Evaluation of the Possibilities of Sodium Silicate Sands Application in Automated Hot-Box Process of Cores Shooting

Abstract

The paper presents the results of preliminary research on the use of silica sands with hydrated sodium silicate 1.5% wt. of binder for the performance of eco-friendly casting cores in hot-box technology. To evaluate the feasibility of high quality casting cores performed by the use of this method, the tests were made with the use of a semiautomatic core shooter using the following operating parameters: initial shooting pressure of 6 bar, shot time 4 s and 2 s, core-box temperature 200, 250 and 300 °C and core heating time 30, 60, 90 and 150 s. Matrixes of the moulding sands were two types of high-silica sand: fine and medium. Moulding sand binder was a commercial, unmodified hydrated sodium silicate having a molar module SiO 2 / Na 2 O of 2.5. In one shot of a core-shooter were made three longitudinal samples (cores) with a total volume of about 2.8 dm 3 . The samples thus obtained were subjected to an assessment of the effect of shooting parameters, i.e. shooting time, temperature and heating time, using the criteria: core-box fill rate, bending strength (R g U ), apparent density and surface quality after hardening. The results of the trials on the use of sodium silicate moluding sands made it possible to further refine the conditions of next research into the improvement of inorganic warm-box / hot-box technology aimed at: reduction of heating temperature and shot time. It was found that the performance of the cores depends on the efficiency of the venting system, shooting time, filling level of a shooting chamber and grains of the silica matrix used.

Archives of Foundry Engineering

“…The occurrence of defects in the cores is also the result of the operation of the nozzle venting system in the shot head of the blowing device [5]. Partial elimination of these defects can be achieved by a thorough analysis of each of the tested parameters of the shooting process as well as a properly conducted process of modification of the shoot-and-vent system for a specific core types.…”

“…The advantage of modern core shooters is their versatility and high degree of automation, as well as, in the case of small sizes such as the LUT/c/CO2/An device, mobility. This type of device can successfully work in the following technologies: hot-box, warm-box, cold-box and warm-air processes [2,3] or CO 2 [4], in the system of organic and inorganic binders [3,5,6]. The solutions combining the advantages of: a properly designed [1,5,7] shooting and venting system of the device with process modelling [8,9], simulation [1,10], selection and control of parameters of sandmix filling [5,[11][12][13], time of its storage in a core-box [3,5] with inorganic moulding mixtures are particularly interesting.…”

“…The combination of the advantages of an automated moulding machine equipped with a system enabling full control and stabilization of the process with the technology of moulding sands with ecological inorganic type binders can be an excellent alternative to the widely used cold-box process. An example can be moulding sands with hydrated sodium silicate (sodium silicate bonded sand -SSBS) [14], which can be successfully hardened by physical [2,5,15,16], chemical [17,18] and combined [19] hardening methods. The improvement of the moulding sand technology based on inorganic binders [20][21][22][23][24][25][26] is a response to the growing quality requirements of casts.…”