Livarski vestnik 52 / 2005 Nr. 2
Mihael Brunčko, Ivan Anžel, A. Križman:
Monitoring of the solidification process by electric resistance measurements
H. Roedter:
Defect ductile iron castings - what have you to do to solve the problem?
Mihael Brunčko, Ivan Anžel, A. Križman:
Monitoring of the solidification process
by electric resistance measurements
by electric resistance measurements
Abstract
In this paper the applicability and the efficiency of in-situ electrical resistance measurements by a four-probe method for monitoring the solidification process are presented. For this purpose a special measurement cell was developed. It enables simultaneous in-situ electrical resistance and the temperature measurements during the solidification (the ERT measurement method) to characterize L → S phase transformation of metals and alloys. The method was experimentally confirmed on the eutectic Pb-Sn (61.9 wt.% Sn) alloy. Additionally, the L → S phase transformation was also verified and compared to the conventional DTA analysis. The results of our investigation show that in carefully prepared experiments and properly designed measuring instruments the ERT measurement method determines the exact position of the starting end ending point of the L → S phase transformation from the resistance curve R(t) and the temperatures of these points.
Key words: Solidification, L → S phase transformation, simultaneous in-situ electrical
Key words: Solidification, L → S phase transformation, simultaneous in-situ electrical
Defect ductile iron castings -
what have you to do to solve the problem?
what have you to do to solve the problem?
Abstract
The most expensive charge material in the foundries is the scrap casting. Since there is a reason why castings with defect are produced, it is important to think what can be done to reduce the problems related to the scrap castings. There are several foundries that have financial problems due the high scrap rate under the production. If the scrap rate is too high, it means that the production process is not under the proper supervision.
To bring the scrap rate to a very low level first of all you need good skilled workers in the foundry. Many processes in the production of castings are directly related to the workers quality of work. Many issues within the sand preparation, moulding, melting and fettling area are mechanized but still there are many steps that are managed by workers. Generally, the casting production is a labour intensive. In the last years many things have been changed in favour of using more automatic controlled mechanized equipments. On one side the mechanization helps to increase the productivity and on the other side a repeatable constant process is organised.
The normal classical foundry has the annual production of about 30 t per worker. Today a modern foundry has a production of more than 80 t per worker and the scrap rate is below 3%. To increase the profit and to decrease the production costs means to increase the casting yield and to lower the production of scrap castings. It is very important for the foundries to produce constantly the high quality castings in order to be competitive on the international market. More and more customers pay a lot of attention to a good casting surface quality. Fettling and grinding is very often allowed only in the special casting areas. Many customers wish to get an appropriate cast surface. If the cast surface dose not satisfy such requirements than a lot of time for shotblastings has to be spent.
Key words: casting defects, constant process, casting quality with process automatisation
To bring the scrap rate to a very low level first of all you need good skilled workers in the foundry. Many processes in the production of castings are directly related to the workers quality of work. Many issues within the sand preparation, moulding, melting and fettling area are mechanized but still there are many steps that are managed by workers. Generally, the casting production is a labour intensive. In the last years many things have been changed in favour of using more automatic controlled mechanized equipments. On one side the mechanization helps to increase the productivity and on the other side a repeatable constant process is organised.
The normal classical foundry has the annual production of about 30 t per worker. Today a modern foundry has a production of more than 80 t per worker and the scrap rate is below 3%. To increase the profit and to decrease the production costs means to increase the casting yield and to lower the production of scrap castings. It is very important for the foundries to produce constantly the high quality castings in order to be competitive on the international market. More and more customers pay a lot of attention to a good casting surface quality. Fettling and grinding is very often allowed only in the special casting areas. Many customers wish to get an appropriate cast surface. If the cast surface dose not satisfy such requirements than a lot of time for shotblastings has to be spent.
Key words: casting defects, constant process, casting quality with process automatisation