Issues with extrusion

Faizan Ali The moisture before extrusion 22-26% after extrusion 18-22%

Faizan Ali The mix moisture around 8%. The starch source we use normally starch like from corn.

Tanatat you can play with the potato or topioca starch for more firm structure of pellet or texture with 1 to 2 % and see results..

I should think the die design could be the problem in the cutter, If extrusion process is complete and cooking has taken place to the desired extent then the vagaries of pellet shape front being larger than the rear might not have anything to the recipe. Dry Extrusion can process recipe vontsining just 7 to 8 % without any problem. Also the thickness of the die plate would be minimal and therefore the time taken for the extrudate will not alter unless the moisture content various in the feed stock. The only way it can happen is when the die has a taper where each hole for drilled has a taper in the wrong direction. Usually a taper is provided but if the product expands then the die holes need to be looked into

Sankaran Suresh Sundaram On extrusion cooking being completed the starch should bind the product string enough not allow any variation in expansion. However it is very unlikely that product expansion alone is the problem. One would have to look at the die plate and die holes more closely. Take a product like kurkure, which has multiple expandable starches will surely have this same variation.

Sankaran Suresh Sundaram For the die plate I'm not sure that which factor is the main one that i should change to solve this issue. Like the picture above we use die diameter 7 mm with 33 holes and the die land about 4 mm. thckness.

D.V.Sambasivarao Land height you mean same as land length right? Do you have number criteria for big diameter to be sufficient? We used diameter around 7 mm.

Tanatat Yes..land height is nothing but a land vertical length..need to use land height more than normal for bigger dia pellets....and also it will depend on fat level and type of extruder ( single or twin screw)...you can use 5 mm land for 7 mm dia die in fat levels between 4% to 6%..

D.V.Sambasivarao Ok thanks for your information. If the fat in formula is more(more than 6%) i have to increase the land length more right?

D.V.Sambasivarao Last time i testing more with the longer land length from 4 mm to 6 mm but the issue not been solve.I'm not sure that other factor that i need to be checking more?