sections based on their function. The depth of the flutes in each section decreases sequentially without noticeable abrupt changes, creating a smooth, "gradual" structure.

The feed section typically accounts for 20%-30% of the total screw length. The compression section, the middle section of the screw, accounts for the largest portion (40%-50%) and is the core of the gradual structure. The flute depth begins at its maximum in the feed section and gradually and evenly decreases along the length of the screw, forming a "compression zone."

The homogenization section further mixes and agitates the melt, ensuring uniform melt temperature and viscosity. The material is then delivered to the die head at a stable pressure and flow rate, ensuring consistent quality of the extruded product.

Nanhaiya's gradual-type single screw barrels have undergone numerous R&D and improvements and are now integrated into various manufacturers' production lines, achieving state-of-the-art performance. We offer a 1-2 year warranty, depending on the specific material addition ratio. Nanhaiya's barrels undergo a nitriding process, with a 0.8~2m thick layer of nickel-tungsten alloy spray-welded on the most wear-prone areas. This increases the surface hardness of the barrel is HRC55~62, boosting wear resistance by 2-3 times.

Technical Parameter

Feature And Application

Nanhaiya's gradual-type single screw extruder features a three-stage structure with clearly defined functional divisions. The corresponding process parameters (temperature, speed, and back pressure) can be adjusted logically, making operation much easier than with specialized screws.

Easy Temperature Control: The three-stage temperature setting follows a "gradient increase" principle. The feeding section has the lowest temperature (only required to soften the material, such as 50-80°C for PE processing), the compression section gradually increases in temperature (to reach the melting point, such as 160-180°C for PE), and the homogenization section stabilizes at the melting point (such as 180-200°C for PE). Complex local temperature adjustments are not required.

Linear Correlation between Speed and Output: Within a reasonable speed range (typically 30-150 rpm), output increases approximately linearly with screw speed, eliminating the need for frequent backpressure compensation adjustments. This makes it suitable for novice operators and facilitates continuous and stable large-scale production (such as 24-hour continuous extrusion of pipes and films).

Low back pressure requirement: The screw groove depth in the homogenization section is constant and shallow, and only a conventional back pressure of 3-8 bar is required to ensure melt uniformity. Excessive back pressure will increase screw torque, increase energy consumption, and even cause melt overheating, and the process parameter "tolerance" is high.

The gradual-type single screw extruder is suitable for producing PE (polyethylene) films (such as food wrap, supermarket shopping bags, and waterproof express delivery bags), PP (polypropylene) strapping tape, and PVC (polyvinyl chloride) heat shrink film. It can also produce PVC drainage pipes, PPR water pipes, PE gas pipes, and plastic window frame profiles. It can also produce PE plastic basins, PP plastic buckets, PVC cable trunking, and plastic storage boxes. It can also pelletize PE and PP recycled materials and produce PE pipes filled with up to 10% calcium carbonate.

Product Details

Advanced tempering, precision machining, and nitriding processes ensure the comprehensive performance of core components.

Vulnerable areas of the screw and barrel are reinforced with a nickel-tungsten alloy layer, achieving a 0.8-2.0mm thick layer and significantly improving wear resistance.