Shipulski On Design

Posts Tagged ‘Design for Assembly’

Why do factories have 50-ton cranes? Because the parts are heavy and the fully assembled product is heavier.  Why is the Boeing assembly facility so large?  Because 747s are large. Why does a refrigerator plant have a huge room to accumulate a massive number of refrigerators that fail final test?  Because refrigerators are big, because volumes are large, and a high fraction fail final test.  Why do factories look as they do?  Because the design demands it.

Why are parts machined? Because the materials, geometries, tolerances, volumes, and cost requirements demand it.  Why are parts injection molded? Because the materials, geometries, tolerances, volumes, and cost requirements demand it. Why are parts 3D printed? For prototypes, because the design can tolerate the class of materials that can be printed and can withstand the stresses and temperature of the application for a short time, the geometries are printable, and the parts are needed quickly.  For production parts, it’s because the functionality cannot be achieved with a lower-cost process, the geometries cannot be machined or molded, and the customer is willing to pay for the high cost of 3D printing.  Why are parts made as they are?  Because the design demands it.

Why are parts joined with fasteners? It’s because the engineering drawings define the holes in the parts where the fasteners will reside and the fasteners are called out on the Bills Of Material (BOM).  The parts cannot be welded or glued because they’re designed to use fasteners.  And the parts cannot be consolidated because they’re designed as separate parts.  Why are parts held together with fasteners?  Because the design demands it.

If you want to reduce the cost of the factory, change the design so it does not demand the use of 50-ton cranes. If you want to get by with a smaller factory, change the design so it can be built in a smaller factory. If you want to eliminate the need for a large space to store refrigerators that fail final test, change the design so they pass. Yes, these changes are significant. But so are the savings.  Yes, a smaller airplane carries fewer people, but it can also better serve a different set of customer needs.  And, yes, to radically reduce the weight of a product will require new materials and a new design approach.  If you want to reduce the cost of your factory, change the design.

If you want to reduce the cost of the machined parts, change the geometry to reduce cycle time and change to a lower-cost material.  Or, change the design to enable near-net forging with some finish machining.  If you want to reduce the cost of the injection molded parts, change the geometry to reduce cycle time and change the design to use a lower-cost material.  If you want to reduce the cost of the 3D printed parts, change the design to reduce the material content and change the design and use lower-cost material.  (But I think it’s better to improve function to support a higher price.)  If you want to reduce the cost of your parts, change the design to make possible the use of lower-cost processes and materials.

If you want to reduce the material cost of your product, change the design to eliminate parts with Design for Assembly (DFA).  What is the cost of a part that is designed out of the product?  Zero.  Is it possible to wrongly assemble a part that was designed out? No. Can a part that’s designed out be lost or arrive late?  No and no.  What’s the inventory cost of a part that’s been designed out?  Zero.  If you design out the parts is your supply chain more complicated?  No, it’s simpler.  And for those parts that remain use Design for Manufacturing (DFM) to work with your suppliers to reduce the cost of making the parts and preserve your suppliers’ profit margins.

If you want to sell more, change the design so it works better and solves more problems for your customers.  And if you want to make more money, change the design so it costs less to make.

Startups are good at making something work in the lab for the first time. However, startups are not good at moving their one-in-a-row prototypes to the manufacturing floor.  But if startups are to scale, that’s exactly what they must do.  For startups to be successful, they must continually change the design to enable the next level of production volume.

To do that, I propose a 10, 100, 1000 approach.

After the one-in-a-row prototypes, how will you make 10?  Can the crude assembly process produce 10 prototypes?  If so, use the same crude assembly process.  The cost of the prototypes is not a problem at this stage, so there’s no need to change the manufacturing processes to reduce the cost of the components.  And at these low volumes, it’s unlikely the existing assembly process is too labor intensive (you’re only making 10) so there’s likely no need to change the process from a “time to build” perspective. But if the variation generated by the assembly process leads to prototypes that don’t function properly, the variation of the assembly process must be controlled with poke-yoke measures.  Add only the controls you need because that work takes money and time which you don’t have as a startup.  Otherwise, build the next 10 like you built the first one.

After the first 10, how will you make the next 100?  Building 100 units doesn’t sound like a big deal, but 100 is a lot more than 10.  Do you have suppliers who will sell you 100 of each part?  Do you have the factory space to store the raw materials?  Do you have the capability and capacity to inspect the incoming material? Do you have the money to buy all the parts?  If the answer to all these questions is yes, it’s time to ask the difficult questions.

