FAQ's

Mash feed:
animal feed consists of different ingredients to make a balanced diet in terms of protein, carbohydrates, fats, vitamins, minerals and medicines etc. in manufacturing of feed in mash form, there are few ingredients like DORB, rice polish etc. which are already available in the powder form, while some of these like grains, fish, GNE, soya etc. are available in solid form and has to be converted to granular form to particle size suitable for the animal. For this purpose grinding of these ingredients is carried out with the help of grinder or hammer mill. After converting all the ingredients in the powder form, these have to mix in right proportions to get the homogenous feed. Mixers are employed for this purpose. So there are two basic operations of grinding and mixing in feed manufacturing of feed in the mash form.

Pellet feed:
pelleting is a process in which mixed feed in powder form is converted into pellets by mechanical compression in combination with moisture and heat. Process is achieved by a set of rolls and die of suitable hole size and shape. As the die & roll rotate, the product passes through the nip of roll & dies and pressed into die holes to make pellets.

The process has both the physical and nutritional benefits of it. Among physical benefits, we can count - improved ease in handling, reduced ingredients segregation, less feed wastage and increased bulk density.

Nutritional benefits - Decreased feed wastage, reduced selective feeding, decreased ingredients segregation, less time and energy expended on prehension, destruction of pathogenic organism, thermal modification of starch and protein, improved palatability

Both feeds have their own significance and advantages depending upon the breed, flock size and weather conditions. People generally prefer pellet feed over mash in broiler and mash feed in layer birds. Considering standard parameters and desirable conditions few advantages of pellet broiler feed over mash feed are:

• Pelleting results in a saving of 15-20% of total feed cost.
• Feed wastage is reduces.
• Drinking water remains clean in troughs.
• It is easier for a bird to eat a crumble or pellet than to eat mash.
• Pelleted feed has a higher nutrient density.
• Pelleting reduces bulkiness of feed by 15 to 18%.
• It reduces selective eating by birds.
• It reduces toxic organisms like salmonella, E coli, etc. during processing.
• Digestibility of certain nutrients is increased.
• Birds need less time to consume the feed.
• FCR: Minimum 0.15 to 0.20 difference in FCR.( for 1 lac broiler farmer – monthly saving = approx. 17 lacs )
• Minimum 3 % difference in Bone to meat Ratio difference.
• Minimum 5 % difference in Meat – Live Bird Ratio
• Approx. 3-4 days difference in ready bird.

Selecting a suitable project in terms of Investment, space, capacity, running hours, future plans is very important thing. We have to consider following points before selecting a project:

Project cost:
Many other costs involved in the project other than Feed mill like boiler, transformer, genset, civil work, taxes, transportation, Weigh Bridge, ware house, building construction, working capital etc. Hence considering all the costs in the project report is necessary.

Capacity Utilization:
Minimum 40 % capacity utilization is must for break-even point.

Market study:
Future trends and concentrate of livestock , poultry and other animal production, demand & availability of feed, demand & availability of raw material , grain surplus or deficit area, kind of feed grains grown and fed , future trends in feed potential etc. We can cover approx. 200 kms radially in terms of transportation cost.

Competition in market:
Kinds & prices of feeds sold, credit policy of competitors, services offered to customers, share of local market, man power availability & cost , nature of farmers & traders , discount policy , trend of on-farm grinding and mixing.

Selecting the site:
Condition of roads, availability of power, water and manpower, drainage & nature of soil, water level, federal and local regulations for pollution & air quality, attitude of local people and government towards a new feed manufacturing unit, taxation and subsidy rules etc. All these factors must be taken into consideration while selecting a site for feed mill.

Project Feasibility:
Raw Material + Processing cost + Packaging + over heads = Total Cost of production Where raw materials are grains like Maize, Soya, Mustard, GNE, Cakes, DORB, Oils, Molasses, Medicines, Supplements etc.; processing cost involves Boiler Fuel, Electricity, Labour, Maintenance, general Wear & Tear; packaging cost for PT Bags, overheads are depreciation, bank interest, salaries, promotions & branding etc.
Hence all above factors affects the cost of production and considering all these factors along with working capital, selling price & profits we can easily calculate the project feasibility & return on investment.

Several factors affect pellet quality, such as dietary nutritional composition, feedstuff particle size, conditioning time and temperature, feed moisture content, compression rate of pellet die, gap between the pellet press roll and die, etc. In addition, the major factors that play an important role in pellet quality are:

Formulation:
Ingredients characteristics like protein content , fat/oil content , fibre content , ingredient variability ( sources like weather , soil, irrigation , fertilizer etc.) , directly affects the pellet quality as hard , fibrous & abrasive materials are difficult to pellet and soft materials are easy to pelletize.
Same machine and die behave differently with different feed ingredients;
Broiler contains less fibers and more oil %age (soft formulation), which provides better pelleting properties, less frictional load on pellet die; on the other side –layer and breeder feed are more dry & fibrous which directly reduces the pelletizing properties.
Formulation factor covers approx. 40 % in pellet quality.

Particle size:
Reducing particle size increases particle surface area relative to its volume, thereby increasing the number of contact sites among particles. This directly increases the penetration of heat and moisture to the centre of the feed particle, consequently reducing heat-treatment time. Better conditioning results in better feed quality and good PDI. This factor covers approx. 15-20% in pellet quality.

Conditioning:
Conditioning is essential to obtain good physical quality of the feed. During conditioning, steam breaks down the structure of starch, resulting in its gelatinization, as well as changes protein tertiary structure. Starch gelatinization combined with protein plasticization allows binding among feed particles, and thereby it is important for the manufacturing of durable pellets.
There are different studies relating conditioning with pellet quality and PDI which stated that; temperature, moisture and retention time up to certain limits directly affects the pellet quality. Conditioning controls approx. 15-20% in Pellet Quality.

