Is Heat Treatment for Metal a Special Process?

[Sidney Vianna]

Heat treatment is a classical example of a special process.

Heat treatment in my experience - not opinion - has always been something that cannot be checked - adequately - after the product has been processed!

So, why is it that ISO 9001 leaves it open and does not have a statement to the fact that

7.5.2 Validation of processes for production and service provision
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The organization shall validate any processes for production and service provision where the resulting output cannot be verified by subsequent monitoring or measurement and, as a consequence, deficiencies become apparent only after the product is in use or the service has been delivered.​

Heat treatment and welding are ALWAYS special processes that need to be validated. ​

If what you say is incontestable, wouldn't it be much easier for the TC 176 to list all the processes that MUST be validated?

 

[AndyN]

So, why is it that ISO 9001 leaves it open and does not have a statement to the fact that

If what you say is incontestable, wouldn't it be much easier for the TC 176 to list all the processes that MUST be validated?

Not if it takes them 8 years to do a revison...they'd always be behind technology advances.........

 

[Randy]

Maybe there ought to be some validation of TC176 done as part of the whole process

 

[charanjit singh]

That was a good one regarding reference to TC 176 and quite lively discussion too including the 'free advice' that is given by some of us.To take away the 'heat' from the Heat Treatment - if I may say so - here is a quote (source: anonymus)

"If you are wise, take this advice: Never give advice."

Jupitor

 

[Umang Vidyarthi]

Its a very healthy and lively discussion on the subject, and experts have covered all the views- for & against -in granting 'Heat treatment' a special process.

I would like to focus attention on the relevant clause:

3.4.1 Process NOTE 3 - A process where the conformity (3.6.1) of the resulting product (3.4.2) can not be readily or economically verified is frequently referred to as a "special process".

Since a heat-treated product can not be readily or economically verified, that it has achieved the desired result after the process, IMO it falls under the category of a "Special Process"; and needs validation under 7.5.2.

Umang

 

[arin_23]

i think it is not special process because we have a device to measure the Hardness of metal

Determining the Rockwell or Brinell hardness number from a heat treated sample would not be able to tell you whether this requires validation or not IMHO.This may come under 8.2.4 - measuring and monitoring of product, that too the result would be a general result and for the whole batch sent for heat treatment in the furnace.

In My opinion for a clear understanding you may stick to the "recipie" concept, if there is a defined recipie for something it needs to be validated for adequacy from time to time, this is also true that if you are able to do a 100% inspection without causing any kind of damage to the product then you can do away with clause 7.5.2.

The heat treatment depends on a lot of things like heating time, heating temeperature, type of material , no. of batches in operation whether normalization is required or not...etc. But it is worth mentioning that 7.5.2 talks about validation of the "PROCESS" (of heat treatment),not the "PRODUCT" (output of the heat treatment process).

Regards,

Arin

 

[Randy]

Define....can not be readily or economically verified

 

[Caster]

If you supply automotive, HT is special, and even has its own special process audit.

https://www.aiag.org/source/Orders/index.cfm?mystartrow=11&realstartrow=21&section=orders&activesection=AiagPubs&task=0&search=S


If you supply me, I would want to know that you control your HT process, not just do a few hardness tests.

Every time I see spacial processes, I hear Dana Carvey on SNL as the Church Lady!

"Now isn't that special!"

http://www.geocities.com/Hollywood/Agency/5280/DanaCarvey.html

 

[somashekar]

i think it is not special process because we have a device to measure the Hardness of metal

Dear Tech.
I think your ability to measure hardness is in a way giving you the confidence to say it is not special. However as said in one of the thread here, heat treatment is a very complex process and the desired results can be achieved only in the controlled conditions necessary for the desired result.
I have this list for you to think and make a judgement about it :
1. How big is the heat treatment furnace ?
2. Are you able to get the same range of temperature at all zones of the furnace ?
3. What is the load everytime to the furnace ? Is it same or it varies ?
4. Do you measure the hardness of parts heat treated from all zones of the furnace each time ?
Hardness measurement capability that you have is one of the required measure to assess that the set parameter for the heat treatment process is good. It helps you to validate and revalidate the heat treatment process as and when charge batch changes or a maintenance schedule on the furnace is executed or any such repairs are done to the furnace. Hence on a larger look you have to notice that you have ability to validate the heat treatment process and that is the requirement.
Hence with just the ability to measure hardness, do not dilute the requirment of validation of this very critical metal process. It needs validation and constant revalidation as you go along.
I hope you are able to appreciate the requirement my friend .... good luck

 

[Sidney Vianna]

I think some people are showing they have a hard time, thinking out of their boxes. Specially in auditing, this is a very bad trait. ISO 19011 reminds us that auditors must be open minded.

Imagine that I design and install automated gates. One of my sliding gates (see example below) rolls back and forth on a metal rail. My years of experience tell me that, when dealing with heavy gates such as this, there is a lot of wear on the parts of the rail that are in contact with the metal rollers. So, I decide to improve the product by hardening that surface on the rail and I have established a hardness requirement, based on my experience. I use a simple MAPP (methacetylene propadine) gas torch to harden the metal. I check the hardness of the metal surface with a properly calibrated hardness tester in 10 different spots, which provides me with confidence that the part will last for the projected life cycle of the gate. So, there you have it: a heat treating process that can be fully verified at the end. No validation required.