Identifying Critical Items and Key Characteristics - Product Realization Process
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Check this thread: Special Requirements, Critical Items and Key Characteristics - AS9100 Requirements. Especially posts # 4&5.
A key characteristic is an attribute or feature that has a significant impact when it varies. If it does vary, the performance, form, fit, function, producibility, or service life of the product is affected. An example would be a plate that has holes drilled into it, and it is to mate with another part. If the spacing or size of those holes varies, the above can be impacted.
Here's an example of a critical item where I work; we manufacture twin engine turboprop aircraft and the plane utilizes a high-strength steel restraint rod on the trailing edges of the wings where the wing connects to the fuselage. The purpose of these rods is to prevent the wings from breaking loose and swinging forward during a front impact crash. If the wings do rotate forward, the engines and propellers impact the sides of the cockpit with horrifying results. These beefy, expensive steel rods are carefully protected during install with wrap and are always handled with gloves; if the rods are scratched, dented or are in any way marked or damaged, they are scrap. They must not fail, so they must be as close to perfect as possible.
If you really want to have some fun, ask two different registrars what the definition of these two terms is, and watch the fur fly. It's definitely something that can be defined more effectively in future revisions.
Here's an example of a critical item where I work; we manufacture twin engine turboprop aircraft and the plane utilizes a high-strength steel restraint rod on the trailing edges of the wings where the wing connects to the fuselage. The purpose of these rods is to prevent the wings from breaking loose and swinging forward during a front impact crash. If the wings do rotate forward, the engines and propellers impact the sides of the cockpit with horrifying results. These beefy, expensive steel rods are carefully protected during install with wrap and are always handled with gloves; if the rods are scratched, dented or are in any way marked or damaged, they are scrap. They must not fail, so they must be as close to perfect as possible.
If you really want to have some fun, ask two different registrars what the definition of these two terms is, and watch the fur fly. It's definitely something that can be defined more effectively in future revisions.
In Para. 3.3 defining Critical Items, does "software" include both the software controlling the process of the subject item/service or just the software controlling the function of the subject item in service? I can make a case for either circumstance. In the first case, "dumb" part with no connection to any form of software inputs or outputs, the conclusion of "the widget does have or use software to function so we don't have to consider item for criticality. True - false?
critical characteristic
A characteristic designated by the design authority, where the responsibility for its definition is outside the scope of this recommended practice. [9013]
Any feature throughout the life cycle of a critical item (e.g., dimension, tolerance, finish, material or assembly, manufacturing or inspection process, operation field maintenance, depot overhaul requirement) that if nonconforming, missing, or degraded may cause the failure or malfunction of the critical item. [9017]
key characteristic (KC)
An attribute or feature whose variation has a significant effect on product fit, form, function, performance, service life or producibility, that requires specific actions for the purpose of controlling variation. NOTE Special requirements and critical items are new terms and, along with key characteristics, are interrelated. Special requirements are identified when determining and reviewing requirements related to the product (see 7.2.1 and 7.2.2). Special requirements can require the identification of critical items. Design output (see 7.3.3) can include identification of critical items that require specific actions to ensure they are adequately managed. Some critical items will be further classified as key characteristics because their variation needs to be controlled. [9100][9110]
The definition in 9100, clause 3.4, applies with the following clarification for software. Key characteristics in software are those measurable attributes where variability can be measured by the project and can, if left unchecked, adversely impact the project or product in areas (e.g., schedule, cost, maintainability, testability, reliability, portability). Examples of key characteristics include defect severity, complexity factors, nested menus, memory, timing, response time, and throughput targets. [9115]
AS9100/EN-9100/JISQ 9100 definition: The features of a material or part whose variation has a significant influence on product fit, performance, service life, or manufacturability. This definition is further explained as follows:
? Key Characteristics for a part, subassembly or system are those selected geometrical, material properties, functional and/or cosmetic features, which are measurable, whose variation control is necessary in meeting Customer requirements and enhancing Customer Satisfaction.
? Key Characteristics for a process are those selected measurable parameters of a process whose control is essential to manage variation of part or system Key Characteristics.
? Substitute Key Characteristics may be identified when a Customer-defined Key Characteristic is not readily measurable within the production setting and other characteristics may need to be controlled to ensure conformance. [9103]
features of a material, process, or part whose variation has a significant influence on product fit, performance, service life, or manufacturability. (EN 9100)
NOTE 1: EN 9103 provides a standard for variation management of key characteristic. [IAQG-history]
Key characteristic owner is the person or function who defines the Key Characteristics and recognizes the reasons for the selection of the Key Characteristic. Typically, these responsibilities are held by Internal or External Customer Design, Quality or Manufacturing Engineering, and should be identified by a cross-functional team. [9103]
person or function who defines the key characteristics and recognizes the reasons for their selection. [IAQG-history]
Source: IAQG International Dictionary