Die specification:
Selecting a die as per formulation is very important. As Broiler contain less fibers and more oil %age (soft formulation), which provides better pelleting properties, less frictional load on pellet die. Hence, we can use compression ratio of 1:12, 1:13 & even more.
Using high compression ratio for layer feed may leads to poor die life, die chocking, non-uniform PDI, more power consumption in layer feed, low output, more wear & tear.
And using low compression dies in soft broiler formulation may lead to poor PDI (Pellet Durability Index – Pellet Strength) .Considering all above factors using separate die for both layer & broiler feed is a better and cost effective solution. Die selections governs approx. 10-15% in pellet quality.

Cooling & crumbling:
Purpose is to remove moisture and heat generated during the conditioning and pelleting process. Pellet "shock" can occur if air volume or the temperature or humidity of the cooling air is too low, resulting in stress cracks in the pellets. Pellet quality and shelf-life will be reduced if air volume is too low or if the ambient humidity is too high. Improper cooling directly affects the pellet strength which results - increase in percentage of fine. Also improper crumbling increases dust percentage in finish feed. These two factors covers approx.5-10% in pellet quality.

Pellet quality is usually expressed as the pellet durability index(PDI) and measured by using a tumbling can device , in which the pellet sample to be tested is first sieved to remove fines, then tumbled in the tumbling can device for a defined period of time.
PDI = weigh of pellet after tumbling / weight of Pellet before tumbling x 100

The principal objective in feed mixing is to assure that an animal receives all of its formulated nutrient allowances every day. Most feed manufacturers use the coefficient of variation or CV to measure mixer performance and mixture uniformity. A 5 to 7% CV is the industry standard for most ingredients. The CV is defined as 100 X Standard deviation / Mean.

Gelatinization is defined as the irreversible destruction of the crystalline order in a starch granule so that the surface of every molecule is made accessible to solvents or reactants. As a result of gelatinization of starch, digestibility is improved considerably because:

• It enhances the ability of starches to absorb large quantities of water and this leads to improved digestibility in almost all cases and to improved feed conversion in many cases.
• It increases the speed at which enzymes can break down the linkages of starch to convert it into simpler and more soluble carbohydrates, including blood sugars.

Pelleted feed is an outcome of several sub processes of feed milling process. Feed mill productivity depends on those sub processes. Few factors are:

Recipe Management:
It will take around 30-40 minutes to change recipe. It’s better if we run one recipe a shift as it saves lots of time.

Formulation:
Hard formulations (layer & breeder) reduce production capacity of machine while soft formulations are easier to produce. Same machine producing 10 ton/hr. at broiler feed will produce 7-8 ton/hr. at layer & breeder feed.

Power Failure/ Trips:
Machines require a starting time to achieve their full capacity load. One time power failure hampers the production by minimum 20 minutes.

Boiler:
Proper steam of good quality is required for better performance of machines and feed quality. Steam parameters required are:

• Dry Saturated Steam Minimum 9-10 kg/cm2 at boiler.
• 2-2.5 Kg/Cm2 after PRV
• Good & reputed make boiler, Water softener & Chimney.
• Proper Steam traps, insulation of steam line and supporting valves.

Operational Parameters & Skills:
operational parameters and skill of operator plays an important role in plant performance. Same die with similar technical specifications behaves differently in different pellet mills.
The operator should regularly check the:

• State of wear on the deflectors and scrapers and also the roll adjustment: To avoid uneven wear on the die and consequently inefficient pelleting.
• The state of wear of the conditioner paddles: To ensure efficient pre-conditioning.
• Steam traps and filters: To ensure that no condensate is being passed into the conditioner.
• Press Roll slippage due to increased moisture content, it leads to die roll over.
• Observing wearing pattern of die; it is recommended to change the side of die (front side – Back side) for more uniform wear.

Preventive Maintenance:
The primary goal of maintenance is to avoid or mitigate the consequences of failure of equipment. This may be by preventing the failure before it actually occurs which Planned Maintenance and Condition Based Maintenance help to achieve. It generally covers greasing of bearings, tension of elevator belts, cleaning of magnets, running condition of sprockets & chain drives etc.

Man Power Management:
Good results certainly cannot be achieved without the adequate availability of skilled & unskilled manpower. Timely response of labour & supervisors to automation controls , over filling / under filling bins / alarms etc. helps in smooth production.

Well, “A stich in time saves nine”. Maintenance is an important part of feed mill management. The main purpose of regular maintenance is to ensure that all equipment required for production is operating at 100 % efficiency at all times. It must be a part of the daily schedule.

As we all know, livestock needs feed on daily basis and there is no space for unwanted breakdowns in feed mills. Every feed miller must be aware of the importance of preventive maintenance. For this we developed special checklists & formats in different languages. We run awareness & training programs at Feed Mills to aware the operators regarding maintenance and optimum use of consumable parts. Some time we use the consumable parts more than their standard life but loose much more in feed quality and life of other parts which directly related to them. Like for an average die life cycle it is recommended to use 5 pieces (2.5 set) of roll shells for a better die life and uniform PDI feed quality. Hence using the roll shells & beaters more than recommended life results in great losses in terms of grinding texture, conditioning, pellet quality and specific energy consumption.

In present times of rising energy prices, shortage of resources, emissions targets and frequent changes in government policies the feed industry is challenged with limiting energy consumption.

