What is SFIC Core – Understanding SFIC Cores, Keys, Locks & SFIC vs LFIC | CNCLATHING


Interchangeable cylinders differ from standard cylinders as they allow to change the locks quickly by replacing the keyed core. There are two main types of IC cores: SFIC and LFIC. In this article, we’ll introduce what is SFIC core and learn about the basics of SFIC locks and keys, as well as SFIC vs LFIC.

What is SFIC Core?

An interchangeable core (IC) is an adaptable lock cylinder, the interchangeable mechanism uses a specialized control key for insertion and extraction of the essential combination components. Small Format Interchangeable Core (SFIC) is in standard form among lock manufacturers, differently, Large Format interchangeable cores come in varying sizes. SFIC core is very popular in commercial uses, it is not only versatile but also very easy to maintain. If there are some issues where you have to lock someone out, all you have to do is pop put one of the old cores and put a new core. You don’t have to take the lock off the door or disassemble it, it’s really simple. But it’s complicated at least from the outside if you’ve never worked on them and all the little pins, if you see people pin them up, when you see control keys and work keys it can just get really confusing.

Understanding Keys of SFIC Cores

– Keyway. You may want to figure out what keyway you’re going to be working with and the easiest way to do that is to grab an existing key and to look towards the bottom of the head of the key, then you’re gonna find a little letter stamped right there and that’s gonna tell you what the keyway is. It may be A, B, J, L, WA, WB, or others. There are a variety of different keyways for locks. That’s gonna tell you what keyway you’re gonna need, so that way you can figure out what type of keyway you need to order. 

– Cuts. The second thing is how to read the cuts. When you look at a code handwritten, we always read it from left to right, however, the cuts on the key are actually opposite that and the reason for that is because of the tip stop, lay the key horizontally, there is not a shoulder for the key to stop on right, there’s not gonna be a starting place and that’s because the tip stop on these keys is on the very bottom tip of the key and when you put the key in and it stops there that’s where that first number goes, so if you were going to be reading out a code when you look at the key, it’s gonna be starting from right and going left.

– Length. For small format interchangeable core, both 6 and 7 pin keys are the same length. That means whether you are working on a 6 pin SFIC core or a 7 pin core, the keys are gonna be exactly the same length.

Understanding Locks of SFIC Cores - SFIC Locks

When you’re working with the small format interchangeable core, you have to make sure the locks you’re working with are prepped for it, this isn’t going to be a big deal if you go to an existing project, but if you’re adding a lock, or if you’re adding a motor cylinder, then you have to make sure it’s prepped for it. You cannot take a commercial lock that’s made for a normal Schlage cylinder. You’re gonna be dealing with two types of tailpieces, including a fixed and a loose one, the lever is gonna be just using a loose tailpiece. When it comes to how the lock is prepped, they’re gonna typically have the keyway stamped, so you’re gonna find a little L or K, now not all manufacturers do this, but it is very common and it’s very helpful if it doesn’t have one, the only way to figure out what keyway it is is by sticking in a bunch of keys and figuring it out. 


How do the SFIC locks work? The core in SFIC locks can be replaced quickly using a control key, which operates and releases a retainer that holds the core inside the lock. After sliding the cores out, the control key can be used to insert new cores. SFIC core allows the rekeying of multiple locks on a property quickly, SFIC is widely used where rekeying is regular, including offices, universities, government buildings, and more. 

SFIC vs LFIC - Large Format vs Small Format Interchangeable Core

1.LFIC (Large Format Interchangeable Core) are lock cylinders made by major manufacturers like Schlage and Yale, LFIC core similar to SFIC core, but an LFIC core differs from an SFIC core in that the size and shape of the core from different brands may vary. 

2.The face of both cores looks like a figure 8. In small format interchangeable core, both circles are concentric but with large format, the bottom circle is larger.  

3.In addition, SFIC is more universal than LFIC, SFIC cores are cross-compatible while LFIC cores are not cross-compatible, but the keys used for SFIC locks should have a lower profile than most commercial keyways.