The HAG is a fully automated solution for XRF fused bead production, measurement of moisture, and thermogravimetric analysis (TGA) / loss on ignition (LOI) determination. It is available with 4, 6 or 8 fusion stations.
The system has the following components which can be flexibly combined:
- Input tray magazine
- Dosing module
- Fusion module
- Cleaning module
- TGA/LOI module
Plastic vials with 20 to 50g of sample material are manually or automatically placed into the tray of the input magazine. All of the subsequent steps are fully automated with no need for operator intervention.
Input tray magazine
Several options for the sample input magazine are available, including 62, 200, 300 or 400 position magazines. They can be connected to an automated sample preparation cell or they can be manually loaded. There is also a 10 position manual sample input in the dosing module where samples can be registered. This is useful for entering quality control samples.
The magazine has an XY gripper which transports the vials within the unit, and to the barcode scanner and output position. Vials are sent to the fusion system to be processed, and then returned to the magazine in case a bead is rejected and the sample needs to be rerun.
The dosing module consists of up to three dosing stations, a sample mixing station, buffer position for the TGA and platinum crucibles, and an optional release agent dosing station. All stations are tended to by a small 6-axis robot arm. Sample vials from the input magazine are placed into one of the three dosing stations.
For the fusion process, flux and sample are alternately weighed into the crucible to achieve the optimal dilution ratio. The crucible is then transferred to the mixing station for mixing, and optionally to the dosing station for the addition of the wetting agent.
For the TGA / LOI, the sample is weighed into a TGA crucible and transported to the TGA module for moisture and LOI determination.
The control system allows for dosing of different types of flux as well as different sample and flux volumes.
Depending on the configuration, the fusion module will consist of 4, 6, or 8 heating stations. Each station has a separate position for the crucible and casting dish. The overhead linear transport transports the sample from the turntable to the heating station, fused bead to the XRF belt, and dirty crucibles and casting dishes to the cleaning station.
The HAG system uses modern high frequency generators for stepless induction heating from 385°C to 1300°C. The temperature is continuously monitored using infrared pyrometers which allows for very reliable temperature control for the whole process. Crucibles are heated automatically according to the predefined sample program. During the fusion process, the sample can be swirled in an elliptical motion to ensure a homogenous and bubble free melt. The casting dish is heated at the same time to a predefined temperature.
Once the fusion is complete, the sample is poured automatically into the casting dish where it is left to be cooled. Different cooling regimes can be set such as fast cooling with compressed air. Before being transported to the XRF, a detector confirms that the bead is not cracked or misshapen.
After the fusion process, the casting dishes and crucibles are cleaned in the heated ultrasonic baths. 14 crucibles and casting dishes can be cleaned simultaneously in the citric acid solution. Afterwards they are rinsed with distilled water and dried with hot air to ensure unbiased results.
This module consists of 2 to 4 TGA furnaces each running at a predefined temperature, usually in accordance with ISO specifications. The number of furnaces depends on the number of temperatures at which the LOI needs to be reported. A multi arm transport moves the samples between furnaces as well as to the cooling and cleaning station.
Advantages of the automated fusion process
Every sample is processed identically and not subject to human error. Since the TGA analysis is carried out simultaneously, sample moisture can be determined and corrected for in the analysis. This eliminates the need for storing samples at 100°C to avoid moisture uptake.
Improved health and safety:
Automation totally eliminates the need for manual handling of hot crucibles for fusion and TGA. Certain manual systems have open flames and require the use of highly flammable gases.
Reduced risk of sample mix up:
Automation drastically reduces the risk of mix ups and losing sample data. As long as the samples are input correctly, then all of the subsequent analyses will be correct, with the results being instantly captured by the PrepMaster software.
Elimination of repetitive tasks and reduction of labour required:
Mundane and physical tasks can result in operator fatigue and mistakes being made. Automation significantly reduces these risks and frees up personnel for other tasks.