The Ultimate Design Review Checklist

Regulation

Yes it’s a must, but complex and continuously evolving

Does the product meet all applicable regulations?

Do you have the latest version of the standard?

Of all forecasted countries? not only the head-office

Also the standards in draft mode currently?

Do you have a process in place to alert on evolving standards?

Does the product have all the required labels?

(in this design review checklist so as in the legal definition, “label” includes all markings, on the product, packaging, in any accompanying document)

Legal labeling of the product, including

• materials marking in the molds/part,
• on the packaging
• instruction for the IFU … is it needed & has it started? (we recommend starting a draft of the IFU at the same time the design is made)

… with all local marking or translation or approvals for all the intended marketS (and images and pictograms may save you a lot of translations here)

Check our Plastics Design Tricks Collection article for plastic parts markings

Environmental, Robustness, and Ageing

Frequently a tradeoff between quality, weight, and price …

Advice: be very careful if averaging the use condition to some mean or average, aka “product is on average at 25°C”, or “product is used on average 2h a day” … some users may be continuously at one side of the scale while some others will be continuously at the other extremity, thus making you a correct average calculation, but all these products WILL fail prematurely.

check IP code link for the IPXX table

can the product be rotated upside voluntarily and then required a higher IP rate? and accidentally?

96h or 100h (frequent values) salt mist test is frequently not enough for a product that can be close to the seaside (not even mentioning boat conditions)

Is there any dissimilar pair of metals or alloys having different electrode potentials? Including frequently basic overlooked parts (screws, washers, springs …)

Were cleaning chemical agents taken into account? Do you recommend some particular ones?

Ex.: polycarbonates (PC), even at big thicknesses, in fact even faster at big thicknesses, if there is a local constraint, can crack within minutes if some solvent (MEK) is applied on its surface.

Indicating minimal temp in the IFU may not be enough. Mind involuntary misuses.

Batteries (based on chemistry, the cold always slows down its reactions) Have you done specific aging and cycle tests?

Lubricants and sealings becoming harder and losing their performance and even blocking the moving mechanism (piston type) or lowering the flow/pressure (regulator)

Many materials become brittle. Tested?

A phone under the windshield of a car in the summertime will be exposed to much more heat than in Death Valley …

Also, mind some concentrating/magnifier effect. Ex.: the mirrored windows of some elegant modern New York building with a concave shape was concentrating the sun on the nearby street 😉

Related but not necessarily the same as temperature. Tested?

Related but not necessarily the same as temperature and UV

Extremely tricky with some plastic and rubber material (Nitrile, EPDM …): it may come back literally to dust in 10-15 years even if well stored, with no constrain, and not exposed to sun or temperature. Or fail in 2-3 years if constraints or tight properties are needed.

Does your product include some gluing?

Have done some accelerated Ageing? Accelerating aging simulations, if not backup with normal aging, with too high temperature, or not appropriate Aging Factor (Q10) is valid only with history or reference.

Plastic additives (color, UV resistance, filler …) can change properties a lot compared to a know reference.

Mind dust or even more sand. Fine not perfectly sealed mechanisms will not survive 5 minutes on the beach.

Even if no regulation, a quality product or costly product should withstand typical user misuse.

Ex: for a displaceable good, dropping from the height of a table could be expected to be “normal”. While a breakage could be understood by the user for a cristal Champaign glass,  maybe less and less for a slippery glass-coated thin phone.

See Mean Time Between Failures theory.

Or is this product in a High Availability class?

Intellectual Property (IP)

Once the product is out, or if marketing has communicated, it’s too late… so this should be included in any Design Review Checklist also if not already too late because of any external communication.

Can be made knowingly (careful!) … especially if another patent is close to expiring. (for the original owner is the cost of attorney > gain on the remaining period ?)

In all distributed countries?

Sometimes seems obvious to the designer, but is not and is indeed novel…

In your field? or in other domains?

Colleagues, but external partners also (mandatory to be listed in patent, even if they may have already been paid for this)

Tip: looking at a similar product name in search engines is not always done …. and brings already a lot in no time and no money long before any attorney work.

For consumer goods or high volumes: and its variants? With “-” or “_” if the name is in several parts? plural, singular variants also?

And various TLDs (net, org ….)?

Manufacturability

Manufacturing process, suppliers, their location compared to the company and to end customers, and cost should be part of any Design Review Checklist.

It is frequently said that 80% of the product price is already frozen at the design phase. Do not ask the purchasing team to make miracles on suppliers hunting too late.

Does the material fit the function? (& has a “fff”, Fit Form and Function analyses been made at all?)

