Nowadays, the reduction of production costs is one of the critical factors to survive within the global market. This also applies to the glass industry. A helpful means for achieving this target is to increase the degree of automation at the production and to reduce the labour costs respectively. At this point, the laser, successfully been used in the automotive and metal industries for decades, can also be used in the glass industry.
One of the important advantages is the flexibility of laser light. By focusing the laser beam it is possible to cut quartz glass or to scratch borosilicate glass for a subsequent cracking-off process. A glass heating used for forming or joining processes can be realized by the adjustment of larger laser beam diameters on the glass. Each kind of glass, from quartz glass to AR-glass, can be processed with a laser source.
The advantages of the laser can be seen at the following summary:
Fully automated working processes
■ several processes with „one tool“
■ focused cutting, defocused heating
■ possibility of production starting from initial tube and not with
pre-cut tube segments
Precise temperature control at heating processes
■ independently adjustable temperature profiles, adapted to the
■ high reproducibility: „same process sequence – same process
■ force-free processing – no flame pressure
No chemical influence to the glass during the process
■ no condensation water or soot
■ no remaining residual stresses (which are caused by chemical
influence) in the glass after annealing
Defined and efficient energy transfer to the glass
■ fast heating
■ no /low heating of the machine periphery
Adjustable intensity distribution in the heating zone
■ heating zone on the glass surface can be adapted (in terms
of heat distribution and/or shape)
e.g. linear, circular, elliptical, etc.
■ by system flexibility
■ short process times
■ multiple use of one laser source on several work stations
■ low maintenance resp. maintenance-free
■ marking /
Several process steps are often necessary to achieve the final product of the requested laboratory device. For instance, at the production of thermometers the glass tubes are initially tapered, separated in the tapered zone, and then joined at this position with smaller glass tubes that match the tapered diameter. Both ends of the thermometer have to be sealed during the subsequent manufacturing process.
(also glass metal sealing)
(wall thickness, diameter)
■ marking / engraving
One important process step at the production of lamps is the cutting of glass tubes.
The cutting is differently realized depending on the kind of glass. While glasses with higher coefficients of thermal expansions are cut by thermal shock or scratched and cracked-off, quartz glass is typically sawed.
(also glass metal sealing)
Besides laser cutting, glass tubes can also be heated with laser radiation for complex forming processes like flanges etc.. The laser heating is e.g. used for production of heat pipe evacuated-tube collectors.
urthermore, tubes can be joined by a laser in butt joint. A special highlight is the glass-metal-sealing, which is also used in solarthermics.
The ARNOLD modular system
Our concepts are based on our standard modular design for glass processing machines. Upon request, the basic machines can be supplied with respective forming tools, automation concepts for automatic loading and unloading of machines. According to customer’s application a suitable laser source is chosen and implemented. Of course, we also quote solutions perfectly adjusted to your individual production process.
When processing glass by means of lasers, in principle several kinds of lasers are applicable. Glasses behave transparent in the visible range of light and in the near-infrared (possible laser wavelengths of about 500nm to 1100nm) respectively. Therefore, they can be marked within the volume by means of solid-state lasers that emit radiation in this wavelength range. This method is known as volume engraving (e.g. for design applications).
If glass has to be heated (e.g. for subsequent forming or joining processes), CO2 lasers are recommended. They emit radiation in the mid infrared range; a typical CO2 laser wavelength is 10600nm. The chart clarifies that glass, regardless of the kind of glass, behaves opaque and not transparent when irradiated with this wavelength. Thus, the laser radiation is absorbed and / or reflected at the glass surface. The ratio of the reflection depends on the radiation situation and the angle of incidence and is about 20%. Consequently, 80% of the emitted laser radiation is absorbed on the glass surface and is used to heat the glass.
Due to the geometrically defined heat input while using lasers for glass processing, forming tools can usually operate during heating which leads to shorter process times. Common materials for forming tools can be gray cast iron, graphite or stainless steel. The material is based upon the forming process and the kind of glass to be formed.
