Technical Meeting Monday 4th November 2019
Manufacturing Director (Tipton)
Branch President Mark Holliday, Prof MICME, welcomed members and guests to the evenings lecture and introduced the speaker for the evening, Norman Wallace, Manufacturing Director of Ervin Amasteel.
Norman introduced his talk on the manufacture of steel shot with information about the company Ervin Amasteel. It was founded in 1920 by John Ervin in the USA and it remains a family business with the 3rd generation of the family now in control. It is the worlds’ 2nd largest producer of steel shot and the worlds’ largest producer of stainless steel shot. The company filed a patent for the production of steel shot in 1939 and built its own testing machine in 1947 to help in the control of the products quality. In 1992 it purchased Barton Abrasives in Tipton and it is this manufacturing facility on which the presentation is based. This plant is now the only shot manufacturer in the UK. The plant produces both shot and grit in high carbon steel and stainless steel for cleaning, surface preparation, peening and cutting and has a capacity of 40,000 tonnes per year.
Ervin chooses to make shot and grit from steel with a high carbon content, which makes it harder than the low carbon product some of its competitors makes. Ervin maintains that high carbon abrasive is a superior product than its low carbon equivalent cleaning faster and consuming less product for the same amount of work done. Some markets have a history of using the low carbon product but Ervin are making inroads into these area by proving the beneficial use of their products in tests both at their testing facility and at the customers own factory.
To begin the process of shot production graded steel scrap is analysed and then melted in an arc furnace. A sample of the molten steel is taken from the furnace for analysis and then trimming additions made to the melt before the ladle is transferred to the atomising station. The atomising takes place over a large water tank with a header box which is filled with molten steel to a consistent level before the steel is released through 4 pairs of nozzles into water jets. It is the force of the jets of water which breaks up the metal stream and the solidifying particles of steel form into balls which fall into the tank to be extracted by magnet. Keeping the header box filled throughout the pour is essential for product consistency. The temperature of the metal is measured at the start and during the process. Just as important is the pressure and volume of water through the jets as variations here will also affect the quality. Water temperature is controlled by circulating it through coolers to ensure product quality.
The product is lifted from the tank by magnets and checked for analysis, size, shape and structure. It is screened and then heated and quenched. After further screening it is tempered to achieve a tempered martensitic structure and thereby the required hardness range. Shot and grit can be supplied in 4 different hardness ranges and this is achieved in the tempering process. The material is given a final screening before being put into 25kg bags, bulk bags or steel drums. The larger diameter material is taken for grit production where it is fed into rollers, collected and returned to the rollers until it is broken down to meet the desired specification. After screening the grit is taken for packing and placed into stock for delivery.
Product quality is controlled at all stages of the process. Chemical analysis of the charge materials, molten metal and the resulting product is closely monitored as is the shape, size and freedom from defects. Periodically samples will be taken for a full test which consists of all the above plus a performance test in the Ervin performance test machine.
A lively Q&A session followed after which David Hall Prof MICME, gave a vote of thanks to Norman for an entertaining and informative presentation. Members and guests then enjoyed an excellent buffet sponsored by Ervin Amasteel.