Hammer mill and pellet mill consumes more than 70% of the total energy. Optimizing these processes has an immediate effect on energy consumption. Few ways to save energy in a feed mill are as mentioned:

Timely replacement of Spare Parts:
Some time we use the consumable parts more than their standard life but loose much more in feed quality and life of other parts which directly related to them. Like for an average die life cycle it is recommended to use 5 pieces (2.5 set) of roll shells for a better die life and uniform PDI feed quality. Hence using the roll shells & beaters more than recommended life results in great losses in terms of grinding texture, conditioning, pellet quality and specific energy consumption

Operational parameters:
Preventing idle time and down time of machines, better interlocking sequence between machines , switch off transport systems, machines, lighting, heating and ventilation when not in use can save a lot of energy.

Process Parameters: (Moisture addition)
Good quality raw material, (appropriate grain structure, moisture content), fine grinding, better conditioning can lead to an energy saving of up to 20%. During conditioning, moisture diffuses deeper in the feed meal and makes the meal better deformable. Less mechanical energy is required for a good quality uniform pellet

Selection of Hammer mill screens & Pellet Die:
Using perfect die configuration as per formulation like 1:13 or more in broiler feeds having good oil content & soft in structure and 1:10 or 1:11 minimum 3.5 mm hole size in layer /Breeder will give good results with better pelleting properties and save lots of energy during pelleting.
Similarly in hammer mill by matching the screen perforation perfectly to the required structure of the formula energy can be saved. The application of a 3 mm perforation instead of a 2.5 mm perforation may yield a saving up to 15%.

Pre-grind refers to the storage of individual raw materials after grinding which are held in bins before weighing and mixing in their specific formulation. With post grind, the raw materials are weighed out in batches as required from their main storage bins before each batch is ground prior to mixing.

Both systems have their own advantages & disadvantages as mentioned:

Few Advantages of Pre –Grind Systems

Machine down Time :
In pre –grinding system as grinding process is independent & not an integral part of the complete process; in case of repair and maintenance of hammer mill, there would not be a direct effect on the production output

Ease In operation :
As process is continuous and not depends upon batching time; there is less idle time, more uniform load on hammer mill, most of the time at single product hammer mill runs on single setting. Frequent change of products affects the hammer mill performance in post-grinding systems.

Energy consumption :
As there is no idle time and it is unnecessary for the milling to take place at the same time as the remaining production process which in some cases allows use of the cheaper energy tariffs.

Selection of screen as per product :
we can use: As we grind the material one by one we can use the screen size matching the raw material initial particle size and grinding required.

Post – Grind Systems – Advantages

LessOperational expenses :
In post grinding system no extra intake section for powder ingredients is required, which results in lower investment and operation costs. Also no separate operators are required for the grinding process as grinding operation is an integrated part of the total feed preparation.
While in pre-grind system we need extra material handling equipment’s for powder ingredients which increases the project & running cost.

Bins Capacity :
As ground material occupies more space; high volume of storage bins are required for same storage capacity in case of pre grind system. Hence space utilization of bins is maximum in post grind system.

Grinding of fibrous material :
Maize and some high density grains helps other low density fibrous material ( less in percentage ) to come out through screen ; that would not be possible in pre-grinding system as for low density fibrous materials required to be pulverized.

Life of storage bins :
In Pre Grind system, top layer of ground material in storage bin releases moisture which leads to corrosion/wearing of bin walls & top sheet.

Flowability of Ingredients :
Storing ground ingredients for a longer period of time causes flowability issues; complicate and precise design of batching feeders, weight fluctuation while batching.

Flexibility in required grinding texture :
The fineness of grinding can be adjusted per batch. This is very important when different types of feed are to be produced in one feed mill, e.g. coarse feed for layers, fine feed for broilers and extra fine feed for fish, mash concentrate feed. Sometime clients asked for different grinding textures.

Both systems have been used in the feed milling industry for many years, whereby the choice between one and the other was sometimes purely a matter of personal preference.

The increase in the quantity of raw materials, the variable physical properties as well as the increase of the number of formulas has led to the introduction of the post-grinding system.Considering all factors mentioned above post grinding system now a days is more prevalent and optimum solution for better results.

Feed safety and quality are major issues for all feed millers and can have serious consequences when control is lost. A systematic approach is required for reducing risk and improving quality. Few factors that directly affect the feed hygienic are:

Raw material:
The use of suitable, safe and good quality feed ingredients is of paramount importance to livestock production. Safe feed is an essential element to reduce and prevent food safety hazards entering the food chain. Quality and safety of feed ingredients are essential for the production of safe and quality feed, which are critical to the production of safe and quality animal food products, such as meat, milk, eggs, etc. Required parameters like moisture, fungus, protein, silica, fibre etc. must be checked before processing feed ingredients.

Process Control:
Maintaining consistent control over the quality and safety of the finished product requires applying quality assurance procedures at each step of the feed manufacturing process. Procedures have been developed for:

Grinding Operation:
Maintain equipment according to manufacturer’s recommendations, clean magnets daily, Inspect screens and hammers weekly, Check appearance of ground grain, Check screens for holes.

Batching & Mixing:
Check mixer drum, bins, elevator chutes & pits – weekly, Verify flushing procedures, check dry & wet mixing process. Check & clean oil - molasses dosing tanks weekly. Check medicine hopper cleanliness to avoid cross contamination.

Pelleting & Conditioning:
Check moisture and temperature before and after conditioning process, Check cleaning of conditioner drum and paddles- weekly, check steam quality and quantity, PRV, steam trap valves – daily, flushing die before stopping the pellet mill and at the change of formulation. Application of food grade grease & oils. Check boiler parameters and quality of feed water daily.

