Extrusion Screw Barrel Overview

Plastic extrusion equipment is mainly consist of two parts, main extruder and auxiliary parts. Main extruder include screw barrel, heating elements, gearbox, motor and feeding system, in which screw barrels are the core plasticizing and conveying parts. The size of extruder screw barrels normally range from 20mm to 250mm depends on application field and extrusion output requirement. Rootier industry can offer bimetallic extruder screw barrels with much longer wear resistance performance

Application Field of Extrusion Molding

Extrusion screw barrel process can be used on various molding applications, such as pipes, profiles, tubes extrusion, blowing film, blow molding and casting films...

• Pipe & Profile extrusion

Pipe and profile extrusion are the most common molding processing with extruder equipment and with industry standard, the pipe can be single or max. to 9 layers, Rootier can offer optimize design for your pipe and profile extrusion screw barrel

• Blowing film

Blowing film machine are widely used for packaging industry, and material by PP, PE (HD/LD/LLD), and screw barrel can be use nitrided or bimetallic grade for longer lifetime, product like shopping bag, agriculture film, screw barrel design with mixer for better homogenization.

Plastics and Application Industry

Parts Include for Supply

Extrusion screw barrel set are consist of Screw, Barrel, Flange, Heaters. 

• Screws: main plasticizing and feeding elements for extruder, screw will rotate inside barrel and take material from the back feeding position to front die head. And with outside heating, polymers will become melted and flexible for shaping

• Barrels: main holding part for the plasticizing unit, there are heating band outside barrel for provide proper temperature to melt the plastics. Barrel can be one section or parts jointed by flanges or threads. Extrusion barrel optional nitrided or bimetallic barrels

• Flanges: for connect barrel to gearbox or die head side with holes for fixing nuts. barrel flange can have round or square shape

• Band heater: main heating elements for extruder machine, to control the temperature and to melt plastics. available stainless steel heater, ceramic heater, copper heater, spring heater and alluminium overmold heaters  

Different Extruder Screw Design

Extruder screw design are relate to many factors like plastics, products, rotation speed, torque and temperatures..

• General purpose single flighted screw, for most regular use application, the single flighed screw is suitable for simple extrusion of virgin material without much reinforced additives. Full length flight can armored with bimetallic alloy, and easy to process also with fast delivery. It's designed still with polymer-tailored compression ratio, L/D, feeding depth & metering depth, to guarantee proper shearing of plastics

• Barrier type screw: barrier type extruder screw are designed to seprate un-melted polymer and second processing to lead to evenly melt polymers before delivery to die head. It's benefit with lower melt temperature and high output application where there is not enough L/D & time for homogenization. 

• Mixer type screw: for certain polymers processing and final product requirement, some screw cant mix resins quite well and need dispersive mixing to increase the production efficiency or to mix color more evenly. By that mixer screws are provided, mixer can have several types, like pineapple mixer, egan mixer, single mixer, which finally applied is according to difference situations also. 

How Is Screw Barrel Made

Screw barrel are made by special machining equipment with projectable and flexible process depends on the geometry design and treatment required. The basic process for screw barrels are like below

• Screw: Quench & Annealing, Round Turn, Channel Milling, Flight Milling, Alloy Armor Spray, Polish, Key machining, Grinding, Inspection & Packing

• Barrel: Round Turn, Drilling, Deep Boring, Out Machining, Centrifugal Casting, Grinding, Inspection & Packing

Popular Brand of Extrusion Equipment

Popular rated Extruder Machines List

1. Coperion

2. Krauss Maffei

3. JSW

4. Useon

5. Jingming

6. Jwell

7. Beier

8. DXS

9. Battenfeld

10. Shibaru

11. Leistritz

12. Sumitomo

13. Davis Standard

14. Dakumar

15. Tongjia

Extruder Screw Barrel Material

Extrusion machine screw barrel material select should meet the polymer processing and wear situation. Regular use are nitrided, bimetallic and fully hardened grade. 

• Nitrided screw barrel are for virgin material without reinforce additives. Also resin material should not be corrosive while processing

• Bimetallic screw barrel are used lot while process with recycled material or mixed with recycle material, and also engineer plastics or with additives like calcium, which have much wear on screw barrel and want longer life service time, it can be 3-4 times longer lasting than nitrided screw barrel with high wear situation

• Fully hardend screw barrel are for high abrasive polymer processing, because screw complete by quenched treatment whih can get same hardness for whole piece and makes it much lasting. 

• Stainless steel screw barrel or chrome plated screw barrel are used with corrosive situation, for like PVC processing can get much better performance of protection. chromed is proven of simple and economic choice and give reasonable protect from corrsion dot on screw barrel surface.