Frequently Asked Questions
How does high-speed drying work?
The extreme time saving factor is based mainly on 3 parameters:
- The wavelength of the special infrared light is perfectly adapted to the spectrum of water, only affecting the surface but not going deeper.
- A highly turbulent air whirl with a top speed of more than 8 m/sec.
- Extremely dry air, the humidity is sometimes less than 8 %.
A special air-cooling system ensures that the shell temperature does not exceed the pre-selected nominal value. The following values have to be registered continuously to control the system: The actual air humidity, the chamber temperature and above all the surface temperature of the tree. All three values are coordinated to make sure that the wax temperature does not exceed 25°C and that the shell does not crack. The balance of the complete system is achieved by the perfect coordination of these three parameters. If one parameter is not met, the system will cease to work.
Which time saving factor can be achieved with this new technology?
On principle, it is not possible to quote a general time saving factor, as it depends on too many different values, such as number of layers, transport distances to and from the drying process and the ratio between the number of layers with water-based binders and layers with alcoholic binders.
The rule of thumb is: The building of a shell so far has taken about 3 days plus 1-2 days for the drying. This new technology reduces this time to 4 hours and the de-waxing can be started immediately afterwards. There are also shells that so far have required a production time of 9 days, which can now be reduced to 11 hours. Here, the main focus is not on the shortest possible drying time but the safer and more effective way.
In general, it can be said that the application of this new drying technology reduces the drying time by a factor of 20 – 30.
What about the R.O.I. (Return on Investment)?
This question can either be answered very easily or not at all. How can the time saving factor really be calculated?
As the importance of the factor “time to market” is increasing steadily, the advantage of a drastically reduced drying time is very obvious. And if more and more companies apply this new high-speed drying, it will be very difficult to explain delivery times of several weeks to customers in the future.
Based on an investment of several hundred thousands and a daily throughput rate, i.e. 60 shells per day (booster and tunnel), the machine will have paid itself off after 2-3 years, provided that the additional costs of 6-7 EUR per shell are accepted. The fact that the conventional technology is more labour-intensive, and demands more space and energy has not even been taken into consideration for the above calculation.
Does this technology only work with special waxes, slurries and sands?
The high-speed drying process works with all standard materials und does not require any special substances. All standard water-based slurries, sands and waxes used in the conventional investment casting can also be applied for the Cyclone process.
Which slurries can be used – water-based or alcoholic?
The system only works with water-based slurries because of the given spectrum of infrared lights. At present, alcoholic slurries cannot be dried with this new technology.
Many investment foundries are especially interested in the new process, because they want to replace the alcoholic slurries by water-based slurries in order to save costs and for environmental protection. So far, the argument for alcoholic binders has always been, that water-based slurries have much longer drying times. By using the Cyclone technology this argument is no longer valid.
Do the increased drying temperatures lead to a higher risk of cracks and wax deformation?
As the maximum temperatures of 38-40°C only affect the surface and do not penetrate more deeply, the wax remains stable. It is supported by the evaporation cooling which equals 10 %, cooling the wax automatically.
As the parameters drying time maximum drying temperature and minimum humidity can be pre-selected independently, cracks can generally be avoided. The parameters need to be coordinated very carefully
What are the effects of the process on shell strength and permeability?
All tests at MK Technology as well as at industrial investment casting companies have proved that the new process has positive effects on the strength of the shell and on the permeability. At least, it appears not to show any negative influence. In general the strength as well as the permeability is increased.
The higher permeability is among others is achieved by a smaller number of layers, whereas the increased strength of the shell can be explained with a stronger bond between the SiO² colloids based on the higher surface temperature and the stronger diffusion gradient within the layer.
Can this technology also be applied for complex structures, shadowed parts and deep hollow spaces?
Yes, without reservation or exception. Yes.
The extremely reflecting interior assures that the red light also shines on complicated inner structures, at least for a short while. Furthermore, the turbulent and dry air reaches even the most remote angles.
So far, every part, even the most complicated, can be dried with this new technology.
Is there a standard program for all layers, geometries and different dimensions?
No, there is no standard program.
Every layer has to be processed differently, and also the geometry and dimension of the part has to be taken into consideration when pre-setting the 3 main parameters. In general, we give recommendations for the processing of the different layers but the vernier adjustment
must be attended to by the operator.
Is this system only applicable for Rapid Prototyping or have you already developed solutions for serial investment casting?
The first machine was developed for the field of Rapid Prototyping, containing the high-speed drying, slurry tanks, rainfall sander and linear drive.
As the serial investment industry showed tremendous interest in this drying technology, we have developed pure drying systems, which have already been put into operation. The Booster is a vertical single drying chamber for the acceleration of the drying of single trees.
The modular constructed and extendable drying tunnel is a continuous drying system that can be integrated in to an existing serial production processes. All systems – Cyclone, Booster and Tunnel are already in operation at numerous companies.
Who is already using this technology?
The first machine was developed for the field of Rapid Prototyping, containing the high-speed drying, slurry tanks, rainfall sander and linear drive.
As the serial investment industry had shown tremendous interest in the drying technology, we have developed pure drying systems, which have already been put into operation. The Booster is a vertical single drying chamber to accelerate the drying of single trees.
The modular constructed and extendable drying tunnel is a continuous drying system, which can be integrated in to existing serial production processes. All systems – Cyclone, Booster and Tunnel – are already in operation at numerous companies