Design rules

John Gyorki
March 01st, 2007.

Numerous books and courses are available that systematically cover Project and Product Design Procedures, so I expect every engineer to know how to attack a new consumer or industrial product design and carry it through to successful completion. But with countless new products I have studied and purchased recently,

I find that most contain one or more obvious, serious defects. Moreover, the defects do not always come from Accounting’s attempt to cut costs.

I could cite scores of examples, but first consider the powered USB 2, 4-Port Hub I bought yesterday. Three ports each are located on opposite sides of a 1 oz, 2.5-in. square box; two USB I/O plus power on one side, two USB I/O plus PC connection on the other side, and indicating LEDs on the top. I wanted it next to my monitor so I could see the LEDs, but the bulky wires ruled that out. I ended up taping it to the wall above my monitor so I could see it. In contrast, the 7-port USB hub I bought for my other computer has all I/O on the rear and LEDs on the front. Obviously, this is the way to go; it is much easier to install and monitor.

I suffer the same anguish over software, but worse. For example, I owned a Model 3500 scanner for about three years. I purchased a new Model 3100 3-in-1 copier, printer, and scanner from the same manufacturer last week. I installed the 3100 software and a “Solution Center” menu appeared that replaced the original 3500 software and menu. It is supposed to handle both products. Unfortunately, I have not yet been able to figure out how to scan several documents in sequence and have all of them saved to the file where the instructions say they will go. (The so-called Help Menu is too convoluted to help much.) Only the last or first item scanned is saved when I follow the directions. Well, as far as the directions go, that is. After “accepting” the scan, I don’t know how to save it, manually or automatically. So, I have to scan one document at a time, close the file, and open it again to scan another document. Before I bought the new scanner, I could scan as many documents as I needed, and at the end of the session, the software saved all the documents in my file. Now I need a real “Solution Center.”

I don’t recall having this kind of problem in my 40-year design-engineering career. Probably because I managed three specifications throughout a new product design and development process, which prevented these defects. My design team started with a Preliminary Design Specification (PDS). It specified the environment, the power input, the input and output signals, precision, accuracy, size, weight, myriad fine details, and often, the target cost. The engineering manager wrote this spec, which included input from the customer, marketing department, and engineering staff.

We conducted monthly reviews and an FMEA (Failure Modes and Effects Analysis,

or equivalent) throughout the development process. Consequently, modifications were made on successive prototypes. We changed the preliminary spec to accommodate the modifications, which then became a working Development Specification (DS). Eventually, this working spec became the Final Product Specification (FPS), which replaced it. This final spec described the product that Manufacturing made and Marketing sold.

Potential defects were culled out during development. We have fantastic hardware

and software tools today, but they don’t replace solid specs, thorough planning, and clear thinking.

What methods and documents do you use to help design and develop new products and machines, especially to prevent defects like those that I mentioned? Share your expertise with the Design World community, both in print and on the Design World Web site.

E-mail your comments to jgyorki@designworldonline.com.

(Excuse me; I was just alerted of an automatic software update from the scanner manufacturer!)