The cost of the units is likely still not a problem because the volumes are still small.  There’s likely no need to change the manufacturing process (e.g., moving from machining to casting) to reduce the cost of the units.  And it’s unlikely the time to build the units is becoming a problem because a super long build time isn’t all that problematic when building 100 units.  So it’s not time to reduce the number of parts in the product (product simplification through part count reduction – aka, Design for Assembly).  But it’s likely time to reduce the variation of the assembly process and eliminate the rework-inspect-test loop that comes when each unit that emerges from the production process is different.  It’s time for assembly instructions, assembly fixtures, dedicated tools at each workstation, measurement tools to inspect the final product, and a group of quality professionals to verify the product is built correctly.

After the first 100, how will you make the next 1000? If you can, avoid changing the design, the manufacturing processes, or the assembly process.  Keep everything the same and build 1000 units just as you built the first 100.  But that’s unlikely because the cost will be too high and the assembly time will be too long. For the most expensive parts, consider changing the manufacturing process to one that can support higher volumes at a lower cost.  You likely will have to buy the parts from another supplier who specializes in the new process and for that, you’ll need a purchasing professional with a quality background.  To reduce build time, do Design for Assembly (DFA) to eliminate parts (fasteners and connectors).  And for the processes that generate the highest rework times and scrap, add the necessary process controls to reduce variation and eliminate defects.  Do the minimum (lowest investment dollars and design time) to achieve the appropriate cost and quality levels and declare success.

After 1000 units, it’s time to automate and move to new manufacturing processes.  For the longest assembly processes, change the design (the parts themselves) to enable automated assembly processes. For the highest cost parts, change the parts (the design itself) to enable the move to manufacturing processes with lower cost signatures.  The important idea is that the design and its parts must change to automate and enable lower-cost manufacturing processes.  You’ll need new suppliers and purchasing professionals to bring them on board.  You’ll need quality professionals to verify the quality of the incoming parts and the output of the assembly process.  You’ll need manufacturing and automation engineers to simplify and automate the manufacturing processes.

The 10, 100, 1000 process is rather straightforward but it’s difficult because it requires judgement.  At what production volume do you move to higher volume manufacturing processes to reduce costs?  At what production volumes do you change the design to automate the assembly process to reduce assembly time?  At what point do you add assembly fixtures to reduce variation?  Which assembly processes do you improve and which do you leave as-is?  When do you spend money on improvements and when do you buckle down and grind it out without making improvements?

The answer to all these questions is the same – hire a pro who has done it before.  Hire a pro who knows when (and how) to do Design for Manufacturing and when to keep the design as it is.  Hire a pro who knows when (and how) to add poke-yoke solutions and when to keep the assembly process as it is and rework the defects because that’s the lowest cost and fastest way to go. Hire a pro who knows when to change the design to reduce assembly time (Design for Assembly) and when to change the design and invest in automated assembly.  Hire a pro who knows how (and when) to implement a full-blown quality system.

When it’s time to move from the lab to the factory floor, it’s time to hire a pro.

Image credit — Jim Roberts Gallery

I hear it’s a good idea to move manufacturing work back to the US.

Before getting into what it would take to move manufacturing work back to the US, I think it’s important to understand why manufacturing companies moved their work out of the US.  Simply put, companies moved their work out of the US because their accounting systems told them they would make more money if they made their products in countries with lower labor costs. And now that labor costs have increased in these no longer “low-cost countries”, those same accounting systems think there’s more money to be made by bringing manufacturing back to the US.

At a low level of abstraction, manufacturing, as a word, is about making discrete parts like gears, fenders, and tires using machines like gear shapers, stamping machines, and injection molding machines.  The cost of manufacturing the parts is defined by the cost of the raw material, the cost of the machines, the cost of energy to power the machines, the cost of the factory, and the cost of the people to run the machines. And then there’s assembly, which, as a word, is about putting those discrete parts together to make a higher-level product.  Where manufacturing makes the gears, fenders, and tires, assembly puts them together to make a car.  And the cost of assembly is defined by the cost of the factory, the cost of fixtures, and the cost of the people to assemble the parts into the product.  And the cost of the finished product is the sum of the cost of making the parts (manufacturing) and the cost of putting them together (assembly).

