Mixer, check ring

Figure 10.4 18 mm Injection moulding (TMR type) check ring cavity mixer, (a) Components, (b) Assembled. 

Figure 10.5 View inside injection moulded caps with back lighting, (a) Without check ring mixer, (b) With check ring mixer.

Figure 10.6 Check ring mixer in forward and rear position with bore extended...

By transferring the check ring mixer concept to extrusion, the mixer can be accommodated within the barrel as part of the screw. Being without the non-return valve function required for injection moulding it can be described as a floating... 

The disadvantage is that there will be less screw available for melting/pumping, and the length of the mixer is restricted. Although initial costs will be lower than for addon mixers, the need for occasional replacement of worn injection moulding check rings may also apply to extruders. 

---