Cooling:
Moist pellets tend to gain fungus with time. Final feed moisture must be below 11% and temperature should be around +- 5 degree of ambient temperature. Cooler bed, distribution system, bed level, discharge mechanism should be check on regular basis.

Optimum House Keeping:
Care should be taken to minimize deterioration and spoilage at all stages of handling, storage and transport of feed and feed ingredients. Feed spills should be cleaned up immediately. Storage areas for raw materials and finished products should be separated to prevent cross contamination.

Pellet die is a part of pellet mill mainly used to pelletize the ground material into cylindrical granules. Roller shells forces the raw material under intense pressure to produce pellets. Holes & working length of pellet die determine the pellet size.

In the pelletizing chamber, the feed is distributed evenly across the working pad of pellet die where the cross force of pellet die and rollers press the feed stocks through the die holes to mould pellets which are cut off (through knives ) when extruded out of pellet die.

Well , there are different grades of material used for pellet mill dies ; like x46Cr13 commonly called high chrome or stainless steel grade , 20MnCr5 i.e. alloy steel and 18NiCrMo5 – (similar to 20MnCr5 but with a higher alloy content.)

The following terms are often usedin specifying dies:

1.1) Hole Diameter –Pellet Mill Die ( D1) :
Hole Diameter is the actual diameter of the pellet .Typical hole diameters for various feeds varies according to the requirement, i.e. smaller for aquatic feed, a bit larger for poultry and cattle feed.

1.2) Effective Length–Pellet Mill Die : (E)
The effective length is the die thickness that actually performs work on the feed. More is the effective length more is the compactness of the pellet.

1.3) Total Thickness –Pellet Mill Die : (T)
Total thickness is the overall thickness of the die. Overall thickness provides the necessary die material to avoid breakage.

1.4) Relief (Counter bore Depth)–Pellet Mill Die : (R)
Relief provides the way for the pellet feed , so that feed can easily come out from the pellet die .As shown in the figure “ R” is the relief .Lesser is the Relief more compact is the pellet & more is the relief lesser is the pellet compactness. Relief varies in various patterns according to the requirement & feed formulation. Sometime two specific outer rows are having more relief for uniform wearing as the compression by the roll shells on the outer rows is bit less.

1.5) Inner Diameter of the Die–Pellet Mill Die(I.D.) :
The inside diameter is the most common identifying dimension of a die and is always specified during die selection and equals to Outside dia. – (2 X thickness of die).

1.6) Overall Width of the Die–Pellet Mill Die (O.W.) :
The overall width of a die may vary. Often, there is more than one width available for each die diameter according to the die category like standard die, extra wide die.

1.7) Working Width–Pellet Mill Die(W) :
Die working width is measured between the two inside edges of the die grooves. Die working area is the area inside of the two die grooves.

1.8) L/D Ratio–Pellet Mill Die :
The L/D ratio is the effective length (L) divided by the hole diameter (D). High L/d ratios provide high pellet die resistance as feed moves through the hole. Low L/D ratios provide low resistance as the feed moves through the hole.

1.9) Counter Sink Diameter – Pellet Mill Die :
The diameter of the inlet where the feed enters the compression area of the pellet die. Different configurations of the inlet (countersinks, tapered inlets, well inlets, etc) can be used to achieve extra compression if needed for particular materials.

1.10) Inlet (well) depth –Pellet Mill Die :
The depth of the countersink is the inlet depth.

1.11) Degree of Countersink – Pellet Mill Die :
The degree of countersink, also refer to as the choke. This degree is important as it determines the force to which the feed material is pushed into the pellet compression area.

Selecting a die as per formulation is very important. As Broiler contain less fibres and more oil %age (soft formulation), which provides better pelleting properties, less frictional load on pellet die. Hence, we can use compression ratio of 1:12, 1:13 & even more.

Using high compression ratio for layer feed may leads to poor die life, die chocking, non-uniform PDI, more power consumption in layer feed, low output, more wear & tear. (We can use 1:9 or 1:10)

And using low compression dies in soft broiler formulation may lead to poor PDI (Pellet Durability Index – Pellet Strength) .Considering all above factors using separate die for both layer & broiler feed is a better and cost effective solution

Similarly for sinking aqua feed we need better water stability; hence it’s wise to use high L/D Ratio of better PDI & good water stability.

The L/D ratio is the effective length (L) divided by the hole diameter (D). High L/d ratios provide high pellet die resistance as feed moves through the hole. Low L/D ratios provide low resistance as the feed moves through the hole

Example: PelletMill Die of 3 mm hole size with L/D ratio 1: 12 means , 12 ( working ratio ) multiply by hole size i.e. 3 mm = 12 x 3 = 36 mm ( working length )

The effective length is the die thickness that actually performs work on the feed. More is the effective length more is the compactness of the pellet & lesser the working or effective length low is the compactness or PDI.

But we cannot go beyond a certain limit while selecting working length for a pellet mill die; increasing working length above certain limit without knowing the other process parameters like grinding texture, oil & fibers content in formulation may leads to poor die performance & chocking of pellet mill die .

Follow below steps to properly set/adjust the gap between the die and roller shells:

• Shut down the pellet mill
• Make sure that the eccentric shafts, clamps, bolts and the surfaces are clean so that rolls can be turned with ease.
• Clean the inside diameter of the die and outside diameter of roll shells.
• Be sure that there is no feed or dust between the rolls and the die and all surfaces are clean.
• Put a visiting card or paper folds (~0.5 mm) between the die and the roll shells.
• Adjust the roll until it is tight enough against the card so the roll shell cannot be turned against the die.
• Use the same procedure with other roll shell.
• After the rolls have been set up, check both rolls to ensure that they are tightened evenly.

