New Journal of Glass and Ceramics, 2011, 1, 79-91
doi:10.4236/njgc.2011.13013 Published Online October 2011 (http://www.SciRP.org/journal/njgc)
Copyright © 2011 SciRes. NJGC
79
A New Way to Improve Thermal Capacities of
Lubricants for the Manufacture of Flint Glass
Perfume Bottles: Part A—How to Combine
Thermal Analysis and Physico-Chemical
Observations at the Glass/Punch Interface
Philippe Moreau1,2, Dominique Lochegnies1,2, Christine Kermel3, Jean-Marc Carpentier3,
Hugues Vivier4
1PRES Université Lille Nord de France, Lille, France; 2UVHC, TEMPO, Valenciennes, France; 3BCRC, Avenue Gouverneur Cornez,
Mons, Belgium; 4SOGELUB® Special Lubricants, Marquain, Belgium.
Email: philippe.moreau@univ-valenciennes.fr
Received September 6th, 2011; revised October 8th, 2011; accepted October 15th, 2011.
ABSTRACT
In the hollow glass industry, the success of the forming process depends on controlling the thermal exchange at the
glass/mold interface to prevent defects on the glass surface. In the manufacturing process for luxury perfume bottles,
the current practice is to depo sit a resin film on the inner faces of the mold at the beginning of the production process
and regularly swab the mold with a lubricating paste. This study presents a new way to analyze the impact of lubrica-
tion on glass/tool thermal exchanges. The TEMPO Laboratory (Valenciennes, France) has an experimental Glass/Tool
Interaction (GTI) platform, which is a reduced-scale production unit that allows researchers to reproduce the pressing
cycle conditions encountered in the glass industry. To complete the analysis of the thermal exchange at the glass/tool
interface, the BCR Center (Mons, Belgium) took physico-chemical measurements on the produced glass samples after
the trials on the GTI platform. Part A presen ts the experimental conditions on the GTI platform and the therma l analy-
sis with this platform for the first case of flint glass pressing cycles with a punch swabbed with a lubricating paste de-
veloped by our partner, SOGELUB® Special Lubricants Company (Marquain, Belgium). The analysis of the phys-
ico-chemical changes on the pressed glass samples produced with the swabbed punch were completed with our obser-
vations using a Sc an n i n g El ect ron Microscope (SEM) with Energy Dispersive Spectroscopy (EDS).
Keywords: Glass Forming, Lubrication, Pressing, Heat Transfer, Glass/Tool Contact, Physico-Chemical Analysis
1. Introduction
In hollow glass industry, the thermal exchanges at the
glass/tool interface during the forming process are essen-
tial for the final quality of the glass products. Inappropri-
ate thermal conditions lead to the formation of defects on
the glass surface, the adhesion/sticking of the glass to the
forming tools and the rapid damage of these tools. The
heat exchange between the glass and the tools depends
mainly on the initial temperatures of glass and tools, the
materials composing the tools, the tool’s roughness and
the contact pressure between the glass and the tools. The
presence of lubrication between the glass and the tools
also contributes to the success of the forming process. By
preventing the direct glass/metal contact, the lubrication
limits the heat exchange between the glass and the tool,
thus making it possible to not reach critical temperatures
that lead to sticking.
For studies of the glass/tool contact, experimental
platforms have been designed to better understand the
heat exchange during the glass/tool contact [1-3] or to
analyze the adhesion [4-6] and sticking [5-9] events be-
tween the glass and the tool. The main goal is to repro-
duce the industrial forming conditions for the glass con-
tainer production [1-4,7,9] or for the precision molding
of optical components [5,6,8]. These are high tempera-
ture experimental platforms in which the glass (e.g., soda
lime silica glass, borosilicate, lead crystal, flint glass,
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles:
80
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
coloured glass) is heated to a temperature between 900˚C
and 1200˚C. The metal sample (e.g., cast iron, bronze,
stainless steel) standing for the tool has an initial tem-
perature between 450˚C and 750˚C.
All these platforms are instrumented with thermocou-
ples in the metal sample near to the contact surface. Höhne
et al. [2] also placed thermocouples in the glass. De-
pending on the platform, infrared pyrometers are used to
measure the glass temperature before contact, effort sen-
sors are used to control the contact force or to record the
sticking force, and/or rapid cameras are used to film the
process. In terms of the authors’ objectives, the contact
between glass and metal is made with a uncoated tool
[1,2,7,9], a coated tool [5,6,8] or a lubricated tool [3,4].
In these experiments carried out on these experimental
platforms, three approaches were used to bring the glass
into contact with the metallic support.
• The first one involved spreading molten glass beads
[4] or glass gobs [7] on flat metallic substrates, with the
objective of analyzing the adhesion between the glass
and the metal. This approach was based on a photoelec-
tric timing unit that detected the progression of the glass
flow [4] or a rapid camera that filmed the glass flow [7].
• In the second approach, the glass was contained in-
side a crucible. Either the punch contacted the hot glass
according to the required contact pressure [2,3,5,8] or the
glass contacted the punch after the blowing operation [1].
In our first three references [1-3], the glass/tool contact
was thermally characterized using a temperature meas-
urement obtained by the thermocouples located close to
the tool/glass contact surface [1-3] and in the glass [2]. In
Manns et al. [5] and Fischbach et al. [8], the glass/tool
adhesion was investigated using the measurements from
transducer load cell.
• In the third approach, small gobs (weight < 5g)
were pressed between two flat heated substrates in a ho-
rizontal [6] or vertical position [9]. After pressing, the
small gob was detached from the two flat substrates. Rie-
ser et al. [6] measured the separation time, called stick-
ing time, in terms of the initial substrate temperature.
Falipou & Donnet [9] measured the strength of the glass/-
substrate separation with a force transducer.
