in Vol. 16 - January Issue - Year 2015
Awareness of Embedded Specifications
Conformance to a customer or industry specification is an expected requirement for any metal-finishing activity. The relevant specification may be stated on the customer's purchase order, or it may be on the manufacturing drawing for the ordered part. The specification usually dictates what material must be used for the part, or what processes or procedures must be used during manufacturing. The specification may also include required verification tests, quality control values, and technical guidance on material or process control. A thorough review of these specifications is essential to ensure that a part fully conforms to requirements and that the certification of conformity issued for the part or processing is valid.
Whilst a review of this customer or industry specification is a well-understood requirement, mistakes do occur owing to embedded specifications. These are other specifications that are referred to and hence additional requirements which must be met. Therefore, there may be a cascade of requirements flowing down from the originally stated specification. Auditors and customers will look to ensure that any metal-finishing processor has reviewed all the embedded specifications and understands the cascade of requirements.
As an example of this, let us consider the industry specification for automated shot peening, AMS2430, currently at revision "S". A number of prime manufacturers issue their own peening specifications but embed AMS2430 to cover all the general requirements for peening. Moreover, when we review AMS2430, we find further embedded specifications, for example:
New media requirements to AMS2431
Almen equipment to SAE J442
Almen equipment used to SAE J443
Coverage inspected to SAE J2277
Rotap machine conforms to ASTM B 214
Sieves conform to ASTM E 11
These specifications all have requirements that must be met and will also have further specifications embedded within them. So how far down this cascade of requirements must a processor proceed to ensure that they are working to the specification? This depends upon who is responsible for the process, procedure or verification test defined in the embedded specification. If the processor is responsible, they must maintain and review current revisions of the embedded specifications. Accordingly, for a processor required to work in accordance with AMS2430, they must review and conform to current issues of:
AMS2430, for process requirements;
AMS2431, to verify media before use;
SAE J442, to calibrate and inspect Almen equipment;
SAE J443, to verify procedures using Almen equipment;
SAE J2277, to verify coverage inspection procedures.
Note that not every specification listed under AMS2430 Section 2, Applicable Documents, is necessarily required. If the processor does not undertake any activity controlled by the ASTM specifications, current revisions of these specifications are not required. Suppliers to the shot-peening processor would be undertaking these activities so the Supplier Approval procedure must give sufficient confidence that these suppliers are process-capable and provide adequate certificates of conformity for their products.
In addition, AMS2432, Shot Peening Computer Monitored, is listed under Applicable Documents but only because the relationship between this specification and AMS2430 is referred to in the text; therefore, a review of AMS2432 is not required for normal AMS2430 processing.
The processor's specification review procedure should include a step at which any relevant embedded specifications are noted so that these are not missed out at the review stage. Also, the system by which specifications are kept up to date must include the embedded specifications so that revisions to these specifications are captured and reviewed.
Failure to capture the requirements of embedded specifications is a common cause of error within processes and can result in non-conformance findings during audits. A rigorous specification review procedure will help to protect an organization from liabilities resulting from such non-conformances.
For questions contact email@example.com
by Paul Huyton,
MFN Course Director World Wide
more information at www.mfn.li/trainers