Die is the most critical component of any pellet mill and also known as the heart of the pellet mill. It becomes very important for any pellet mill user to take maximum tonnage from a pellet mill with required quality and reduce his cost per ton. Die life depends on a number of factors and we want to discuss the factors on which the life of die depends:

1.) Feed Formulation & composition:
Formulations rich in fiber content are hard , thus pelleting is difficult and therefore the die life is less in this case. Life of dies used for producing layer feed (high fiber, less oil, Calcite) is very less as compare to broiler feed

2.) Characteristics & Properties of the raw materials:
Life of die also depends upon the characteristics of raw materials i.e. fibrous, spongy or dry or good fat content .Raw materials containing marble powder/silica & other abrasive particles wears dies more rapidly

3.) Fat content in feed:
As good fat content in feed acts as a lubricant therefore formula containing 1.5-4% fat run smoother and are less abrasive due to less friction as the fat present in feed reduces friction.

4.) Particle size of the mash:
A die producing pellets from consistent particle size mash will give good life as compared to die producing pellets from uneven and over size of particle size of mash.

5.) Moisture content:
A poorly conditioned mash also reduces the die life. Conditioning parameters play very vital role in increasing die life

6.) Skill of operator:
The operator should regularly check the

• State of wear on the deflectors and scrapers and also the roll adjustment: To avoid un-even wear on the die and consequently inefficient pelleting.
• The state of wear of the conditioner paddles: To ensure efficient pre-conditioning.
• Steam traps and filters: To ensure that no condensate is being passed into the conditioner.
• Press Roll slippage due to increased moisture content, it leads to die roll over.

7.) Changing Side of die:
observing wearing pattern of die; it is recommended to change the side of die (front side – Back side) for more uniform wear.

8.) Cleaning of magnets:
It is recommended to clean magnets every 6 hours.

9.) Timely changing Roll Shells:
It is recommended to use minimum 2 set rolls per die.

10.) It’s recommended to tight roll shell support stud bolt timely.
Some time we use the consumable parts more than their standard life but loose much more in feed quality and life of other parts which directly relates them. Like for an average die life cycle it is recommended to use minimum 4 pieces (2set) of roll shells for a better die life and uniform PDI feed quality. Hence using the roll shells & beaters more than their recommended life results in great losses in terms of grinding texture, conditioning, pellet quality and specific energy consumption.

11.) Using Same die for Broiler & Layer Feed:
Broiler contain less fibers and more oil %age (soft formulation), which provides better pelleting properties, less frictional load on pellet die. Hence, we can use compression ratio of 1:12, 1:13 & even more.
Using high compression ratio for layer feed may leads to poor die life, die chocking, non-uniform PDI, more power consumption in layer feed, low output, more wear & tear.
And using low compression dies in soft broiler formulation may lead to poor PDI (Pellet Durability Index –Pellet Strength). Considering all above factors using separate die for both layer & broiler feed is a better and cost effective solution. For Layer feed – Minimum hole size for die should be or more than 3.5 mm.

Considering all above factors it is very difficult to predict actual life of die; but under standard desirable factors a die should minimum run approx. 600 to 800 hours.

• In case of S.S Die, the change in the size of pellet from start to end of die is negligible, where as in case of M.S Die there is a huge difference in the pellet size from start to end. For example in case of M.S. we start the die of 2.5 mm hole size and it ends with 3.0 mm or 3.2 mm, but in case of SS die, if we start with 2.5 mm hole size, it will end with 2.7 mm hole size maximum.
• The life of S.S Die is approximately 3 times the life of M.S Die, which results in reducing the downtime of plant and helps in increasing the capacity of plant and also helps in reducing the maintenance cost.
• In Case of S.S Die there is immediate start up with full production from the time of installation; But M.S Die initially required some time to start up with the full production, which ultimately affects the capacity of plant.
• Pellet made from S.S. Die has better strength as compared to that of M.S Die.
• In Case of S.S Die because of longer working length, the retention time of mash with die is more, which results in the instant rise in temperature, which helps in gelatinization and reduces the bacterial load.
• Problem of Choking of hole is less in our S.S. dies in the comparison of M.S. Dies.

In order for an SS to be magnetic, a couple of requirements need to be met:

• It must have iron in it.
• It must have its crystal structure be arranged in a ferrite or martensitic structure.

If an SS is mostly comprised of an austenite structure, then it will not be magnetic.

Now if we talk about X46Cr13, it has martensitic structure and classifies as Martensitic stainless steel. Due to this reason X46Cr13 attracts magnet.

A die can be re-countered if the counters have worn out pre-maturely. It can be seen if the die working pad is not in the same plain as the depth of internal grooves, it can be re-countered.

Rollover is the condition of the die face when the hole inlets start to peen closed. If the rolls come into contact with the working surface of the die and damage it, laminating its surface and deforms the entrance of the holes. This peening action has disastrous effects on both pellet quality and the die throughput.

When does “rollover” arise?
When the rolls are too close to the die
When the wear ring (or clamping ring) has excessive play
When the main bearings of the die holder assembly have excessive play

What problems can “rollover” cause?
Inadequate production with the motor at full-load
Excess mill vibration & early breakdowns

Pellet quality is usually expressed as the Pellet Durability Index(PDI) and measured by using a tumbling device , in which the pellet sample to be tested is first sieved to remove fines, then tumbled in the tumbling can device for a defined period of time. Then after tumbling we compare the fines produced during tumbling with actual weight.

