A design is used for longer than it is drawn
Design work tends to focus on the moment a product first works on the bench. Yet the product spends most of its existence elsewhere: being made in quantity, shipped, installed, used, repaired, perhaps modified, and eventually taken out of service. Each of these stages places its own demands on the design, and a choice that is convenient at one stage can be a burden at another.
Thinking about the whole product lifecycle means asking, while the design can still change, how each stage will go. It is an application of the broader habit of treating a design as part of a larger system that extends in time as well as in space.
Lifecycle stages are described differently in different industries, and the names below are a general simplification.
Typical stages
- Concept and development: deciding what to build, designing and testing.
- Manufacture and assembly: producing parts and putting them together.
- Distribution and installation: packaging, transport, storage, set-up.
- Use and operation: the product doing its job in real conditions.
- Maintenance and repair: inspection, servicing, replacement of worn parts, fixes.
- End of life: removal from service, reuse, recycling or disposal.
Not every product has every stage in a clear form. Software has no physical disposal but does have retirement, data migration and long-term support. A building has a very long use stage and often several refits.
Questions to ask at each stage
Manufacture
- Can the design be built consistently with the processes available? Features that are hard to make or measure can raise cost and scrap.
- Are tolerances tighter than necessary? Tight tolerances usually increase cost, so they are best reserved for where they matter.
- Can the assembly be done in a sensible order, with parts that cannot easily be fitted the wrong way?
- How will each unit be tested before it leaves, and is the design accessible to that test?
Distribution and installation
- Will the product survive shock, vibration, temperature and humidity in transit and storage?
- Can an installer set it up correctly with the instructions provided? Clear written procedures matter here.
- What happens if it is installed slightly wrongly?
Use
- Who are the actual users, and what will they do that the designer did not expect?
- What operating conditions, such as dust, moisture, temperature range or power quality, will it encounter?
- How does performance change with wear and age?
- How does the product behave when something fails? Planning for safe behaviour in a fault is part of design, and approaches such as failure modes analysis are meant for this.
Maintenance and repair
- Which parts wear out first, and can they be reached and replaced without removing everything else?
- Can a technician diagnose faults without special tools that are hard to obtain?
- Are consumables and spare parts likely to remain available over the product’s expected life?
- Are maintenance steps documented, and will the documentation be kept current?
End of life
- Can materials be separated for recycling or safe disposal?
- Does the product contain materials that need special handling? Rules about this differ between countries and are changing over time, so check the requirements that apply to you.
- Is there anything that should be erased or removed, such as stored data or hazardous substances, before disposal?
- For software and services, how will users be told, and how will their data be returned or deleted?
A simple illustration
Imagine two ways of fastening a cover on a small electronics enclosure. Glue or permanently welded seams are inexpensive in production and give good sealing. Screws cost a little more in parts and assembly time but allow a technician to open the case, replace a failing board and later separate materials for recycling.
Neither choice is automatically right. If the product is cheap, sealed and expected to be replaced rather than repaired, a permanent seam may be sensible. If the product is expensive, used in demanding conditions and expected to be serviced, screws may pay for themselves. The point is that the decision should be made knowingly, with the later stages in view, rather than settled by whichever is easier on the drawing board.
Cost over the lifecycle
Purchase price is only one part of what a product costs its owner. Energy use, maintenance, downtime, spares, training and disposal can be significant over a long life. A design that saves money at manufacture can cost more overall if it is hard to maintain. Comparing options this way requires estimates, and estimates are uncertain, so it is best to state assumptions openly and revisit them when real data arrives. Techniques such as decision matrices can help compare alternatives against several lifecycle criteria at once.
Practical habits
- Involve other stages early. Ask people who manufacture, install, service and support similar products to review the design. They often notice problems that designers cannot see.
- Write lifecycle needs as requirements. Statements such as serviceability, expected service life or disposal constraints can be included among non-functional requirements so that they are not forgotten.
- Learn from the field. Returns, repair records and support questions show how earlier products behaved after release. Feed that into the next design.
- Plan for change. Components may become unavailable, standards may change and users may find new uses. Design margins and modular structure can ease later changes.
- Document the reasoning. Recording why a choice was made helps whoever maintains the product later.
Limits
Lifecycle thinking can expand without end: nearly everything has some effect somewhere. A practical approach is to focus on the stages and questions where the product has the greatest uncertainty or consequence, and to accept that some future conditions cannot be predicted.
Requirements for safety, environmental protection, product take-back and similar matters vary by country and industry. This article is general background; follow the rules and professionals that apply to your product.