History of the “S.E.I. Resin Lines”
Once, there were very few experts able to work fragile stone. With endless patience, skill and endurance these stone masters could obtain slabs from cracked blocks. However, their small businesses could not grow because of far too low productive capacity and lack of efficient production methods.

The progress in the chemical industry changed this state of things. Indeed, the development of a new generation of epoxy resins allowed the stone processors to repair broken slabs and to reinforce the delicate ones. Still, the use of artificial resins was far from easy in practice. For example, synthetic resins had to be poured onto absolutely dry slabs, and after the application it was necessary to expose the stone to high temperatures so that the layer of resin hardened reasonably quickly. Driven by the sheer determination to find a solution of its researchers, S.E.I. designed a series of “horizontal ovens” for the drying of the stone and hardening of the resin. Next, the company made a quantum leap forward by devising a proper production line characterized by a systematic operating system to carry out the entire process.

The members of the design team spent months studying their task, until they felt ready to reveal their invention: a closed-cycle plant whose method of working involved the slabs transported on steel trays undergoing a sequence of drying, mesh backing or resin coating and resin hardening at workstations. The revolutionary so-called “Linea di Resinatura” plant opened in 1991 could produce ten “mesh backed” or “resin coated” slabs per hour, an extraordinary achievement for that time causing amazement and wonder in the stone world. Such was the interest that a long-sighted entrepreneur approached to sound out the possibility of making another version which would work twice as fast as the previous one. S.E.I. accepted the challenge and manufactured a plant capable of producing one slab every three minutes. This triumph marked the success of the new technology and S.E.I. soon received tens of orders.

Realizing that the slab, strip and tile producers had individual requirements, S.E.I. started offering custom-made Resin Lines. Therefore, many different types of plant were developed and with them auxiliary machines conceived to maximize the level of automation as well as improve the quality of the treatment. At the end of the ‘90s S.E.I. poured all its know-how into its 2nd generation Resin Lines promoting far superior models to those already installed in terms of greater accuracy in assembling and better equipment.

With the 21st century global demand for Resin Lines grew exponentially. With the unexpected opportunity of increasing their turnover many stone machinery producers wondered how to seize their chance. To these shrewd company directors the easiest way seemed to be to get inspiration from the “S.E.I. Resin Lines” and then insist on advertising them as if they were their own inventions. S.E.I.’s response was to innovate and in 2003 its 3rd generation Resin Lines were launched. Extreme strength and reliability made these new Resin Lines suitable for working in difficult environmental conditions.

The resounding success which the 3rd generation plants were met with encouraged the company’s staff and motivated them in their desire to overcome limits and elaborate original and further innovative technical solutions. As a result, in 2005 the “S.E.I. Resin Lines” 4th generation became reality. The level of technology was of such a high standard that some models went into stone industry history, such as the legendary “Res Combi” Resin Lines which despite their reduced dimensions proved they could compete with much bigger versions in terms of productivity.

Wanting to provide its clients with suitable instruments to meet the challenges of the second decade of the 21st century S.E.I. dedicated 2009 to modernizing its plants following two principle aims that is the reduction in energy consumption along with size while maintaining maximum production capacity. Before the end of 2009 both these aims were achieved with the 5th generation.

Truly valid technology must mirror the times and so S.E.I. is always working and investing to create machines which fully meet the real needs of users. In-depth knowledge of materials and difficulties which companies meet while processing stone on an industrial scale, unique experience in the field of Resin Treatment and real passion for research, have given S.E.I. the know-how and energy necessary to design a 6th generation of Resin Lines. S.E.I.’s 6th generation plants represent the gold standard for producing amazing practically unbreakable slabs.

Workings of the “S.E.I. Resin Lines”
The best method to explain the workings of a Resin Line is to introduce the workstations one by one following chronological order of the various processing stages which make up the Resin Treatment of stone. Each workstation has been designed for a specific part of the process. Obviously the quality of the finished product can only meet expectations if all parts are carried out correctly and this means that modern Resin Lines must be equipped with efficient, streamlined workstations which are programmed to coordinate in a rational structured manner.

