4. Application of Coatings 4.1 Mold Preparation Before the new metal type is applied, it must be thoroughly cleaned to remove all grease and rust spots. The used metal type must be completely removed.
At present, the method of cleaning metal type is mainly wire brush cleaning surface dirt, sandblasting blasting and wet chemical non-destructive cleaning method (the company produces wet chemical cleaning and removing agent ANISCOL 100). The cleaned mold is uniformly heated to 300-350 °C. The heating method usually uses the gas burner to be properly distributed inside and around the metal mold. However, heating the metal mold in this way will inevitably cause a temperature difference across the metal surface. Many foundries have now preheated metal molds in dedicated preheat furnaces to ensure an extremely uniform and smooth temperature field throughout the metal form.
4. 2 Mixing and diluting the paint Open the lid, re-mix the paint thoroughly, pour out the required amount, dilute according to the required dilution factor, and continue mixing for a while until it is even.
4. 3 The temperature of the mold should be reduced to about 180 °C. Select the appropriate mold coating according to the performance requirements at different positions of the mold. The operation should be quick and careful, spray from several different angles, keep the spray gun moving to reduce the mold surface. Blind zone. The coating is preferably a thin spray of 3 to 4 layers instead of a thick layer of 1 to 2, the distance between the spray gun and the model is 200 to 350 mm, and the pressure of the spray gun is not more than 200 kPa. The surface quality of the casting will appear. Amazing improvement. The thickness of the coating is controlled at 150 to 250 μm. Many foundries abroad have used a magnetic pen to measure the thickness of the coating and use it as a means of online control. The temperature of the metal type during the spraying process has a great influence on the working performance of the coating. Therefore, more and more foundries use the optical pyrometer or computer-shaped thermocouple to measure the temperature of the metal type. Only by controlling the various process parameters can the temperature be measured. Produce perfect castings.
5 Conclusion When <br> <br> metal casting, coating thickness, and the ratio of components all affect the ability of the alloy filling and directional solidification, the selection and application of coatings to become the production of metal-mold casting quality castings The first step. We believe that as the quality requirements of castings increase, it will lead to the wider adoption of process control technology and the continuous improvement and development of coatings.
Fig. 4 Schematic diagram of DYCOTE 39 coating laminated plate shape
Figure 3: Instantaneous change curve of air gap
Figure 2 Schematic diagram of DYCOTE 34 coating particles
Figure 1 Coating thickness and adiabatic relationship
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