What separates hot and cold forging? Is one more form of forging superior to the other? Below we go through the mechanism of each to discover which is superior.
Heating To The Right Temperature
Before forging, metal needs to be heated to the right temperature to make it ready. The best temperatures are 660 and 220 Fahrenheit. Metal varies and requires different heating temperatures.
Aluminum alloys are heated between 680° and 1148°Fahrenheit, Copper alloys (Bronze and Brass) require temperatures ranging from 1292° to 1472° Fahrenheit. Steel requires higher temperatures of 2102° Fahrenheit.
There are many instances where the metal forging temperatures and their melting point are close.
Hot Forging
The Hot forging process is suitable for metals with a higher formability degree. There are, however, several points to consider when choosing hot forging over cold forging for metallurgy work.
Several considerations and unique results achieved through the hot forging process include:
- The production of discrete pieces with ease
- Grain homogenization
- Getting rid of chemical incongruities
- Formation of scale on the metal
However, there are setbacks in using the hot forging process. The metal is susceptible to warping as the cooling process continues. If the annealed process is delayed, certain metals become brittle, and others break.
Certain metals have a lower tolerance to the hot forging process. Metals have different grain structures and the atmosphere in some instances creates adverse reactions during the forging process.
The Hot forging process is the most preferred method for airplane parts and aerospace products since the heat produced makes the metals shape with ease.
Cold Forging
A forging process known as cold forging because temperatures are set either near or at room temperature. Most metals used in this processes include copper, gold, silver and brass which are forged to form elegant jewelry mostly from recycled precious metals. The majority of cold forged pieces are steel products.
The difference between hot and cold forging is, hot forging takes place above the metal’s recrystallization point while cold forging occurs below the metal’s recrystallization point. Due to the low temperatures, cold forging is perfect for softer metals.
The process is less expensive as hot forging and demands minimal finishing work. After the cold forging procedure is administered, tempering (A heating procedure) is undertaken to solidify the metal.
Cold forging is a process that is undertaken by placing the metal in a die shaped case, and a hammer is used to force the metal into the die and take its shape.
Cold forging metals are less susceptible to contaminants and various environmental stressors. The process produces a superior finish than hot forged method. Moreover, cold forging metals impart directional properties with ease.
Cold forging method has its share of disadvantages, and the metal scale needs to be taken out before the forging begins and the resultant metals become less stronger than hot forged metals.
Cold forging causes residual strains on the metal because it requires powerful and heavy equipment, the process ends up creating greater problems than solving.
In conclusion, the ability to transform metals into beauty and practical products requires talent and passion. Both forms of forging (hot and cold) will remain relevant in the creative spectrum for decades to come.