It seems pretty straightforward to make more money by moving the manufacturing of discrete parts back to the US.  All that has to happen is to find some empty factory space, buy new machines, land them in the factory, hire the people to run the machines, train them, source the raw material, hire the manufacturing experts to reinvent/automate the manufacturing process to reduce cycle time and reduce labor time and then give them six months to a year to do that deep manufacturing work.  That’s quite a list because there’s little factory space available that’s ready to receive machines, the machines cost money, there are few people available to do manufacturing work, the cost to train them is high (and it takes time and there are no trained trainers).  But the real hurdles are the deep work required to reinvent/automate the process and the lack of manufacturing experts to do that work.  The question you should ask is – Why does the manufacturing process have to be reinvented/automated?

There’s a dirty little secret baked into the accounting systems’ calculations.  The cost accounting says there can be no increased profit without reducing the time to make the parts and reducing the labor needed to make them.  If the work is moved from country A to country B and the costs (cycle time, labor hours, labor rate) remain constant, the profit remains constant.  Simply moving from country A to country B does nothing.  Without the deep manufacturing work, profits don’t increase.  And if your country doesn’t have the people with the right expertise, that deep manufacturing work cannot happen.

And the picture is similar for moving assembly work back to the US.  All that has to happen is to find empty factory space, hire and train people to do the assembly work, reroute the supply chains to the new factory, redesign the product so it can be assembled with an automated assembly line, hire/train the people to redesign the product so it can be assembled in an automated way, design the new automated assembly process, build it, test it, hire/train the automated assembly experts to do that work, hire the people to support and run the automated assembly line, and pay for the multi-million-dollar automated assembly line.  And the problems are similar.  There’s not a lot of world-class factory space, there are few people available to run the automated assembly line, and the cost of the automated assembly line is significant.  But the real problems are the lack of experts to redesign the product for automated assembly and the lack of expertise to design, build, and validate the assembly line.  And here are the questions you should ask – Why do we need to automate the assembly process and why does the product have to be redesigned to do that?

It’s that dirty little secret rearing its ugly head again.  The cost accounting says there can be no increased profit without reducing the labor to assemble the parts.  make them.  If the work is moved from country A to country B and the assembly costs (labor hours, labor rate) remain constant, the profit remains constant.  Simply moving from country A to country B does nothing.  Without deep design work (design for automated assembly) and ultra-deep automated assembly work, profits don’t increase.  And if your country doesn’t have the people with the right expertise, that deep design and automated assembly work cannot happen.

If your company doesn’t have the time, money, and capability to reinvent/automate manufacturing processes, it’s a bad idea to move manufacturing work back to the US.  It simply won’t work.  Instead, find experts who can help you develop/secure the capability to reinvent/automate manufacturing processes to reduce the cost of manufacturing.

If your company doesn’t have the time, money, and capability to design products for automated assembly and to design, build, and validated automated assembly systems, it’s a bad idea to move assembly work back to the US. It, too, simply won’t work.  Instead, partner with experts who know how to do that work so you can reduce the cost of assembly.

With inflation on the rise and sales on the decline, the time to reduce costs is now.

But before you can design out the cost you’ve got to know where it is.  And the best way to do that is to create a Pareto chart that defines product cost for each subassembly, with the highest cost subassemblies on the left and the lowest cost on the right.  Here’s a pro tip – Ignore the subassemblies on the right.

Use your costed Bill of Materials (BOMs) to create the Paretos.  You’ll be told that the BOMs are wrong (and they are), but they are right enough to learn where the cost is.

For each of the highest-cost subassemblies, create a lower-level Pareto chat that sorts the cost of each piece-part from highest to lowest.  The pro tip applies here, too – Ignore the parts on the right.

Because the design community designed in the cost, they are the ones who must design it out.  And to help them prioritize the work, they should be the ones who create the Pareto charts from the BOMs.  They won’t like this idea, but tell them they are the only ones who can secure the company’s future profits and buy them lots of pizza.

And when someone demands you reduce labor costs, don’t fall for it.  Labor cost is about 5% of the product cost, so reducing it by half doesn’t get you much.  Instead, make a Pareto chart of part count by subassembly.  Focus the design effort on reducing the part count of subassemblies on the left.  Pro tip – Ignore the subassemblies on the right.  The labor time to assemble parts that you design out is zero, so when demand returns, you’ll be able to pump out more products without growing the footprint of the factory.  But, more importantly, the cost of the parts you design out is also zero.  Designing out the parts is the best way to reduce product costs.

