CONTROLS IN THE PRODUCTION PROCESS OF OUR CHAMPAGNE CORKS "BAC"
2. MONITORING DURING MANUFACTURING
2.1 Granulated cork substance
Before being used, the granulated cork substance is cleansed of any dust that may have accumulated and adjusted to the correct moisture level (6-8%). It is passed through a set of sieves to get rid of both very large and very small grains in addition to any extraneous material. In this way, uniformity of the granulometry of this granulated substance is obtained.
2.2 Agglomerated cork
During the manufacturing of the bars
of agglomerated cork, the relative humidity of the environment
is monitored constantly, as is the temperature of the reaction
chambers, the speed of formation and the state of polymerisation
(see Picture 6).
The average density of the agglomerate is maintained at 270 kg/m3.
The recovery power is:
Instantaneous: 92-94%
After 24 hours: 95-97%
To ensure that compression is uniform,
the bars of agglomerate are weighed one by one in a machine which
in turn classifies them by weight. The newly formed bars then
begin their minimum repose period of 15 days to ensure total
polymerisation of the binder (polyurethane glue) as well as physical
recovery of the cork, before they are cut to obtain the agglomerate
units that will be joined to the natural cork discs. In this
way, the state of polymerisation of the glue attains values of
between 97 and 100% (see Pictures).
2.3 Disc classification
Following prior classification by our suppliers, all discs are hand selected to eliminate critical flaws such as green or woody cork, dry vein and so on. They then undergo a further selection process by means of an electronic machine (see Picture 7), which separates them into different categories, so that well-defined qualities can emerge from the following phase of production, glueing.
2.4 Disc glueing
The state of the glue (rheology) and its correct application (visually) are monitored. Once glued, drying is carried out at a moderate temperature so as not to alter either the state of the glue or the structure of the cork. For correct drying-hardening of the glue and to ensure the recovery of the natural cork, corks should be left in repose for 8-10 days with monitoring of the state of the glueing based on the moisture present in the glued areas. Data is noted on a control sheet, to be kept together with other documents in a specific envelope for each order.
2.5 Subsequent calibration of corks
Corks are calibrated according to the demands of each customer, with a permitted tolerance level of 0.3 mm for diameter and 0.5 mm for length. Disc thickness must be 11.0 mm ( 1.0 mm.
The parameters of diameter, length
and bevelling are monitored every hour and noted on the corresponding
control sheet.
2.6 Subsequent classification of corks
After calibration, which also includes bevelling, and a subsequent dimensions check, the corks are classified by an electronic machine that monitors both the quality of the disc and the sides of the cork.
Next, each of these qualities is revised, by manual selection, to eliminate any cork flaws that the optics of this machine have been unable to detect, such as, for example, dozy cork, green cork and abnormal growths.
Once this selection has taken place,
the section head proceeds to a final revision of the visual quality,
comparing the sampling carried out in each lot with the standard
samples of each quality. The cork dimensions are then monitored
once again. The sampling accomplished and the results of this
monitoring are noted down and kept in a specific envelope for
this purpose. Should the results prove to be unsatisfactory,
a new selection will get underway to achieve the correct quality.
2.7 Marking de corks
Before marking gets underway, the corks are checked once again for quality and dimensions. Using a control sheet, the section head monitors the correct composition of the marking. The clearness of the brands and the dimensions of the corks, including the bevel edge, are checked every hour. These observations are noted on the corresponding sheet, which is kept in the proper envelope.
2.8 Final treatment
Before the final treatment gets underway,
the section head carries out an entry-acceptance check. He will
ensure that the quality, dimensions and brand of the corks that
have to be treated are correct and tally with the order. Only
after this test will the corks receive approval for their subsequent
treatment, which begins with the dust-elimination process.
The emulsions used for the treatment are authorised according
to alimentary standards.
A double circuit ensures correct vacuum packing in a sulphur
dioxide (SO2) environment in polyethylene sacks.
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