Types and Functions of Milling Machines

December 15, 2022May 27, 2023 Agric4Profits

A milling machine is a tool in the metal industry that has numerous functions. Each machines as a cutter that operates at a various range of speed so you can form the required shape.

With its adjustable feature, each milling machine can be regulated for a more precise cut. The machines is capable of handling multiple tasks such as carving, threading, milling, drilling and cutting.

Milling machines comes in various types with a variety of functions based on certain standard specifications. Some of the commonly used machines are the following:

1. Hammer Milling

In the feed process there maybe a number of ingredients that requires some form of processing.

These feed ingredients include coarse cereal grains, corn which require particle size reduction which require particle size reduction which improve the performance of the ingredient and increase the nutritive value.

Advantages

Are able to produce a wide range of particle sizes
Ease of use
Lower initial investment when compared with a roller mill
Minimal maintenance needed
Particles produced using a surface that appears polished.

Disadvantages

Less energy efficient when compared to a roller mill
May generate heat (source of energy loss)
Produce greater particle size variability (less uniform)
Hammer mills are noisy and can generate dust pollution.

2. Feed Mixer

The feed will not be the balanced formulation it is designed to be unless it is properly mixed. Dry mixers are a mechanical means of achieving this and come in two (2) main types – vertical mixers and horizontal mixers.

The Vertical Mixer consists of one or more vertical screws which elevate the ingredients to the top of the mixer where they fall by gravity to the bottom, to be mixed and re-elevated. Vertical mixers are the most common type found in small livestock feed mills.

However, the vertical type is less well suited to aquaculture, poultry and fish feeds than the horizontal type, which are much more efficient in blending in small quantities of liquids (such as added lipids) or in mixing ingredients with different particle sizes.

The Horizontal Mixers consist of a series of paddles or metal ribbon mounted on a horizontal rotor within a semi-circular trough. The Mixers usually discharge the mixed product from the bottom, using the same mixer blade action.

Another type of mixer, which is similar to the horizontal type in action, has a bowl- shaped or flat-bottomed container in which a series of paddles are mounted on a spindle driven by a motor mounted either above or below the mixer.

This type of mixer has the same advantages over the vertical type of mixer as the horizontal mixers mentioned earlier.

In addition it is cheap and is therefore frequently used in farms, particularly in South East and South Asia. It can also be used for mixing moist feeds.

Vertical mixers are unsuitable for mixing wet ingredients. Horizontal mixers are most suitable but, because of their complex construction, are often difficult to clean properly. Efficient mixing is the key to good feed production.

Pellet Mills

The process of pelleting consists of forcing a soft feed through holes in a metal die plate to form compacted pellets which are then cut to a pre-determine size.

The machinery which has been developed for this purpose is now very diverse in design and there is much controversy between different equipment manufacturers as to which type is the most effective.

Pelleting is a key to the production of high quality nutritional feeds as they ensure that the feed formulation is in the correct quantities for all that eat them. Each bite of a pellet will have the same designed formulation ensuring all the stock are feed as intended.

Most pellet mills now have one or more conditioning units mounted above them where liquids such as water and molasses can be added to improve pelletability.

The water is sometimes added in the form of steam which softens the feed and partially gelatinizes the starch content of the ingredients, resulting in firmer (and for aquafeed more water solubles) pellets.

Extruders

Extruders are the machinery used to produce extruded pet food, (floating) extruded aquatic feeds and extruded animal feeds. The extrusion cooking process, because it causes a high level gelatinization of starches, results in feeds with good water stability.

It can produce expanded floating feed as well as sinking pellets. The process also improves the digestibility of the products. However, extrusion cookers are usually very large and expensive to purchase and operate.

Feeds which have ingredients such as soyabean meal and cereal grains can be made more digestible, and the nutrient are therefore more available.

Floating feeds are made using extruders along with highly water-stable sinking feeds which can be made with extruders as well.

In some cases, extruders are used just to prepare feed materials, such as dry extrusion of soyabeans.

Basically, an extruder is a long barrel with a screw auger inside which is specially design to subject feed mixtures to high heat and steam pressure.

When feed exit the die at the end of the barrel, trapped steam blows off rapidly, the soft warm pellets expand, and a low density floating pellet is produce.

Extruders are very versatile, and can make feed with many different characteristics. The main problem with extruders is that, they are expensive to buy and maintain, and the feed manufacturers pass this cost on to feed buyers.

Crumbler (Pellet Feed)

A crumbler is a roller mill with rolls specially designed for breaking up pellets into smallers particles. Usually, the crumbler consist of two (2) corrugated rolls situated below the cooler/dryer exit.

The pellet can then be diverted into the crumbler, if crumbles or granules are desired, or they can bypass it.

Dryers (Pellet Feed)

Pellets from dry pelletters may exceeds at up 88⁰C and 17 -18% moisture. The temperature must be quickly reduced to an ambient or less and the moisture level to 10-12% or less for proper storage and handling.

Pellets must therefore be cooled or dried. Moist pellets, if they are going to be converted to dry pellets, also need drying although their temperature is not normally much elevated during manufacture.

Coolers/Dryers are of two (2) basic types namely Horizontal and Vertical.

In the Horizontal type of cooler/dryer the pellets are conveyed on a perforated steel mesh or moving belt through which a cooling air stream is passed.

The horizontal method is best for sticky dry pellets or for moist feeds (if it is necessary to dry the latter).

Heat can also be applied to the air supplied to horizontal driers for reducing the high moisture contents of moist feeds to those of dry pellets for storage.

This type of drier is standard in production in production of noodles and spaghetti and other pastas. Horizontal dryers may be very large and often arranged on several spatial levels.

In the Verticaltype of dryer, pellets usually run by gravity into a chamber through which air is sucked by a fan.

Other milling machines include the following;

1. Column

This is the most common milling machine which has 5 basic components, they are the work table, saddle, head, knee and over arm.

Considered as the simplest machine type, its cutting device is vertically suspended to all cutting device is vertically suspended to allow drilling of metals. This is typically used when creating car parts because it is small and handy.

2. Turret

The turret is also known as the Bridge port-type and can be reposition anytime you want making this machine very functional.

Its versatility makes it more practical since a variety of products can be made in addition to car parts.

3. C-frame

Because it is sturdier than a turret, this type is popular in industrial settings. It comes with a hydraulic motor, which makes it very powerful.

4. Horizontal

The machine runs parallel to the ground. The table from which the object to be worked on is placed moves sideways while the cutting device goes up and down.

5. Bed type

The worktable is located on the bed itself, instead of being paced on top, its usual position. The knee part of the machine is omitted to allow movement in a longitudinal direction.

6. Planer-style

This machine type is basically the same as the bed mill. However, the planner- style includes cutters and heads that allow for a wider range of milling actions.

7. Tracer controlled

This type o machine has the ability to reproduce parts based on master model. Most of the industrial sectors, especially the automotive industry, choose this type of machine because it make production and specialization of machine parts easier.

With the vast classifications of milling machines, you need to choose the one you need according to how you intend to use it. However if you find it difficult to decide, do not hesitate to seek the help a specialist who can help you select the one that will give you maximum benefits.

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Types and Functions of Milling Machines