![Key-Relevance](https://upload.wikimedia.org/wikipedia/commons/6/66/Key-Relevance.jpg)
In master
locksmithing
Locksmithing is the science and art of making and defeating locks. Locksmithing is a traditional trade and in many countries requires completion of an apprenticeship. The level of formal education legally required varies from country to country ...
, key relevance is the measurable difference between an original
key
Key or The Key may refer to:
Common meanings
* Key (cryptography), a piece of information that controls the operation of a cryptography algorithm
* Key (lock), device used to control access to places or facilities restricted by a lock
* Key (map ...
and a copy made of that key, either from a wax impression or directly from the original, and how similar the two keys are in size and shape. It can also refer to the measurable difference between a key and the size required to fit and operate the
keyway of its paired
lock
Lock(s) may refer to:
Common meanings
*Lock and key, a mechanical device used to secure items of importance
*Lock (water navigation), a device for boats to transit between different levels of water, as in a canal
Arts and entertainment
* ''Lock ...
.
No two copies of keys are exactly the same, even if they were both made from
key blank
Key or The Key may refer to:
Common meanings
* Key (cryptography), a piece of information that controls the operation of a cryptography algorithm
* Key (lock), device used to control access to places or facilities restricted by a lock
* Key (ma ...
s that are struck from the same
mould or cut from the same duplicating/
milling machine
Milling is the process of machining using rotary cutters to remove material by advancing a cutter into a workpiece. This may be done by varying direction on one or several axes, cutter head speed, and pressure. Milling covers a wide variety of d ...
with no changes to the
bitting settings in between. Even under these favorable circumstances, there will be minute differences between the two key shapes, though their key relevance is extremely high.
In all machining work, there are measurable amounts of difference between the design specification of an object, and its actual manufactured size. In locksmithing, the allowable tolerance is decided by the range of minute differences between a key's size and shape in comparison to the size and shape required to turn the tumblers within the lock. Key relevance is the measure of similarity between the key and the optimal size needed to fit the lock, or it is the similarity between a duplicate key and the original it is seeking to replicate.
Key relevance cannot be deduced from a
key code
A key code is a series of alphanumeric characters used by locksmiths to create a key. There are two kinds of key codes: blind codes and bitting codes.2A8G
Blind codes
These are codes that require a chart or computer program to translate the b ...
, since the key code merely refers to a central authoritative source for designed shapes and sizes of keys.
Typical modern keys require a key relevance of approximately to (accuracy within 0.75% to 1.75%) in order to operate.
[
]
Other applications
"Key relevance" may also be applied to types of
electronic lock
An electronic lock (or electric lock) is a locking device which operates by means of electric current. Electric locks are sometimes stand-alone with an electronic control assembly mounted directly to the lock. Electric locks may be connected to ...
s when used to refer to similarities in magnetic signatures or radio codes, though truly digital-coded radio signals do not have key relevance ratings because they must have precise unlocking codes, with no degree of difference whatsoever in order to operate.
The term has also occasionally been co-opted by broader
mechanical engineering
Mechanical engineering is the study of physical machines that may involve force and movement. It is an engineering branch that combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and ...
to refer to the similarity of fit between two interlocking machined parts, although "tolerance" or
"backlash" has gained far wider adoption and acceptance in usage.
See also
*
Margin of error
The margin of error is a statistic expressing the amount of random sampling error in the results of a survey. The larger the margin of error, the less confidence one should have that a poll result would reflect the result of a census of the ent ...
*
Process capability
The process capability is a measurable property of a process to the specification, expressed as a process capability index (e.g., Cpk or Cpm) or as a process performance index (e.g., Ppk or Ppm). The output of this measurement is often illustra ...
*
Specification
A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard.
There are different types of technical or engineering specificati ...
*
Engineering tolerance
Engineering tolerance is the permissible limit or limits of variation in:
# a physical dimension;
# a measured value or physical property of a material, manufactured object, system, or service;
# other measured values (such as temperature, hum ...
*
Tolerance stacks
Tolerance analysis is the general term for activities related to the study of accumulated variation in mechanical parts and assemblies. Its methods may be used on other types of systems subject to accumulated variation, such as mechanical and elec ...
References
External links
History of locksTechnical requirements for DIN EN1303 and DIN 18252
{{Locksmithing
Locksmithing
Locks (security device)
Engineering concepts
Mechanical standards