Pro tip – Set a cost reduction goal of 35%.  And when they complain, increase it to 40%.

In parallel to the design work to reduce part count and costs, design the test fixtures and test protocols you’ll use to make sure the new, lower-cost design outperforms the existing design.  Certainly, with fewer parts, the new one will be more reliable.  Pro tip – As soon as you can, test the existing design using the new protocols because the only way to know if the new one is better is to measure it against the test results of the old one.

And here’s the last pro tip – Start now.

Image credit — aisletwentytwo

We’ve heard a lot about long supply chains that have broken down, parts shortages, and long lead times.  Granted, supply chains have been stressed, but we’ve designed out any sort of resiliency.  Our supply chains are inflexible, our products are intolerant to variation and multiple sources for parts, and our organizations have lost the ability to quickly and effectively redesign the product and the parts to address issues when they arise. We’ve pushed too hard on traditional costing and have not placed any value on flexibility.  And we’ve pushed too hard on efficiency and outsourced our design capability so we can no longer design our way out of problems.

Our supply chains are inflexible because that’s how we designed them.  The products cannot handle parts from multiple suppliers because that’s how we designed them.  And the parts cannot be made by multiple suppliers because that’s how we designed them.

Now for the upside.  If we want a robust supply chain, we can design the product and the parts in a way that makes a robust supply chain possible. If we want the flexibility to use multiple suppliers, we can design the product and parts in a way that makes it possible.  And if we want the capability to change the product to adapt to unforeseen changes, we can design our design organizations to make it possible.

There are established tools and methods to help the design community design products in a way that creates flexibility in the supply chain.  And those same tools and methods can also help the design community create products that can be made with parts from multiple suppliers.  And there are teachers who can help rebuild the design community’s muscles so they can change the product in ways to address unforeseen problems with parts and suppliers.

How much did it cost you when your supply chain dried up? How much did it cost you the last time a supplier couldn’t deliver your parts? How much did it cost you when your design community couldn’t redesign the product to keep the assembly line running? Would you believe me if I told you that all those costs are a result of choices you made about how to design your supply chain, your product, your parts, and your engineering community?

And would you believe me if I told you could make all that go away?  Well, even if you don’t believe me, the potential upside of making it go away is so significant you may want to look into it anyway.

Image credit — New Manufacturing Challenge, Suzaki, 1987.

Bottom line growth is good, but top line growth is better.  But if you want to grow the bottom line, ignore labor costs and reduce material costs. Labor cost is only 5-10% of product cost. Stop chasing it, and, instead, teach your design community to simplify the product so it uses fewer parts and design out the highest cost elements.

Where the factory creates bottom line growth, top line growth is generated in the market/customer domain. The best way I know to grow the top line is to broaden the applicability of your products and services. But, before you can broaden applicability, you’ve got to define applicability as it is.  Define the limits of what your product can do – how much it can lift, how fast it can run a calculation and where it can be used.  And for your service, define who can use it, where it can be used and what elements without customer involvement. And with the limits defined, you know where top line growth won’t come from.

Radical top line growth comes only when your products and services can be used in new applications.  Sure, you can train your sales force to sell more of what you already have, but that runs out of gas soon enough. But, real top line growth comes when your services serve new customers in new ways.  By definition, if you’re not trying to make your product work in new ways, you’re not going to achieve meaningful top line growth.  And by definition, if you’re not creating new functionality for your services, you might as well be focusing on bottom line growth.

If your product couldn’t do it and now it can, you’re doing it right. If your service couldn’t be used by people that speak Chinese and now it can, you’re on your way.  If your product couldn’t be used in applications without electricity and now it can, you’re on to something.  If your service couldn’t run on a smartphone and now it can, well, you get the idea.

For the acid test, think no-to-yes.

If your product can’t work in application A, you can’t sell it to people who do that work. If your service can’t be used by visually impaired people, you’re not delivering value to them and they won’t buy it. Turning can’t into can is a big deal. But you’ve got to define can’t before you can turn it into can. If you want top line growth, take the time to define the limits of applicability.

No-to-yes is powerful because it creates clarity. It’s easy to know when a project will create no-to-yes functionality and when it won’t.  And that makes it easy to stop projects that don’t deliver no-to-yes value and start projects that do.

