Matthew John Zaluzec

Pulsed thermographic inspection of spot welds

In automotive manufacturing, the lack of nondestructive methods for assessment of spot weld integrity has been a critical shortcoming, with enormous economic consequences for both domestic and foreign auto makers. At present, auto body welds are subjectively evaluated using destructive pull tests, or visual examination after the weld has been mechanically separated using an impact tool. Pulsed thermographic evaluation of spot welds offers a fast, noncontact method for quantitative assessment of the weld nugget. The technique can be applied using either one or both faces of the weld. Results on steel resistance welds will be presented, along with correlation to weld process parameters.

Metal Inert Gas (MIG) Welding Process Optimization for Joining Aluminum 5754 Sheet Material Using OTC/Daihen Equipment

The development of lightweight vehicles, in particular aluminum intensive vehicles, require significant manufacturing process development for joining and assembling aluminum structures. Currently, 5xxx and 6xxx aluminum alloys are being used in various structural applications in a number of lightweight vehicles worldwide. Various joining methods, such as MIG, Laser and adhesive bonding have been investigated as technology enables for high volume joining of 5xxx, and 6xxx series alloys. In this study, metal inert gas (MIG) welding is used to join 5754 non-heat-treatable alloy sheet products. The objective of this study is to develop optimum weld process parameters for non-heat-treatable 5754 aluminum alloys. The MIG welding equipment used in this study is an OTC/Daihen CPD-350 welding systems and DR-4000 pulse power supply. The factors selected to understand the influence of weld process parameters on the mechanical properties and metallurgy (weld penetration) include power input (torch speed, voltage, current, wire feed), pulse frequency, and gas flow rate. Test coupons used in this study were based on a single lap configuration. A full factorial design of experiment (DOE) was conducted to understand the main and interaction effects on joint failure and weld penetration. The joint strengths and weld penetrations are measured for various operating ranges of weld factors. Post weld analysis indicates, power input and gas flow rate are the two signficant factors (statistically) based on lap shear load to failure and weld penentration data. There were no 2-way or 3-way interaction effects observed in ths weld study. Based on the joint strength and weld penetration, optimum weld process factors were determined.Copyright

Influence of Metal Inert Gas (MIG) Welding Factors Wire Feed Rate and Weld Travel Speed on Aluminum Weld Joint Strength

The purpose of the study was to understand effects of weld travel speed and wire feed rate in metal inert gas (MIG) welding on the aluminum materials joint strength. Initial experiments indicated a noticeable positive effect of travel speed on weld strength with an over 95% statistical significance. Nonetheless further experimentation at a significantly lower wire feed rate proved the opposite with similar statistical significance. A negative effect of welding travel speed on joint strength was measured at lower wire feed rates. In order to understand the weld travel and wire feed rate on the joint strength, a Design of Experiment (DOE) was conducted. For this experiment, weld system process factors were set constant (wave control, gas flow rate, torch angle, trim and wave type) except for travel speed and wire feed rate. A two-factor two-level full factorial design of experiment (DOE) was conducted in order to understand the effects of these two factors on weld strength. Additional welding at higher wire feed rates were conducted in order to confirmed the trend found. Results showed travel speed effects on joint strength as a result of its direct interaction with wire feed rate. This occurrence can have significant economic implications if proven to be repeatable and will be the subject of this and future MIG welding studies as they relate to aluminum structures.Copyright

Infrared in automotive applications

As the automotive industry continues to develop advanced materials and manufacturing processes, infrared imaging has the potential to become a major tool in process monitoring and closed loop process control. This paper reviews five novel applications of infrared imaging in applications such as product testing, component manufacture, and vehicle assembly. Infrared was found to be effective as a diagnostics tool for characterizing disc brake systems and electronic engine control sensors. The effectiveness of infrared to qualify fuel nozzle backspray was used to optimize hardware design for fuel systems. Finally, infrared was found to be useful in vehicle assembly operations in the installation of windshield glass and instrument panel hardware where visual inspection was impractical. The speed of image capture and the availability of image processing software for real time image processing and closed loop process control will no doubt find more applications as infrared imaging finds its niche in the automotive industry.