Among all these platforms for analyzing the thermal
and mechanical behaviors at glass/tool interface, only
three studies [5,6,9] allowed the glass to contact the tool
during the pressing cycle, as in industrial situations. The
solution of these authors was to reproduce the frequency
and duration of the contact between the glass and the tool,
with the goal being to reproduce the thermal cycle of
industrial tools within the experimental platform’s metallic
support and to detect the important forming parameters
that lead to the glass sticking to the tool.
In addition to the experiments on their platform, cer-
tain authors examined the metal and glass surfaces, be-
fore and after the contact, with Atomic Force Micros-
copy (AFM) [7] or optical profilometers [8]. The objective
was to study the surface morphology or the corrosion
state of the contact surface. Other authors determined the
surface composition of the contacting materials using
measurements made with an Scanning Electron Microscopy
equipped with energy-dispersive X-ray Spectroscopy
(SEM/EDX) [5,7-9] and X-ray Photoelectron Spectros-
copy (XPS) [9].
This study proposes a new way to analyze the impact
of the lubrication on glass/tool thermal exchanges in the
manufacturing of luxury perfume bottles. The TEMPO
Laboratory has an experimental Glass/Tool Interaction
(GTI) platform, which is a reduced-scale production unit
that allows researchers to reproduce the pressing cycle
conditions encountered in the glass industry. Part A of
this study defines the joint experiment carried out by the
TEMPO Laboratory and the BCR Center to analyze the
lubrication’s impact on thermal exchanges and physico-
chemical changes at the glass/tool interface. Part A pre-
sents our experimental conditions and the available ther-
mal results on the GTI platform for the case of contact
between flint glass and a punch swabbed with the lubri-
cant developed by our partner, SOGELUB® Special Lubri-
cants Company. To complete the analysis, the BCR Center
took physico-chemical measurements on the glass samples
produced after trial. Part B of this study presents our
analysis of the different lubrication situations under in-
dustrial processing conditions.
2. The Glass/Tool Interaction Platform
In order to continue its investigations on the glass/tool
interface [10], the Glass Forming and Tempering (GFT)
research team in the TEMPO Laboratory (Valenciennes,
France) purchased a Glass/Tool Interaction (GTI) plat-
form in July 2007. This platform is a small production
unit designed by the Philips Glass Research Center in
Eindhoven (Netherlands). With GTI, this Center conduc-
ted investigations on the glass/tool interface with their
production units to manufacture cathode ray tube (CRT)
TV screens. For the GFT research team, the main object-
ive of purchasing the GTI platform was to investigate the
thermal impact of lubrication at the glass/tool interface
under industrial processing conditions.
2.1. The GTI Platform and Its Components
First The GTI platform is composed of four main parts:
the furnace, the cutting device, the pressing device, and
the computer-aided control and acquisition system (Fig-
ure 1(a)).
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles: 81
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
• Furnace: The furnace is composed of an Inconel tank,
which can be filled with 40 dm3 of cullet. This tank is
placed in a 10kW electric furnace. The maximum tem-
perature for melting the glass is 1060˚C. At this tem-
perature level, the molten glass flows by gravity through
the cylindrical tube located in the tank center. There is an
electrical resistance around the tube to increase the glass
temperature up to a maximum of 1130˚C, thus adjusting
the flow rate to the desired level.
• Cutting device: The glass flow is automatically cut
into gobs by the controlled shear blades of the cutting de-
vice. The cutting time and the glass temperature at the
furnace tube exit determine the gob weight. For example,
with an interval of 7s between two cuts and a flint glass tem-
perature of 1100˚C, the weight of the gob is close to 40g.
• Pressing device: The glass gob is then transferred
into the pressing device via a delivery mechanism, which
then drops one of three molds on the mold conveyor (Fi-
gure 1(a) and 1(b)). The conveyor rotates, and the glass gob
is pressed by the punch according to the preset forming
parameters given by the control system (Figure 1(a)). (More
details on the pressing operation are given in section 2.2.)
Mold 1
Mold 2
Cutting
device Computer
control and
acquisition
system
Mold 3
Furnace
(a)
(
b
)
Pressing
device
Figure 1. The Glass Tool Interaction platform: (a) the four
main parts, (b) the three molds placed on the mold con-
veyor belt.
The punch temperature on the GTI platform may be ad-
justed between 20˚C and 700˚C, and the contact pressure
between 0.1MPa and 0.6MPa. Depending on the glass
weight, the sample produced by pressing on the GTI
platform has a maximum diameter of 40mm and a maxi-
mum height of 10mm. After a second rotation of the con-
veyor, the glass sample is ejected to be cooled at ambient
air temperature for the next physico-chemical analysis.
• Computer-aided control and acquisition system: The
computer-aided control and acquisition system of the GTI
platform is connected to specific components, such as
local electrical heaters, shear blades, the mechanical
components related to kinematics of the pressing device,
and the thermal and mechanical sensors. For the control,
these elements permit us to reproduce on the GTI plat-
form the experimental conditions as close as possible to
industrial practice. For the acquisition, the sensors on the
GTI platform make it possible to analyze the thermal
behavior at the glass/tool interface. (More details on the
input and output data from the GTI platform are given in
sections 2.2 and 2.3.)
One trial on the GTI platform will match the perfor-
mance cycle of glass melting, glass cutting, the routing
for the mold load cycle in the pressing device, the press-
ing of the glass in the mold by the punch, and glass ejec-
tion from the mold.
2.2. The GTI Platform’s Pressing Cycle
The main purpose of the GTI platform is to analyze the
glass/tool interface throughout successive pressing cycles.
In this section, we describe the pressing cycle on the GTI
platform in detail. The pressing device (Figure 1(a)) is
the critical place where the contact between the glass and
the punch occurs. On the top, there is a punch and a ring
around it. On the bottom, there is a conveyor with three
molds (Figure 1(b)). Each mold is made up of two parts:
the cylinder and the ejector (Figure 2(a)). As shown in the
cross-section in Figure 2(a) and 2(b), the punch, the ring,
each ejector and each cylinder are instrumented by
type-K thermocouples with a diameter of 1mm. For each
thermocouple, the temperature measurement is carried
out at 1.5mm from the surface of the metal items (i.e.,
punch, ring, cylinder, and ejector). Two piezoelectric
force sensors are respectively located below the ejector
and above the punch to control the contact force effort of
the contact between the punch and the glass. On the GTI
platform, the acquisition rate is 1000 measurements per
second for each channel.
