Shipulski On Design

Posts Tagged ‘DFA’

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.

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

John Teresco of Industry Week wrote a good article that shows how up upfront design enables the next level of improvments in Lean and Six Sigma.

Here are several excerpts:

At Hypertherm Inc., a manufacturer of plasma cutting systems, the DFMA software enabled a first pass part count reduction as high as 50%, says Mike Shipulski, Hypertherm’s director of engineering. About 500 parts were eliminated from the product, a main power supply sub-assembly that originally contained about 1,000 parts. Shipulski says the resulting reduction in assembly floor space requirements made it possible to satisfy a growing market demand within the existing building. “We didn’t have to add floor space.” Read the rest of this entry »