LABORATORY OF RAPID PRODUCT MANUFACTURING BY LASER ADDITIVE TECHNIQUE
The laboratory is equipped with two LENS (Laser Engineered Net Shaping) type systems:
- laboratory MR-7,
- semi-industrial 850-R,
purchased under the LAPROMAW project.
The MR-7 system is designed specifically for the needs of materials science. It enables the production of items no larger than 300 x 300 x 300 mm from a maximum of quaternary powder mixture (a set of four feeders with powder mixer - composites, continuous and discrete gradients, dispersion strengthened alloys). It is equipped with 500 W power fiber laser. Technical solutions allow for precise control of the supplied energy and the cooling rates (even above 1000 degC/s) of "irradiated" element zones (important in the case of strongly exothermic reactions taking place, such as Fe-Al). Numerically controlled stages allow for the laser and feed nozzles transfer in the Z-axis and movement of the table in X, Y axis, with a positioning accuracy of ± 0.25mm and a linear resolution of ± 0.025mm. The process takes place in strictly controlled atmosphere in which the oxygen content is below 10 ppm which gives, among others, possibility of sintering of highly pyrophoric powder (in combination with an appropriate laser power control and cooling rate).
The system is equipped with variety of software: CAD / CAM package - to quickly define the shape of the workpiece, the "Rapid set-up" package - supporting the implementation of the idea "develop a new material in 10 minutes", and hardware-software package Therma-Viz, Thermal Imagers and Melt Pool Sensor that allows for full and automatic control of the thermodynamic conditions during the sintering process and analyze the cause and effect relationship of laser power, cooling rate, structure, and properties of the resulting material / component interdependence. Upon using LENS MR-7 one can also make finished items (after previous optimization) with a small gauge and relatively simple shape, such as trial series for supplies testing. Tested on a laboratory scale, a material can be then used to produce specific items of machinery parts.
The LENS 850-R has a larger working space (900 x 1500 x 900 mm), laser power of 1 kW, larger capacity of feeders and the same positioning accuracy, resolution, and control of the atmosphere as the MR-7. In addition to enhanced working chamber, LENS 850-R has another major advantage with respect to the laboratory system, namely the ability to control the movements of the five axes (X, Y, Z - head, tilt, rotation - working table). Presented number of degrees of freedom of the working facilities, enables to make practically any shape in conjunction with advanced CAD / CAM software. By combining the two LENS systems - laboratory and semi-industrial – there is a possibility of rational menagement of time, cost and scientific ideas. The use of concurrent designing reduces the production time of the finished element even down to one third, as compared to the time needed for model sequence.
Manufacturing capabilities of the laboratory based on LENS technology are virtually limitless. Rapid design and manufacturing of new generation materials, adapted structurally and with functional features level to meet the requirements for a specific machinery elements, abilities of programmed and controlled production of zonal heterogeneity of the material in these elements and the local reclamation of used machinery parts, is a step towards new standards in materials science. Step by step reconstruction of 3D geometry programmed using CAD technology is in reference to the operating conditions of a given element during the LENS process and enables the formation of such a structure that will, for example, ensure to achieve an optimum elastic and endurance properties in the areas of the largest exertion, and in the areas exposed to highly aggressive environment – an optimal corrosion resistance. It is noteworthy to mention that it is also possible of completing defects in the operating parts of the machine using LENS technique. A suitable software enables to restore the original shape of a given part, maintaining at the same time the accuracy of the dimension and its rapid regeneration. The individual design effect and fabrication process, which is relatively easy to achieve, creates a major perspective to solve social problem related to "bio-exchangeables". Visualized by CT scan, diagnosed knee joint can be made by a metal and individually tailored prosthesis can be prepared, taking into account physical activity and weight of the patient. The proposed technology is environmentally friendly. The systems are equipped with respective filters: utilized gases generated during the sintering process, retaining loose powder particles suspended in the chamber volume, as well as systems for the recovery and recycling of the unused powder.
SPECIFICATIONS OF TWO-STAGE LENS SYSTEM
|Laser [W]||IPG YLR-1000||IPG YLR-500|
|Working area [mm]||900x1500x900||300x300x300|
|Number of powder feeders||2||4|
|Protective atmosphere||argon (O2, H2O < 10ppm)||argon (O2, H2O < 10ppm)|
|Precision of positioning [mm]||0.25||0.015|
|Linear resolution [mm]||±0.25||±0.0025|
|Max. scanning velocity [mm/s]||60||60|
|Software||Work Station, Materialise Magics, PartPrep Slicing||Work Station, Materialise Magics, PartPrep Slicing|
|Additional equipment||Melt Pool Sensor*, Thermal Imager**||Melt Pool Sensor*, High Overhang Head***|
* Control system of the size of liquid metal pool (feedback between the size of the pool and power of the laser)
** Temperature and a cooling rate control system of liquid metal pool
*** Head allowing for the manufacturing of components with complex geometry