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What You Need to Think About When Specifying Your Design
A good designer gathers input from all parts of the company to develop the most efficient, producible design possible. Graphic courtesy of Sauter Industrial Design.
There is a chain of custody for your design, from obtaining materials, to manufacturing, storage, shipping, and eventually, the buyer, or end user. Every part of that process must be considered.
By Ken Sauter
We all make assumptions. Sometimes we make many more assumptions than we are aware of. Yet assumptions have consequences, particularly with relation to design specifications.
Every design incorporates assumptions, and while most of those assumptions reflect the way we normally do things, it is important to understand what assumptions you are making when you design something, and what implications those assumptions have.
A few years ago, I developed what I called a “Design Requirements Specification,” thinking it was a good way to help customers completely specify a design. It was three pages long and covered all the critical things–in my opinion–that define a design. The intent was to make it easier for me to develop a design that reflects what my customers wanted, and to fully specify it.
I wanted to avoid making my own assumptions about what my customers wanted. What I failed to realize was that it takes a lot of thought and application to completely specify a design–much more thought and application than any one person has available.
I had at least one customer acknowledge that it was a great idea, but he never took the time to fill it out. He simply didn’t have the time available, and he was too busy with other things. What usually happens is that a customer will, verbally, with some rudimentary drawings or sketches, describe what they want, and I will proceed with the design based on that information. We are usually working closely enough that a regular review of the design will reveal anything that needs to be changed. If the customer is happy with the resulting design and they can produce it economically, everyone is happy.
It became clear to me that the only way to fill out that document properly was for the customer to convene a meeting for the purpose of discussing and specifying design requirements for a particular product. That meeting would have to include all the critical stakeholders for that design, and it would take all day, a few days, or even weeks, to completely specify the product and answer all the questions that came up during that specifying process.
You have to determine how much effort is required, and available, to completely specify your design. Weighing the ramifications of a successful–versus an unsuccessful–design has to be considered.
Regardless of whether you begin with a simple sketch and a verbal order, or whether you have a multi-page document that specifies your design requirements in excruciating detail, your design needs to address a number of things. What you don’t specifically address will be assumed. You need to know what those assumptions are, and you need to make certain those assumptions are acceptable.
The first thing you must determine is who your customer is. The buyer isn’t always the customer, although it usually is. Who is the person, or group of people, who want this design done and have a purpose for it? They will drive the design specifications.
The buyer is whom you usually deal with, but you need to understand who is driving the design and what their purpose for it is. Every design has multiple customers. It’s never just the buyer or the original specifier. There is a chain of custody for your design, from obtaining materials, to manufacturing, storage, shipping, and eventually, the buyer, or end user. Every part of that process must be considered. If you are simply making a variation on an existing design that you have in production, most of those things are already established.
You may have a design that your customer thinks is great and is ready to buy, but if you can’t store it or ship it, you can’t get it to your customer. And your manufacturing process must be able to build the product. Manufacturing is an internal customer, and manufacturing is going to have a say in how your product is designed. If they can’t build it, you won’t ship it or make any money on it.
Everyone who handles your product, from the time it leaves the proverbial drawing board until it’s delivered to the end user, is a customer and must be satisfied. Your design must accommodate their needs and desires just as certainly as your end customer’s needs and desires. A successful design incorporates a great deal of intelligence about how you design, build, store, and ship your products.
Once you’ve established who the customer is, several other critical things need to be established. How many units you’re going to produce has to be determined. Your manufacturing process determines how many units you can produce. Whether you produce batches of product in multiple short runs, one or two thousand over a year or two, or millions at a time over days or weeks determines quite a bit about your design.
Economies of scale come into play when your production numbers go up. The parts you specify for your design must be available in the quantities you need, without overbuying or underbuying. It is a mistake to think if you can find it in a catalog or on the internet, it will be available to include in your design at the price and in the quantities you need. It is very easy to make assumptions about a part’s availability, then find out you can’t get what you need in the quantities and configuration necessary for your design, or at the price you need to make your design economical.
Most of the products I’ve been involved with were produced in multiple runs of dozens or hundreds, and usually involved custom-molded parts. We had to decide what kind of mold to use. A steel mold would make more parts, but an aluminum mold was considerably less expensive, although it would wear out sooner. We had to balance how many we expected to produce versus what it would cost to produce them. As it was, we ended up using aluminum molds far beyond their expected life, which introduced its own problems.
