SNOWFLAKE CODE MARKING AND READING
Bar codes are the most common and cost effective way of coding products which have to be automatically scanned.
However due to the way a bar code is read, the code must be always be applied precisely and the code reader is very sensitive to the accurate maintenance of the distance between the bars or if the code is distorted. Only a limited number of marking methods can achieve this, and normally it is done by pre-printed labels or by a thermal transfer printer.
When marking hot steel the direct application of readable bar code to a hot, uneven surface is difficult if not impossible. However, the use of labels has the additional cost of the label material and the printing and fastening of the tag by nail or welding. This can result in problems of mark survival due to the high temperatures or the integrity of the fixation.
IEL’s solution to this problem is to propose the use of a Snowflake™ code which can be applied directly to a very hot product surface (1000 oC) alongside conventional characters. This is achieved by a standard IEL metal spray marker or, on cooler products, by a Dot Matrix Paint Marker or Stamper.
The size of the marked code and characters can be varied to suit the product. The code consists of a matrix of dots containing the data plus a check sum. Error correction can be incorporated into the code which allows reading of the data when part of the snowflake is obscured or missing. The coded information usually consists of a heat / strand / cut number up to 11 digits as sent by the clients computer.
The marked Snowflake code can be read by a standardised, low cost, fixed or hand -held CCD camera system which converts the code into a data format suitable for a computer. This can read stationary or moving products, for example slabs or billets on roller tables. The reading equipment is much more tolerant than OCR systems, and reading is possible under adverse conditions such as bad lighting or even when code has been marked on uneven or irregular surfaces.
The Snowflake code was developed and patented by Electronic Automation Ltd, (EAL) located in Hull, UK who has vast experience in the supply of optical reading systems.