We process hot rolled and cold rolled steel coils by slitting and cutting operations to produce them in desired sizes. The cold rolled material, which is consumed by automotive and white goods industries, have stringent quality norms for strip surface. Thus, the product must be inspected for both top and bottom surfaces during processing to identify the defects. In the existing processing lines, the visual (manual) inspection is carried out by running the lines at low speed and thus losing productivity considerably. Apart from productivity loss, it causes operator fatigue.
Advanced inspection systems are available in the market but the cost is prohibitively high. It is also not feasible to install them in multiple processing lines as the volumes are low about 100 KTPA only.
At present visual inspection is done by an operator standing continuously in front of the machine. It is a manual & inefficient process. Though the operator is able to identify all the defects, the productivity is low and causes operator fatigue. Currently lines are running at 40% of the optimal speeds to enable manual inspection.
As this is a manual process there is no record of historic data, therefore traceability and root causes analysis becomes laborious activity.
Following are the details about the material that is inspected and the defects that are identified:
Material rolled: MS ( CRCA, Galvannnealed, GP).
Min strip thickness: 0.4mm
Max strip thickness: 3.2mm
Min strip width: 80mm
Max strip width: 1540mm
Max strip speed: 200 mpm
Type of the line: Slitting lines
Inspection requirement: Inspection is done on both the sides of the strip. It is done both before and after slitting process
Type of the defects detected:
Dent Marks, SPM Matte less Mark, Roll Mark, SPM Pinch Mark, Rubbing Mark, Scratch, Sliver, Lamination/ Flying scab, Gauge Mark, Carbon soot mark, Oxidation mark, Rust patch, Holes, Black/brown patches, Scratch, Rubbing marks, Coils slips, Fold marks etc. Minimum size of defect is 5mm. Click on the following link to look at the images of the defects: https://www.dropbox.com/s/nceizhf00pdlc4f/Visual Standard of RM defect.pdf?dl=0
The solution should clearly explain how the following points are addressed:
1. Completely automatic setup.
2. Cost effectiveness; Similar solution will be replicated in processing lines in all the plants (about 15nos. processing lines). The upper limit is Rs. 5 lacs per equipment for an end to end solution
3. Inspection of both top and bottom surface inspection at rated speed (max strip speed: 300 Meter per minute).
4. Facility to capture images, detect the defects and classify and label them
5. Reviewing options for Off-line analysis and visualisation.
6. If the type and/or quantity of defects cross an upper threshold an alarm should be triggered and processing line is stopped automatically.
Success Criteria & Measures of success
1. Facility to capture, store, review and analyse defects and option to develop and enhance defect library.
2. The device should stop the processing line automatically in case of defect severity goes beyond the acceptable limits.
3. The speed of the processing lines should not be compromised as losing productivity is not preferred.