News and press releases

04/09/2007 Roll machining with cutting inserts from CERATIZIT. Customer report from the Åkers roll foundry in Sweden. Including interview with customer!

Åkers Styckebruk is situated close to Stockholm in the Swedish province Södermanland. The landscape is extensive with little development. The motorway is almost empty. Forests, meadows and lakes follow one another. In this quiet, almost forgotten area operates the largest roll manufacturer in the world: Åkers.

Since 1580 the company has been involved in casting. Once Åkers produced cannons for the Swedish army. The first roll was produced as far back as 1806. Today 1,400 employees produce high-quality rolls for sheet metal production in 12 factories in 6 countries achieving a turnover of 300 million euros. Other Åkers production sites can be found in Belgium, France, Slovenia, the USA and recently also in China.

Every week up to 50 rolls are produced, more than 123,000 tons per year.
Every week the Styckebruk site produces between 35 and 40 medium-sized rolls and around five large rolls. In 2006 the total production of the group amounted to 123,600 metric tons, out of which 44% were sold in Europe, 24% in Asia and 25% in North America. Åkers is a solid family-owned company which successfully relies on sound corporate values. The goal of Åkers is to secure and further extend its position as the worldwide leading roll manufacturer. Some of the Åkers customers are steel works like Mittal, Tata and Bao Steel.

From the car body to the coin – everything made of sheet metal
Sheet metal is the base material for numerous products used in everyday life i.e. car bodies, housings of electronic devices, coins and sinks are stamped or formed out of sheet metal. These sheet metals are produced in steel mills. Aluminium or steel billets are rolled to sheet metal applying a warm forming procedure with several roll passes at temperatures between 700 and 1,200 degrees centigrade until they have the required thickness. Depending on the end product, cold rolling is used to make hot rolled strips thinner and to improve the surface quality.

Everything is larger
Åkers thinks big - and in this company everything is larger than elsewhere; the workers in the halls resemble miniature figures. Kennet Önnestig, Production Engineering, describes the production process. “In a first step the rolls are cast. For this purpose the requested iron alloy is melted and subsequently poured into a casting mould. The base material is iron scrap which is bought in locally and then alloyed. Åkers applies two casting procedures: conventional static casting and centrifugal casting. During centrifugal casting the molten metal is poured into a giant centrifuge which is built into a hole in the ground. At 600 to 700 revolutions per minute the centrifugal force makes sure that the molten metal is hurled against the internal wall of the casting mould.” The advantage of this method is that the surface of the roll is not as rough as in rolls produced with conventional procedures. Machining is therefore easier.

Up to 50% of the material is removed from every roll
In a second step the rolls are ground, turned, parted-off and milled. This is where the rolls really ‘loose weight’: up to 50% of the material is removed from every roll and returned to the foundry as iron scrap. For the machining of rolls CERATIZIT provides Åkers with ceramic and carbide inserts. “In roll machining tool life and security are crucial“, says Hans Axelsson, cutting tools sales manager for North Europe. “The machining of a roll can take several hours or even days, the process therefore has to be stable, insert changes necessary due to breakage or premature wear must be avoided, as this would mean extra time. Sometimes the cutting depths are enormous, even up to 100 mm.”

Interview with Kjell Andersson - Purchasing Manager of the Åkers Group

Mr Andersson, what are the most important quality criteria of a roll?
Andersson: “A roll should be in action as long as possible without having to be reworked as this always means a lot of effort and loss of production time. The customers usually rework the rolls themselves.”

How are the rolls transported to the customer?
Andersson: “The smaller rolls, let’s say up to 25 tons, are transported by truck, the larger rolls by train or by ship. Most customers have their own rail connection.”

What are the trends in the roll industry?
Andersson: “There are two trends: one trend is towards high-tech rolls, these are rolls with a higher percentage of alloys added. In this way the shell of these rolls becomes harder and more resistant, so the service life is longer, however they are also more difficult to machine. The second trend is that grinding in the first machining phase is becoming ever more important than rough machining. Grinding however has the disadvantage that the waste material can no longer be melted down directly as the grinding slurry is contaminated by the coolant. I am therefore almost sure that grinding will never entirely replace rough machining.”

How did cooperation with CERATIZIT begin?
Andersson: “In milling CERATIZIT (the former Plansee Tizit) has been a reliable partner for many years. When we extended our group by the plants in France we realized that the turning, parting-off and grooving strategy at these sites was very successful. The Thionville and Sedan sites were supplied with tools from Cerametal. We took a detailed look into this and decided that we would do the same in Sweden.”

What are CERATIZIT's strengths?
Andersson: “CERATIZIT offers very good technical support and implements projects quickly. Within a year the new cutting strategy was introduced and the process was stable. CERATIZIT does a good job and makes also very good suggestions for roll machining. This is exactly what we need!”