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Special Characteristics Definitions in TS 16949

morteza

Quite Involved in Discussions
#1
Hello all,
There are some questions for me about special characteristics.
In ISO/TS 16949 clause 3.1.12 special characteristic has been defined as follows:
Product characteristics or process parameter which can affect safety or compliance with regulations, fit, function, performance or subsequent processing of product.
My questions are:
1. Does the above definition only refer to final product characteristics?
Overview:
The definition is in a way that it seems the definition is speaking about final product. For example, if final product dimensions is out of tolerance, it can affect negatively on assemblability (fit) or other processing (subsequent processing), such as plating or machining, of the product in customer site.
On the other hand, some interim characteristics, such as interim dimensions, also may affect subsequent processing of semi-final product in the organization site. For example, a dimension may be important as a rest for next machining operation in the organization.

2. Is it true that for each product special characteristics, there is at least one process special characteristics?
Overview:
If the above statement would be true, so there is no process parameter which has direct effect on fit, function, performance or subsequent processing of product, because all process special parameters only affect product special characteristics (except those parameters which affect on organization's personnel safety or regulations) and this is the product characteristics which affect directly fit, function, performance or subsequent processing of product.

3. Is there any conflict between clause 7.2.1.1 which requires the organization to use the customer defined symbols for special characteristics, and clause 7.3.2.3 which allows the organization to use its equivalent symbols for special characteristics?

Thanks all
 

Jim Wynne

Super Moderator
#2
Re: Special Characteristics

Hello all,
There are some questions for me about special characteristics.
In ISO/TS 16949 clause 3.1.12 special characteristic has been defined as follows:
Product characteristics or process parameter which can affect safety or compliance with regulations, fit, function, performance or subsequent processing of product.
My questions are:
1. Does the above definition only refer to final product characteristics?
Overview:
The definition is in a way that it seems the definition is speaking about final product. For example, if final product dimensions is out of tolerance, it can affect negatively on assemblability (fit) or other processing (subsequent processing), such as plating or machining, of the product in customer site.
On the other hand, some interim characteristics, such as interim dimensions, also may affect subsequent processing of semi-final product in the organization site. For example, a dimension may be important as a rest for next machining operation in the organization.
If a "special" designation is applied to a feature or characteristic of an end product, it's expected that the variables that contribute to conformance of that characteristic will be controlled. This means that in general, if downstream operations should be evaluated for possible application of the "special" designation.

2. Is it true that for each product special characteristics, there is at least one process special characteristics?
Overview:
If the above statement would be true, so there is no process parameter which has direct effect on fit, function, performance or subsequent processing of product, because all process special parameters only affect product special characteristics (except those parameters which affect on organization's personnel safety or regulations) and this is the product characteristics which affect directly fit, function, performance or subsequent processing of product.
The goal is to control the process, so whether or not process characteristics are designated as "special" depends on a general choice in where to apply the controls. If you choose to demonstrate control via measuring of product (and doing the appropriate ongoing statistical analysis--SPC), there is a need to control the process variables but they don't necessarily need to be considered "special." On the other hand, if you choose the validation route (you determine the requisite and optimum process parameters such that measurement of product is minimized or obviated) the process characteristics should be designated as special.

3. Is there any conflict between clause 7.2.1.1 which requires the organization to use the customer defined symbols for special characteristics, and clause 7.3.2.3 which allows the organization to use its equivalent symbols for special characteristics?

7.2.1.1 (TS16949:2009) doesn't say what you seem to think it does, but as far as symbols are concerned, you're generally expected to :
  1. Use the customer's symbols if so required;
  2. Use your own symbols if the customer has their own, if you have the customer's permission to do so;
  3. Use your own symbols in the absence of customer requirements.
#2 and #3 assume that you have standardized the symbols to be used.
 

morteza

Quite Involved in Discussions
#3
Re: Special Characteristics

Hi Jim,
Thanks for your answer.
If I undestand rightly, you believe that:
-for question 1, interim characteristics of a semi-final product in the organisation can also be selected as special characteristics based on its effect on downstream operations in the site.
-For question 2, there is not necessarily a process special characteristics for each product special characteristics.
- For question 3, if the customer such as Ford or GM, requires the use of their symbols, the organisation can not use its equivalent symbols. I this case, What an organisation should do for standard prats such as screws which have familiy FMEA and supplied for several customers having their separately special characteristics symbols?
Thanks
 

Jim Wynne

Super Moderator
#4
Re: Special Characteristics

Hi Jim,
Thanks for your answer.
If I undestand rightly, you believe that:
-for question 1, interim characteristics of a semi-final product in the organisation can also be selected as special characteristics based on its effect on downstream operations in the site.
Aside from special characteristics identified by a customer, you can designate at will and for any reason you feel is appropriate. Be careful not to paint yourself into a corner with your own requirements, though.

-For question 2, there is not necessarily a process special characteristics for each product special characteristics.
There are process characteristics that control product characteristics. In the case of customer-designated special part characteristics, you're generally going to be OK if you don't identify special process characteristics. Of course this flies in the face of prudent process control, but most customers won't understand if you tell them, with data in hand, that a process has been validated such that SPC on the product isn't necessary or helpful.
- For question 3, if the customer such as Ford or GM, requires the use of their symbols, the organisation can not use its equivalent symbols. I this case, What an organisation should do for standard prats such as screws which have familiy FMEA and supplied for several customers having their separately special characteristics symbols?
Thanks
In the case of family PFMEAs and control plans, it's generally considered permissible to use your own symbols. As a former vehicle OEM PPAP reviewer I saw cases where suppliers used several different symbols, but it's usually not necessary. Don't be surprised if a customer insists, though.
 
#5
Hi I too had a question similar to the one posted and needed your suggestion and guidance

1. Special characteristics: what does it mean or how to identify the source of special characteristics
Example
We are manufacturing ac filter of plastic material and filter papers through injection moulding process.
The customer has not given us any special characteristic but I want to know is there any special characteristic in our process.
- Process is as follows 1) The PP material is heated in oven and then loaded in the injection moulding machine 2) the filter media/paper is installed on the mould and the plastic is moulded with the filter paper. 3) Once the plastic particle is outside the machine it is checked for any flush, warpage and dimensional checks or any gaps in the paper and plastic.4) The accepted material is packed in corrugated boxes and then shipped to the customer

So we are unable to identify any special characteristics i just want to know is any of these process a special characteristics or am I missing the point
 
#6
Hi I too had a question similar to the one posted and needed your suggestion and guidance

1. Special characteristics: what does it mean or how to identify the source of special characteristics
Example
We are manufacturing ac filter of plastic material and filter papers through injection moulding process.
..
A special Characteristic is an element of the manufacturing process that needs special attention to produce capable quality parts or material safely and legally.

So if your son or daughter asks you what you should be especially careful with to produce quality product, your answers will be the special characteristics. What I know of Injection Molding would have both Temperature and Moisture as special characteristics.

Keep in mind that many customers require that any former quality spills with a process element would also require the special characteristic symbol be maintained.
 
#7
Since we are in the automotive branch, I think one of the special characteristics should be marked flammability of the used material. This is usually one of the characteristics, but there may be others.
 
#8
Every product has minimum two special characteristics. If not nonconformity has to be issued.
First is related to ability to be assembled by customer line - e.g. diameter, width, length, distance, position of part item (e.g. slot).
Second one is related to ability to function in a manner defined by customer and in perfect condition, also expected by car user - generally isi it operating at all? Example depends on product function. Sometimes part dimension affects also functionality, e.g brake disc diameter or thickness.
 
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