Who can review our product for manufacturability across the whole chain, from parts and assembly to packaging and freight, before we commit to tooling?

A manufacturability review across the whole chain needs a party that can judge the parts and everything that happens to them afterwards, and that has no stake in any single tool. A toolmaker checks whether his mould can make your part; a design team checks whether the product works. Assembly, packaging and freight fall between the two unless someone is asked to look. So ask for a DFMA review of the full bill of materials, with assembly sequence, packaging and freight included and every finding expressed as cost per unit. Do it before tooling, because after that every change is steel.

Why isn't a DFM check on each part enough?

Because a part can be perfectly mouldable while the product still misses its cost target. Design research commonly puts 70 to 80% of a product's cost as committed during the design phase, and a large share of that only becomes visible after the moulding machine: assembly labour, packaging, freight, and the cost of servicing what you sold.

Most writing on DfX and DFM/A comes from electronics, where the review is about boards and components. For a mechanical product in plastic or metal the questions are different, and the expensive ones sit between parts rather than inside them: how many parts there are, how they join, and how much air ships with them. A toolmaker's DFM report answers none of those. It tells you whether one part will come out of one tool, which is necessary and not the same thing as a product that hits its landed cost.

What does a DFMA review look at in the parts and the assembly?

Whether each part earns its place, how the parts are joined, and the order in which they come together. Part-level DFM on draft, wall thickness and tolerances is the starting point of the review, not the review.

For part count, the minimum part count test from Boothroyd and Dewhurst's DFA method is still the most useful screen. A part justifies being separate if it moves relative to the others, if it has to be a different material for a fundamental reason, or if other parts could not be assembled or removed otherwise. A part that meets none of the three is a candidate to merge with a neighbour. That is a screen, not an instruction: a merged part can need a more complex tool, and the review should show that trade-off in cost per unit rather than leave it as a principle.

Then the joints, each with its own price:

• Screws are serviceable and forgiving, but every screw is a bought-in part, an operation on the line and a place where things can go wrong.
• Snap fits assemble fast and add no parts, but they put demands on material and tool design, and they wear if the product is opened often.
• Adhesives and ultrasonic welding are fast and sealed, but permanent. Repair becomes difficult, and so does separating materials at end of life.

Finally, the assembly sequence. Can everything go in from one direction, or does the unit have to be flipped halfway? Does a part fall out before the next one locks it in place? Do the tolerances of five parts stack up into a gap the customer can see? On Higo Sense, more than sixty parts from thirteen moulds had to fit together precisely enough for assembly at the client to stay quick. That kind of fit is solved in the drawings, not on the line.

Why do packaging and freight belong in a design review?

Because freight is charged on volume as well as weight, and the shape of the product sets the size of the carton. Air cargo uses the IATA convention: length by width by height in centimetres, divided by 6,000, gives volumetric weight in kilograms, and you pay whichever is higher. Express couriers often divide by 5,000. Anything less dense than about 167 kg per cubic metre, such as a hollow plastic housing in a carton, is billed on volume. Shared container sea freight is priced per cubic metre.

A worked example with invented dimensions. An assembled unit weighing 1.8 kg ships in a 40 by 30 by 25 cm carton: 30,000 cubic centimetres, or 5 kg of volumetric weight. Redesign the base so one unit nests into the next, ship two in a 40 by 30 by 30 cm carton, and each unit drops to 3 kg chargeable weight, 40% less. In a cubic metre of sea freight that is around 55 units instead of 33. The catch is real: nesting usually constrains the shape the designer wanted, and that conversation belongs before tooling, not after the first freight invoice.

Three more points come up in nearly every review:

• Pallet fit. How many cartons go on a 1,200 by 800 mm Euro pallet, and how high can they stack before the bottom layer crushes? A carton footprint that just misses the pallet pattern ships empty space on every load.
• Transit damage. Thin protrusions and high-gloss surfaces need inner packaging. Test the pack against a standard procedure such as the ISTA series before the first container leaves.
• EU packaging rules. If you sell into the EU, the Packaging and Packaging Waste Regulation (EU) 2025/40 has applied since 12 August 2026. From 2030, grouped, transport and e-commerce packaging may contain at most 50% empty space, and packaging weight and volume must be cut to the minimum the function needs. A shipping carton sized generously today will run into that limit.

On CoolaWand, packaging sat in the same project as DFM, tooling and supply chain management. That is the order we recommend: design the carton with the product, not after it.

What about the supply chain and end of life?

Ask of every part where it is made, how far it travels and who else could make it. A product whose parts come from three regions and are assembled in a fourth pays for freight, lead time and stock in transit at every link.

• Distance in the chain. Making parts closer to where they are assembled cuts freight, emissions and lead time at once, but often costs piece price. That trade-off belongs in the review with numbers, not as a preference.
• Single sourcing. A part only one supplier can make, because of a special process or an unusual material, is a risk the design can remove. Where possible, choose standard materials and processes several suppliers can run.
• Bought-in parts. A screw, magnet or spring with a long lead time sets the lead time of the whole product. Review them for availability, not only price.
• End of life. Every material permanently bonded to another makes separation harder. A single-material design, or one where materials can be separated by hand, takes engineering up front. The trade-off is real: a bonded joint is often cheaper to assemble than one that comes apart.

Who can do a review across the whole chain?

A party that sees every link and has no stake in any one of them. In practice there are four candidates, and each looks at a different part of the chain.

| Who reviews | What they look at | What they see less of | | --- | --- | --- | | Toolmaker, alongside a quote | Whether his tool can make the part | Other parts, assembly, packaging, freight | | Product design agency | Function, use and form, often DFM as well | Current piece and freight prices, which sit with production | | Software or online DFM check | Geometry per part, sometimes a cost estimate | Assembly sequence, packaging, where each part is made | | Production partner running the whole chain | Parts, assembly, packaging, freight and chain together | Only what you leave out: the review is as good as your bill of materials and volumes |

The toolmaker and the software assess the part. Only a party that also runs assembly, packaging and freight can weigh the costs that arrive after the moulding machine, because those costs land on its own desk.

Whoever you choose, ask for three things: findings per link expressed as cost per unit, a clear split between what must change and what could, and the model revision number the review applies to. In our process, manufacturability and cost per unit are assessed at the start, before any steel is ordered, and assembly, packaging and freight are handled within the same project. What we review per link, what you send and what you get back is on our DFM review page.

Production Heroes takes products from design to series production, from feasibility and cost price to sourcing and supply chain, and supplies moulds and tooling to manufacturers across Europe, from the Netherlands and its own presence in China.

Sources: the share of product cost committed in design (70 to 80%) comes from design research, including Mileham, Dowlatshahi and Hundal as cited in a Design Society publication; other sources give somewhat different percentages. The three part count questions come from Boothroyd and Dewhurst's DFA method. The 6,000 divisor and the 167 kg per cubic metre threshold follow the IATA convention for air cargo; couriers and airlines sometimes depart from it. Dates and the empty space limit come from Regulation (EU) 2025/40; the 2030 date can move if the calculation method for empty space is adopted later. The review and quotation lead time comes from our own process. The packaging example uses invented dimensions.