Application and Upgrading of On-line Monitoring System for Measurement and Processing of Electric Signals at Arc Stud Welding Process
As the application of on-line monitoring system is shown to be a good solution during monitoring of main welding parameters at different welding processes, this paper describes application and upgrade of on-line monitoring system developed at Mechanical Engineering Faculty in Slavonski Brod. Experimental part of the paper shows application of on-line monitoring system during welding of two types of studs with application of activating flux for ATIG process (VS-2E) on the base metal surface. Monitoring of main welding parameters (welding current and voltage) was conducted during welding of studs usually used in steam boiler production (stud diameter: 10 mm), and welding voltage was monitored on the studs (shear stud) of 22 mm diameters used in bridge construction. The goal of monitoring and analyse of main welding parameters is to evaluate the connection of electric arc parameters variations with the presence of activating flux.
The influence of shielding gas composition and insufficiency on MAG welding process stability and weld quality
In this paper, some problems related to MAG welding process stability and weld quality changes due to influence gas shielding are investigated. Experimental welding was performed with solid and rutile flux cored wire, with shielding gasses CO2 and Krysal 18 (82% Ar + 18 % CO2) and without shielding gas protection. Adopted welding speed was 45 cm/min and shielding gas flow rate was 15 l/min. In order to evaluate the influence of gas shielding composition and its insufficiency on arc welding stability, changes of welding current and voltage as well as the sound alternations during welding process were on-line and off-line analyzed.
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.