No-to-yes is the key element of a compete-with-no-one approach to business.

image credit – liebeslakritze

Product costs, without product thinking, drop 2% per year. With product thinking, product costs fall by 50%, and while your competitors’ profit margins drift downward, yours are too high to track by conventional methods. And your company is known for unending increases in stock price and long term investment in all the things that secure the future.

The supply chain, without product thinking, improves 3% per year. With product thinking, longest lead processes are eliminated, poorest yield processes are a thing of the past, problem suppliers are gone, and your distributers associate your brand with uninterrupted supply and on time delivery.

Product robustness, without product thinking, is the same year-on-year. Re-injecting long forgotten product thinking to simplify the product, product robustness jumps to unattainable levels and warranty costs plummet. And your brand is known for products that simply don’t break.

Rolled throughput yield is stalled at 90%. With product thinking, the product is simplified, opportunities for defects are reduced, and throughput skyrockets due to improved RTY. And your brand is known as a good value – providing good, repeatable functionality at a good price.

Lean, without product thinking has delivered wonderful results, but the low hanging fruit is gone and lean is moving into the back office. With product thinking, the design is changed and value-added work is eliminated along with its associated non-value added work (which is about 8 times bigger); manufacturing monuments with their long changeover times are ripped out and sold to your competitors; work from two factories is consolidated into one; new work is taken on to fill the emptied factories; and profit per square foot triples. And your brand is known for best-in-class quality, unbeatable on time delivery, world class performance, and pioneering the next generation of lean.

The sales argument is low price and good payment terms. With product thinking, the argument starts with product performance and ends with product reliability. The sales team is energized, and your brand is linked with solid products that just plain work.

The marketing approach is stickers and new packaging. With product thinking, it’s based on competitive advantage explained in terms of head-to-head performance data and a richer feature set. And your brand stands for winning technology and killer products.

Product thinking isn’t for everyone. But for those that try – your brand will thank you.

As an engineering leader you have the biggest profit lever in the company. You lead the engineering teams, and the engineering teams design the products. You can shape their work, you can help them raise their game, and you can help them change their thinking. But if you don’t win their hearts and minds, you have nothing.

Engineers must see your intentions are good, you must say what you do and do what you say, and you must be in it for the long haul. And over time, as they trust, the profit lever grows into effectiveness. But if you don’t earn their trust, you have nothing.

But even with trust, you must be light on the tiller. Engineers don’t like change (we’re risk reducing beings), but change is a must. But go too quickly, and you’ll go too slowly. You must balance praise of success with praise of new thinking and create a standing-on-the-shoulders-of-giants mindset. But this is a challenge because they are the giants – you’re asking them to stand on their own shoulders.

How do you know they’re ready for new thinking? They’re ready when they’re willing to obsolete their best work and to change their work to make it happen. Strangely, they don’t need to believe it’s possible – they only need to believe in you.

Now the tough part: There’s a lot of new thinking out there. Which to choose?

Whatever the new thinking, it must make sense at a visceral level, and it must be simple. (But not simplistic.) Don’t worry if you don’t yet have your new thinking; it will come. As a seed, here are my top three new thinkings:

Define the problem. This one cuts across everything we do, yet most underwhelm it. To get there, ask your engineers to define their problems on one page. (Not five, one.) Ask them to use sketches, cartoons, block diagram, arrows, and simple nouns and verbs.  When they explain the problem on one page, they understand the problem. When they need two, they don’t.

Test to failure. This one’s subtle but powerful. Test to define product limits, and don’t stop until it breaks. No failure, no learning. To get there, resurrect the venerable test-break-fix cycle and do it until you run out of time (product launch.) Break the old product, test-break-fix the new product until it’s better.

Simplify the product. This is where the money is. Product complexity drives organizational complexity – simplify the product and simply everything. To get there, set a goal for 50% part count reduction, train on Design for Assembly (DFA), and ask engineering for part count data at every design review.

I challenge you to challenge yourself: I challenge you to define new thinking; I challenge you to help them with it; I challenge you to win their hearts and minds.

Rumor has it, manufacturing is back. Yes, manufacturing jobs are coming back, but they’re coming back in dribbles. (They left in a geyser, so we still have much to do.) What we need is a fire hose of new manufacturing jobs.