The procedure begins with the loading of the material to be treated on the Resin Line. The “Loading Workstation” is what we call the segment of the plant where the slabs are put onto steel Conveyor Trays which are their means of transport. The “S.E.I. Resin Lines” can be equipped with manual, semiautomatic or automatic loading systems. A Manual Loading Workstation consists of an “MTB” Tilting Bench and a jib-crane connected to a hoist-and-clamp or a vacuum pad. Moving on fixed rails the “ATB” Tilting Bench reaches the A-frame supporting the slabs, so that they can be put on the Conveyor Trays with minimum physical effort by the workers. This explains why a loading workstation with an “ATB” Tilting Bench is considered semiautomatic. High-capacity plants are equipped with automatic robot loaders. The recently launched “VK ROB” Robot boasts all the latest technology in terms of picking up and moving defective and irregularly shaped slabs. Whoever has the need of automatically loading raw travertine we propose the “KT ROB” Robot whose unique movement eliminates the risk of the vacuum pads dropping the slabs due to the large number of holes in the material. The inclusion of an “RP” Automatic Rotating Platform allows complete exploitation of the productive potential of the plant because it prevents a slow down through insufficient slabs in the loading area. Finally, it is worth underlining the importance of the afore-mentioned Conveyor Trays because it is thanks to them that the users of “S.E.I. Resin Lines” are able to process stone of any size and shape. These Trays have steel close-mesh tops which can carry huge granite slabs or tiny onyx slabs or pieces of broken slabs to glue together or even strips and tiles.

The thorough drying of material is an essential part of the treatment and the final result depends on this. Therefore, the second workstation of any Resin Line is aimed at drying the slabs before a mesh backing or resin coating is carried out. For the drying of the stone to be thorough the drying system must meet precise levels of effectiveness and efficiency. From the beginning S.E.I. realized the importance of this problem as the amount of research carried out by the company demonstrates. The outcome was three essential factors: time, ventilation and temperature. Considering that the chemical composition of stone varies according to material and with that the absorption of humidity, it is obvious that managing these three factors needs flexibility. Some examples may clarify and underline this concept. Let’s imagine drying slabs of granite, travertine and onyx. As long as we are not talking about so-called exotic granite, in the first case there should be no particular problems or precautions necessary given the compact nature of the material and its low absorption rate. In the second case drying should last as long as possible with intense air flow at high temperature because travertine absorbs and retains water rather like a sponge. In the third case we need to avoid exposing the material to very high temperatures which could damage it, and compensate a lower temperature with greater air flow for a longer time. The area of the Resin Line where the slabs are dried is called the “Drying Unit” and it consists of a sort of thermally-insulated chamber connected to heat producing device which gives out heat in the form of a flow of air. The form and capacity of drying unit varies from one plant to another and there are many different types of drying chambers because the range of Resin Lines is so vast. The most common are horizontal ovens, tunnel ovens, combined tunnel ovens, oven sections and multi-shelf ovens.

The “Mesh Attachment and Resin Application Workstation” is where these parts of the process are carried out. If the fibreglass mesh is attached incorrectly and the resin carelessly applied the desired strengthening and enhancement of the stone will not take place. Therefore, the design of any Mesh Attachment and Resin Application Workstation needs to follow criteria. While a modern Resin Line is able to treat all types of stone, in practice it is advisable to bear in mind what the most frequently treated materials will be and the quantity of daily production. For example, a company dealing in a large quantity of “coloured” marble, breccia and onyx needs to repair fragile or broken slabs on a large scale. Since these slabs are damaged by numerous cracks their repair involves a repeated number of retouches, which is only feasible if each slab can be treated at various “work stops” corresponding to workbenches. In the case of limited space in which a line of tables would be impossible the solution is found in the “SK” series of Stackers aimed at stacking up to ten slabs within the confines of the workstation so as to extend the time separating the initial resin application from successive retouches. Sometimes it makes sense to equip the plant with automatic mesh dispensers and resin applicators. Generally, automatic machinery is suitable for the treatment of naturally sound material like most types of white marble and granite. In an up-to-date factory there should be a dosing and mixing machine to ensure the correct proportions of resin and catalyser are maintained. All factories must fulfil their legal and moral responsibility to install fume extraction systems in the resin application areas, to safeguard workers’ health and the environment.

