Monday, 20 May 2019


          The paper machine headbox is an equipment that supply low consistancy pulp (stock) uniformly into the forming section. The formation and uniformity if the final paper product depends on the dispersion of fibre and fillers. Machine headbox had major effect on paper qualities. There are different types of headboxes are present, all are not suitable for for all grades and types of paper and machine speed. Awell constructed headbox will give good quality paper. So the design headbox should be proper. The headbox is also called as "Stuffbox" or "Flowbox". 

Paper machine headbox types:

          In general the Headbox is catogarised into 3 major types, as Open type, Air padded type, and Hydraulic type.
         Hydraulic type of headbox is designed for high speed paper machines (speed above 350 m/min). Whereas open type open type headbox is designed for low speed paper machine. In Hydraulic and Air padded headedbox, the discharge velocity from the slice depends on the feeding pump. For this reason they are generally called as "Pressurised Headbox". The hydraulic headbox has no air pad, it is fully closed.
          Incase of air padded headbox pond level is maintained. Above the pond level it containes pressuried air. To maintain this air pressure we use headbox blowers. The stock level is known as Head, which is controlled by air pressure. The head determines the slice jet velocity or speed. These type of headboxes contains two or three "Holey rolls or rectifier rolls", and a "headbox shower".
          Multi layered headbox is available for making Tissue paper and light weight container board. Foe each layer it has different furnish compositions and delivary system.

Headbox jet velocity calculation:

          Jet velocity is the very important factor in the manufacturing of high quality paper. We have to maintain jet-to-wire velocity ratio; 0.97 to 1.03. The headbox jet velocity can be calculated from Bernoulli's equation:

Headbox Functions:

           The headbox serves many functions among them the following three functions are very important in the paper production process. If the headbox doesnot perform these three functions acceptbly, the quality of the paper produced will be greatly diminished.

1. Spread the low consistancy stock uniformly along the width of the wire.
2. Accelerate the stock and maintain constant velocity according to the paper machine operating speed.
3. Create control turbulance and suspend the pulp fibres throughout the out going slurry to eliminate fibre gathering.

Parts of Headbox:

The Headbox generally contains following parts:

1. Diffuser
2. Compressor line
3. Holly rolls
4. Rotating shower
5. Bottom lip
6. Top lip

Holey roll or Rectifier roll or evenor roll:

These rolls are genreally 2 to 3 present in headbox. These rolls are used for controlling both even outflow irregularities and to create turbulance to keep the fibre dispersed up to the slice opening. Normally hole diameter is 3 to 4 cm.

Rotating shower:

          This shower is used for continous headbox cleaning purpose and also consistancy maintenance.

Paper machine headbox slice:

          The paper machine headbox slice is a full width nozzle with a completely adjustable opening to give the desired rate of flow. The slice contains two lips; Top lip and Bottom lip. Among them bottom lip is adjustable; we can up or down or move sides also by hand operated or motor driven. On the otherhand top lip is fixed. The distance between the top lips are called Slice opening. The slice opening controls the stock jet velocity which is very importnat for the paper fromation.
The slice spindle contains a gearbox, connecting rod, Spindle, and hook which lifts bottom lip. 

Wednesday, 15 May 2019


          A Screw conveyor or Auger conveyor is a mechanism that uses a rotating helical screw, usually within a tube (Trough), to move liquid or grannular materials. The rotating part of this type of conveyor is called Auger.

          Screw conveyor in modern industry are often used horizontally or at a slight inclined as an efficient way to move semi-solid materials, including food waste, boiler ash, powder materials, agricultural material and many other. The first type of screw conveyor was the Archimede's screw, used since ancient times to pump irrigation water.

          They usually oncist a trough or tube containing either a spiral blade coiled around a shaft, driven at one end and held at the other end, or a "Shaftless spiral", driven at one end and free at other end. The rotational rate of shaft is directly proportional to the rate of material transfer.

          Screw conveyors can be operated with the flow of material inclined upward. As the angle of inclination increases, the capasity of a given unit rapidly decreases.

Types of screw conveyors:

1) Horizontal screw conveyor
2) Inclined screw conveyor
3) Shaft less screw conveyor
4) Vertical screw conveyor

Source take from Wikipedia

Monday, 6 May 2019


Mechanical Seals are the devices which arrests leakage of fluids when joined the parts or mechanisms together. Mechanical seals are available in different designs. We have to understand first how they function, it will help us to select the suitable for our application.
Different types of mechanical seals are mentioned below they are:
1. Conventional
2. Pusher
3. Non-Pusher
4. Blanced
5. Unbalanced
6. Cartridge 
7. Cortage

1. Pusher type:

Saturday, 4 May 2019



          Air knocker is a kind of process automation equipment, designed to eliminate problems occuring due to the deposition of powder inside a hopper. This equipment consists of a "Magnetic Piston". Due to the interaction between Magnetic Piston and Air pressure this equipment dislodges some force on hopper. 



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