Statistical Modeling of Pin Gauge Dimensions of Root of Gas Turbine Blade in Creep Feed Grinding Process
Creep feed grinding is a recently invented process of material handling. It combines high quality of the piece surface, productivity, and the possibility of automatic control. The main objectives of this research is to study the influences of major process parameters and their interactions of creep feed grinding process such as wheel speed, workpiece speed, grinding depth, and dresser speed on the pin gauge dimensions of root of gas turbine blade by design of experiments (DOE). Experimental results are analyzed by analysis of variance (ANOVA) and empirical models of pin gauge dimensions of root are developed. The study found that higher wheel speed along with slower workpiece speed, lower grinding depth and higher dresser speed, cause to obtain best conditions for pin gauge dimensions of root.
Selections of working conditions for creep feed grinding. Part(II): workpiece temperature and critical grinding energy for burning
In this study, the workpiece temperature is predicted by the thermal model presented in the previous paper. Also, the grinding energy when the fluid begins to cause boiling is defined as the critical grinding energy for the workpiece burning. Thus, a sequence of experiments are performed. The results show that the predicted workpiece temperatures have great agreement with experimental and published data. Hence, the validity of the thermal model is proved. From the measured signals of grinding force and workpiece temperature, the occurrence of workpiece burning is accompanied with the abrupt rise of both signals. At the moment, the experimental grinding energy is also greater than the critical grinding energy. Thus, the workpiece burning can be predicted or evaluated so as to avoid the working conditions of burning occurrence.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.