Manufacturing jobs are trickling back from low cost countries because companies now realize the promised labor savings are not there and neither is product quality. But a trickle isn’t good enough; we need to turn the tide; we need the Mississippi river.

For flow like that we need a fundamental change. We need labor costs so low our focus becomes good quality; labor costs so low our focus becomes speed to market; labor costs so low our focus becomes speed to customer. But the secret is not labor rate. In fact, the secret isn’t even in the factory.

The secret is a secret because we’ve mistakenly mapped manufacturing solely to making (to factories). We’ve forgotten manufacturing is about designing and making. And that’s the secret: designing – adding product thinking to the mix. Design out the labor.

There are many names for designing and making done together. Most commonly it’s called concurrent engineering. Though seemingly innocuous, taken together, those words have over a thousand meanings layered with even more nuances. (Ask someone for a simple description of concurrent engineering. You’ll see.) It’s time to take a step back and demystify designing and making done together. We can do this with two simple questions:

• What behavior do we want?
• How do we get it?

What’s the behavior we want? We want design engineers to understand what drives cost in the factory (and suppliers’ factories) and design out cost. In short, we want to connect the engineer to the factory.

Great idea. But what if the factory and engineer are separated by geography? How do we get the behavior we want? We need to create a stand-in for the factory, a factory surrogate, and connect the engineer to the surrogate. And that surrogate is cost. (Cost is realized in the factory.) We get the desired behavior when we connect the engineer to cost.

When we make engineering responsible for cost (connect them to cost), they must figure out where the cost is so they can design it out. And when they figure out where the cost is, they’re effectively connected to the factory.

But the engineers don’t need to understand the whole factory (or supply chain), they only need to understand places that create cost (where the cost is.) To understand where cost is, they must look to the baseline product – the one you’re making today. To help them understand supply chain costs, ask for a Pareto chart of cost by part number for purchased parts. (The engineers will use cost to connect to suppliers’ factories.) The new design will focus on the big bars on the left of the Pareto – where the supply chain cost is.

To help them understand your factory’s cost, they must make two more Paretos. The first one is a Pareto of part count by major subassembly. Factory costs are high where the parts are – time to put them together. The second is a Pareto chart of process times. Factory costs are high where the time is – machine capacity, machine operators, and floor space.

To make it stick, use design reviews. At the first design review – where their design approach is defined – ask engineering for the three Paretos for the baseline product. Use the Pareto data to set a cost reduction goal of 50% (It will be easily achieved, but not easily believed.) and part count reduction goal of 50%. (Easily achieved.) Here’s a hint for the design review – their design approach should be strongly shaped by the Paretos.

Going forward, at every design review, ask engineering to present the three Paretos (for the new design) and cost and part count data (for the new design.) Engineering must present the data themselves; otherwise they’ll disconnect themselves from the factory.

To seal the deal, just before full production, engineering should present the go-to-production Paretos, cost, and part count data.

What I’ve described may not be concurrent engineering, but it’s the most profitable activity you’ll ever do. And, as a nice side benefit, you’ll help turn around the economy one company at a time.

There’s an unnatural attraction to lean – a methodology to change the value stream to reduce waste.  And it’s the same with Design for Manufacturing (DFM) – a methodology to design out cost of your piece-parts. The real rain maker is Design for Assembly (DFA) which eliminates parts altogether (50% reductions are commonplace.) DFA is far more powerful.

The cost for a designed out part is zero.  Floor space for a designed out part is zero. Transportation cost for a designed out part is zero. (Can you say Green?) From a lean perspective, for a designed out part there is zero waste.  For a designed out part the seven wastes do not apply.

Here’s a recipe for unreasonable profits:

Design out half the parts with DFA.  For the ones that remain, choose the three highest cost parts and design out the cost.  Then, and only then, do lean on the manufacturing processes.

For a video version of the post, see this link: (Video embedded below.)

A Recipe for Unreasonable Profits.

Design for Manufacturing (DFM) is all about reducing the cost of piece-parts. Design for Assembly is all about reducing the cost of putting things together (assembly).  What’s often forgotten is that function comes first.  Change the design to reduce part cost, but make sure the product functions well.  Change the parts (eliminate them) to reduce assembly cost, but make sure the product functions well.

Paradoxically, DFM and DFA are all about function.

Here’s a link to a short video that explains DFM and DFA: link to video. (and embedded below)