The Simuwu Square Tripod weighed 833 kilograms, how was this giant vessel cast in the Shang Dynasty?

The answer is that it was cast in its entirety using the traditional Hun casting method.

First of all, the copper needed to cast the tripod should have been at least 1,000 kilograms. The question is how to melt that much copper material at once without modern high-capacity furnaces and metallurgical technology, even with coal and coke.

At a four-wooden house tripod unearthed at the Yinxu site in Anyang, archaeologists found a tripod named ? General's Helmet? a vessel that may have been used in melting copper during the Shang Dynasty. The vessel is 32 centimeters high and 23 centimeters in diameter. It could melt 12.5kg of copper at a time. Calculated on the basis of 832 kg of Da Ding, 70 helmets would need to be melted at the same time. In addition, more than 300 people were needed for other processes. In addition, a larger crucible with a diameter of 83 centimeters and a wall thickness of about 5 centimeters was found in the copper casting workshop at the Anyang site, with a soluble copper content of about 200 kilograms. Thus, only five to six large crucibles were needed to make the cauldron.

Second, was the Simuwuding so large that it was cast in one go? Or was it made into parts and then welded and assembled?

Many people had analyzed that the only way to make such a huge bronze tripod was to cast the tripod ears, body, and feet separately and then cast them as a whole. But then some experts believe that the Simuwu tripod is still cast with the traditional casting method of the Xiongnu. Before casting, it was cast with clay and then the mold was turned over. The fans were cast in clay and divided into belly fan, top fan, bottom fan and door fan. After the mold is made, the inner and outer molds are assembled into a tripod mold with a space in between to cast liquid copper. The tripod is attached to the entire mold. Some tripods are used as casting ports and others as exhaust ports to prevent the interior from becoming clogged with air and not being completely filled with liquid bronze.

In order to facilitate casting and minimize the loss of precious copper, a large casting pit was dug in the ground, and the mouth of the tripod was placed on the ground with the pouring spout. The large crucible is placed close to the pouring pot gate, forming a copper flow channel between the crucible and the gate. In order to ensure that the crucibles are mudded and cast in a single pour, all crucibles need to be dissolved in copper at the same time so that the liquid copper can be continuously injected into the sprue during the pouring process.

It should also be mentioned that the thickness of each part of the tripod is different. The average wall thickness of a tripod is 3cm-15cm. if the quadruped is cast as a solid core, the wall cools fast and the quadruped cools slow. The coefficients of expansion for thermal expansion and contraction are different. If the tetrapod is cast at once, the tetrapod and the body may break and not be able to form at all. Later, experts through the X-ray examination of the tripod, found that the tripod is not solid, but the hollow core, to solve the casting process due to uneven thickness caused by the problem, reflecting the craftsmen at that time obviously mastered the principle of thermodynamics, intentionally casting the quadrupeds into the hollow core.