Twin screw floating fish food pellet maker machine barrel temperature is set per section and judged by the pellet, not raised to a maximum. The melting zone runs at 120–125 °C, the final heated zone at 130–140 °C, and the homogenizing cooling zone at 40–50 °C. Floating and sinking feeds require different temperature settings.
Two plants run the same formula on machines of the same barrel diameter and report different pellet quality. One holds the melt section at the top of its range through the shift. The other sets the melt section to the value the formula needs and cools the end section before the die.
Both machines run within their specifications. The difference is which section was raised, and what the raise was expected to fix.
This article covers the job of temperature in each section, both ends of the range, the product differences and the readings that show a setting is correct.
- Temperature is set per section. The melt section is held at 120–125 °C while the end homogenizing section is cooled to 40–50 °C in the same run.
- Raising the melt section above 120–125 °C changes the material state upstream of the die, and the later sections cannot correct it.
- The last heated section runs at 130–140 °C depending on the formula, and material leaves the conditioner above 85 °C.
- Sinking feed is run below 1.3 expansion and floating feed at 2–3 or above, so the two profiles differ at the end section.
- Control is correct when pellet quality, cook degree, expansion, motor load and energy use stay stable at the setpoints that produce them.
What Barrel Temperature Does in Each Section of a Twin-Screw floating fish feed extruder machine
Barrel temperature is set section by section, and each section has a different task.
The feed section is not heated. Its function is to pass material downstream at a steady rate, and heat at that point makes the material sticky and reduces conveying.
The melt section is heated and held at 120–125 °C, and the upper value is a limit. Starch gelatinization and the change of state in protein take place there, and material heated past this range arrives at the later sections in a state they are not set to handle.
In normal production the last heated barrel section runs at 130–140 °C depending on the formula. The value inside that band follows the recipe and is read together with the melt section.
The end homogenizing section is cooled to 40–50 °C. Cooling at this point reduces the energy the material carries and limits the water that goes into super-saturation, which holds expansion after the die within the target for the product.
Heat also enters before the barrel. Material leaves the conditioner above 85 °C, and that temperature is the starting point the barrel sections work from.
Send the section setpoints in use, the measured value at each section and the product through the what the conditioner delivers to the barrel, and the profile is compared with the requirement.
What Happens If the Barrel Temperature of a Twin screw floating fish food maker machine Is Too Low?
A low Twin screw floating fish food maker machine barrel temperature leaves the material under-processed, and the result appears in the pellet rather than on the controller.
- Cook degree. Starch gelatinization and the change of state in protein stay incomplete. A cut pellet shows unprocessed material in the cross-section and a softer body after drying.
- Expansion. A floating pellet that should reach 2–3 or above comes out below that figure and does not hold buoyancy. A sinking pellet stays dense but breaks up in water sooner than the specification allows.
- Stability. Surface, hardness and fines change between hours with the feeder setting unchanged, because the material is running at the limit of its processing range.
A low reading at one section has other causes: wet raw material, a feed rate that was changed, or a blocked die. Temperature is read with those in view before the setpoint is moved.
The handling of temperature faults and weak expansion in small fish feed lines is set out in this article on abnormal temperature and insufficient puffing.
What Happens If the Barrel Temperature of a Twin screw floating fish feed making machine Is Too high?
High barrel temperature changes the material before the die, and the change is carried into the pellet.
- Material state. Once the melt section passes 120–125 °C, the state the material reaches there is fixed for the rest of the barrel. The metering and end sections pass it on rather than reversing it.
- Expansion. Pellets come out over-expanded with thin walls, and part of the run collapses at the surface while the rest holds. The expansion figure moves between samples taken minutes apart.
- Colour and texture. The pellet darkens and the surface hardens while the expansion figure is moving, and both changes stay after drying.
- Heat load. Where the feed specification sets a limit on heat load for nutrient retention, a higher barrel temperature uses part of that limit.
The machine side shows the same rise: motor load climbs, steam flashes at the die face, and discharge becomes uneven when moisture and die pressure are not raised with the temperature.
The temperature held at the discharge end is one of the conditions that set how fast screws and dies wear, which is covered in the service life of screws and dies on twin-screw fish feed machines.
Different Products Need Different Barrel Temperature Profiles
The profile follows the product, and a profile written for one product does not transfer to another.
- Dry pet food. The setting is judged on cook degree, pellet shape and the quality grade of the finished kibble.
- Fish feed. The setting is judged on the species, the feed type and the sinking or floating requirement. Expansion separates the two lines: sinking feed is run below 1.3 and floating feed at 2–3 or above.
- Vegetable protein. The setting is judged on the raw material properties and on the structure the finished piece has to hold.
A pet food profile copied onto a fish feed line meets the kibble standard and misses the float requirement, because the two products are judged on different figures at the end section.
Fish feed with a high oil or fat level adds a condition to the same profile, set out in the process conditions for high-oil and high-fat fish feed. The pet food range and its configuration are covered in this guide to choosing and configuring a dry-type twin-screw pet food extruder.
