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Issue with my double screw extruder

Published: January 27, 2022
By: Sakariyah Shakiru Ariyo

I have an issue with my double screw extruder... When used to process an aggregate materials formulation of less than 30% CP, it will come out fine (I mean - in good shape and floating). But, when I use an aggregate materials formulation of more than 30% CP, it'll come out very poor in shape and will not float.

So, anyone with related issues or solution ideas could you please share?

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Sakariyah Shakiru Ariyo
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Michael Joseph
North Carolina State University - NCSU
31 de enero de 2022

Mr. Ariyo,

It seems that you are talking about twin-screw extruder. Double screw extruders are extruders with two single screws mounted separately on the equipment. From what you have mentioned, it's not clear what changes in other ingredients do you do when you increase the CP to be >30%.

Floatation of the feed is an effect caused by the expansion starch in the formula. A minimum 20% starch is helpful to provide the pellet with enough expansion to make it float. the pellets float even at 17% starch but then the expansion is lower. So, as a first step, I would suggest that you look at the starch amount in the formulation when you have 30% CP.

Michael Joseph

2 de febrero de 2022
Michael Joseph Dear sir, higher protein content can not be impact always on floating of feed....mainly fat content can be impact on floating of feed.....whenever if feed protein content is lower or higher , mainly fat content of formulation only impact the floating...higher fat tends to high density and lower fat means lower density of feed( excellence floating)
Sakariyah Shakiru Ariyo
2 de febrero de 2022
Michael Joseph As regards the increase to > 30 CP, I changed the quantity of some ingredients which I believe and I think it is the problem of sinking I'm currently facing. However, thanks for this response... It's really helpful, I will check the starch % as indicated above. Thumbs up for.
Mel Raymundo
10 de febrero de 2022
D.V.Sambasivarao, Excess fats in the formulation can be arranged using a vacuum coater or a fats spray, in order not to hinder the expansion of collets. Its a post extrusion application.
2 de febrero de 2022
But the same time we need to consider minimum 20% of starch in formulation of feed
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