PDI = weigh of pellet after tumbling / weight of Pellet before tumbling x 100

At PDI lower than 85 pellets tends to break during crumbling; producing more fines which results in more recycling of feed and low final output.

Enlarged holes are counter-bored into the die to reduce its working length and provide the proper compression ratio (L/D) while maintaining the total thickness needed to prevent die breakage. Specific rows of die holes, such as the two inner and outside rows, also sometimes are counter-bored to greater depths to encourage feed flow through these outer rows of holes to help dies wear more evenly, this is referred to as (VR) variable relief. Some examples of various die relief patterns can be seen in this diagram:

Types of relief:

1. NO RELIEF:

This means that the working length or effective length of die hole is equal to the total thickness of die. There is no relief present. Usually in dies which require very less total thickness, for example, sinking fish feed or shrimp feed dies.

2. STRAIGHT or SINGLE STEP RELIEF:

The relief is uniform across the die to obtain the desired effective thickness

3. DUAL STEP RELIEF

This type of relief is normally used in dies with large thickness to maintain the die strength along with the required ease of pelleting.

4. VARIABLE RELIEF:

In this type of relief pattern, the relief on the outer rows is made deeper, reducing the working length of these rows. This is done to prevent uneven wear of die from the outer sides because the powder feed tends to escape from sides due to resistance offered during pelleting. Therefore the purpose is to encourage the pelleting evenly across the die.

5. STAGGERED RELIEF:

This is another type of variable relief. In this case the relief of outer most is deepest and then counter bore depth decreases towards middle lines. The purpose is same as that of variable relief.

6. TAPERED RELIEF

Tapered relief is used for special applications. Holes are gradually tapered out on the outside diameter of die. It is used for spongy materials such as fish feed or alfalfa. The purpose of this relief is that when due to wear, the hole size enlarges thus decreasing the compression ratio, it is partially balanced by this taper.

Fish feed that floats on water surface due to various reasons like low bulk density, air sacs in extruded feed ,low moisture ,buoyancy –water stability &other extrusion properties termed as floating fish feed.

Fish feed manufacturing basically includes following processes as mentioned:

1. Batching (Auto): In automatic plants, weighing of assorted materials is done as per the formulation requirement. This makes one batch, and is called proportioning or batching. Any number of silos of appropriate capacity is incorporated as per the plant capacity. Mostly, two set of silos or bins are installed - one for main ingredients and other for secondary ingredients

Manual:In manual batching – labor weighs each ingredient as per formulation & put directly into the dump hopper at intake elevator

2. Grinding: Grinding is the reduction of particle size, and is a key function of feed manufacturing. In feed mill a grinder is used to improve the handling of ingredients. Also, the grinding improves mixing properties, feed digestibility, acceptability, & extrusion properties. For better results required texture after grinding process is about 250 microns. (Average particle size)

3. Mixing: The feed ingredients are blended in a feed mixing machine homogeneously (grains + medicines + supplements + oils). It counts on the feed preparation and characteristics of the ingredients. Efficient mixing is essential in quality feed production.

Key features of a good mixing system:

• Efficient mixing to accomplish minimum coefficient of variation in minimal time.
• Effective mixer discharging mechanism for no leakage of gates with minimal residue in drum to avoid carry-over to next batch.

4. Conditioning: Conditioning is performed to add moisture & heat in mixed feed to reach gelatinization as well as making the product more pliable for pelleting. A perfect conditioning system should meet the following aspects:

• It should increase the moisture and temperature of product by direct / indirect heating.
• It should provide desirable retention time in the conditioners.

5. Extrusion: As the material leaves the conditioner, it enters the extruder barrel. Here the major transformation of the raw pre-conditioned material occurs which ultimately determines the final product characteristics.

The initial section of the extruder barrel is designed to act as a feeding or metering zone to simply convey the pre-conditioned material away from inlet zone of the barrel and into the extruder. The material then enters a processing zone where this free flowing material is worked into amorphous dough. The compression ratio of the screw profile is increased in this stage to assist in blending water or steam with the raw material. The temperature of the moist dough is rapidly elevated in the final few seconds of dwell time within the extruder barrel.

Most of the temperature rise in the extruder barrel is from mechanical energy dissipated through the rotating screw assisted by direct injection of steam. The moisture addition & properly configured barrel will result in final moisture of 22-25 % & temperature of 110-125 degree Celsius.

6. Drying: The primary purpose of drying is to reduce the level of moisture in an extruded product. For dry expanded extruded products, the final moisture content need to be less than 10 %.

Some of the moisture is lost due to flash evaporation as the superheated product exits the die & expand. Further moisture will be lost through evaporative cooling, as the product cools during conveying to the dryer. In the horizontal conveyor dryer, the product is spread on a belt that moves through the dryer. Heated air is passed through the bed of product at a particular velocity. Speed & air flow can be controlled with the help of Variable Frequency Drives.

7. Coating: Most dry-expanded extruded products for animals operations apply liquid fat or flavors after drying. Coating of warm product before cooling improves absorption. When oil percentage ranges 3-7 % simple drum coater is used and when oil percentage ranges 10-25 % normally vacuum coater is used. Vacuum infusion draws coating liquids into all air cells within the extruded product while atmospheric processes result only in surface coating of the feed.

8.Cooling: The desired feature of an efficient cooler are: It should be capable to remove the unwanted heat and moisture from pellets to improve its shelf life. The cooling should be uniform from all the sides.

Product final moisture should be around 10 % & temperature +/- 5 degree in range with ambient temperature.

