[Cuis] Economic Design

[Casey Ransberger]

This is a great read. It's always nice to identify places wherein "software engineering" actually *does* parallel real engineering (usually not the case in my view.)

Anecdotal, but fun: dad is a musician, but my grandfather (in between fighting wars to keep the world safe for nerds like me) worked as a railroad engineer. He was one of the first engineers to use the first computer they had at Penn Station. 

It didn't come with a manual;)

He won't tell me anything about the wars, but he did tell me about the computer he used stateside. It was probably part of why I ended up making software.

--Casey

On Jun 5, 2012, at 5:26 AM, Juan Vuletich <juan at jvuletich.org> wrote:

> Hi Folks,
> 
> When I was a kid, my father worked for a company that is generally regarded as a world leader in the automobile market: Mercedes Benz. I remember in the early 80's, an ad for a Basic compiler with advanced structured stuff from Pascal. The ad presented it as "the Mercedes of Basics". These guys were so serious when it comes to product quality, that comparing anything with them was synonym with "top quality". I still read from time to time old stuff from them, because I find their attitude inspiring.
> 
> Today I found an article in a 1974 issue of an internal magazine for the sales organization. It is called "Economic Design", and I was astonished by how directly the ideas apply to our field. Here it is, sightly abridged and translated from Spanish into English (my comments follow afterwards). I hope you enjoy it as much as I do.
> 
> -----------------------------------
> Economic Design
> (Mercedes Benz "Información de Venta", VII./VIII. 1974/2 A/II/031)
> 
> Criteria from our development department on a hot topic, equally interesting to both customers and salesmen.
> 
> The "economic design" subject plays a big part in our house. On one hand we must design for economic manufacture, so we can sell at good prices. On the other hand, we must reduce as much as possible the maintenance and repair costs for our customers. Unfortunately, these objectives might contradict each other, so we need to find a balance between them.
> 
> In early design phases we already try to have a small set of different groups and elements (for example, engines, transmissions, suspension parts) be enough for many different car models and types. We solve this by applying a system of interchangeable elements for the whole series. In this way it is possible to use big quantities of each group or part. This reduces manufacture cost of each one, and also simplifies the storage and logistics of spare parts.
> 
> These groups and their elements are subject of intensive tests both in the test bench and in the real world. In this way we can guarantee the required robustness and service life, while saving unnecessary expense in materials and machining. Value analysis is done to try to make even cheaper parts. Here, the crucial part is to state what stress can be demanded on each part. Exaggerated demands are always bad! From all this, we determine what expense in materials and machining are really required to meet the requirements in the simplest possible way. Costs and benefits must relate in a reasonable way.
> 
> But for car owners, not only purchase price is important. Later expenses are important too. Besides consumption of fuel, lubricants and tires, maintenance and repair costs impact considerably on profitability. Because of this, we try to design a maximum number of parts without maintenance, or at least, that seldom require it. Repairs must also be possible in the simplest way.
> 
> Later, when the product is manufactured in series, a statistics of warranty failures and voluntary repairs tells which parts fail the most. These are subject of rigorous examination, to quickly take action, for example, by adjusting manufacture process or part design. These corrections are then applied to the serial manufacture.
> 
> Design also impacts on repair costs after an accident. As the front-side collision is the most common kind of accident, all Mercedes Benz cars have the front fenders held with screws, not soldered, so they are easy to replace. Even soldered parts are designed to be easy to be partially replaced. The relevant procedures have been described in Mercedes workshop manuals since 1962.
> 
> In short, the Daimler Benz house is doing big efforts to make design help reduce costs. Current world economics will require these efforts to be intensified in the future.
> -----------------------------
> 
> I think this text is a great lesson on software design.
> 
> It agrees with Dan Ingalls' wonderful "Design Principles Behind Smalltalk" http://classes.soe.ucsc.edu/cmps112/Spring03/readings/Ingalls81.html . Dan says "Good Design: A system should be built with a minimum set of unchangeable parts; those parts should be as general as possible; and all parts of the system should be held in a uniform framework. "
> 
> The Mercedes article also sheds new light on why simplicity in design is of paramount importance: It allows us to ship stuff that is better tested and more robust. It makes for a system that breaks less often and is easier to repair.
> 
> It also states that exaggerated requirements go against quality, by raising costs for no reason. Do "the simplest thing that could possibly work". "Make everything as simple as possible, but not simpler". In short, it reduces both short-term and long-term costs.
> 
> Cheers,
> Juan Vuletich
> 
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