Furthermore, individual representatives of the glass industry can gain a certain competitive edge over the competition in this way and develop it accordingly.
But also in terms of cost effectiveness, it is important to take a holistic view of the production processes and analyse them in detail. In the case of lamination systems, the speed of pre-lamination should by no means be regarded as the only way of improving cost effectiveness with this process. After a detailed analysis of all parameters, it quickly becomes clear that many measures relating to the machine and the control system have a significant influence on efficient production.
The four most important points for increasing performance are:
- Machine concept
- Foil placement, foil cutting
- Aligning the glass
1. MACHINE CONCEPT
Cost effectiveness starts with the planning of your own company and by determining the development steps for the future.
The following seven questions are crucial here:
- Which glass products do you want to manufacture?
- What is the planned utilization?
- How do you want to develop?
- Which market segments do you want to develop or open up?
- Current and future proportion of glass sizes and glass quantities?
- Planned return on investment
- (Planned) cost of products
Points 5 to 7 in particular can be regarded as key questions. But it is only when all of these questions have been answered that the entrepreneurial direction will emerge. And only then can you make an informed decision about which lamination systems (width, performance and degree of automation) are the correct ones for your own operation.
The machine width is considerably dependent upon the glass size that a company wants to produce, and has a strong influence on the amount of the investment.
HERE IS A PRACTICAL EXAMPLE:
Customer XY only wants one lamination system in production. Their company mainly processes sheets that do not exceed a width of 2.6 metres (92%) in 3-shift operation. However, the customer requires glass sheets with a width of approximately 2.6-3.0 metres for special productions (8%).
Following a detailed analysis of their business plan and the future direction of their company, they decide on a lamination system for process and cost reasons. And so they are absolutely right in this example. Because the wider system would also have increased the cost of any spare parts, such as rollers, and the level of complexity in terms of foil placement and cutting. This would also increase the investment costs.
Furthermore, the amount of foil wastage in wider systems also increases if the number of foil rolls in the magazine is not increased.
The customer can buy the bigger sheets for the 8% special production, since the proportion in this example is very low. Large companies that use multiple lamination systems also work according to this principle in many cases in order to increase efficiency and reduce production costs.
This approach is heavily dependent upon the customer segment and the products required in this segment. In such companies, the laminated glass products are sorted in advance and assigned to the appropriate lamination system in order to ensure that the process is quick and efficient.
2. FOIL PLACEMENT / FOIL CUTTING
There are also different types of foils that are used to bond glass lites sheets together, depending on their composition, degree of moisture and thickness. Special soundproofing foils are very different from those that have been developed for bulletproof glass, for example, even if the basic functionality is the same.
And these differences also have a significant impact on the price per square metre. For this reason, the foil itself also has a significant influence on the total production costs. Whereas a standard PVB foil costs around 4 euros per m², special foils can cost 4 or 5 times as much.
In terms of cost effectiveness, it is therefore of fundamental importance to place the foil economically and efficiently and to keep the foil overhang as small as possible so that foil wastage can be reduced. If a small glass with a width of 1 m is produced on a lamination system with a foil roll width of 2.6 m, for example, more foil wastage will occur. Wrinkle-free intermediate storage (for example with a foil shuttle) is also essential for this, so that the foil can be reused at a later point in time and overall costs / foil wastage are significantly reduced.
3. GLASS ALIGNMENT
Glass alignment is the real “bottleneck” of a lamination system. The converter places the aligned glass onto the first glass and the foil. The availability of the glass sheets is particularly important when it comes to production speed with this process. However, the cycle time can only be improved with an optimal combination of design with regard to glass alignment and positioning accuracy, and stable automation and programming.
Another very important element with regard to efficiency is pre-lamination, which is the final link in the process chain and is often referred to as the heart of a lamination system.
Pre-lamination has a significant influence on the quality of the finished laminate.
However, in addition to the pre-lamination speed, the upstream process steps of glass alignment, foil placement and cutting must also intertwine in the best possible way to achieve optimal results.
4. PRE-LAMINATION SPEED
The speed mainly depends on the energy supply, but also on the reproduction of the energy. Energy that is extracted from the laminated glass packages during pre-lamination must be recycled as quickly as possible in order to ensure efficient production. Otherwise the cycle time is reduced because the foil cannot warm up quickly enough due to an insufficient quantity of ambient energy.
There are two approaches with regard to this:
- Radiation - energy supply from IR radiator
- Convection - energy supply via the air
It has been shown in practice that a combination of both approaches is the most effective. With low-E glass, the radiation (heating energy) is very strongly reflected by the coating. This means that the foil takes more time to reach the right temperature. This effect can be compensated for to a considerable extent by means of convection.
However, with clear glass, which represents the majority of laminating glass, energy-efficient IR radiation is required to speed up the heating of the foil. The use of radiation or convection alone therefore not only weakens the energy transfer into or through the glass, but also the supply of energy for the next laminated glass package.
In addition to speed, the waste that can arise in pre-lamination also plays a significant role when it comes to increasing cost effectiveness. This particularly applies to the processing of expensive foils or with expensive glass lites sheets with printing as well as tempered glass lites sheets.
Experience has shown that pre-lamination with a spindle drive for the pressing roller infeed leads to significantly greater stability and process reliability and significantly reduces waste resulting from having an edge seal that is not optimum.
Pre-lamination can be described as the “heart” of a lamination system. But when it comes to increasing efficiency, there are many factors to consider. Only after a detailed analysis of all parameters should the decision be made as to which lamination system is right for your own operation. But the foils themselves, as well as the processes of foil placement and cutting and glass alignment, also have a fundamental influence on the overall cost effectiveness of the lamination process.