After the shear blades cut the glass, the gob falls into
the mold via the delivery mechanism (Figure 2(a)). One
pressing cycle on the GTI platform includes the follow-
ing six steps:
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles:
82
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
1) The conveyor rotates one quarter turn to carry the
mold-gob set below the punch (Figure 2(b)).
2) The mold-gob set moves upwards so that the cylin-
der enters in contact with the ring. The gob and the ejec-
tor are in an intermediate position. Due to the space be-
tween the punch and the ejector at this time, the glass gob
does not come in contact with the punch (Figure 2(c)). Tem-
perature and effort measurements are begun at this time.
3) The ejector now moves upwards (Figure 2(d)) to bring
4 Thermocouples30 mm
Mold 1,
2 or 3
in Fig.1 b
Cylinder
Ejector
Glass
(a)
1
2
(c)
1
2
3
4
(d)
1
2
3
4
Pressing
devi c e
Ring
Punch
(b)
1
2
3
4
Figure 2. One pressing cycle on the GTI platform—(a) ele-
ments of the mold in the initial position; (b) elements of the
pressing device and the location of thermocouples; (c) in-
termediate position during the pressing cycle; (d) position
during the glass/punch contact.
the glass gob into contact with the punch, with the con-
tact pressure and the contact duration defined by the user.
The minimum contact duration is 20s to let a glass sam-
ple be sufficiently cooled to be ejected from the mold.
4) At the end of the forming process, the punch moves
upwards from the glass surface. Temperature and effort
measurements are stopped at this time.
5) The glass sample and the ejector return to the inter-
mediate position. The punch moves upwards to its initial
position. The cylinder-ejector-glass sample set moves down-
wards.
6) The mold conveyor rotates one quarter turn, and the
glass sample is ejected. Meanwhile, the next mold loaded
with glass gob is brought under the punch to be pressed.
To perform one trial on the GTI platform means per-
forming a number n of pressing cycles, with each press-
ing cycle consisting of the steps described above.
2.3. Experimental Procedure on the GTI Platform
The objective of the present trials performed on the GTI
platform was to compare output temperatures under dif-
ferent lubrication conditions of the punch surface. For
that purpose, we developed an experimental procedure to
guarantee the repeatability of the trials for the same lu-
brication conditions. In addition, to accurately compare
between the trials under different lubrication conditions,
we had to guarantee that, except for the lubrication on
the punch, the other GTI input data remained quite stable
over a set of trials, even if they were performed over a
large time interval.
The experimentation was carried out according to the
following experimental procedure. Since the melted glass
flows by gravity at the exit of the furnace, before each
GTI trial, the same volume of cullet (25 dm3) is loaded
into the Inconel tank. Twenty-four hours before the trial,
the cullet is melted to reduce most of the air bubbles in
the melted glass. The surfaces of the cylinders, the ejec-
tors of the three molds, and the punch are polished to
obtain a surface roughness approximating the inner faces
of a new blank mold used in the perfume bottle industry
(i.e., a roughness Ra from 1 µm to 2 µm). After polishing,
the cylinders and ejectors are lubricated to prevent oxida-
tion and binding during testing. Then, the molds (i.e.,
cylinders and ejectors) and the punch are pre-heated to
450˚C for four hours before beginning the trial.
In this study, four lubrication conditions were analyzed:
a bare punch and no lubrification, a punch swabbed with
a lubricating paste, a punch coated with resin, and a
punch first coated with resin and then swabbed with a
lubricating paste. According to the lubrication conditions
to be tested, the experimental procedure was thus different
because of the punch lubrication. In Part A, we present
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles: 83
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
the trials which used a punch swabbed with a lubricating
paste. (The trials with the other lubrication conditions are
presented in Part B).
In the trials with the lubricating paste, the swabbing of
the punch was performed with a cotton swab just before
the beginning of the trial. This cotton swab was saturated
with the lubricant. To reproduce the same lubrication con-
ditions for each trial, the cotton swab was only used for
one single trial.
When the resin film was added, the coating on the punch
is put on eight hours before the trial, and the roughness was
measured again after drying in the open air. Pre-heating
the punch to 450˚C for four hours allows the resin film to
tighten and extends the lifetime of the resin film. In the
case of the trial with a coated/swabbed punch, preheating
the punch makes swabbing the punch surface with the lu-
bricating paste optimal.
To perform a trial on the GTI platform, we distinguish
input data, related to the instructions that are entered, from
output data, given by different sensors on the platform.
Input data for the GTI control system concern the tem-
perature of the electric furnace, the temperature level of
the heating resistance at the exit of the furnace, the cut-
ting time, the initial temperature of the molds and the
punch, the duration of the gob pressing, and the contact
pressure between the glass and the punch. Values used for
GTI trials in Part A and Part B were respectively 1060˚C,
1130˚C, 7s, 450˚C, 20s and 0.2MPa. We explain in Part
B the choice of these input data values in terms of the
industrial process used to manufacture perfume bottles.
A distinction was made between the output data used
for control and the output data used for analysis. During
the trial, the weight of each glass sample was the first out-
put control data on the GTI platform. The glass weight
was checked after each ejection throughtout the trial.
With n pressing cycles in one trial, less than n glass sam-
ples were obtained because some samples were broken
during the ambient-air cooling period. The objective was
to keep the glass weight constant for each pressing dur-
ing the trial in order to get a constant value for the press-
ing force delivered by the punch.
In fact, the thermal exchange at the punch/glass inter-
face is totally dependent on the pressure level [3], and
the pressing force must be constant during all the trials.
With a cylindrical cavity for each mold, a minimum
glass volume must be present to fill the mold in order to
apply a given pressure distribution on the glass during each
punch pressing cycle. As the mold diameter is 43.4 mm
and we wanted to produce glass pieces with a height of at
least 10mm, the total glass volume is 14 800g/mm3.
