Dry Type Single Screw Floating Fish Feed Pellet Machine: Factory Test Results
2026/08/17
Dry Type Single Screw Floating Fish Feed Pellet Machine: Factory Test Results
Key Takeaways
- Factory tested : MIKIM verified extrusion stability, pellet formation, expansion effect, and floating performance on a dry-type single-screw floating fish food pellet maker machine.
- No steam boiler needed: The machine uses mechanical friction, compression, and shear to generate heat and pressure inside the extrusion chamber, eliminating the need for an external steam boiler during extrusion.
- Floating performance depends on more than the machine: Raw material formulation, starch content (typically 20–30%), moisture, screw speed, feeding rate, die size, and extrusion conditions all affect pellet expansion and density.
- Test before purchase: Factory testing with customer-supplied raw materials lets customers evaluate the actual extrusion process before purchase and provides a practical reference for selecting the right machine configuration.
Factory Test Overview & Results
MIKIM Machinery carried out a factory test of a dry-type single-screw floating fish feed pellet machine on August 17. The test focused on the machine’s extrusion stability, pellet formation, expansion effect, and floating performance under real operating conditions.
During the test, prepared fish feed ingredients were fed into the machine through the feeding system. The rotating single screw continuously conveyed, compressed, mixed, and sheared the material inside the extrusion chamber. As pressure and friction increased, the material was heated and cooked before passing through the die. When the extruded material suddenly moved from the high-pressure chamber to atmospheric pressure, part of the moisture rapidly vaporized, creating an expanded and porous pellet structure.
This pressure-release expansion is one of the key mechanisms behind floating fish feed production. According to the FAO aquaculture feed production manual, extrusion is a process in which suitable formulations and processing conditions produce expanded pellets with lower bulk density, allowing them to float on water.
Test Conditions and Parameters
| Parameter | Value | Notes |
|---|---|---|
| Machine model | MIKIM MK-120 | Dry type, single screw |
| Motor power | 22 kW | Direct drive |
| Screw speed | 340 rpm | Adjusted during test |
| Die diameter | 3.0 mm | For tilapia grower feed |
| Feeding rate | 130 kg/h | Stable throughout |
| Extrusion temperature | 135–148 °C | Generated by friction only |
| Test duration | 45 minutes | Continuous operation |
Measured Results
| Measured Indicator | Result | Industry Reference |
|---|---|---|
| Floating rate (30 min) | 92% | ≥ 90% is considered excellent |
| Pellet bulk density | 0.42 g/cm³ | < 0.5 g/cm³ = floating |
| Pellet diameter (after expansion) | 3 mm | ± 0.2 mm from die spec |
| Pellet length | 4–6 mm | Controlled by cutter speed |
| Output capacity | 120 kg/h | At 22 kW motor |
| Water float duration | > 8 hours | Before significant sinking |
| Expansion ratio | 1.6:1 | Diameter ratio after/before die |
Figure 1. MIKIM MK-120 dry-type fish feed pellet machine during factory test, August 2026.
How Does a dry-type single-screw floating fish food extruder machine Work?
The working process can be summarized as:
Raw Material Feeding → Screw Conveying → Compression & Shearing → Frictional Heating → Extrusion & Expansion → Cutting → Floating Fish Feed Pellets
Raw Material Feeding
Finely ground and properly mixed ingredients enter the extruder through the feeding hopper. Typical fish feed formulations contain ingredients such as:
- Corn or maize flour
- Soybean meal
- Fish meal
- Wheat bran
- Cassava
- Other protein, starch, and nutritional ingredients
The formulation must be suitable for extrusion. In particular, starch plays an important role in pellet expansion and the development of a porous structure. Research in extrusion cooking literature has shown that feed formulation and starch availability strongly influence the expansion characteristics of extruded floating feed.
Conveying and Compression
The single screw rotates inside the extrusion barrel and pushes the material forward. As the material moves through different sections of the screw, the available space decreases and compression increases. At the same time, mechanical shear and friction generate heat.
Unlike a wet-type extruder that relies heavily on steam conditioning, a dry-type extruder generates much of the required processing heat through mechanical energy. In the August 2026 test, the extrusion chamber reached 135–148 °C using friction alone.
