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A Product Design Specification (PDS) is a structured document that defines the a distinct set of requirements to be met by all aspects of an enterprise to achieve a successful new product. At a high level, the PDS states what the product should do or meet, but not how it is achieved.
For example, a new bike lock is desired. An environmental consideration you might specify in the PDS for this product could be "corrosion resistance." This requirement could be met through various solutions, such as stainless steel usage, protective coatings, galvanization, etc. The PDS does not need to dictate the solution, but rather defines the performance requirement.
In design and production, countless decisions must be made throughout a product's lifecycle. It is impractical to axnticipate and document every action or choice in advance. The PDS serves as a framework that enables team members to make decisions that support the product's goals without requiring exhaustive approval processes.
Some key benefits of a PDS include the following:
The PDS evolves over time. The PDS is not a static document. It evolves and changes throughout the product development process. A multidisciplinary team can utilize the structure of a PDS to be aware of changes across all business areas.
The following 29 elements help prepare a comprehensive PDS. Each element should be considered and documented as applicable to your product.
Consider the following factors:
For the bike lock example, one might specify that the lock must resist at least 3,000 lbs of shearing force, or that it must operate in temperatures from -20° C to 50° C. These specifications define product features rather than the ways in which those might be achieved.
Note: Be as specific as possible while specifying PDS elements! Vague phrases such as "strong" or "durable" must be avoided to increase the efficiency of the design process. Go back to your user needs and specifications if you need help being more specific. If it isn't measurable in some way, then it is not possible to verify your product meets the specification.
Any product might encounter a variety of environments during its lifetime including:
In each of these environments, consider temperature and humidity ranges, pressure or altitude conditions, exposure to chemicals, noise levels, biological factors, user expertise level, etc.
Returning to the bike lock, one might specify that the lock must withstand high humidity levels (up to 85
Service life defines how long the product should remain functional and against what criteria. Measurement criteria could include calendar time, operating hours, distance traveled, number of cycles or revolutions, etc. Some considerations while determining the service life of a product are the following:
As a product engineer, you might design the bike lock to maintain full functionality for at least 10 years under normal use, which could correspond to approximately 15,000 lock–unlock cycles.
Note: Service life is different from the shelf life of a product! While shelf life includes the time that the product remains unused, service life only considers the time over which the product remains in use.
Not every product will remain maintenance-free throughout its lifetime. When developing the PDS, the designer should clearly define the product’s maintenance philosophy and associated requirements. Some key questions to consider are listed below:
For the bike lock, it is reasonable to expect the product to remain largely maintenance-free, requiring only occasional use of basic tools—such as lubricants—to ensure smooth operation.
Establish cost targets from the project outset and validate against market realities.
Conduct thorough competitive analysis to avoid "reinventing an inferior wheel."
Market Gap Identified: No mid-priced lock with integrated GPS tracking and smartphone alerts
Differentiation Strategy: Smart features at traditional lock pricing
Determine distribution and delivery logistics.
Project annual sales volume, as this profoundly impacts all design decisions.
Define packaging requirements for multiple purposes.
Retail Display:
Sustainability: 60
Dimensions: Standardized to retail hanging systems
Anti-Theft: Difficult to remove from package without damage
Define manufacturing constraints and opportunities.
New Equipment Needed:
Make vs. Buy:
Assembly: Semi-automated assembly line in existing facility
Quality Control: Leverage existing testing infrastructure
Define maximum, minimum, or optimum size constraints.
Portability: Must fit in jersey pocket or small backpack
Weight with Mounting Bracket: Complete system under 3 lbs
Ergonomic Minimum: Key grip area minimum 0.75" diameter
Market Research: Users prefer compact designs but prioritize security over extreme minimization
Compatibility: Sized to secure bike frame + wheel to standard bike racks
Storage: Fits standard bike frame mounts
Define weight targets considering maximum, minimum, and optimum values.
User Impact: Cyclists comfortable carrying 2-3 lbs on rides
Shipping Impact: Weight allows economical shipping rates
Material Implications: Requires high-strength steel alloy to minimize weight while maintaining security
Distribution: Weight acceptable for retail hanging displays
Define appearance requirements proactively, not reactively.
Obtain input from sales, marketing, and industrial designers early in the process.
Surface Finish:
Branding: Subtle logo embossed on lock body
Visual Security Cues:
Protective Cover: Black rubberized coating (prevents scratching bikes)
Professional Input: Industrial designer consultation on ergonomic key design and grip surfaces
Define required or prohibited materials based on technical needs, company policy, and market requirements.
Estimate how long the product will remain marketable.
Implications:
Identify all applicable standards, regulations, and legal requirements.
Define the man-machine interface requirements.
Document customer preferences, prejudices, likes, and dislikes.
Define quality metrics and reliability requirements.
Define storage duration and conditions before sale.
Shelf Life Requirement: 3 years minimum
Storage Conditions:Define required or preferred manufacturing processes.
Define lead times for all development phases to meet launch targets.
Define all testing requirements and procedures.
100% Testing (Every Unit):
Must withstand >3,000 lbs before failure
Must resist 42" bolt cutters for >60 seconds
Environmental Testing:
Define safety requirements, standards, and warnings.
User Safety:
Pinch Points:Shackle release could pinch fingers
Sharp Edges: Cut hazards on edges
Key Breakage: Broken key could cause cuts
Lock Failure: Shackle could release unexpectedly causing bike to fall
Coating Materials: No toxic heavy metals
Product Markings:
Identify internal limitations and requirements that affect the design.
Document market-driven limitations and considerations.
Security Rating Systems: Different countries prioritize different standards
Document the landscape of intellectual property and the prior art.
US Patent 8,765,432: "U-lock mounting bracket with automatic release"
Consider broader societal impact of the product.
Address end-of-life considerations for the product.
Material Recyclability:
Primary Path (Expected for 70% of units):
Secondary Path (20% of units):
Premature Disposal (10% of units):