Cost

Recyclability (see below)

any over-constraint dimension?

units, language if any, type of projection

Be particularly clear, or maybe have a dedicated document, if outsourcing to far-east countries as logic, focus & ways of working are different

Tip: values into brackets are typically a source of confusion between countries, so as a way to indicate control dimensions or values to be adjusted in the tool or at production time.

At the design phase, we recommend the first one, but depending on the later process, that may add an additional level of drawing, increasing complexity. This must be evaluated with the manufacturing/supplier on a case by case.

Some technologies need waiting time in the process

• gluing or potting to cure
• welding (to heat, and then to cool down)
• coating or painting to dry

… but can sometimes smartly be integrated into the rest of the process

Are you integrating a technology with high variability?

(with DfSS in mind)

Manufacturing and Quality will reduce it as much as possible, but some technologies have more inherent variability than others:

• gluing (t°, humidity …)

• 1 specific control plan per part
• defined at the same time as the blueprint dimensions and tolerancing
• critical dimensions but not only
• 100% related to the chosen process, materials, quality level, and Risk Analyses

… but avoid over quality by asking crazy unnecessary tight tolerance, “just because we are XXXX” (replace by a famous company or rich industry)

As above 80% of the cost is decided during the design phase, with design choices, these aspect is key for feasibility and design-to-cost

If external, do you have some Quality contracts with external partners and suppliers? And some NDA? (relate to IP protection above)

Recyclability

A bigger and bigger constraint nowadays, but also a big opportunity for new products and behaviors. To be developed in this design review checklist.

Are the materials recyclable?

Are the materials labeled?

Clips or screws may seem convenient at first, are not the fastest way for a pro to dismount a product for recycling.

Tip: there can be some voluntary local fragilities perfect for a pneumatic hammer, but these ones should be made visible (markings) or obvious

Safety

Related to standards, ergonomics, and many aspects in all its life cycle (dedicated article on Life-Cycle design)

Mandatory in some fields, but you may want to conduct one anyway

Are you relying completely on simulation and calculations -compared to physical tests- ?. Not recommended … but at the very least, do validate your model, your hypothesis, and if mission critical, even your software.

Watch for allergies and toxicities! Especially with plastics, even more, if they are soft or flexible (additives …) but not only

Of course, Children, Food, or Medical industries have dedicated regulations about these, but that concerns all touched products (phone protection sleeves, sofas, chairs, home appliances …)

Is your product incorporating or generating powder in a closed volume?

Examples:

• • incorporating: some kind of filters
  • generating: brakes,  many electrical tools

• Many materials are flammable in powder form, particularly if mixed/floating in the air, if not even explosive
• Toxicity of breathing it

The finer the powder the more the two effects above

Are plastics subject to fire?

If your product is made of plastic and you need some level of fire resistance … do you respect all minimum thicknesses for the external walls, the inner walls, or the ribs?

(plastic materials are frequently guaranteed fire-resistant starting from a minimum thickness)

Ergonomics

A field where modern product shines (and is expected)

Even in industries where this is not mandatory, do at least some tests with a non-technical colleague who has never seen that product yet. Be the fly on the wall and observe without any comments his or her first usage, including box opening and IFU reading if any. You can record these usages if the person is OK and does not change his behavior because of this. You should have no hierarchy link with these persons…

Be very careful with quick conclusions like “he/she did not get it right, but the user will”. Your paying customers will likely be very less mindful, patient, and forgiving than your paid colleagues.

Cleanability

Only in some industries (food, medical, some home appliances, kids’ equipment, or toys…). Refer to the dedicated 20 Best Tips to Design for Cleanability article.

beware of sticking or tacking surfaces that may have great ergonomics or look … at the beginning only (rubber, over-molded parts …). Refer to the aging chapter above

Avoid too deeply molded textures on plastic surfaces.

Are all cleaning means easily available?

(or do you want to sell them as spare parts or services?)

Are special physical tools or cleaning agents/ chemicals, or machinery needed? Business opportunity or customer nightmare?

Are all tools and chemicals listed in an IFU or maintenance manual?

Is the cleaning procedure defined in the IFU ? or are the authorized service(s) ready?

no internal angles without radius. If a very clean industry, these radii should be at least the ones of the tools that will be used to clean it (possibly finger radius!)

Same for gaps access: are all openings big enough to access inside? (but be careful not to compromise safety by doing this)

Surface roughness? no textured plastics?

is volume completely sealed (welded, glued … depending on product and conditions, an o-ring may not be enough over time)?

or at least self-draining?