There is frequently more than one customer for a product, especially with very large customers like the government. Someone recognizes a need and says something, someone specifies what needs to be designed, a program authority authorizes the purchase, a purchasing authority somewhere takes responsibility for purchasing the design, and the end user is the one who actually uses the product. All parties must be dealt with and satisfied. Graphic courtesy of Sauter Industrial Design.
If you’re building electronic products, there is usually a particular architecture you’re going to employ. I don’t presume to know all about electronic or programming architecture, but I know that once you’ve established an architecture to build your design around, a number of things about your design are already determined.
You have to think about the implications of using a particular architecture and whether that makes your design flexible or boxes you into certain requirements. How you specify what your end product is going to do determines the best architecture for your product.
If you’re using electronics, you’re likely also doing some programming to make it work. All of that has to be considered. If you don’t specify it, potentially dangerous assumptions are going to be made.
Size is another thing to consider. Whether you’re designing a hand-held product that gets shipped in a box, or a 200-foot rocket that has to be moved on multiple trucks makes quite a difference in how you specify what you are doing. Again, I don’t presume to know all about designing everything, but my experience has been that a lot of assumptions are made when we specify our designs, and those assumptions have a direct effect on how our designs get built and how they perform in the field.
The size of your product partly determines how you package it and ship it, as well as how and where you build it. You may have to figure out what quantities of your product you can fit in a semi-trailer, or what size pallet a department store can handle. You may leave that specification to someone else, but you should be aware of what happens to your product until it is out of your control.
Something that frequently gets missed is the environment that your design performs in.
If you are regularly producing a product, it usually has a given environment it is used in. We simply assume that whatever we design is going to perform in that same environment and leave that out of our design specifications. This becomes a problem when that environment changes during the product’s use. If you’re designing a spaceship, everything must work in a surface environment on earth as you build it and test it, but it also must work in the vacuum and cold of space, which is a completely different environment. Don’t think that if it works in your design environment, it will automatically work in any environment you put it in.
We were designing some units at one point for use in extremely cold environments. We soon found out there are a lot of materials that are specified to work down to -40°F (which is the same as -40°C, by the way), but they either wouldn’t work below that temperature, or the manufacturer wouldn’t certify them to. In that case, we had to test the design, with the materials we specified, to see how they would perform in those temperatures. That is the point where you take full responsibility for your design. You can’t throw a failure back on the material supplier if you’re using it outside the specifications they provide.
In addition to temperature, you may have to consider the chemical environment your design is used in, or whether it’s going to be immersed in water or some other substance, and how much pressure it must withstand. Sealing can become an issue when the external or internal pressure on your design changes. And your product may have to perform in an extreme environment. We once discovered that the internal pressure in a unit caused the glass to shatter at altitude in an airplane, due to the pressure differential. It was an unexpected result, but it had to be dealt with. All of that needs to be understood and specified.
I used to design weapon sights. We had to consider weapon shock, and how that affected the internal, as well as external, parts of the design. We found out, after doing some tests, that weapon shock varies depending on how far something is from the weapon. That changes the requirements for different parts of the design. The parts that are further from the weapon don’t have to withstand as much shock. Sometimes specifications will change based on where the part is, relative to the active part of the design.
When you’re designing around optics, you need to consider thermal expansion, and what that does to your prescription. Optics are very unforgiving. They have to be carefully mounted and held firmly in place, yet withstand weapon shock, immersion, and other factors without allowing the prescription to change, depending on what purpose your optics are serving. And they have to be sealed.
There is no way I can cover all the factors necessary to fully specify a design, but my fundamental concern is this: Don’t make assumptions. Consider everything your design will do and can be used to do–where, how, when, why, and who will use it–and be purposeful about specifying every part of that.
Only by developing a complete set of design requirements in this way, and checking your assumptions, will you have the best possible shot at producing a successful design. I cannot emphasize checking, and double-checking, enough.
No Designer Is an Island
Never forget that no designer is an island. While there are lots of things to consider in specifying your design, it is also critically important to include the people who are involved in developing and producing your design, particularly the people in your company that will be involved with producing your design.
I like to think I’m pretty good at what I do. Most of my designs go into production with no more than the usual problems. I’ve heard a rumor or two of a design that went into production without any problems, but that’s not normal, even if it does happen. The fact is, there are always issues when getting a new design into production, and no one person has all the answers. We depend on each other to get things done right.