With the goal of obtaining a 0.2MPa pressure on the
glass during the pressing cycle, the preliminary trials on
the GTI platform permitted us to determine that the
weight of the glass sample has to be at least equal to 37g.
There are 6 other output control data elements issued
from sensors at different locations in the GTI platform:
the air temperature given by the type-K 1mm-diameter ther-
mocouple located near the heating resistance, the glass tem-
perature given by the bi-chromatic pyrometer just before
the cutting area, the three ejector temperatures given by
the three type-K 1mm-diameter thermocouples (Figure
2), and the force given by the piezoelectric force sensor
in the ejector. They were used to verify that GTI trials were
made under the same conditions.
Only one output analysis data element was used for
the thermal analysis of the punch. This data element was
obtained by the type-K 1mm-diameter thermocouple in-
side the punch (Figure 2). The output data recording started
at the beginning of each pressing cycle. With a 20s con-
tact duration, the total acquisition duration for each out-
put data element during one trial is t = 22s x n, where n is
the total number pressing cycles in one trial.
In the research presented in Part A and Part B, the sin-
gle parameter that distinguished the different trials is the
lubrication on the punch. Each trial is repeated three times
for each lubrication condition. Consequently, for each out-
put data element, the average value and the relative stan-
dard deviation along time t were computed. The prelimi-
nary trials made on the GTI platform permitted us to de-
termine the maximum accepted value for the relative stan-
dard deviation for each output control data element. Thus,
if the relative standard deviation during one trial reaches
or exceeds the critical value of the output control data
element, the trial was performed again with the same input
data. By using the same input data, we could verify the
repeatability of the trial made on the GTI platform for
cases of very similar output control data.
3. Analysis of the Thermal Exchange at the
Glass/Punch Interface with the GTI
Platform
This section presents our main results for the analysis of
the thermal exchange at the glass/punch interface. Part A
concerns the trials performed with a punch swabbed with
the lubricating paste. The punch was made of cast iron,
like in industrial practice. The lubricating paste was de-
signed by our partner, SOGELUB® Special Lubricants
Company. According to the experimental procedure, the
punch was lubricated only once at the beginning of the
trial.
3.1. Temperature Evolution of the Punch During
the Pressing Cycle
According to our experimental procedure, three trials
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles:
84
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
were performed to guarantee trial repeatability, to estimate
average temperature evolution, and to observe the impact
of lubrication on the thermal exchange at the glass/punch
interface. On the GTI platform, a hundred pressing cy-
cles are possible with 25 dm3 of cullet and 37g glass
gobs. In the preliminary trials, we observed no signify-
cant results if the trials were performed in order to empty
the cullet tank. In order to obtain a reasonable duration for
one trial, we decided to perform 51 pressing cycles for
each trial. Each of the 3 molds on the conveyor belt (Fi -
gure 1(b)) was filled 17 times, which led to 51 glass sam-
ples produced. With a 22s duration of the pressing cycle
and a 20s contact time between the glass and the punch,
the total time for the 51 pressing cycles is 1122s, and the
total contact time between the glass and the punch is 1020s.
As mentioned in section 2.3, there were 7 output data
elements from the GTI platform, which were used to
check the trial validity. In Appendix, Table A.1 gives the
average values of these 7 output data elements, with the
relative standard deviation in parentheses. These data
were analyzed in two steps. In the first step, we analyzed
the data, trial by trial, to check that no data drift appeared
in the input data during the trial. In this analysis, the in-
formation in the Table 1 had to be scrutinized, line by
line, for the first three lines. In the second step, we ana-
lyzed the three trials together to prove that the experi-
mental conditions were similar for the three trials. The
last line in Table A.1 gives the results for this second
step for the 7 output data elements.
For the first analysis, the stability of the glass sample’s
weight during the trial was the first priority, given the
pressing force during each pressing cycle throughout one
trial. In Table A.1, the weight of the glass sample for the
3 trials is greater than 37g, allowing us to set the pressure
equal to 0.2MPa during the 3 trials. For the 6 other out-
put data elements, the relative standard deviations for the
3 trials are between 0.1% and 3.7%. We conclude that
the output data were stable during each trial, and there-
fore the experimental conditions did not vary during each
of the 3 trials. For the second analysis, given in the last
line in Table A.1, the relative standard deviation for the 7
output data varies between 0.32% and 3.6%. We thus con-
clude that the output data were stable around similar values
during each of the 3 trials, thus proving that the 3 trials
Table 1. EDS results for the bare punch surf ac e.
Elements %
E1 96.6
E2 2.4
E3 0.6
E4 0.4
were performed under the same experimental conditions.
The analysis of the thermal exchange at the glass/punch
interface is based on the temperature evolution during
each pressing cycle, given by the type-K 1mm-diameter
thermocouple located 1.5mm from the punch surface in
contact with the glass gob during the pressing cycle
(Figure 2). According to our previous analysis of the 7
output data elements for the 3 trials performed in the
same experimental conditions, the average temperature
inside the punch was computed from the evolution of the
3 temperatures obtained in the 3 trials.
This average temperature was used to analyze the im-
pact of the lubrication on the thermal exchange at the
glass/punch interface. During the 51 pressing cycles, the
punch pressed the glass in mold 1, 2 or 3, one after the
other, through the rotation of the mold conveyor belt
(Figure 1(b)). As shown in Figure 3, among the 51 press-
ing cycles, we distinguished the 17 temperature evolu-
tions for mold 1 (solid black lines), mold 2 (solid grey
lines), and mold 3 (dotted black lines).
Our first global analysis of the temperature evolution
led us to distinguish 2 phases in the punch’s temperature
evolution.