9. Screening & Bagging: After cooling it is important to screen out any small pieces or fines that may have developed during the drying, tumbling & cooling operations. Those fines may be recycled back into the raw mix prior to extrusion so that no loss of product occurs.

After screener, the finished product is filled into bags. In small to medium plants, bagging can be carried out manually but for higher output it is better to go for electronic bagging machine. Electronic bagging machine can perform bagging with high accuracy and much faster rate.

Raw materials of floating fish feed mainly includes fish meal, fish oil, DORB, rice polish, de-oiled cakes, minerals & vitamins pre-mix. Starch,Protein, fat & crude fibre are major compounds of fish feed ingredients.

Ingredients selection has a tremendous impact on final product texture, uniformity, extrudability, nutritional quality, and economic viability. Within certain limits set by a nutritionist, the extrusion cooking process can produce a wide range of products. In general, during the extrusion cooking of cereal grain and protein blends, the moistened granular or floury materials are converted into dough. The starchy components gelatinize, resulting in a substantial uptake of moisture and an increase in dough viscosity. Role of few ingredient properties like starch,protein,fiber& fat is as mentioned:

a. Starch: Mainly used for carbohydrate & important source of energy in livestock feed. When gelatinization occurs during extrusion cooking, starch becomes soluble and absorbs large quantities of water. Starch also contributes to both expansion and binding in the final product, especially important for aquatic feed. Floating fish feed required minimum 20 % starch in formula.

b. Protein: Because protein is the most expensive component of fish feed, it is important to accurately determine the protein requirements for each species and life stage cultured. Proteins are formed by linkages of individual amino acids. Although more than 200 amino acids occur in nature, only about 20 amino acids are common. Of these, 10 are essential (indispensable) amino acids that cannot be synthesized by fish.The most common sources ofanimal proteins include fresh meat, poultry byproductmeal, fish meal, meat and bone meal, blood meal, and gelatin.

Protein levels in aquaculture feeds generally average 30 to 35 percent for shrimp, 28-32 percent for catfish, 35-40 percent for tilapia, 38-42 percent for hybrid striped bass, and 40-45 percent for trout and other marine finfish. In general, protein requirements are typically lower for herbivorous fish (plant-eating) and omnivorous fish (plant and animal eaters) than they are for carnivorous (flesh-eating) fish. Protein requirements are higher for fish reared in high-density systems (e.g., recirculating aquaculture) compared to low-density culture (e.g., ponds).Protein requirements are generally higher for smaller as well as early life stage fish. As fish grow larger, their protein requirements usually decrease. Protein requirements also vary with rearing environment, water temperature, and water quality, as well as the genetic composition and feeding rates of the fish. Protein is used for fish growth if adequate levels of fats and carbohydrates (energy) are present in the diet. Proteins are composed of carbon (50 percent), nitrogen (16 percent), oxygen (21.5 percent), and hydrogen (6.5 percent), and other elements (6.0 percent).

Fats /Lipids: Lipids (fats) are high-energy nutrients that can be utilized to partially spare (substitute for) protein in aquaculture feeds. Lipids have about twice the energy density of proteins and carbohydrates. Lipids typically make up about 7-15 percent of fish diets, supply essential fatty acids, and serve as transporters for fat-soluble vitamins.Fat sources include tallow, poultry fat, vegetable oils, marine oils, and various blends from all sources.

Fiber: Within commercial animal feed rations, most definitions of fiber refer to the material present that is neither digested nor absorbed by the animal and which provides physical bulk or substance to a ration. Commodities that have a high protein and low crude fiber content, such as fishmeal, generally have a high economic value; while materials having low protein content and usually a high fiber content, including straw and rice hulls, are generally regarded as having a low economic value.

Minor ingredients: Vitamins are an important category of minor ingredients. Each vitamin has its own characteristic behavior during thermal processing, and some are unstable during storage. Vitamin stability during extrusion cooking is affected by moisture, pressure, shear, and temperature. Fat soluble vitamins, which include vitamins A, D, and E, are fairly stable during extrusion, although 15 to 20 percent losses have been experienced.

Extruders are basically screw pumps through which feed mix is forced and in that process is subjected to heat, pressure & shear forces. Extrusion is a process, which combines several unit operations including mixing,cooking,kneading,shearing, shaping and forming.

It is very crucial for fish farmers to ensure that the fish get all the food they require, both in terms of quantity and quality. In fact, feed accounts for almost 60% of the total production cost. So, farmers need to spend a lot of time and efforts in determining the right feed. Floating feed has so many advantages as mentioned:

a. Feed Utilization: Due to the physical and chemical changes in the extruded process, the extruded feed generally produces powder within 1%, which directly improves the effective use of feed. Under normal circumstances, the use of extruded floating feed to raise fish can save 5-10% of feed compared with powdered feed or other pellet feed.

b. Digestion & absorption: Due to the high temperature and high-pressure processing conditions, the starch in the feed is well matured which is more favorable to digestion and absorption, and the fiber structure and cell wall are destroyed and softened, thereby improving the palatability and digestibility of the feed.

c. Water quality: The extruded floating fish feed will not dissolve in the water for a long time. The floating time of high-quality floating fish feed can be as long as 12 hours, and it is easy to observe and control the bait, reducing or avoiding the influence of powder and residual bait on the water.

d. Observation regarding fish growth, feed requirement & feed intake habits: Since the extruded floating fish feed can float on the water for a long time, the feeding situation of the fish can be observed well after the feeding, and it is convenient to adjust the feeding amount according to the requirement of the fish; at the same time, it can be more accurately- according to the changes of the fish feeding amount and understand the growth & health status of the fish feeding on the surface.

e. Wide range of feed size: Due to high pressure, temperature & moisture range we can get wide range of feed size from extruder die, ranges from 0.8 mm to 5 mm; as per fish growth & species.

