In this article, I’m going to explain to you what is sc & cc characteristics. Also called as Special characteristics.
Nowadays in the industry, we are handling many documents related to controlling the Product and Processes.
So among these documents, standards, and working culture, Engineers are more confused with the terms Significant Characteristics (SC) and critical Characteristics (CC).
So in this post, we will look into details about, what is SC & CC Dimensions / Characteristics.
First of all, we first see what is Characteristics.
What is Characteristics?
A characteristic is a dimension or a physical, chemical, electrical, mechanical, or visual feature of a part defined by design data.
Therefore a characteristic must be measurable, either directly or indirectly, and either variable or attribute data types.
You can learn what is variable and attribute data in control chart post.
Attribute characteristics are qualitative data that is checked and results in conformance or non-conformance, pass or fail.
Variable characteristics are quantitative data that can be measured, and the result is an absolute measurement reading e.g. Millimeter, Inch, Kg, Newton, etc.
There are three types of Special characteristics explained below:
- Key Characteristics
- Significant Characteristics (SC)
- Critical Characteristics (CC)
You will also understand, What is the difference between sc and cc characteristics.
Key Characteristics
This characteristic is nothing but the dimension of part, material, process, or assembly.
So the variation of a Key Characteristic leads to an effect on product fitment, assembly performance, service life, or manufacturability of components.
Significant Characteristics (SC)
A Significant Characteristic (SC) is also the dimension of part, material, process, or assembly.
But, it is usually observed at the lower assembly levels.
Therefore achieving the SC characteristics within specification limits leads to getting the best final product fitment.
It is very important for the next/final assembly part fitment, performance, service life, and/or manufacturability.
Significant characteristics are identified and defined in DFMEA and PFMEA and have a relation with the cause and effect of potential failure modes.
In the FMEA, Significant Characteristics (SC) related to cause and effect are rated as severity 5 to 8, Also if the cross-function team decides, it can be rated as less than 5 severity.
The Significant Characteristics (SC) have more effect on the manufacturing process. So, if the SC characteristics get out of specification limit will lead to producing defects in the manufacturing process.
Therefore Manufacturing process needs special controls to maintain the process capability and customer requirements.
Then the next important Characteristic is Critical Characteristics.
Critical Characteristic (CC)
A Critical Characteristic (CC) is the dimension/feature of a material process, part, or assemblies.
The CC Characteristics is mainly given for regulatory requirement (safety, regulation/Legal, or environmental) purpose.
Therefore, If there is a missing or not conforming to design, not as per the quality requirement will result in unsafe conditions for everyone. And also non-compliance with regulatory requirements.
Critical characteristics are identified and defined in DFMEA and PFMEA and have a relation with the cause and effect of potential failure modes.
In the FMEA, Critical Characteristics (CC) related to cause and effect are rated as severity 9-10.
Finally, the Critical Characteristics (SC) have a more severe effect on the manufacturing process. So, if the CC characteristics get out of the specification limit, it will lead to producing defects in the manufacturing process.
As well as the company may face legal issues and may damage the brand value.
Therefore Manufacturing process needs special controls to maintain the process capability and customer requirements.
Now you know which are Significant and critical Characteristics, then the final question is where you find these characteristics,
How to find Critical (CC) and Significant (SC) Characteristics?
These Characteristics mainly mentioned in drawings by designers/customers.
SC CC characteristics symbol
The Significant Characteristics (SC) mainly mentioned as the Triangle 2 symbol in the drawing as below.
The Critical Characteristics (CC) mainly mention as Triangle 1 symbol in the drawing as below.
Symbolic re-presentation may vary from company to company OR different manufacturers use different symbols. You will get these details in their Quality Manuals / CSRs (Customer Specific Requirements).
Some below symbols took from the customer CSR’s.
FORD special characteristics symbols
Refer below special characteristics symbols of Ford Motor Company.
PSA special characteristics symbols
PSA has a major symbols they follow as:
- Safety characteristics
- Regulatory Characteristics
- Safety and regulatory characteristics shown in below snap.
FCA US (Fiat Crysler Automobile) special characteristics symbols
They have specific symbols such as
- The Shield <S> / <E>
- The Diamond <D>
Safety / Regulatory requirement is <S>.
Government-related Regulatory Emission requirement is <E>.
The Symbol <D> identifies key but non-safety/non-regulatory product characteristics or process characteristics.
Conclusion:
- These are important Characteristics such as Significant Characteristics (SC) and Critical Characteristics (CC).
- These characteristics have a major impact on the design and manufacturing process.
- You will need more stringent control in the manufacturing process to control these characteristics.
- How do you find these characteristics in drawing?