The first phase is related to the time interval between 0s
(beginning of the trial) and 132s (end of the 6th pressing
cycle). During this interval, the temperature inside the
punch gradually increases. Although the punch had been
initially heated to 450˚C, the punch was now heated by
coming into contact with the glass during the first 132s
of the cumulated contact time. After 132s, the punch’s
temperature became stable, even though oscillations ap-
peared due to the ambient air cooling the punch when it
is no longer contact with the glass.
Considering now the pressing cycle for one mold (i.e., 1,
2 or 3), the temperature inside the punch evolves quite
similarly after 132s. The temperature increases followed
by decreasing temperatures for a reduced time. This is
explained by the fact that, during the 22s of the pressing
cycle, the punch is in contact with the glass in the first
20s, after which the punch is no longer in contact with
the glass and is cooled by ambient air. The temperature
evolutions are similar in the 3 consecutive pressing cy-
cles for mold 1, mold 2 and mold 3. However, the initial
temperature of the punch at the beginning of the pressing
cycle is different. The temperature of the punch has the
lowest value for the pressing cycle for mold 1 and the
highest value for mold 3. The explanation is related to
the conveyor rotation between two consecutive pressing
cycles. Between mold 1 and mold 2 and between mold 2
and mold 3, the conveyor (Figure 1(b)) rotates a quarter
revolutions, but between mold 3 and mold 1, the con-
veyor has to rotate three-quarters of a revolution in the
reverse direction to place mold 1 once again under the
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles:
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
Copyright © 2011 SciRes. NJGC
85
Figure 3. Temperature analysis using the GTI platform—average temperature evolution of the punch in the 3 trial repetitions
for the pressing cycles for molds 1, 2 and 3.
punch. Consequently, the punch is cooled by ambient air
much longer.
Guilbaut et al. [11] and Zhou et al. [12] have measured
the temperature in the molds during industrial glass press-
ing. In their studies, the temperature in the industrial mold
evolved in function of the cumulated pressing time and
presented a similar evolution our results for mold 1, 2 or
3 (Figure 3). Guilbaut et al. [11] and Zhou et al. [12]
also highlight a transient phase when the mold tempera-
ture increased after the beginning of production and a
stable phase in which oscillations were observed depend-
ing whether the punch was in contact with the glass or
was cooled by ambient air. Consequently, the GTI plat-
form, with a reduced number of pressing cycles (i.e., 51
on the GTI platform versus several hundreds for the stud-
ies Guilbaut et al. [11] and Zhou et al. [12]), was able to
reproduce the thermal behavior at the glass/tool interface,
as observed in a industrial context.
Using Figure 3, we analyzed the temperature evolu-
tion in the punch, looking each of the three molds, on
case-by-case basis. Figure 4 presents the temperature evo-
lution in the punch when the pressing occurs for mold 1.
For this case, only the 17 temperature evolutions in so-
lid black lines shown in Figure 3 were plotted. For each
pressing cycle, the punch’s average temperature during
the pressing cycle was computed from the 22000 tem-
perature values, with a 22s pressing cycle and a 1000Hz
acquisition rate.
By interpolating these 17 average temperatures with a
6th degree polynomial, the interpolated average tempera-
ture evolution was obtained (solid grey line in Figure 4).
Based on the numerous preliminary trials performed on
the GTI platform, we conclude that this interpolated av-
erage temperature evolution for mold 1 is an important
assessment criterion for analyzing the thermal exchange at
the glass/punch interface. If the interpolated curves ob-
tained for mold 2 and for mold 3 were considered, simi-
lar evolutions were obtained in our study of the impact of
lubrication on the thermal exchange at the glass/punch in-
terface. Moreover, using mold 1, mold 2 or mold 3 as a
reference, identical conclusions are founded, even though
temperature in the punch at each pressing cycle begin-
ning is different. The comparison with other different
lubrication conditions (Part B of this study) was based
only on this interpolated average temperature obtained
from the pressing cycles performed for mold 1. The in-
formation comes from the punch’s average temperature
evolution for the 51 pressing cycles after 3 trials repeated
in the same experiment.
3.2. Temperature Evolution on Two Specific
Pressing Cycles
Figure 3 shows the average temperature evolutions for
all of the 51 pressing cycles during the trial with the punch
swabbed with the lubricating paste. We now focus more
specifically on one pressing cycle in the transient phase
between 0s and 132s (132 s in Figure 4 corresponds to
the end of the 6th pressing cycle) and one pressing cycle
in the stable phase after 132s.
In the transient phase, we selected the first pressing
cycle. The first pressing cycle is specific because the
punch’s initial temperature, which is one of the input data
for the GTI platform, is strictly identical in all the trials
in this study, whatever the lubrication condition of the
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles:
86
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
Figure 4. Temperature analysis using the GTI platform—average temperature evolution of the punch in the 3 trial repetitions
for the pressing cycles for mold 1, evolution of the average temperature for each pressing cycle, and interpolated average
evolution of the punch for the pressing cycle for mold 1.
punch. Figure 5(a) presents the 5 first seconds of the tem-
perature evolution of the punch, obtained during the first
pressing cycle with the swabbed punch. We selected only
the 5 first seconds because 5s is representative of the in-
dustrial practice in terms of the length of the 2 successive
blowing operations used to produce luxury perfume bot-
tles. During these 5 first seconds, the temperature increase
at 1.5mm from the punch surface is significant (+ 50˚C),
and the variation over time is almost linear (Figure 5(a)).
In the stable phase, any pressing cycle located after the
6th pressing cycle could be chosen since the punch’s tem-
perature evolution during each pressing cycle is similar.
The 10th pressing cycle was arbitrarily chosen. Figure 5(b)
provides the average temperature evolution during the
first 5s of this 10th pressing cycle. The temperature in-
crease at 1.5mm from the punch surface is reduced com-
pared to the first pressing cycle, with + 35˚C.
Moreover, after 6 pressing cycles, the punch’s initial
temperature at the beginning of the pressing cycle is now
546˚C (+ 102˚C compared to the first pressing cycle) be-
cause the punch has been heated by the hot glass during
the first 9 pressing cycles. With the punch’s initial tem-
perature higher than at the beginning of the trial and a
reduced temperature increase (+ 35˚C compared to + 50˚C),
we may conclude that the heat exchange at the glass/punch
interface in the stable phase is less significant than in the
first pressing cycle. Thus, the temperature evolution in
Figure 5(b) is no longer linear.
