How to Produce Both Floating & Sinking Feed with One Dry Type Floating Fish Feed Pellet Making Machine?
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How is it Possible?
The difference between floating and sinking feed comes down to the Expansion Ratio.
- To make Floating Feed: You maximize expansion by using high starch (20%+), high screw speeds (friction heat), and low moisture. This creates air pockets that reduce pellet density.
- To make Sinking Feed: You minimize expansion by reducing starch, lowering screw speed (RPM), and increasing moisture/fat. This creates a dense, solid pellet that sinks immediately.
1. Comparison Matrix: Floating vs. Sinking Settings
| Control Lever | Floating Feed Mode | Sinking Feed Mode |
| Starch Content | High (20% – 30%) | Low (10% – 15%) |
| Raw Material | More Corn/Wheat flour | More Fish/Meat meal |
| Screw Speed (RPM) | High (Intense friction) | Low (Reduced shear) |
| Internal Moisture | 15% – 18% | 20% – 25% (Denser) |
| Expansion Ratio | High (Porous) | Low (Compact) |
| Internal Heat | 120°C – 140°C | 100°C – 110°C |
2. The 4 Technical Levers of Density Control
Lever 1: The Formula (Starch is the Key)
Starch is the "expanding agent" in extrusion.
- Floating: Starch gelatinizes and traps steam, forming a sponge-like structure.
- Sinking: By replacing starch with high-protein ingredients (like soybean or fish meal) or fiber, the "matrix" becomes too heavy to trap air, causing the pellet to sink.
Lever 2: Moisture Management
In a dry type extruder, water acts as a lubricant.
For Sinking: Adding slightly more water (up to 25%) reduces the friction inside the barrel. Less friction means less heat, which prevents the "flash expansion" at the die. The result is a heavy, water-saturated pellet.
Lever 3: Mechanical Shear (Screw Speed)
The speed of the screw determines the Friction Heat.
- For Floating: Run at high RPM to generate maximum heat and pressure.
- For Sinking: Slow down the motor. This reduces the energy put into the material, keeping the pellet dense and unexpanded.
Lever 4: Die Configuration
- Floating: Use a die with a longer "land" or smaller holes to build back-pressure.
- Sinking: Some operators use a die with larger openings or a shorter path to allow the material to exit without building enough pressure to "pop" or expand.
3. Step-by-Step: Switching from Floating to Sinking
- Adjust the Mixer: Change your batch to a low-starch, high-protein formula.
- Increase Moisture: Add 3-5% more water than your floating recipe.
- Slow the Cutter & Screw: Adjust your VFD (Variable Frequency Drive) to lower the RPM.
- Check Density: Drop a sample in a bucket of water. If it floats, reduce the starch further or add more moisture until it sinks.
How to use a dry-type fish feed pellet extruder to produce sinking feed?
★More Information About the Dry-Type Floating Fish Feed Pellet Machine
4. FAQ:
Q1: Can I make shrimp feed with a floating feed machine?
Answer: Yes. Shrimp require sinking feed. By using the "Sinking Mode" parameters (High protein + Low RPM + High moisture), a dry type floating fish food pellet maker machine can produce high-density pellets suitable for bottom-feeders like shrimp and crabs.
Q2: Will sinking feed produced this way have good water stability?
Answer: It depends on the formula. To ensure sinking feed doesn't dissolve too fast, you may need to add a small amount of binder (like guar gum or extra wheat gluten) since you are reducing the starch that normally acts as a glue.
Q3: Is a dry type floating fish food pellet extruder machine as good as a dedicated sinking feed machine?
Answer: A dedicated sinking feed machine (often a pellet mill) is more efficient for mass production. However, for a small-to-medium farm, the dry type floating fish food extruder machine is more versatile because it allows you to serve two different markets with only one investment.
Q4: Why are my "sinking" pellets still floating?
Answer: This is a common issue. Usually, it's because the internal temperature is too high. Even with a sinking formula, if the machine is too hot, it will expand the pellets. Try increasing the moisture or decreasing the screw speed to cool the process down.
5. Final Verdict: Flexibility vs. Specialization
- Choose this Dry Type floating Fish Feed pellet making machine if: You have a diverse farm with Tilapia (floating) and Catfish/Shrimp (sinking), and you want to minimize equipment costs.
- Watch out for: Sinking feed production on an extruder consumes more energy per ton because the material is denser and the throughput may be slightly lower.
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