The Effect of Sand Blasted Mill Rolls Upon SCR Rod Dust Levels, Roll Life and Residual Oxide Levels

The Effect of Sand Blasted Mill Rolls Upon SCR Rod Dust Levels, Roll Life and Residual Oxide Levels

November 29, 2000

This paper is a summary of work done at two small SCR systems, CFT in Viet Nam and ALPHA in Malaysia. The data was not directly disclosed by ALPHA to Southwire and therefore should not be discussed with ALPHA until they directly disclose it to Southwire.

Backgound:

CFT is a modern SCR 2000 system started up in May 1999. This system has a 2100 sq mm bar, 12 tph casting rate and our standard high pressure descaling sprays installed. It is usually operated two to four 24 hour days per week. They are using GWR rolling oil without Irgamet 42. CFT earlier this year began to concentrate on lowering rod dusting levels after complaints from customers. Earlier this year, Southwire had asked CFT to evaluate the effect of Irgamet 42 to see if it had any effect on rod dusting levels. To date, CFT has not added Irgamet 42, but is poised to do so. Normal monthly production for CFT is 1000 to 1500 tons/month.

ALPHA is a 9 tph SCR with a 1548 sq mm bar. It was originally Walsin Lihwa #1 and moved from Taiwan. They were using HRL-MB with emulsifier from the April 1999 questionnaire. They do not have high pressure soluble oil sprays on the bar. Alpha had reported in July 1999 that the use of alcohol in the rolling mill significantly reduced roll life, but made the smooth rolls look shiney.

Summary(摘要)

CFT was able to lower dust levels to 2 mg for a 10 inch sample while simultaneously achieving a residual oxide level of 250 to 300 Angstroms. [1 to 2 mg dust is as low as CDS normally produces with a much larger bar and sometimes up to 5 mg or higher]. Using SMD smooth rolls and high pressure descaling at CFT gave rod dust levels of 10 mg. As a by-product of using the sand blasted rolls, roll life was significantly increased while still using alcohol in the mill. The main change to achieve low dusting levels and long roll life is to sandblast the first four stands of the rolling mill. Alcohol in the rolling mill cut the residual oxide level on the rod in half when using sand blasted rolls. Smooth rolls and alcohol in the soluble oil gives low roll life. I believe the sand blasting of rolls and dust level discovery was first made at CFT, then later confirmed by trials at ALPHA.

Alpha was measuring about 37 mg dust on a 10 inch sample using standard smooth H13 rolls without high pressure sprays. Alpha achieved an average of 8 mg of dust using Southwire shot peened rolls. Buffing a sandblasted or shot peened roll negates the effects