Since the evolution shown in Figure 5(b) is quite the
same during the rest of the trial, we may also conclude than
no significant change appears in the thermal exchange at
the glass/punch interface during the 45 pressing cycles in
the stable period. According to the GTI trials and observations
Figure 5. Average temperature evolution of the punch dur-
ing 5 seconds: (a) for the 1st pressing cycle, (b) for the 10th
pressing cycle.
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles: 87
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
of the temperatures inside the punch throughout the trial,
we may also conclude that no significant loss of the lu-
bricating paste on the punch has occurred during the 51
pressing cycles, as well as during the stable period after
132 s (Figure 3, Figure 4). The same pressing cycles
(i.e., the first one at the beginning of the transient period
and 10th pressing cycle in the stable period) were also
used to compare the different lubrication conditions in
Part B of this study.
4. Physico-Chemical Analysis on the
Surfaces of the Glass Samples Pressed on
the GTI Platform
4.1. Use of a Scanning Electron Microscope with
Energy Dispersive Spectrocospy
We used a Scanning Electron Microscope (SEM) (JEOL
JSM-5900LV) with Energy Dispersive Spectrocospy (EDS)
detector on the SEM to analyze and characterize the glass,
with the objective of tracing any lubricant transfer on the
glass samples during the pressing cycles. The composi-
tion obtained by EDS should not be regarded as the exact
composition of the analyzed sample, but it allowed us to
compare the compositions of materials obtained on the
same equipment under the same conditions. We used a
constant primary electron beam (20 kV) and a constant
sample/detector working distance (12mm). Due to the size
of the SEM chamber, both the punches and the glass
samples pressed on the GTI platform can be investigated
in their entirety.
To identify the elements of the resin film or the lubri-
cating paste as markers in order to detect any lubricant
transfer on the glass samples, a first EDS analysis was made
on the bare punch to produce the forming tools (Table 1).
(To respect the confidentiality of our industrial partners,
the elements are denoted with Ei, where i is equal to 1, 2,…i,
depending on their presence in the successive EDS ana-
lyses in all the tables.) In industrial practice, the forming
tools are coated before being swabbed with a lubricating
paste. Table 2 and Table 3 respectively present the EDS
analysis made on a coated punch with the resin film and
of a coated punch swabbed with the lubricating paste
(Both the resin film and the lubricating paste are the pro-
ducts of the SOGELUB® Special Lubricants Company.)
These punches were heated on the GTI platform to 450˚C
for four hours, which is the same procedure before the
GTI trials described in Section 2.3. Five new elements
(E5 to E9) were detected in the resin film (Table 2)
compared to the EDS analysis of the bare punch (Table
1). Two new elements (E10 and E11) were detected in
the lubricating paste (Table 3).
Comparing the results obtained for the coated punch
(Table 2) and the coated punch swabbed with a lubricating
Table 2. EDS results for the coated punch surface with no
lubricating paste.
Elements %
E1 38.2
E5 33.8
E6 19.6
E2 4.3
E7 1.9
E8 1.4
E9 0.6
E3 0.3
Table 3. EDS results for the coated punch sur face, swabbed
by the lubricating paste.
Elements %
E1 48.9
E6 23.0
E5 22.9
E2 1.4
E8 1.2
E10 0.9
E11 0.7
E3 0.6
E7 0.4
paste (Table 3) with those for the bare punch (Table 1),
the characteristic elements were selected as markers for
the lubrication products. The two main elements present
in the resin film and in the lubricating paste (E5 and E6
in Tables 2 and 3) were not considered as markers be-
cause they were present in both the film and the paste.
Since the markers only present either in the resin film or
in the lubricating paste but not in the punch nor in the
glass (Table 4) could not be determined, the following
compromise was made:
• E2 and E7 were chosen as representative of the re-
sin film because they are the predominant minor ele-
ments in the resin film (Table 2).
• E10 and E11 were chosen as representative of the
lubricating paste for the same reason (Table 3).
Although the markers, E2 and E7, were present in the
glass in different quantities (Table 4), a significant in-
crease in the EDS signal for these elements highlights any
lubrication transfer from the coated punch on the surface
of the pressed glass sample. To realize the phys-
ico-chemical analysis of the glass samples pressed on the
GTI platform, the EDS analysis of the Pochet de Courval
flint glass is given in Table 4.
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles:
88
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
Table 4. EDS results for the flint glass.
Elements %
E6 46.2
E2 33.8
E8 10.5
E10 6.2
E7 1.1
E12 1.0
E9 0.6
E13 0.5
4.2. Our Observations for the Glass Surfaces
Pressed with a Punch Swabbed with a
Lubricating Paste
To analyze the possible transfer of the lubricant on the
glass samples during the GTI trials, we developed a pro-
tocol. The pressed glass samples were collected for each
trial and were referenced by their pressing cycle order
(i.e., from 1 to 51 since 51 pressing cycles were performed
on the GTI platform for each trial). The samples were
taken at regular intervals—every tenth sample—for ob-
servation. In case a notable change in the aspect, size
and/or quantity of markers on the glass surface was ob-
served between two consecutive samples, further inter-
mediate sampling was done.
The observation protocol on a glass sample pressed on
the GTI platform was to use a SEM to scan the surface in
contact with the punch during the pressing cycle, thus
locating possible traces of foreign matter. Once the for-
eign matter on the surface was detected, a focused EDS
analysis was done to identify the source of the foreign
matter (i.e., the resin film, lubricating paste or other mat-
ter). For Part A, we made similar observations on the
three series of glass samples pressed for the three repeti-
tions of the trial with the punch swabbed with the lubri-
cating paste (designated as repetition 1, repetition 2 and
repetition 3).
