Sunday, October 1, 2023

Difference between SC and CC

significant characteristics (SC) & 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: Special 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).

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).

What are significant characteristics (SC)?

Significant 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 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. 


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