A. Site & Project Selection:
a. Location: Condition of roads , availability of power , water and manpower , drainage & nature of soil , water level , federal and local regulations for pollution & air quality , attitude of local people and government towards a new feed manufacturing unit , taxation and subsidy rules etc. All these factors must be taken into consideration while selecting a site for feed mill.

b. Feed mill Design: Plant layout design plays an important part in the design and engineering phases of any industrial facility. Ease of operation; avoiding disturbance in material flow i.e. raw material & finish goods, sufficient space for turning of vehicles , space for movement of fire fighting vehicle, parking , other utilities like Boiler , Weigh Bridge , Electric Transformer , Bulk storage for oil & water as per ease in operating & material handling.

c. Warehouse size for Raw material & Machines: Minimum 12000 sq. ft. godown for raw material , finish goods & machines is required to run 2 tph project . Project can be installed In-line , L shape or C shape as per space availability .

d. Provision for future Expansion: Selecting layout with no room for expansion is a mistake. Even with the best planning, most successful plants will make changes in future years that could not have been foreseen. Therefore, it is wise to allocate some area of the site for future growth and expansion. And always select the location of feed mill in such a way that there should be space for expansion towards the raw material godown (In direction of chain conveyor).

B. Machines & Technology- Desired Features :
a. Hammer Mill: Can Provide 250 micron average particle size with minimum power consumption & operational cost, low in maintenance & ease in operation.

b. Mixer: Can provide good homogeneous mixed feed with minimum heat generation & CV <=5.

c. Extruder: low Power consumption, provision of steam & water addition, VFD at Main motor & Cutter assembly, Heavy duty gearbox, can provide 0.8 mm to 5 mm pellet, ease in operation & low in maintenance. Good grade – hardened alloy steel material for screw & barrel with precise machining.

d. Dryer: Air quantity, feeding speed, belt speed can be adjusted as per requirement. Good grade stainless steel for better life. Ease in operation, low in power & steam consumption. Provision to clean last layer of bed – dust /left over material. Feed spreader – for uniform layer of feed. Adjustments for different diameter pellets – 0.8 mm to 5 mm.

e. Coater: Dosing adjustments with uniform spray arrangement.

f. Cooler: Good feed distributionarrangement for uniform bed level, adjustments in level sensors as per bed level required, minimum dead angles /corners to avoid cross contamination, provision of bed adjustment during power failure.

g. Screening: Good light weight design to minimize power consumption & fatigue failure. Self-cleaning provision for better efficiency.

C. Raw material or Formulation: Raw materials of floating fish feed mainly includes fish meal, fish oil, DORB, rice polish, de-oiled cakes, minerals & vitamins pre-mix. Starch, Protein, fat & crude fibre are major compounds of fish feed ingredients. If we talk about typical pangasius fish formulation – protein range is about 26-32 % , starch 18-22 % , lipids /fats -5-8 % &fibre approx. 8-12 % ( depends upon fish size, breed & weather condition ) .

D. Process & Operating Parameters:

• Particle size: Particle size before extruder should be in range of 220-250 microns.
• Moisture: Moisture range in raw material before grinding should be in range of 9-12 % , after extrusion in range of 18-24 % , after dryer : 14-18 % and after cooler below 10 % .
• Temperature: Temperature after extrusion should be in range of 110- 125 degree Celsius.

E. Cost of feed Production:Feed productioncost mainlyincludes:

a. Raw material: Considering a sample formulation as mentioned (just reference data):
Soya Doc – 220 kg @ 38-42 rs , Mustard oil cake – 185 kg @ 17-19 rs , wheat Flour – 220 kg @ 19-22 kg , rice flour -170 kg @ 19-22 kg , Fish Meal – 60 kg @ 37-40 rs , Shrimp meal – 70 kg @ 50-60 rs , Veg Oil -50 kg @ 55-65 rs , vitamin / Pre mix – 15 kg @ 180-210 rs , CMC,Anitioxidants , Carotenoid - @ 190-210 rs = average cost per kg of whole batch will be around 30-32 rs

b. Production cost: Production cost is inversely promotion to the quantity of feed produced – less for 5 TPH project & more for 2 TPH project. Production cost mainly includes – Power , Boiler & labor = Total of these three will be around 2.6-2.8rs /ton ( approx.)– considering 250 KW power connection for 2 ton project ( running + fixed charges ) + 0.5 rs /kg of wood + labor charges approx. 0.35 rs /kg of feed production.

c. Maintenance /Consumable parts –This includes cost of wearing parts like dies , cutters , screw , barrel , beaters , screens , elevator belts , pneumatic & electrical maintenance , gear oil , grease , water , stationery etc.

d. Over-heads /Staff: This includes staff salaries,incentives, travel expenses,security , dealer margin etc.

e. Packaging: That includes HDPE bag cost

f. Other indirect expenses: Includes marketing, branding &promotions, bad debts , bank interest etc.

F. Final Feed characteristics: Main Characteristic of floating fish feed is floatability as mentioned:

a. Floatability:The water stability of fish feed pellet refers to the performance of keeping constituent from dissolution and diffusion after fish feed soaked in water for a certain period time. Floatability mainly depends upon formulation & grains (specially starch content) , binding agents /oils in formulation , particle size , conditioning in pre-conditioners & gelatinization , heat –shear force & moisture in extrusion , buoyancy – combination of surface area – bulk density & water stability.