The presence of small dark spots was observed on the
surface of the glass samples throughout the pressing cy-
cles, not at the beginning or the end of the GTI trial. Fig-
ure 6 to 9 shows typical pictures of these spots, respe-
cttively obtained during the 20th, 30th and 50th pressing
cycles of repetitions 1 and 3. The presence of these small
spots was irregular on the surface of the glass samples,
and the spots were mainly grouped on areas less than a
few square millimetres large. Most of these spots were
between 10 and 100 µm in size (Figure 6, 8 and 9). As
shown in Figure 7, some were larger, about 500µm, and
these larger spots, observed in series 1, 2 and 3, looked
like clusters of small spots.
Figure 6 shows a representative SEM picture (sample
30/repetition 1) of the foreign matter traces on the glass
sample surface. The dark traces are the foreign matter on
the grey background of the glass. The EDS analysis for
the trace marked by the white square in Figure 6 was
realized and the composition puts forward the presence
of elements E10 (16.5%) and E11 (11.3%). The other traces
in Figure 6 were analyzed, and similar percentages were
found. The elements E10 and E11 are markers for the
lubricating paste. Lubricating paste residues were found
in the dark grey spots, so we concluded that the lubricat-
ing paste spots were transferred on the pressed glass sur-
face by the punch.
Figure 6. SEM image of lubricant traces (dark grey) on the
surface of the 30th glass sample pressed with Punch 1 on the
GTI platform.
Figure 7. SEM image of lubricant traces (dark grey) on the
surface of the 20th glass sample pressed with Punch 3 on the
GTI platform.
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles: 89
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
Figure 8. SEM image of lubricant traces (dark grey) on the
surface of the 50th glass sample pressed with Punch 3 on the
GTI platform.
Figure 9. SEM image of lubricant traces (dark grey) on the
surface of the 50th glass sample pressed with Punch 1 on the
GTI platform.
Furthermore, tiny white points (Figure 6 to 9) were of-
ten observed in the area surrounding the lubricating paste
traces. A closer EDS analysis on these points showed
that they are rich in an element present in the lubricating
paste but not already designated in Table 3, which re-
ported the results of the EDS analysis of the swabbed
punch. The explanation is that some of the elements pre-
sent in a very small quantity in the resin film or in the
lubricating paste were not detected by the global EDS
analysis on the punch coating before the GTI trial. Con-
sequently, they were not listed in Table 2 for the coated
punch, nor were they listed in Table 3 for the coated and
swabbed punch. Nevertheless, they became detectable by
the close analysis of the areas where the traces of the
lubricating paste or resin film from the punch were con-
centrated. According to the close EDS analysis done on
the series of glass samples (not only for the coated and
swabbed punch but also for the others presented in Part
B), this element detected in the tiny white points, denoted
E14, is a potential marker simultaneously in the lubricat-
ing paste and the resin film. It was an important element
in the modification of the actual composition of the lu-
bricating paste, as presented in Part B.
5. Conclusions
In this study, the TEMPO Laboratory (Valenciennes, France)
and BCR Center (Mons, Belgium) has proposed a new
way to analyze and improve thermal capacities of lubri-
cants for the manufacturing of flint glass perfume bottles.
In Part A, we considered the pressing of the flint glass
with a punch swabbed with the lubricant developed by
our partner, SOGELUB® Special Lubricants Company.
For the GTI platform, we developed an experimental
procedure to guarantee the repeatability of the trials that
respects the initial input data conditions. After 3 trials on
the GTI platform under the same input data conditions,
the average temperature evolution of the punch was cal-
culated throughout the pressing cycle. For the Physico-
Chemical analysis using SEM and EDS observations, the
BCR Center developed a procedure to detect the possible
lubricant traces on the surfaces of the pressed glass samples,
and EDS was used to analyze the samples, case by case.
The thermal analysis results with the GTI platform are:
• The average temperature evolution obtained for the
51 pressing cycles on the GTI platform presents a tran-
sient phase when the punch was heated by the hot glass
during the first six pressing cycles.
• For the following pressing cycles, the average tem-
perature during each pressing cycle is almost stable, with
oscillations due to duration of the contact of the punch
with the glass and the ambient-air cooling times.
• The temperature increase at 1.5mm from the surface
of the punch during the first 5 seconds of the first pressing
cycle is important (+ 50˚C), and the variation over time is
almost linear.
• In the stable phase, during the first 5 seconds of the
10th pressing cycle, the temperature increase in the punch
is less in the first pressing cycle (+ 35˚C) due to its higher
initial temperature at the beginning of the pressing cycle
(+ 102˚C). The temperature evolution is no longer linear.
We conclude that the heat exchange at the glass/punch
interface in the stable phase is less important than at the
beginning of the trial. According to the GTI thermal mea-
surements, with the stable state of the punch’s average
temperature over one pressing cycle after 6 pressing cy-
cles and similar oscillations due to the contact duration
and the ambient-air cooling, we also conclude that there is
no significant increase of the heat transfer at the punch/glass
interface, and thus no significant loss of the lubricating
paste during the pressing cycle.
Copyright © 2011 SciRes. NJGC
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles:
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
Copyright © 2011 SciRes. NJGC
90
With the first EDS results on three punch conditions
(i.e., bare, coated and coated/swabbed) before the GTI trials,
markers were identified for the resin film and for the lu-
bricating paste. For the case of the GTI pressing cycles
with a swabbed punch presented in Part A, the results of
the physico-chemical analysis on the glass samples were:
• Typical small traces (between 10 and 100 µm) of the
lubricating paste were detected on the glass samples,
though not at the beginning or at the end of the GTI trial.
• Some clusters of these traces with a larger size
(500µm) were also present on some glass samples.
• Other traces from one element of the lubricating
paste were also detected because during GTI trials, there
was a concentration of this element, present in a very small
quantity in the lubricating paste.
We conclude that the total amount of the lubricant trans-
ferred after 51 pressings is very small, only witnessed by
the presence of sporadic traces on the glass surface in very
small quantities on the 51 pressed glass samples through-
out the GTI trial, though not at the beginning or at the end.