Cooking and Starch Gelatinization
The combination of heat, pressure, moisture, and mechanical shear changes the physical properties of the feed mixture. For floating feed, sufficient starch gelatinization and expansion are particularly important. The FAO aquaculture feed manual notes that raw starch is an important factor in producing expanded floating pellets, while final pellet density is influenced by both formulation and extrusion conditions.
Important: Simply increasing machine temperature does not automatically guarantee better floating performance. The formulation and the complete extrusion process must be considered together.
Die Extrusion and Expansion
When the cooked material reaches the die, pressure forces it through the die holes. As the material exits into atmospheric pressure, the sudden pressure drop causes rapid moisture vaporization and expansion. The material forms a porous structure and is then cut into pellets by the rotary cutter.
This is why the same extruder can produce different pellet characteristics by changing factors such as die size, screw speed, feeding rate, and formulation.
Dry-type single-screw floating fish feed pellet machine test in our factory
Test Your Formula Before You Buy
What Was Checked During the Factory Test?
The purpose of a factory test is not simply to demonstrate that the machine can produce pellets. A meaningful test should examine whether the machine and processing conditions work together consistently. During the August 2026 test, MIKIM engineers checked the following five areas.
Feeding Stability
The test checks whether the raw material can enter the extrusion chamber continuously without excessive bridging, blockage, or unstable feeding. In this test, the feeding rate remained stable at 130 kg/h for 45 minutes with no interruptions.
Stable feeding is important because sudden changes in feed rate can alter pressure and temperature inside the extrusion chamber.
Extrusion Stability
The operator observes the running condition of the main motor, screw, extrusion chamber, and die. A stable extrusion process should maintain relatively consistent material discharge rather than producing frequent interruptions or significant fluctuations. The MK-120 maintained a steady discharge with current fluctuation below 5%.
Pellet Shape and Size
The die determines the approximate diameter of the extruded pellets, while the cutter controls pellet length. In this test, the 3.0 mm die produced pellets of 3.2 mm diameter after expansion, and pellet length was controlled at 4–6 mm by cutter speed.
Different fish species and growth stages require different feed sizes, so the appropriate die should be selected according to the target application. See our fish feed die selection guide for details.
Floating Performance
Floating performance is one of the most important indicators for floating fish feed. The measured floating rate was 92% after 30 minutes on water, with pellets remaining afloat for more than 8 hours.
Note: Floating rate should not be evaluated independently from the feed formula. A formulation with insufficient expansion characteristics may produce sinking or partially floating pellets even when the machine itself is operating normally.
Pellet Structure
The cross-section and appearance of the pellet provide useful information about expansion. A properly expanded pellet has a lighter internal structure than a dense, unexpanded pellet. In this test, pellet cross-sections showed a uniform porous structure with an expansion ratio of 1.6:1.
The expansion level directly affects bulk density and therefore influences whether the feed floats or sinks.
Figure 2. Pellet cross-sections (left) and floating test results (right) from the August 2026 factory test.
What Raw Materials Are Suitable for Floating Fish Feed?
Common ingredients used in extruded fish feed include:
- Corn/maize + soybean meal + fish meal + wheat bran + cassava + nutritional additives
However, there is no universal formula that works identically for every fish species and extruder. Starch-containing ingredients are particularly important for expansion. The FAO aquaculture feed manual explains that cereal grains can expand substantially during extrusion, while protein concentrates with low starch content may provide less expansion.
In practice, floating fish feed generally requires 20–30% starch content in the formulation for adequate gelatinization and expansion. Therefore, when a customer wants to produce floating feed, MIKIM recommends testing the actual formula rather than selecting a machine based only on theoretical capacity.
What Factors Affect Floating Fish Feed Quality?
The machine is only one part of the extrusion system. Several variables need to be controlled simultaneously to achieve consistent floating feed quality.
| Factor | Influence on Floating Feed | Typical Operating Range |
|---|---|---|
| Raw material formulation | Determines starch availability, protein level, density, and expansion potential | 20–30% starch content |
| Moisture | Influences extrusion stability, friction, expansion, and final pellet texture | 18–25% moisture in mix |
| Particle size | Affects mixing, heat transfer, cooking, and pellet uniformity | 0.5–1.0 mm grind |
| Screw speed | Changes shear intensity, residence time, and extrusion pressure | 300–400 rpm typical |
| Feeding rate | Influences machine load and material residence time | 80–90% of rated capacity |
| Die diameter | Determines pellet diameter and affects back pressure | 2.0–6.0 mm common |
| Cutting speed | Controls pellet length | Adjusted with die size |
| Extrusion temperature/pressure | Influences cooking and expansion | 120–160 °C |
Research on single-screw extrusion has also demonstrated that ingredient composition, particle size, and process conditions significantly influence extrusion yield and floating-feed production.