I once designed a fixture for a simple operation where we needed to stake something, and I thought I would just design it, build it, and test it without consulting anyone else. After all, it was a simple operation and I thought I knew what I was doing.
It didn’t work at all. The manufacturing engineer who would have used it commented that he was usually pretty proud of what I did, but I screwed up this time. That taught me that consulting with people who are going to use my designs is critical to developing a good design. There’s nothing like feedback from people who are interested in the process to inform your design work.
No designer works in a vacuum. We are part of a system, and every part of the system is necessary to generate a well-specified design that gets built properly, functions well, and pleases the customer. We are usually buried down in the system somewhere away from the customer, but what we do ultimately affects the customer, and everyone else in the company that is involved in producing our design. We have to trust that the people who give us the job have done their homework in understanding what is needed and fully specifying the design.
I have learned over the years that everyone involved in developing a design has something to say about how it gets done and how it is produced. It is our job as designers to consider what those people have to say about how a design is developed and produced. When we do our job well and consider everyone who is involved in producing our design, the design is much more successful than it otherwise would be. When people feel that their ideas have been considered, they are inclined to do their best in producing it.
I used to go down to the production floor fairly often to see how my designs were being produced and listen to the assemblers talk about whatever issues they were having in putting it together. Sometimes the issues were things I could correct, and sometimes we had to adjust our process to deal with vendor problems that forced us to do things we really didn’t want to do, but had to, in order to get the product out the door. The product still functioned properly, but it was a lot harder to put together. The production floor is always dealing with problems, and it was very helpful to me to do my best to understand what the issues were in order to make it easier to put the product together.
I worked on the production floor for a year or so, and it was hard to get anything done because something had to be dealt with about every five minutes. Anyone who thinks parts always come in on time and meet specs, and always go together properly, needs to work on a production floor. There’s no end to the issues that come up when you’re trying to produce something.
I designed a night vision sight several years ago, and I thought I would make it a point to consult with everyone who had anything to say about the design.
I worked with the electrical engineers regularly to make sure they were able to pack all of the electronics into the unit, and there was a fair amount of back-and-forth with the optical designer as I worked to get image planes and focus mechanisms all into the space allotted and working properly. Part of this effort was trying to use existing parts so that we didn’t have to reinvent the wheel to get something done. I also talked with production people so that we didn’t end up with something we couldn’t produce. The result was a well-produced design and a happy customer. All of that consulting with other people who had an interest in the design paid off. The unit was relatively easy to build, and we produced a few thousand of them.
Every designer is part of a system that is structured to produce a certain kind of design that is unique to your company, and that system involves everyone in your company.
Purchasing always has some direct input to the process, and it is important to listen to what they have to say. If they can’t purchase the parts you need, you can’t build the design. And they know about purchasing parts and what kinds of problems are native to that process. Quality control and calibration are also involved. Quality control needs to check the parts when they come in, and you, as a designer, have to tell them what must be checked, and what for. Shipping is usually able to handle whatever you’re building, but sometimes you even have to discuss things with them in order to get the product packaged and shipped properly.
No one person understands everything. Smart CEOs and managers will defer to individuals who have expertise in specific areas. When you work with something every day, you generally know more about it than someone who doesn’t. It is the wise manager who knows how to put people together in a way that produces a good product. It is a wise designer who consults with all the people involved in producing his or her design, in order to make it the best design possible.
To generate the best possible design, you first have to fully and accurately specify the design so that it will do what is intended. Secondly, you must consider all the people who are involved in producing that design so that it gets produced properly and economically. Generating a great design is a cooperative effort among everyone involved. The more cooperation there is, the better the design. It is your job as a designer to facilitate as much cooperation and understanding as possible.
About the Author
Ken Sauter is president of Sauter Industrial Design (www.sauterindustrialdesign.com), Garland Texas. An expert in designs involving optics and electronics, Ken has extensive experience in designing complex optical systems–including night vision equipment for the military–for manufacturability and reliability. His work includes projects ranging from a large-scale microwave oven for a hospital to an interior for a custom airplane; a flight simulator; plating equipment; sheet metal NEMA boxes; and truck bodies. Ken also has experience with sheet metal, weldments, molded parts, machined parts, and many other methods of manufacturing that are used to produce his clients’ designs.
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