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Two Dimensional Nozzles For Controlled Burnishing And Scratch Reduction On Disk Media

IP.com Disclosure Number: IPCOM000015136D
Original Publication Date: 2002-May-18
Included in the Prior Art Database: 2003-Jun-20
Document File: 2 page(s) / 115K

Publishing Venue

IBM

Abstract

Disclosed is a new nozzle design for airwipe process for burnishing of hard disks. These nozzles provide uniform and effective burnishing and cleaning without scratching the disk surface. It is a very simple and effective method to reduce scratches and missing bits and provide a much better quality media. Tape burnish is one of the important processes for disk media. The purpose of the burnishing process is to remove the surface contamination and asperities introduced by the pre sputter and post sputter processes. The burnishing process is done on sputtered and lubed disks before they go for certification. In this process air nozzles are used to apply local pressure on the tape having embedded aluminum-oxide particles. The pressure is transmitted to the rotating disk via tape. This enables it to remove the hard asperities and particles. The magnitude and distribution of this applied pressure is very important for asperity removal as well as surface scratching. Scratching of disks during the burnishing process could lead to missing bits, corrosion, file test failures and other problems. A new nozzle design was proposed and implemented to provide a well distributed controlled burnishing. This invention provides a significant reduction in terms of scratches and missing bit counts. The standard nozzles typically have several orifices (holes) for the air-jets in a row as shown in figure 1. At high rotation speeds (3000 and above) this line contact reduces to a point contact and tape fluttering occurs. The objective was to design the nozzles, which can provide a uniform, two-dimensional soft contact and eliminate the tape fluttering. The new nozzle has 4 rows of holes with a total of 36 holes. The hole size is 0.5mm , inner diameter, same as the 5 hole nozzle but without a counter-sink drill. At the standard inlet valve pressure the airflow rate with the old nozzles were measured as 60 liters/min. At the same inlet pressure airflow was 90 liter/min with the new design. The mass flow rate can be related to the jet m velocity at hole outlet as: nAv Here n is the number of holes, A is the hole area and v is the jet-velocity. For standard 5 hole nozzles it will be: 1 m 1 5 Av

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  Two Dimensional Nozzles For Controlled Burnishing And Scratch Reduction On Disk Media

Disclosed is a new nozzle design for airwipe process for burnishing of hard disks. These nozzles provide uniform and effective burnishing and cleaning without scratching the disk surface. It is a very simple and effective method to reduce scratches and missing bits and provide a much better quality media. Tape burnish is one of the important processes for disk media. The purpose of the burnishing process is to remove the surface contamination and asperities introduced by the pre sputter and post sputter processes. The burnishing process is done on sputtered and lubed disks before they go for certification. In this process air nozzles are used to apply local pressure on the tape having embedded aluminum-oxide particles. The pressure is transmitted to the rotating disk via tape. This enables it to remove the hard asperities and particles. The magnitude and distribution of this applied pressure is very important for asperity removal as well as surface scratching. Scratching of disks during the burnishing process could lead to missing bits, corrosion, file test failures and other problems. A new nozzle design was proposed and implemented to provide a well distributed controlled burnishing. This invention provides a significant reduction in terms of scratches and missing bit counts. The standard nozzles typically have several orifices (holes) for the air-jets in a row as shown in figure 1. At high rotation speeds (3000 and above) this line contact reduces to a point contact and tape fluttering occurs. The objective was to design the nozzles, which can provide a uniform, two-dimensional soft contact and eliminate the tape fluttering. The new nozzle has 4 rows of holes with a total of 36 holes. The hole size is 0.5mm , inner diameter, same as the 5 hole nozzle but without a counter-sink drill.

At the standard inlet valve pressure the airflow rate with the old nozzles were measured as 60 liters/min. At the same inlet pressure airflow was 90 liter/min with the new design. The mass flow rate can be related to the jet &=mvelocity at hole outlet as: nAv Here n is the number of holes, A is the hole area and v...