Dry-Type vs. Wet-Type Floating Fish Extruder Machine
The main difference between dry-type and wet-type extruders is how heat and moisture are introduced into the extrusion process.
| Feature | Dry Type | Wet Type |
|---|---|---|
| Heat source | Mechanical friction and shear | Steam + water conditioning |
| Steam boiler required | No | Yes |
| Typical capacity | 100–500 kg/h | 500–5,000 kg/h |
| Moisture/temperature control | Limited, friction-based | High, steam-injected |
| Equipment configuration | Compact, simple | Requires steam-generation equipment |
| Best suited for | Small and medium-scale farms | Large commercial aquafeed production |
| Installation and operation | Relatively simple | More complex |
| Investment level | Lower | Higher |
Neither type is universally “better.” The appropriate choice depends on production capacity, formulation, pellet requirements, available utilities, and investment budget.
Case Study: Factory Test for a Tilapia Farm
Customer profile: A tilapia farm in Nigeria planning small-scale floating feed production.
Objective: Verify whether the customer’s locally available formulation could produce floating pellets on a MIKIM dry-type single-screw floating fish feed extruder machine.
Test formulation (customer-supplied): 40% maize flour, 25% soybean meal, 20% fish meal, 10% wheat bran, and 5% premix and additives.
Machine settings after adjustment: Screw speed 340 rpm, die 3.0 mm, feeding rate 130 kg/h.
Results:
- Floating rate: 92% after 30 minutes
- Bulk density: 0.42 g/cm³
- Output: 120 kg/h
- Pellet diameter: 3.2 mm, length 4–6 mm
Outcome: The customer confirmed the machine configuration and ordered the MK-80 with a 1.0 mm die set . The customer’s formula required no major changes — only moisture adjustment from 22% to 20% was recommended before extrusion.
Frequently Asked Questions
Can a dry-type single-screw floating fish feed pellet extruder machine produce floating fish feed?
Yes, a dry-type single-screw floating fish feed pellet extruder machine can produce floating fish feed when the formulation contains sufficient starch (typically 20–30%) and extrusion conditions are properly adjusted.
Moisture content, screw speed, feeding rate, die configuration, and extrusion temperature all influence the final pellet density and floating performance. In MIKIM’s August 2026 test, a 92% floating rate was achieved with a corn-soybean-fishmeal-based formulation.
Does a dry-type single-screw fish feed extruder need a steam boiler?
No, a dry-type single-screw fish feed extruder does not require an external steam boiler for the basic extrusion process.
The machine generates heat through mechanical friction, compression, and shear inside the extrusion chamber, which simplifies equipment configuration and reduces installation cost compared with steam-based wet extrusion systems.
Why do fish feed pellets sometimes sink instead of float?
Fish feed pellets sink when the formulation lacks sufficient starch for expansion, moisture is inappropriate, pellet density is too high, or extrusion conditions are incorrect.
Common causes include unsuitable formulation, insufficient starch or expansion, excessive pellet density, or an unsuitable die configuration. Floating performance should therefore be evaluated together with both the formulation and machine settings.
Can one machine produce different fish feed pellet sizes?
Yes, different die holes and cutter settings can be used to produce different pellet diameters and lengths from the same machine.
The suitable pellet size depends on the fish species and growth stage. For example, fry feed may need 1.5–2.0 mm pellets, while grow-out feed commonly uses 3–6 mm.
Is factory testing available before purchasing a dry-type single-screw fish feed making machine?
Yes, MIKIM can conduct machine testing with customer-supplied or representative raw materials before shipment.
Test results can be used to evaluate pellet size, expansion, floating performance, and operating conditions before final equipment configuration.
How much does a dry-type single-screw floating fish feed pellet maker machine cost?
A dry-type single-screw floating fish feed pellet machine typically costs between $3,000 and $15,000, depending on capacity, motor power, and configuration.
