Difference between
Significant characteristics (SC) and Critical characteristics (CC)

Both SC & CC come under special characteristics. Reference
of special characteristics in mentioned in IATF 16949, terminology section.

Definition of special characteristics:
characteristics are product characteristics or manufacturing process parameters
that have high impact on safety (S), conformance to governmental regulations
(G) or fit, form, function, performance, further processing (F).

Difference between Significant characteristic (SC) and Critical Characteristics (CC)

Significant characteristics and critical characteristics are
mostly used in engineering drawing, FMEA and control plan. SC and CC both have
meaning and indication which need to be understood by each quality engineer.
Difference between these two characteristics should also be known by QA.
Difference between SC and CC is mostly asked in interviews.

 Apart from SC and CC there are also key characteristics
which are nothing but important indications for product dimension and process
parameter for safe quality. 

Here in this article I am going to discuss about significant
characteristics (SC) and critical characteristics (CC).

are significant characteristics (SC)?

characteristics (SC) are product and process parameters which can affect fit, function, performance, durability,
customer satisfaction or manufacturability

Example of significant characteristics Product
dimensions, Material property-Hardness, Surface treatment spec- 5 micron
plating, etc.

Significant characteristics are decided in drawing to
control manufacturing quality of product. It is important to maintain SC for
next operation of manufacturing. If significant characteristics get out of
specification, then continuously defective product will be manufactured which
can be reworked or repair or may be scrapped or may not be.

Significant Characteristics (SC) refer to functional
requirements. Mean the product should function as per requirement. Significant
characteristics are added in drawing, DFMEA, PFMEA, PQCS (Control plan) and
product /process check sheet. SC to be maintained and monitored in special
control while manufacturing. SPC & MSA study also planned for these SC.

What are Significant characteristics?

What are
critical characteristics (CC)?

Critical characteristics (CC) are product and process
parameter which can affect safety and
violation of government regulation

Example of critical characteristics (CC) – Product
dimensions, Material type, Hazard element –ELV, etc.

Critical characteristics are decided in drawing to maintain
safety and regulation requirement of product. Each manufacturer must have to
maintain critical characteristics of product. If it get out of its
specification then product will be useless for any customer, it will be
scrapped. Here entire production will be scrapped.

These critical characteristics also added in drawing, DFMEA,
PFMEA and control plan and later on Process/product check sheet for controlling
and monitoring in manufacturing.

Critical characteristics can be any dimension which could
lead to failure of completed product, Wrong material selection could be a major
failure mode for disaster, addition of any banned hazardous element in chemical
composition of product may also lead to scrapped final build product. Fire safety
and exhaust requirements all come under critical characteristics (CC).


What are critical characteristics?

What are difference between
SC & CC?

Difference between SC and CC is explained in below table. 

Characteristics (SC)

Characteristics (CC)

Can affect fit, function & Performance

Can affect safety and law compliment

Failure modes of these characteristics have severity of 5-8

Failure modes of these characteristics have severity of 9 or 10

Occurrence criteria for SC are 4 or higher.

There is no occurrence criteria for CC.

If SC gets out of spec then defective part will be produced in
manufacturing. Here rejection is not 100%.

If CC gets out of specification, then entire production will be
scrapped. Here rejection is 100%

What are key
characteristics in drawing?

Key characteristics are nothing but an indication to
critical dimension, requirement or any drawing note. Key characteristics word
is used in some industries instead of using SC and CC.

Symbol representation of Key characteristics in engineering
drawing: – Usually symbols are represented by letter in triangle.

In drawing symbol and representation of characteristics can
be different from organization to organization. Some company represent letter
in triangle or some simply write CC or SC in drawing. For key characteristics
you can see some triangle and circle or half color circle for representation of
key characteristics.

Critical characteristics can be express by different symbol
or indication in any component drawing. Company to company it varies.

  • Safety indication: – S word in triangle or A in circle, etc
  • Regulatory indication: – R in triangle
  • Fire prevention Indication: – F in triangle
  • Exhaust gas control: – E in triangle 

This was all about SC and CC. Hope you like this post and if anything miss please let me know. Also support my work by subscribing and sharing with your post if below social media icons.

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