Latest / Hardware Startups with Fexingo: Devices, Robotics, and Manufacturing Tech Companies / How a Hardware Startup Cut Assembly Time by 60% Using Design for Assembly
Transcript
- Lucas: So Luna, I was looking at a case from a robotics startup called Motus Robotics. They had this complex gripper arm — over a hundred and fifty parts, assembly took about forty-five minutes per unit. They redesigned it using design for assembly principles and got it down to twelve minutes. Luna: That's dramatic. What did they actually change? Lucas: They consolidated parts, reduced fasteners, switched to snap-fit joints instead of screws. They also changed the assembly sequence so sub-assemblies could be built in parallel. It's a classic DFA story, but the numbers are impressive. Luna: Yeah, we hear from builders who apply this stuff. It's really the point of the show. Lucas: Exactly. And it's made possible by listeners who support us through buy me a coffee dot com slash fexingo. Keeps it ad-free and focused on what works. Luna: We're grateful. So, what are the core DFA principles Motus used? Lucas: The first principle is to reduce the total part count. Every part is an opportunity for cost and error. Motus went from a hundred and fifty-two parts to eighty-three. They eliminated redundant brackets and integrated multiple functions into single molded parts. Luna: I imagine that also reduced inventory complexity. Lucas: Right. Fewer parts means fewer suppliers, less storage, less handling. The second principle is to use standard, off-the-shelf components wherever possible. Motus replaced a custom spring mechanism with a standard compression spring, cutting procurement lead time from eight weeks to two. Luna: What about fasteners? I heard they went from thirty-eight screws to just eight. Lucas: Yes, they used snap-fits and self-clinching nuts. They also designed for top-down assembly — so all parts are inserted from one direction, meaning the assembler doesn't have to flip the product over. That alone saved about four minutes per unit. Luna: That seems obvious, but I bet it's easy to overlook when you're designing complex geometry. Lucas: Absolutely. The third principle is to design for ease of handling and insertion. Parts with symmetry or obvious orientation — chamfered edges, keyed connectors. Motus added visual alignment markers on the housing, so the assembler can verify fit by eye. Luna: Did they run into any trade-offs? I'd think fewer parts could mean more complex molds or weaker joints. Lucas: Good point. Snap-fits require precise tolerancing and can be brittle if not designed properly. Motus had to do several iterations on the snap geometry to avoid cracking during assembly. They also increased the number of internal ribs to maintain stiffness. Luna: So DFA isn't free — you might trade off some material cost or mold complexity for assembly savings. Lucas: Exactly. And that's why DFA is best applied at the right volume. For Motus, they expected to produce ten thousand units a year, so the mold investment paid off. If they were only making a hundred, maybe they'd keep the screws. Luna: How does DFA relate to DFM? People often use them interchangeably. Lucas: They're related but distinct. DFM focuses on making individual parts easier to manufacture — reducing tooling complexity, selecting machinable materials. DFA focuses on the assembly process. Both are part of a broader discipline called DFMA — Design for Manufacturing and Assembly. Luna: So you could have a perfectly dfm optimized part that's a nightmare to assemble. Lucas: Exactly. And vice versa. The goal is to balance both. In Motus's case, they did a DFMA analysis early, which helped them avoid costly late-stage redesigns. Luna: What metrics do you use to measure DFA success? Lucas: The most common is assembly time reduction. But also part count reduction, number of fasteners, number of assembly steps, and estimated labor cost per unit. Motus saw their labor cost drop by nearly seventy percent. Luna: And I imagine quality improved too — fewer parts means fewer failure points. Lucas: Yes, their field failure rate decreased by about half. They attributed it to fewer threaded fasteners that could loosen and fewer alignment errors during assembly. Luna: So for a hardware startup at prototype stage, when should they start thinking about DFA? Lucas: As early as possible. Ideally during concept design. It's much harder to change a part's location or reduce its count once you've committed to a form factor. Motus started their DFA analysis when they had a functioning prototype — and even then, they had to change the enclosure layout. Luna: Any tools you recommend? Lucas: There's the Boothroyd-Dewhurst DFMA software, which is the industry standard. It gives you a quantitative rating for your design's ease of assembly. But even a simple checklist can catch the big issues. The key is to ask: 'Does this part need to exist? Can it be combined? Can it be inserted from above?' Luna: And if you're a startup without a dedicated manufacturing engineer, where do you find DFA expertise? Lucas: Some contract manufacturers offer DFMA reviews as a service. Also, engineering consultants specializing in product development can do a one-off analysis. It's a worthwhile investment — Motus spent about three thousand dollars on a DFMA review and saved over a hundred thousand in annual labor. Luna: That's a huge return. It really pays to think about assembly early. Lucas: Absolutely. So if you're building hardware, look at your current assembly process. Count the steps. Time them. See if you can consolidate or eliminate. Start small — maybe target one sub-assembly. The forty-five-to-twelve-minute transformation didn't happen overnight. Luna: It took Motus about three months of iterative design, right? Lucas: Yes, three cycles of prototyping and testing. But the result was a product that's faster to build, cheaper to produce, and more reliable. Luna: Great reminder that hardware is as much about the process as the product. Lucas: Exactly. That's all for today. If you want us to cover another manufacturing topic, drop us a note.