Vidromecanica* outlines the development of its hot-end coating hood, which enables uniform and high-quality treatment of glass container surfaces.
In the surface treatment of glass articles such as bottles, flasks, and plates, Vidromecanica has developed two complementary systems: hot-end coating and cold-end coating.
These systems are applied before and after the thermal treatment process that eliminates glass tensions (annealing lehr), see Pic 1 below.
Advantages of hot-end coating include: increased internal pressure of the bottle; reduced risk of rupture; improved abrasion resistance; and an enhanced appearance of the articles.
Hot-end coating hoods
Vidromecanica has been manufacturing hot-end coating hoods for over 30 years.
In the past, coating was done with small hot-ends, less than 1m in length, with minimal consideration for product contamination in the surrounding environment.
However, environmental concerns have grown, and the need for research and development to reduce or eliminate weaknesses in the equipment has become more pronounced.
To determine the capacity of the equipment, factors such as the type and number of articles passing through the hood, product concentration inside the hood, and passage time of the articles in the tunnel need to be considered.
These parameters are well-characterised, and there should be a balance between length, product concentration, and time to maximise coating efficiency, minimise product consumption, and reduce environmental contamination within acceptable norms.
Our hot-end coating hoods ensure uniform distribution and high-quality treatment of the surface of bottles and containers. Only with a uniform hot-end coating can we achieve effective adhesion of the cold-end coating.
Vidromecanica's standard production includes the following models (customised hoods can also be developed at the customer's request):
Special Models:
VTSQ – 17: Hood for small articles
VTSQ – 20: Special hood for tableware
Product deposition is ensured based on the hood's dimensions and can be achieved through laminar single-flow, double-flow, or triple-flow systems.
The choice of deposition system depends on the application and production rate, with adjustable product spraying concentration and one, two, or three loops of recirculation. The equipment also allows for easy regulation of air circulation speed.
To achieve desired results, we implement draining ratings in the construction, projecting product onto articles using production circulation loops.
The concentration of product is higher in the central part and lower near the entry and exit doors. These adjustments, based on the article's diameter, minimise product leakage into the environment.
The new convergent/divergent geometry of the interior ducts enables better temperature control, distribution, and uniformity of the coating film across the entire bottle diameter.
The equipment is constructed with either mild steel or stainless steel and has a modular design that can be easily adapted to accommodate different glassware dimensions.
It performs well with coating thickness levels of 35 CTU (Coating Thickness Units) in the bottle's body, with a deviation of 5 CTU.
The equipment is managed by an HMI+PLC system with online communication to a PC. It provides temperature control, product weight, product flow, and article flow information.
Standardised Processes
Our company's expertise is the result of over 30 years of dedicated research and development.
We have extensively tested and experimented with a wide range of technical solutions to meet the specific needs of our customers.
Our machinery is designed to deliver a top performance and can operate continuously for 24 hours a day in long-term production.
Over the past few decades, our technology has proven its value in the production of high-quality glass machinery. Our machines are widely used in glass production plants globally.
*Vidromecanica, Marinha Grande, Portugal
