Electrical Gold Melting Crucible Melting Furnace Induction Heater

Considerations when using the furnace:

1. Fit the supplied lid handle, found in the spares bag, to the lid. The other bits are for any ceramic spacers or insulators if replacement is needed. There is also a spare fuse.

2. Set the furnace on a stable flat surface such as a sturdy bench. Position the mould close to the furnace, so that the distance that you are carrying the hot crucible is minimal.

3. It is good practice to set a low temperature first, to allow the crucible to warm up slowly, such as 250*C. Let the furnace stay at that temperature for about five minutes. This also makes sure that the crucible and its contents are dry. Never use a moist crucible or add moist contents into the crucible.

4. It is also good practice to then set a medium temperature such as 650*C, let it settle, then set the final temperature such as 1140*C.

5. This implies that you are aware of the correct melting temperature of the metal that you are wanting to melt. The following table is to be used as a guide.

6. Do not guess the temperature that you need to set. Make sure that it is correct for the type of metal and the considerations of the mould design.

7. Be aware that during the heating process, the indicted temperature will most likely overshoot before settling down to the correct temperature. This is not a problem as the real temperature of the crucible contents is actually lower, due to the lag in temperature of the crucible contents. It is good practice to set 2/3 a final temperature, wait for it to settle, then set the final target temperature. This will greatly reduce the indicted temperature overswing.

8. Do not add moist metal to a molten metal bath. The result will be at minimum, a major splash over, at worst, an explosion of the crucible contents.

9. When pouring molten metal into a mould, make sure that the mould has been pre-heated so that there is no possibility of moisture in the mould. It is good practice to heat the mould anyway as that will reduce the possibility of molten metal freezing in the mould before it has flowed to all parts of the mould. When pouring into a refractory mould, such as Plaster of Paris, make sure that the refractory mould has been oven dried.

10. Do not overfill the crucible. Fill only to about 2/3 capacity as you may spill molten metal during the crucible transfer to the mould.

11. Clean out the crucible after use, make sure that there is no stuck metal on the sides, gently use a scraper to clean metal out of the crucible. This is to prevent hot spots in the crucible and also to reduce contamination of the next melt.

12. It is vital that you accurately measure the wear of the crucible. Document what the inside and outside dimensions are, so that you can see how much wear has taken place. Use a digital ruler / micrometer to measure the wear. Do not go past more that 40% wear compared to the original new crucible dimensions. Most repairs of the furnace are caused by using the crucible past its useful life. This causes metal run-outs and / or flux boil overs.