According to the GTI results and the results of physico-
chemical analysis, no significant loss of lubricating paste
was detected during the 51 pressing cycles (i.e., during
1122 seconds of the swabbed punch pressed against the
hot glass).
Part B presents the joint TEMPO Laboratory-BCR
Center experiment to analyze the different lubrication con-
ditions in an industrial context. For this purpose, the tri-
als on the GTI platform were performed with a bare punch,
a swabbed punch, which is before coated by a resin film,
and a punch swabbed by a new lubricating paste.
6. Acknowledgements
This research was supported by International Campus on
Safety and Intermodality in Transportation, the Nord/Pas-
de-Calais Region, the Walloon Region, the European Com-
munity, the Regional Delegation for Research and Tech-
nology, the Ministry of Higher Education and Research,
the National Center for Scientific Research, and the Ver-
reries Pochet du Courval. The authors gratefully acknow-
ledge the support of these institutions.
REFERENCES
[1] C. J. Fellows, F. Shaw, “A Laboratory Investigation of
Glass to Mould Heat Transfer during Pressing,” Glass
Technology, Vol. 19, No. 1, 1978, pp. 4-9.
[2] D. Höhne, B. Pitschel, M. Merkwitz and R. Löbig,
“Measurement and Mathematical Modelling of the Heat
Transfer in the Glass Forming Process, in consideration
of the Heat Transfer Coefficients and Radiation Influ-
ences,” Glass Science and Technology, Vol. 76, No. 6,
2003, pp. 309-317.
[3] P. Moreau, D. Lochegnies, S. Gregoire and J. César de Sa,
“Analysis of Lubrication in Glass Blowing : Heat Trans-
fer Measurements and Impact on Forming,” Glass Tech-
nology: European Journal of Glass Science and Technol-
ogy, Part A, Vol. 49, No. 1, 2008, pp. 8-16.
[4] W. C. Dowling, H. V. Fairbanks and W. A. Koehler, “A
Study of the Effect of Lubricants on the Adherence of
Molten Glass to Heated Metals,” Journal of the American
Ceramic Society, Vol. 33, No. 9, 1950, pp. 269-273.
doi:10.1111/j.1151-2916.1950.tb12797.x
[5] P. Manns, W. Döll, G. Kleer, “Glass in Contact with
Mould Materials for Container Production,” Glastech Ber
Glass Science and Technology, Vol. 68, No. 12, 1995, pp.
389-399.
[6] D. Rieser, G. Spieß and P. Manns, “Investigations on
Glass-to-Mold Sticking in the Hot Forming Process,”
Journal of Non-Crystalline Solids, Vol. 354, 2008, pp.
1393-1397.
[7] J. Pech, G. Berthomé, M. Jeymond and N. Eustathopou-
los, “Influence of Glass/Mould Interfaces on Sticking,”
Glass Science Technology, Vol. 78, No. 2, 2005, pp.
54-62.
[8] K. D. Fischbach, K. Georgiadis, F. Wang, O. Dambon, F.
Klocke, Y. Chen and A. Y. Yi, “Investigation of the Ef-
fects of Process Parameters on the Glass-to-Mold Stick-
ing Force during Precision Glass Molding,” Surface and
Coatings Technology, Vol. 205, 2010, pp. 312-319.
doi:10.1016/j.surfcoat.2010.06.049
[9] M. Falipou, C. Donnet, “Sticking Temperature Investiga-
tions of Glass/Metal contacts—Determination of Influ-
encing Parameters,” Glastech Ber Glass Science and
Technology, Vol. 70, No. 5, 1997, pp. 137-145.
[10] S. Gregoire, J. César de Sa, P. Moreau and D. Lochegnies,
“Modelling of Heat Transfer at Glass/Mould Interface in
Press and Blow Forming Process,” Computers and Struc-
tures, Vol. 85, 2007, pp. 1194-1205.
doi:10.1016/j.compstruc.2006.11.023
[11] R. Guilbaut, D. Lochegnies, P. Moreau, “In and Outside
Vision of Glass Blow and Blow,” In: D. Lochegnies and
P. Moreau, Eds., Proceedings of the 2nd International
Colloquium Modelling of Glass Forming and Tempering,
Valenciennes, France, Presses Universitaires de Valen-
ciennes, 23-25 January, 2002, pp. 57-64.
[12] H. Zhou and D. Li, “Mold Cooling Simulation of the
Pressing Process in TV Panel Production,” Simulation
Modelling Practice and Theory, Vol. 13, 2005, pp.
273-285. doi:10.1016/j.simpat.2004.11.006
A New Way to Improve Thermal Capacities of Lubricants for the Manufacture of Flint Glass Perfume Bottles: 91
Part A – How to Combine Thermal Analysis and Physico-Chemical Observations at the Glass/Punch Interface
Appendix
A. Output data from GTI
Table A.1. Average output data for the reference trial with the relative standard deviation in % in parentheses.
Repetition
number
Average glass
sample mass (g)
Average
temperature of the
heating resistance (˚C)
Average glass
temperature at the exit
of the furnace (˚C)
Average
temperature of the
ejector n 1 (˚C)
Average
temperature of the
ejector n 2 (˚C)
Average
temperature of the
ejector n 3 (˚C)
Average pressing
force (N)
S1 38.2 (1.4) 1100 (0.2) 966 (2.3) 556 (1.9) 561 (2.1) 566 (2.3) 405 (3.2)
S2 38.7 (3.3) 1106 (0.1) 958 (2.5) 552 (2.0) 557 (2.2) 562 (2.5) 402 (3.7)
S3 37.6 (1.3) 1101 (0.1) 963 (2.2) 556 (1.6) 562 (1.9) 566 (1.9) 396 (3.4)
For the
3 trials 38.2 (2.5) 1102 (0.32) 962 (2.6) 555 (1.9) 560 (2.1) 565 (2.3) 401 (3.6)
Copyright © 2011 SciRes. NJGC