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Parameters Analysis for Low Power Q-Switched Laser Cutting in Singulation Process of HDD Manufacturing The 4th AIT Masters Theses Competition Present By Sujin Wanchat Industrial Systems Engineering Asian Institute of Technology May 18, 2009 OUTLINE - Introduction - Statements of Problem - Objective - Methodology - Results - Conclusions INTRODUCTION Hard Disk Drive (HDD) = A main digital data-storage in a computer. A HDD suspension = A part of HDD that carries the read-write head flies over the disk media. INTRODUCTION Manufacturing process of HDD suspension Etching stainless steel Component forming Assembly all components Functional forming Cutting (singulation) INTRODUCTION The suspension bridge and the cutting line INTRODUCTION Laser cutting Die cutting INTRODUCTION Laser cutting has more advantage in reducing clinging particles on cut-finished surface. Laser cutting can not avoid the thermal effect which may cause malfunction of HDD suspension. Thus, the surface roughness (Ra) and heat affected zone (HAZ) must be reduced as much as possible. STATEMENTS OF PROBLEM - According to die cutting process, the number of waste products still appears. - The tool wearing can be found in die cutting, but does not exist in laser. - The laser cutting shows the evidence of better cutfinished surface than conventional die cutting technique. STATEMENTS OF PROBLEM Quality Rate Edge quality Kerf width Scrap and swarf Distortion Noise Metal + nonmetal Complex shapes Punch Abrasive Laser Plasma Nibbling (die) fluid jet Multiple layers Equipment cost Part nesting Flexibility Tool wear Automation Heat affected zone Clamping Blind cuts Weldable edge Tool changes Numerical control milling Ultrasonic Oxy flame = Advantage = Disadvantage Sawing Operating cost High volume Wire electric discharge machining (EDM) OBJECTIVE To investigate the influent parameters which affect the surface roughness of cutting plane and the HAZ length based on Nd:YAG pulsed laser METHODOLOGY Laser Types CO2 Non-metal Nd:YAG Metal Wavelength = 10.6 m Wavelength = 1.06 m Laser Modes CW Pulsed - Cannot modify “power profile” - Reduce interacting time - Raise peak power METHODOLOGY DOE is analyzed based on the experimental data using “24 factorial designs with addition of center points” technique. Controllable factors Low level Medium level High level (-) (0) (+) Beam focal spot size, (m) 46.279 50.545 61.327 Pulse frequency, f (Hz) 50103 72.5103 95103 Cutting speed, v (m/s) 1,000 1,150 1,300 16 17.5 19 Laser power, P (Amp) Controlled factors: 1. The same work piece’s model 2. Pulse width, Td = 2 s 3. Room temperature = 28 C 4. Each specimen has thickness of 25 m, and the bridge’s width of 2 mm. METHODOLOGY Conduct the real experimental data from the total 20 cases. METHODOLOGY 2 1 3 1. Workpiece after cutting 2. Surface Profile 3. Ra value reported RESULTS Ra 3rd 2nd 1st A = Beam focal spot size (m) C = Cutting speed (m/s) B = Pulse frequency (Hz) D = Laser power (Amp) RESULTS HAZ 5th 3rd 4th 1st 2nd A = Beam focal spot size (m) C = Cutting speed (m/s) B = Pulse frequency (Hz) D = Laser power (Amp) CONCLUSIONS ABD (+) Low A, B, and D consequently Low Ra Significant Factor for Ra CD (+) A = Beam focal spot size (m) B = Pulse frequency (Hz) C = Cutting speed (m/s) D = Laser power (Amp) Low C and D consequently Low HAZ Significant Factor for HAZ CONCLUSIONS Ideal pulsed laser for cutting process must have: short wave length, very short Td, very high f, high Pp, small and fast cutting speed.