With the launch of laser processing machines, the controls of Arnold machines have been basically redesigned. It is now possible to create freely programmable process sequences via Drag & Drop by means of a graphics-based programming platform. Pre-programmed sequencers, with limited allowance to the individual working process of the machine are a thing of the past. The new software AEPS+ can be installed at any commercially available computer. The communication with the machine control system (PLC) is realized via Ethernet interface. The creation of the fully-automatic program sequence is then effected via Drag & Drop. Here, from a defined tool box (picture, left hand column) the symbol for the individually to be accessed hardware is selected and moved to the desired program step (picture, right hand column) and then parameterized.
As shown at the sample program in the graphic, the axis for the burner support is moved with 3000 mm/min to position 600mm at the first step (Step1). In the next step, the burner is switched-on, ramped up to the defined flow rates and operated for 10 seconds with these flow rates. The third step involves the switch-off of the burner. At the fourth step, the burner support is moved to position 200mm and the sequence ends. After creating this program it is now passed on to the machine control by pressing just one button. After this transfer, the computer is not longer necessary and can be unplugged, since the process sequence is now performed by the machine control.
Advantages for the use of AEPS+
1. Creation or modification of program sequences without
external software engineer
■ No disclosure of internal process Know-how to external software
■ High flexibility and independency
■ Short reaction times at urgently required adjustments of process
■ High cost savings
■ Permission management
2. Intuitive graphical machine programming per Drag&Drop
■ No programming skills of the system operator / process specialist
■ Creating of new / adjustment of existing program operations in
the shortest time possible without training
■ Sequence programming is carried out on commercially available
Notebook / PC
■ Theoretically infinite numbers of program sequences can be
created / stored
■ Creating redundant backups to external media is possible
Arnold glass working lathes are used in the laboratory glass production and electronics industry for joining, forming and fusing operations. They are also used in quartz glass industry for calibrating the diameter and/or the wall thickness of large, long tubes as well as for joining and forming operations with special tools and machine equipment. Another range of applications is the fiber industry with special machine concepts for individual process steps.
Depending on the application and customer requirements with regard to the cycle time, the glass working lathes can be equipped with ball screw spindles or linear motors.
This drive concept is characterized by high acceleration and top speeds. Due to the non-contact transfer of driving forces between the working head and the machine bed, these drives work almost wear-free.
ARNOLD Präzisions-Glasdrehmaschinen eignet sich besonders für Laseranwendungen zum Beispiel in der Labor- und Lampenglasindustrie aufgrund seines Aufbaus mit einem stabilen und verwindungssteifen Maschinenbett sowie der für jeden Arbeitskopf getrennten Antriebstechnik. Die Maschine ist als kompakte Einheit einschließlich dem Laseraggregat und der Maschinensteuerung aufgebaut und kann wahlweise im manuellen Betrieb oder auch im voll automatisierten Betrieb – z.B. durch Bauteilbe- und Entladung mittels Industrieroboter – betrieben werden.
The machine type P1040 is based on the Arnold Standard Glass working lathe P1040.
This all-purpose precision glass working lathe is especially suitable for laser applications, e.g. in the laboratory and lamp glass industry; possible processes include joining, forming, cutting, flange / thread production, calibrating and drilling. The system is designed with a stable and torsion-free machine bed as well as a separate drive technique for each working head. A continuous adjustment of the laser beam diameter becomes possible by using a motorized axis for traveling the focusing lens.
The machine is designed as a compact system including the laser unit and machine control and can be operated either manually or fully automated, for instance by loading and unloading of work pieces via industrial robot.
NC 56 Laser
The machine NC56 Laser is based on the Arnold standard glass working lathe NC56.
This numerically controlled precision glass working lathe is especially suitable for laser applications, like for instance joining or forming of larger tubes, e.g. in the solar industry or in the chemical apparatus industry. The machine consists of an extremely sturdy and torsion-free machine bed as well as a separate drive technology for each working head. The laser with the required chiller is adapted as separately positioned unit. Via mirrors an economic operation of several machines with only one laser system becomes possible. The machine can be operated either in manual or in automatic mode – for instance with an automatic loading and unloading system of work pieces.
Laser engraving machine
Automated laser machine for engraving a wide variety of surfaces