All About Shackles
We've nearly completed our tour through the history, uses and parts of a padlock. After looking at the different mechanisms, keys and key suites we've finally come to the humble shackle, the most vulnerable part of a padlock and the most likely to be attacked.
The two important things about the padlock shackle are its material (what metal is it made from?) and its length (how much of it is available to cutting tools?)....
We'll start with the material. Is there's an ideal metal for a padlock shackle?
This steel has been case hardened to protect the shackle against saw attack but also retains a malleable core in the same way as the Alloy steel. The chrome plating offers a level of protection from corrosion, but over time it will wear off.
This is a special formulation of steel containing trace elements such as Boron. Once heat treated this gives the shackle an extremely hard surface whilst retaining a softer inner core - necessary to protect the shackle from becoming vulnerable to shattering if hit with a hammer. Steel shackles are often also chrome plated to give them a level of protection from corrosion in case they'll be used out doors.
Used for complete protection from corrosion. On the downside stainless steel can't be heat treated as successfully as other forms of steel, so the shackle becomes more susceptible to being cut.
Brass shackles are an option used with brass padlocks when it's important that no sparks are created, even if the lock is dropped. This makes brass an ideal shackle for hazardous environments but has the drawback of offering the least resistance to cutting.
So is there an ideal shackle metal? Sadly no. It depends on the environment the padlock is going to be used in, taking the weather, the level of security and the danger of the environment into consideration.