The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Shortage control in Pickling and Annealing of stainless steel sheets

April 20, 2011

Sir,

I am Rajesh Ojha From India. I am Production Manager & Quality Control in Stainless Steel Re-Rolling Industry. Our Process Information is like :

1. Our manufacturing process is basically a gauge reduction process for which the raw material i.e. Stainless steel flats are first hot rolled and then cold rolled.

2. The Stainless steel flats are first cut into the required sizes and then hot rolled to convert it into 16 gauge sheet or patta. Hot rolling involves annealing the flat pieces in furnace and then rolling it in heated state itself. End product of this process is Stainless steel sheet of 16 gauge which is called "Hot Patta".

3. Now, the process of Cold Rolling starts. The "Hot Patta" are first annealed in furnace at a temperature range of about 900° C. This is called "Annealing". Then this annealed patta is then pickled in a mixture of various acids such as Nitric Acid, sulfuric Acid etc. This is called "Pickling" and results in "Pickled Patta".

4. The Pickled Patta is then rolled in Roughing Mill. In this process the gauge of the sheet is reduced to 20 swg from 16 swg. After this, the sheet is again annealed in the furnace (oil used for heat is Carbon black feed stock CBFS) and pickled in a mixture of acids (Hydrofluoric acid, Sulfuric acid & Nitric acid.) After this the sheets are again rolled for final gauge reduction and then finishing.

5. After the final rolling the sheets are again annealed. Then the sheets are straightened in Straightening Machine. These sheets are then washed in mixture of acids.

6. This process gives 22 gauge sheets. The process is required to be repeated more number of times for further reduction. Now, the sheets are ready for dispatch.


My Question is about quality control and Cost cutting with controlling of shortage in the manufacturing process. Currently our cost has increased by Rs 2 (INR) per kg and Shortage 1-2 %.
So kindly let me know if any other technique use in process to control shortage.

RAJESH OJHA
QUALITY CONTROL AND PRODUCTION MANAGER - JODHPUR, RAJASTHAN, INDIA