Surely you’ve heard, seen or even used a magnetic key card before. If you’ve ever wondered what sort of trickery makes them get the job done when it comes to unlocking and opening doors, you’ve come to the right place. The reason why the magnetic strip on a card can be encoded or “written” with information is that the tiny iron-based particles that make up the strip can be magnetized in different directions. This is most often done by a device that produces a strong magnetic field.
Magnetic Stripe Card 101
Also called a magstripe or swipe card, a magnetic stripe card is a card made of plastic with a magnetic strip attached to its surface. The stripe is made of very small iron-based components whose magnetism can be modified. This means the components can actually be used to store information – kind of like what you would find in a music cassette or videotape. They are most widely used to handle purchases in credit and debit cards, as well as to provide room access to hotel key cards. Other purposes of the technology include identity cards for entrance to college campuses and corporate premises.
The Magic Behind Magnetic Stripe Cards
The aforementioned tiny iron-based particles that make up the strip can be magnetized in different directions. This is done by a device that produces a strong magnetic field called a solenoid. A solenoid is essentially a coil wound into a tightly packed helix. The coil is wound around a metallic core of high-permeability and produces a strong magnetic field when a current is passed through it. As a result, the device encodes (“writes”) the required information onto the stripe.
Types Of Magnetic Stripes
Magnetic stripes are widely used for a number of different cards today, and there are two basic types of stripes you’ve likely come in contact with. They are:
- High Coercivity cards, or HiCo
- Low Coercivity cards, or LoCo
Coercivity is a measure of a card’s ability to withstand an external magnetic field and serves as a criterion of classification when it comes to magnetic strips. High coercivity cards are encoded to withstand the presence of a very strong magnetic field. These cards are typically used to print bank credit cards because they are highly resistant to most magnets that people generally come in contact with, and are also expensive to manufacture in addition to requiring a strong magnetic field to encode data on them.
Low coercivity cards are more suited for short-term applications, an example of which is temporary access to hotel rooms. Because such key cards are required to be erased and encoded frequently, they are the most cost-effective solution for countless businesses. These cards are very easy to manufacture and only require a low-intensity magnetic field source to encode data on them.