Defining the differences between Prototype vs. Production Guidelines?



A little background:
I am 6 months into a new manufacturing engineering role with a rapid prototyping company. It is set-up as a job shop, we do not perform any design work, we just simply receive 3D cad models and produce parts from the models or drawings.

Within the past 6 years, the company has grown 50% and along with still supporting rapid prototyping services for the ID industry, they now provide solutions for aerospace and commercial customers.

Our weakest process is contract review for production parts.
We complete a contract review for all jobs (which includes reviewing customer requirements, PO, schedule,ect), but production jobs require an even more detailed major contract review prior to starting work.

The problem is, we offer a wide selection of manufacturing technologies and there is no clear definition in the entire company of the difference between prototype parts and production parts.

Generally, prototype parts require very little measurement (6 point vs full FAI) and require nothing more than a C of C for traceability. Production parts generally are serialized, require secondary operations, material certs, and extra QA steps.

I wanted to get some suggestions on how to define the difference between production and prototype.

The definition list I have compiled so far consists of the following:

1. Customer End-Use - If the customer explicitly defines the end use of the product as prototype or production.
2. Customer imposed requirements - If the customer imposes requirements above and beyond, our standard capabilties, then they shall be deemed production parts.
3. Manufacturing Capability - If the parts require additional processing above and beyond our standard capabilties, then they shall be deemed production parts.
4. Critical Applications - For applications such as medical devices, UAV's, and aerospace, they shall all be deemed production parts.
5. Quantity - For any part orders over individual 50 pcs, they shall be deemed production parts.

The goal is to have this added to our quoting procedure and be the guideline for our sales staff and manufacturing managers to adhere to during major contract review and job costing.

When I bring up this lack of definition during staff meetings, everyone tells me it has been debated to death with no clear answer. I am fighting a big battle on this topic since everyone wants to bring up the one instance when something was quoted production as was only used as a mock-up or vice versa.

Any suggestions or insight would be greatly appreciated.
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I like your definitions as stated. And if you beefed that up with some sort of statement during the contract review that required the customer to accept one or the other, then it should be a no brainer. Plus it helps avoid 'scope creep,' especially if the customer's source inspector comes in and he/she has not been part of any earlier discussions.

A previous employer of mine was experiencing the same issues you describe and once we had Sales start clearly stating what we interpreted the scope to be in our response to the RFQ, it made life a lot easier for all concerned. This is especially helpful if the parts in question are aerospace or gov't.


In the company I work for (a medical device/electronics manufacturer), here is what our product life cycle is:

Concept: Just an idea. Initial customer contact.

Design: This is self-explained. In this stage, there may be a few samples built. We call them prototypes or engineering samples. By the end of this phase the design is pretty much finalized.

Development/pilot: In this stage, the focus is the process. by larger volume of "production", we fine tune the process. We call the products validation lots or the such. By the end of this stage, the design and process are finalized. All production related documents are finalized and controlled.

Production: This is the stage we mass produce the product using defined design and process. What manufactured are "production" products.

End of life.

So the fundamental difference between a prototype and a production is that the latter is produced using defined design and process, the output is what the customer exactly wants. The former has a lot of flexibility. If the customer wants to change specs in production phase, I may have to adjust my contract terms. On the other hand, if I want to change manufactuing process in that phase, I'd better get the customer's approval first.

Ajit Basrur

Staff member
I agree with treesei.

In addition,

Wikipedia reference-linkPrototype#Differences_between_a_prototype_and_a_production_design tells the following differences -

In general, prototypes will differ from the final production variant in three fundamental ways:

Materials. Production materials may require manufacturing processes involving higher capital costs than what is practical for prototyping. Instead, engineers or prototyping specialists will attempt to substitute materials with properties that simulate the intended final material.

Processes. Often expensive and time consuming unique tooling is required to fabricate a custom design. Prototypes will often compromise by using more variable processes, repeatable or controlled methods; substandard, inefficient, or substandard technology sources; or insufficient testing for technology maturity.

Lower fidelity. Final production designs often require extensive effort to capture high volume manufacturing detail. Such detail is generally unwarranted for prototypes as some refinement to the design is to be expected. Often prototypes are built using very limited engineering detail as compared to final production intent, which often uses statistical process controls and rigorous testing.


thanks for all the insight, I've compiled all the bullet suggestions and hopefully I will be presenting this next year during our corporate strategy meeting.
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