The possibility of turn off a glass tempering furnace and then turn it on again the next day, without incurring sudden “thermal shocks” or exorbitant costs for restarting, is a topic that is much discussed and often raises doubts, even among experts. Some argue that turning off the oven can cause damage and wear to the metal structures or heat dispersion that could nullify any energy savings, while others believe that it is useless anyway.
But where do these beliefs come from?
THERMAL INSULATION MAKES THE DIFFERENCE
A glass tempering furnace operates at temperatures between 650°C and 700°C (or even higher) and, if theisolation is not adequate, it is inevitable that it drops sharply to room temperature in a short time when it is turned off. In this case we agree that it would create significant stress on the materials and structures at the time of restarting such as not to justify, in terms of advantages, this operation.
In the ovens Mappi International, instead, we adopt Highly insulating and top-quality materials, capable of maintaining an internal temperature of 450-500 °C for many hours after switching off. In practice, the oven “cools down” very slowly, remaining at a relatively high level for a long time, avoiding extreme and sudden temperature changes. Because if heating the oven is a cost, letting the heat disperse is a waste that should absolutely be avoided.
LESS ENERGY TO GET BACK “ON”
When, in the morning, the operator turns on a Mappi oven again, the heating process will therefore not have to start from 20°C but from 450-500 °C: this way, a difference of about 150-200°C will be enough to fill, an operation which in terms of energy balance is extremely advantageous. Furthermore, the steel and other structural components of the furnace do not undergo sudden temperature variations, drastically reducing the risk of micro-cracks, deformations or internal stresses.
But how do we do it? The “secret” lies in a careful Sizing of insulating panels, in the selection of materials with low thermal conduction coefficient and very high quality and a steel structure designed to handle limited thermal stresses — not the extremes of total cooling.
Speaking in engineering terms, it is well known that the thermal gradient (ΔT) influences the life of the machine's construction components. By reducing the difference between the operating and “resting” temperatures, the integrity of the oven is preserved, extending its operating life and guaranteeing the investment in terms of effectiveness and efficiency.
REAL SAVINGS… WITHOUT COMPROMISE
The reduced heat dispersion therefore effectively allows for save energy: no heat is wasted during the night and we need less “fuel” (or electricity) to bring the oven back to optimal operation. Furthermore, the absence of thermal shocks guarantees a easier maintenance, with lower costs and less frequent.
WHY DO MANY PEOPLE SAY THE OPPOSITE?
If an oven has been designed with poor insulation or less performing materials, turning it off really means "zeroing" the temperature and incurring severe construction stress. It is understandable that those who design ovens of this type tend to advise against turning it off, preferring a "constant heat" condition to reduce internal problems or any critical issues. But this approach implies higher energy costs has always been less operational flexibility.
We at Mappi have instead chosen to invest in a quality insulation, materials research and structural design of excellence, allowing our customers to turn off and on again ovens as needed, without risks. Some say that this is impossible? Maybe their ovens are not designed to do this in complete safety. In our case, however, it is a proven feature, which ensures energy savings, waste reduction and maximum reliability. And if others cannot do the same… it probably means that there's still a long way to go to achieve our standards of excellence.
A VISION OF SUSTAINABILITY THAT GOES BEYOND OUR PRODUCTS
This same philosophy also guides our approach to trade fair participation, especially at the next one. VITRUM 2025. For us the VITRUM it is not simply the most important fair in the glass sector in italy, it is the opportunity to trace new paths, rethink consolidated models and create value that lasts well beyond the days of the event.
MAPPI will be the protagonist of this evolution with a stand conceived in a different way, which becomes a tangible manifesto of the idea of sustainability cultivated in the company.
As with our products, which are designed to reduce waste and energy dispersion to a minimum, so Our stand at the fair will be designed with the aim of maximising every resource, recovering and reusing materials in an intelligent and responsible way. It is a concrete commitment that demonstrates how technological excellence and environmental sustainability can coexist, creating authentic and lasting value over time.
We are waiting for you at VITRUM 2025 to talk about it and discuss these issues of fundamental importance! We are ready to change the rules of the game. Are you?
