Forming and NNPB Process .Some notes

Process and products:

PROCESS ARTICLES

Pressing Kitchen,Table Vesseles

Pots,Lenses and Bricks,

Spinning Plates, cathode tubes (Centrifugal Casting)

Blow Blow Bottles

Press Blow Jars,Light Bottles

Press Blow-spin Goblets, laboratory tools

The production of glass containers is a very complex and demanding procedure, which has to be very well controlled and adjusted in order to produce glass containers that satisfy even the most demanding customers, at the same time being competitive on the market. Glass containers have to be maximally light, as well as less expensive. At the same time, glass has to face internal pressure, thermal shocks (pasteurization), and Impact( GOOD QUALITY CONTROL LAB). For the glass containers to be able to meet these requirements, apart from a well-designed container (GOOD DESIGN) it is necessary to achieve excellent glass distribution (uniform thickness of glass container wall), which can be achieved by the production procedure of NNPB (narrow neck press and blow process).

NNPB is usually used for the production of large quantities of light glass containers. To produce glass containers using this production process, constant (uniform) weight have to be ensured so that the entire forming process could be optimally adjusted. The machine operates 24 h a day, 7 days a week, and it is very hard to maintain manually uniform glass gob weight. We had better to install a system which may insure uniform weight of the glass gobs GOB WEIGHT CONTROLLER AND PROCESS CONTROL .At least Blank Capacity Control and Discipline on the Hot End is essential.

A large number of parameters on the furnace and on the glass container producing machine have to be correctly adjusted in order to produce high-quality glass containers.

The raw materials used for the production of glass should have constant chemical composition, optimal grain size, minimal humidity percentage, and minimal content of harmful additives. Also, glass cullet represents a large share in the input raw material. Cullet should be controlled . It should be chemically known and identified as local and foreign. All these raw materials are supplied to the compound mixers where they are mixed and wetted. The melting and the glass quality depend largely on the homogeneity and humidity of the compound.

GLASS TECHNOLOGY MANAGEMENT is necessary. Glass Composition Analysiz Instrument is necessary.

Using belt conveyors the compound is delivered to the furnace storage silos and by means of a batch charger fed into the furnace. The melting of the compound is carried out in the furnaces at a temperature of about 1550-1650 C where the mixed raw materials are transformed into a glass melt. From the furnace the melt is supplied via channels to the feeder. The channel behaves as a pipeline through which the glass melt flows from the furnace to the feeder mechanism, and at the same time acts as a heat exchanger, and has the function of creating homogeneity in glass, its temperature and composition . Thus formed glass flow is cut into single gobs using the shears which act in accordance with the plunger of the feeder mechanism and glass container producing machine. These glass gobs are distributed via the gob distributor and delivery system to certain sections of the blank mould side of the glass container producing machine. In the blank mould side a parison is formed, then transferred to the mould side which this parison is blown in the mould thus acquiring its final form . From the mould side of the glass container producing machine the finished glass containers, after the first visual inspection, are transported to the hot coating unit and further to the tempering furnace. The coating technology is routinely used to protect the external surface of the containers. Firstly, the coatings are deposited at high temperatures (so-called hot-end coatings

(HECs) 500 C). HECs are usually a hard ceramic material. These materials are added immediately after forming when the container surface is still hot. Hence, these coatings offer good adhesion and strength. These reduce further contact damage . Then the containers are sent through a controlled cooling process, known as annealing, which allows containers to cool down to room temperature in a stress-free condition . What follows is the optical, mechanical, and electronic testing of the produced glass containers automatically removing bottles with cracks, inserts, deformations and other defects.QUALITY CONTROL & HOT END MANEGMENT

Fig. 1 shows the technological scheme of the production procedure of glass packaging material

Shaping of glass gob:

Four primary operations for glass manufacturing are: batching, melting, fining and forming . Batching, melting and fining operations are common to all glass manufacturing processes with some variations according to the furnace type. Shaping of glass gobs starts with batching and melting, and after conditioning to the desired temperature, the hot gob (molten glass) is transferred from the furnace to the forming operations through gob feeders .

Using the pull of gravity, glass moves from the melting tank to the forming machine;

The gob feeder controls the weight, temperature and the shape of the gob, all of which are critical to container quality . Glass flow is controlled by the height of the tube in the feeder

. The glass flow undergoes a ‘‘mixing action’’ created by the rotation of the cylindrical ceramic tube. This helps to make the temperature consistent while the downward motion of the plunger accelerates the glass flow. This pumping action is timed with the shearing of the glass flow as it falls beneath the feeder to shape the falling gobs.

The gobs contain the correct volume of glass to make one container. After the gob has been sheared from the feeder it falls into a series of troughs and deflectors where it is delivered to the blank mould on the I.S. machine .

NNPB FORMING:

Gobs enter the I.S. machine and are formed into containers through a process of controlled shaping and cooling of the glass. The machines have anywhere from 6 to 20 sections and each section can produce one to four bottles simultaneously. The total time needed to produce a container varies, but beer and soda bottles take approximately 10 s. Depending on the container’s size and shape, the machine production speed may be as fast as 700 containers/min .

COOLING ON BLANK CONTROLLED IS ESSENTIAL.PLUNGER AND BAFFLE FIXTURES ARE NECESSARY.

Three moulds are used:

- the blank mould,

- the finishing mould,

- the neckring .

The neckring mould is used throughout the process and allows for forming the neck and transferring the parison from the parison mould to the finishing one.

This process starts with gob feeding .

In the press-blow process a metal plunger ( is used to press the parison against the blank mould) . PLUNGER PRESSURE CONTROLLED IS NECESSARY.LUBRICATION OF PLUNGER MEC. IS ALSO ESSENTIAL.

Next the parison is transferred into the blowing section . The final shape is obtained after blowing the parison into the forming mould . The container is then transferred on a chain belt, annealed and treated . Annealing of the glass allows removal of the residual stresses from containers that are formed rapidly from elevated temperatures .

Temperature control is essential to control the glass flow and distribution. It should be noted that the glass elongation under its own load (sagging) is to be considered to achieve optimized distribution of glass. This has become a technological challenge when fabricating light bottles HOMOGENOUS GLASS FROM THE FOREHEARTH. Also, the control of the adhesion between the metal tools and the hot glass requires careful control of the working temperature . While forming, heat is extracted from the glass in a controlled manner. The moulds have to be made of good thermal conductors with a smooth surface aspect GOOD MOLD WORKSHOP and lubricated. These properties determine the forming step and external surface quality . The press-and-blow process has a better control of the shape of the parison and hence of the glass distribution. For obvious economical reasons the glass distribution is optimized to allow for production gains.

Notably, in the press-and blow process internal defects are introduced by the plunger when it comes in contact with the glass parison. These defects affect the mechanical performance of the bottles.