Approved vendor sources and supply chain modeling
Each part in PDXpert PLM software has a Source list, which is a ranked set of approved vendor parts. This application note suggests which sources should be included by the design team, and why vendors' ("OEM") parts are preferred over distributors' part numbers.
A part's approved sources list
Industrial, commercial and consumer products are usually a unique combination of internally-designed and externally-sourced components. Screws, resistors, paint, and other off-the-shelf items are acquired to fulfill standard functions. Often these parts are available at little cost from several different mass producers, any one of which is equally suitable for fulfilling the requirement.
Every purchased part in your warehouse has at least one, and preferably several, approved vendor sources. Multiple vendor parts are interchangeable with each other when their relevant functional and physical properties are equivalent. Part interchangeability - that is: form, fit, or function equivalence - implies that any approved source can be used for the application.
Who creates & conforms to the specification?
One of product designers' principal tasks is identifying which items may be sourced from outside the company, and then qualifying those sources to ensure that they comply with the defined requirements.
The qualification activity generally requires a review of the vendor's specifications, and possibly characterizing the part's performance within the intended environment. There are several implications:
- Functional and performance specifications are defined by the part's vendor.
- If the part meets requirements, it's the result of the original vendor's engineering and production processes.
- If the part fails to meet the published specification, only the vendor can address the problem.
Of course, a local distributor often facilitates communications between customer and vendor. But the distributor can't be more than a facilitator: if you have a problem with the part meeting the published spec, the distributor may give you a refund but certainly won’t review the original design documents, examine the production process, or write a corrective action.
Engineering has qualified the vendor's part using the vendor's technical data, and therefore must identify this item using the vendor's name and part number.
Are distributor substitutions acceptable?
If the vendor's part has been qualified using the vendor's technical data, does this mean that the vendor's distributor will always provide that exact item? Or is it possible that the distributor could provide an "equivalent" item?
When a designer specifies a distributor's part number, the implication is that this part (organization + number) has been qualified. For very complex parts, the distributor will invariably fulfill the order using the vendor's exact part: no distributor will treat current AMD and Intel processors as equivalent and interchangeable under the same part number. On the other hand, simpler parts (screws and other hardware, perhaps ribbon cable or even resistors) may be deemed equivalent between vendors. If a distributor switches alliances, and your qualified part number is the distributor's number, then it's the distributor's judgment whether they can substitute one source for another. After all, you're ordering the distributor part number, not the vendor's number.
If a distributor's part has been separately qualified using the distributor's own specifications, then buyers can rely upon the distributor's part number. However, a distributor part number may not be a reliable indicator of the part's specifications, and the distributor part can't be listed as a qualified source.
Identify the primary suppliers within the PLM system
Although the PLM system must accurately and completely reflect all necessary requirements, we want to provide as much flexibility as possible. Equally important, we'd like to avoid insignificant changes to the product definition, such as adding a new distributor of a previously-qualified part.
In general, Engineering shouldn't identify supply chain alternatives. Engineering only qualifies the ultimate vendor and their assigned part number / datasheet. From a requirements perspective, engineering is neutral on how the part is obtained.
Purchasing must choose the best way to obtain the qualified part, and this choice is affected by the dynamics of business relationships, contracts, schedules, shipping rates, payment terms and (especially) prices. If a new distributor can offer better terms, or quicker delivery, then the decision is within the scope of production rather than design, and no engineering participation is expected.
When to include distributors or intermediate suppliers
While it's usually better to avoid formalizing supply chain details within the product definition, designers often have useful knowledge about where parts can be acquired. To communicate this knowledge, designers can add supply chain recommendations to assist their purchasing colleagues.
If supply chain details would be helpful, then use the source's rank to distinguish your primary (truly qualified) vendor part(s) from secondary (indirectly qualified) distributor part(s). For example, you may want to establish a rule that all indirectly-qualified sources are assigned ranks higher than, say, 20. If you include recommendations on your sources list, any updates would require bumping the internal part's revision and processing a change form.
An alternative for listing recommendations as sources is to add distributors' part numbers into the vendor part record’s Notes field or in a set of custom attribute fields based on the Organizations collection. Since these are item-level properties, updates won't require a change form.
While it's possible to model the entire supply chain in detail — internal part has distributors as immediate source, and distributors' sources show the original vendor's part as their source —, this is an unnecessary complication, and can be rather burdensome in practice.
Although a recommended distributor may appear as a source, it must be understood that the first-ranked vendor parts actually fulfill engineering's requirements. The buyer remains responsible for ensuring that the recommended distributor part is, in fact, the qualified vendor part, and that the distributor is not providing a non-qualified substitute.
Distributor value-added services
A distributor may provide a value-added service such as preparing cable assemblies, programming flash memory or trimming a part parameter to a specific value. These modified parts aren't considered the original vendor parts, and would be assigned unique distributor part numbers that represent the original part source and the process applied by the distributor.
Qualifying contract manufacturers
For internally-developed design parts that are sent to a contract manufacturer (CM), there’s a useful shortcut. Usually Engineering qualifies a CM for some set or style of parts, and Purchasing uses POs to the CM using the Engineering-assigned internal part number.
In this case, you don’t need to create a separate vendor source record for each of your CM parts. You can simply create a single record with that CM as owner, a pseudo-part number such as "Approved", and apply this record as the source for all parts that the CM is qualified to provide.
This avoids having to create a duplicate partner record for each home designed part. Each home part displays which CMs can produce it. The CM "Approved" record's AppearsOn:Source list shows what parts each CM is qualified to produce.
Contact us if you'd like to discuss how the general concepts summarized in this note may be applied to your situation. We'd be happy to address other PLM software good practices - ask us!
PLM Good Practices