Anyone who has tried for themselves to restore fractured slabs will have noticed how difficult it is for the resin to get into the smallest fissures, and this is why the treatment of certain stone is more complicated than it might seem. Until the faults are saturated with resin the strengthening of the material is only an illusion, and vacuum technology is the most effective means to increase the penetration capacity of the resin. The advanced “S.V.S. R1” Vacuum Chamber has been conceived to force the resin to drip into the hairline cracks, which although difficult to see weaken much marble and limestone. Whether it is because they are deep or diagonal they can cause a slab to break up. Granite companies suffer the negative effects of the presence of micro-fractures on the surface of polished slabs because these imperfections cause a loss in value of the material. This is a good reason to turn to the “S.V.S.” Vacuum Chamber, which is the most suitable machine for the enhancement of granite. Factory workers must always carefully check the surface of vacuum-impregnated slabs to locate cracks which remain open and add further resin.

On leaving the mesh attachment and resin application area the slabs pass to the “Polymerization Unit”, a thermally-insulated heated structure which can consist of a multi-shelf oven or oven section. During the time spent in this chamber, the heat accelerates the hardening of the resin to just a few hours instead of the long wait necessary with other rudimental equipment. Real experts in the Resin Treatment of stone claim that the Polymerization Unit is the heart of any Resin Line aware that success depends on methods and time of polymerization as well as good quality appropriate resin. The resin producers are forever developing new resins and catalysers to increase the range of stone which can be treated, so stone processors have to choose from hundreds of resin products available and need a versatile line able to use any of them. S.E.I. Polymerization Units fully meet this need assuring an optimum rapport of the three most important factors: temperature, ventilation, time. It is important to underline that the resin must never be forced to harden too quickly using extreme temperatures. Doing so will cause a dramatic reduction in the capacity of the resin to penetrate the fissures. In conclusion, if the users of an S.E.I. plant follow the technical instructions of the company, the results in terms of strengthening of the slabs will be even better than predicted and background uniformity and colour enhancement will be achieved.

The last stage of the process is the unloading of treated slabs which takes place at the so-called “Unloading Workstation” that may have anything between a low to high level of automation. Choosing an “MTB” Tilting Bench involves having a worker whose job it is to move the slabs from the Resin Line with a jib-crane. In contrast, having a “VK ROB” Robot unloader limits the work to simple control. It is a good idea to have an “RP” Automatic Rotating Platform to flank each Robot so as to avoid congestion in the unloading area which would jeopardise productivity.

About the “S.E.I. Resin Lines” for strips and tiles
As explained above, any “S.E.I. Resin Line” can be used to treat slabs, strips and tiles. However, the core business of some companies is the production of cut-to-size works and to meet their requirements we offer plants specifically designed for repairing, reinforcing and enhancing strips and tiles.

The “S Compact” Resin Lines are ideal solutions for companies needing to process relatively modest quantities of strips and tiles. Their essential design is also economic to run because keeping these Resin Lines in good working order involves few easy interventions. Their hourly productive capacity is at a good level considering the small size: up to 60 square metres of resin treated material.

Companies running large factories with top-of-the-range machinery park will look at the “Res SL” and “Res S Top” models, which are huge Resin Lines capable of processing up to 350 square metres of strips or tiles per hour. The equipment of the “Res SL” and “Res S Top” plants is very comprehensive, including automatic systems for strip storing in the loading area, strip loading, strip turning over (if necessary), resin/catalyser dosing and mixing machines, tunnels for impregnation under-vacuum, strip unloading and strip storing in the unloading area. Furthermore, automatic machines for resin application are available on request.