A very challenging problem to steel producing companies in controlling the caster quality has been that there are no "instant" feedback methods available. What most mills do, is they periodically take a small sample of the cast steel, etch it and then see what problems the steel may have e.g. corner craking, argon bubbles, black spots etc. This causes millions of tons of scrap and remelt across the steel industry since there are no ways of repairing what was cast. The only way to deal with this is to either sell the cast as lower grade or re-melt and try again.

This operation mode is not efficient and the costs are huge from wear on equipment, labour, internal and external transportation and energy to loss capacity and earnings. Now there is a cure for it.

Pesmel has taken the opportunity of been a pioneer and developed together with a customer a new concept where a piece of steel can be analyzed practically on line. The results can be used to control and track the performance of the caster. The system has now been in operation for few months and the results are better than expected. By this system the output of scrap has reduced significantly and earnings increased. According to the customer, the payback time of the investment is not months but weeks.

Slab Inspection Line functions

Pesmel slab inspection line handles and pictures carbon steel slab samples that arrive from the production.  A piece of cast metal (sample) is cut off from slab as soon as it exits the caster.  The sample is cut with torch cutter and lifted onto input conveyor. Material handler, who deposits the sample onto the conveyor keys in the heat number at what time all relevant information of that heat number is transferred from the mill computer system to the information system of the inspection line. Based on the heat number, the system knows if the sample has to be air cooled (to avoid cracking) first, or if it can immediately be deposited to water quench tank.

As the sample is first air and then water cooled, the system automatically moves the sample to a machining center. The heat affected zone of the sample is rout off and the sample proceeds forward in the system. Next, the sample's routed surface is automatically washed, etched and dried.

After this, a high resolution picture is automatically taken from the sample. The picture is saved under the heat number and through the mill computer sent directly to the caster pulpit for the operator to analyze the casting results and adjust the casting process. 

In the analyzing software the operator can zoom in for a closer inspection of the surface. The customer has some standard rulers and triangles available in the PC based system. Each and every picture is automatically stored and, if needed, they can be sent to the end customer as proof of the quality of the steel as it exited the caster. The system is totally automated process with zero operators required.

Success story from a pioneer project

The slab inspection line is one of the kind in the world and it set many challenges to Pesmel professionals when designing this fully automatic system. For example, the high temperature of the slab samples set special requirements to machines and required product development work, as this was a new area of operation to Pesmel. However, the results speak for themselves and the customer is satisfied to Pesmel’s ability to provide comprehensive material handling systems.
This new system helps mills produce higher quality steel without adding any resources to the process. It also reduces the cost of quality sampling, while significantly increasing the amount of sampling, as practically every heat can be etched, sometimes multiple times.

The system provides significant competitive edge to steel producers as they can prove the quality to their quality consciousness customers like automotive industry, for example. Automated slab inspection line also provides outstanding tool to optimize the caster maintenance cycles as the SPC (statistical process control) can be fully implemented.

Among metal industry Pesmel is better known from it’s automated, high capacity handling and packing lines, of which the company has over ten years’ of experience. During these past ten years, Pesmel has been doing pioneering work on the development and automation of the finishing end of the production chain in steel mills. Product development arising from customer needs has already resulted in several competitive products e.g. the through-the-eye wrapping system with automated film roll changing, a body-wrapping technique for coils and a packaging system for sheet bundles. In addition, many smaller devices and modifications have been developed for various stages of the system.

Further information:
www.pesmel.com or pesmel@pesmel.com