Hot heading and cold heading are the two ways to form the head of a bolt. Each process has its own advantages, though there are a few important considerations to make when choosing one over another. Let’s take a look at both processes, how they are used, and what makes them different.
At Birmingham Fastener, hot headed bolts generally range from 3/8” diameter to 2” diameter. Any material grade we supply can be hot headed, including stainless steel. The process of hot heading a bolt involved heating round bar in a furnace, then forming the head of the bolt in a header (like a die form). Hot heading allows for better formability with less “die blows” on certain head styles. Another advantage to hot heading is that tooling cost is lower than cold head tooling. That said, there are some other points to consider before choosing to hot head your bolts. This process is both much slower and more costly than cold heading when it comes to large quantity orders in diameters under 1 1 /8”. Because of the time and money it takes, hot heading is better for low quantity orders and orders over 1 1/8” diameter.
Birmingham Fastener cold heads bolts ranging in size from ½” diameter to 1 1/8” diameter. Most material grade we supply can be cold headed. As its name suggests, cold head forming is performed at room temperature. The round bar is shaped into a head by being squeezed between two die forms. The cold heading process allows for very tight dimensional specification to be achieved. It also allows for complex head shapes to be forged with multiple “die blows.” Cold heading is a very fast and very cost effective process. Keep in mind that while this is a better option for large quantity orders, tooling cost is very high.
While hot heading and cold heading are similar processes, there are a few key differences your company needs to consider before purchasing. While cold heading is a much more timely and cost effective option, we can head a wider range and much larger diameter part through hot heading.