Send the target species, the sinking or floating requirement and the expansion measured on the current pellet through the inquiry form, and the profile is set from those three items.
Adjust Barrel Temperature in Small Steps and Watch Four Signals
Temperature is adjusted one step at a time, and each step is read against four signals before the next step is made.
- Raw material. Check composition, particle size and moisture content. A wetter raw material needs a different setting for the same pellet.
- Material at the die. Check shape, expansion and surface on a sample taken at each step.
- Machine. Check main motor load and feed stability. A load that climbs with the setpoint marks the limit of that section.
- Finished pellet. Check moisture and density after drying, on the same sample basis each time.
Change one section and hold the others. A small step held until the readings stop moving gives a result that can be attributed to that section. Several sections moved together cannot be traced back to a setting.
Record the setpoint and the measured value at each section side by side. A section that never reaches its setpoint is a different fault from one that reaches it and still gives the wrong pellet, and only that record separates the two.
Barrel Temperature Works Together With Moisture, Pressure and Screw Speed
Temperature acts with moisture, pressure and screw speed, so a temperature change alone does not correct an expansion problem.
Water sets the steam that expands the pellet as it leaves the die. More water at the conditioner changes both the temperature the material reaches and the expansion it produces, so a water change and a temperature change are read together.
Die open area and die wear set the pressure the material is held at. A higher temperature with unchanged die pressure releases the extra energy as flash at the die face and leaves the pellet wall thin.
Screw speed is a shared variable in the same balance, adjusted with the temperature setting rather than in place of it. The range and the limits are covered in what extruder speed control changes.
When expansion is poor, five items are checked in order: raw material and formula stability, water addition, the temperature setting against the measured value, screw speed and motor load, and whether the die matches the product.
Table 1. Wet-type twin screw extruder range, heat input by model
Main motor power is the mechanical heat input at the screw. Conditioner power is the heat and moisture input before the barrel. A larger output class carries more of both, so one setpoint does not deliver the same heat input on two machines of different sizes.
Judge Barrel Temperature Control by Pellet Quality and Stable Load
A setting is judged on the pellet and on a stable load. The highest value the machine can reach is a specification figure, not a working target.
- Pellet quality holds within the shift and between shifts.
- Cook degree meets the value the product specification requires.
- Expansion sits at the target: below 1.3 for sinking feed, 2–3 or above for floating feed.
- Motor load and feed rate stay steady through the run.
- Energy use per tonne matches the record for that product.
An increase that improves one line and moves another is a trade, and the product specification decides whether it is acceptable. A pellet that is better cooked and over-expanded fails the float requirement.
Conclusion
Twin screw floating fish feed pellet extruder machine barrel temperature is a profile, and each section holds a value for a reason. The melt section runs at 120–125 °C, the end homogenizing section is cooled to 40–50 °C, and the last heated section runs at 130–140 °C depending on the formula. Material enters the barrel above 85 °C from the conditioner.
A higher setting is the right move only where the pellet, the load and the energy figure stay where the product needs them. The check is made on a sample and on the ammeter.
Send the formula moisture, the expansion measured on the current pellet and the section readings through the contact page, and the profile is reviewed against the product. The wet-type twin screw extruder range shows the machine type these settings are applied to.
Frequently asked questions
Twin-Screw Extruder Barrel Temperature: Common Questions
Does higher barrel temperature always improve cooking on a Twin screw floating fish feed pellet making machine?
No. Cooking degree rises with temperature until full gelatinization, with the melt zone limit at 120–125 °C. Above this range, pellets darken and over-expand with no further cooking gain.
What is the ideal final barrel section temperature for a Twin-Screw floating Fish Feed Extruder?
The last heated barrel section is set at 130–140 °C, adjusted by formula. The downstream homogenizing zone is held at 40–50 °C to cool material before the die.
Why cool the end section of a twin-screw floating fish feed extruder instead of heating?
Cooling reduces material thermal energy and prevents water supersaturation. Without it, pellets over-expand at the die, forming thin walls and partial surface collapse.
Do sinking and floating feed use the same barrel temperature on Twin screw floating fish feed production machines?
No. Sinking feed targets <1.3 expansion; floating feed needs 2–3+ expansion. This gap is controlled by end-section temperature, while melt zone settings depend on raw materials.
Why do pellet colours change after raising extruder barrel temperature?
Cross-check with expansion rate and motor load. Darker pellets with stable expansion signal excess heat; colour shift + rising expansion also involves water and die issues. Revert setpoints and compare pellet cross-sections.
Why won’t pellets expand when a Twin screw fish feed extruder machine hits its barrel temperature setpoint?
Check 5 items in order: formula stability, water addition, actual zone temperatures vs setpoints, screw speed & motor load, die condition. Heating/cooling faults cause temperature lag — raising setpoints alone will not improve expansion.
How to restore barrel temperature after restarting a Twin screw fish feed making machine?
Heat each zone to its setpoint and hold until readings stabilize. Confirm the melt zone at 120–125 °C and homogenizing zone at 40–50 °C before feeding. Premature feeding causes undercooked pellets and load spikes.
