I am working on a custom electronics system which ultimately requires a hand-held case design. Moreover, I would like to use Pro/Engineer to model the electronics case for production using a rapid prototyping system. Consequently, I am wondering if anyone would know of a good book, paper or tutorial on electronics case design, preferably using Pro/Engineer.
How would I align the circuit board inside the case with the outside of the case? How do I create standoffs for the circuit board? How do I effectively deal with the routing of wires inside of the case? Perhaps there are more general books that are available on this type of design. Does anyone have a suggestion?
As an aside, I am also curious as to how it might be possible to design an enclosure for an electro-optical system. How would I integrate lenses and an optical system into the enclosure? Are there standard mounting parts for lenses which I can model in Pro/Engineer (and then produce using rapid prototyping), or would I simply purchase "ready-to-order" mounting parts?
yep, I should have written that book long ago (if I only had time). On the other hand, I guess it would not sell by the million.
Answers to your questions require additional information:
- what does that hand-held have to look like?
- will it require some elegant industrial design?
- who´s going to use this device later on?
- does the housing allow for maintenance later?
- in which environment will it be used?
- how long is its planned lifetime?
- how many of these will be produced eventually?
- what overall production costs are allowed?
- what EMI specs will be applied?
- who is going to produce it and where?
- what materials are desirable/undesirable?
- which methods of production are considered?
- etc. pp.
You´ll need a lot of knowledge about electronics (not only housing), and standard engineering expertise too, e. g. from sheetmetal, plastic injection molding, power supply and thermal management... ...yes, one could very well write a book about.
You may omit some design criteria if RP is the way of choice, but then you´re stuck with high costs and no way to ramp up numbers.
Perhaps you´d better look for some experienced consultant :-)
Through trial end error you will easily waste lots of both money and manpower and make the product a complete failure anyway, especially when you´re not an ace with Pro/E´s functionalities. You will sure have to adapt design to demands that show up later on.
I agree. The topic is worth a book, probably a whole degree program. The books that Spehro Pefhany mentioned are a good place to start in getting a handle on plastic, injection molded enclosures. But, as Walter pointed out, sheet metal ones are also prevalent. Considering the history, extending back to the first radios and auto and aircraft instrument panels, the problems and solutions have been around for a century.
A practical place to start might be project based tutorials. Consider this site and some of its projects; it's loaded with them:
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of them make it pretty clear that a legitimate approach is to find a commercial box and to start modifying it to fit a board, screens, ports, plugs, switches, etc. I think they also make it pretty clear that all enclosure issues begin with the board and its function and requirements. The board raises questions like how will it be powered? how will it communicate with peripherals, humans? will it generate enough heat to require special cooling that an enclosure must accommodate? will it generate or be effected by EMI/RFI and have to be isolated from these effects? will the board and mounting have to withstand vibration, shocks, dust, salt fog or other extreme environmental effects? will it be mounted like a control box on a machine or be hand held like a cell phone?
The answers to these questions greatly effect both board and enclosure design. But the problem set is quite specific to application. The more you can narrow the field, the more you gain access existing solutions and resources.
Yes, I agree that a good book on the principles of this type of design would be useful.
Well, I would like to create a case using rapid prototyping technology, so for now, I don't think that I would completely create molds from scratch. I have access to a rapid prototyping machine, so it wouldn't be too difficult to have the design fabricated. My application is a system for ground-based environmental remote sensing. I would like to incorporate the transducers directly in the case (i.e. the shape of the case is adapted to the transducers). I've been trying a number of different ways to mount the transducers, and each way that I've tried has led to more grief (i.e. transducers falling off, transducers becoming wet from melting snow and rain...)
- what does that hand-held have to look like?
Circuit board mounted inside the case, with connectors attached two or more circular transducers situated on the front of the case.
- will it require some elegant industrial design?
Sure, why not? There's a lot of "elegent" cases that are also somewhat simple to construct. I was thinking about a case with two parts: a bottom, which holds the electronics circuit board, and a top, which helps to hold the transducers in place and functions as a lid.
- who´s going to use this device later on?
The device is currently part of a research project for eventual commercialization.
- does the housing allow for maintenance later?
Sure, if the lid can be fixed in place with screws in a similar fashion to most electronics cases.
- in which environment will it be used?
The device will be used outside, where it may be subjected to rain and snow.
- how long is its planned lifetime?
My guess would be at least a few years.
- how many of these will be produced eventually?
We still have to assess market availability. I would say that there would be interest from environmental engineers and consultants. I would say that it wouldn't be mass production (like an MP3 player), but the number produced may be significant.
- what overall production costs are allowed?
Well, research projects are initially limited, BUT if I use rapid prototyping, the cost rapidly decreases.
- what EMI specs will be applied?
Canadian ICES-003
- who is going to produce it and where?
The project might be sold to a company.
- what materials are desirable/undesirable?
Probably anything plastic is useful.
- Perhaps you´d better look for some experienced consultant :-)
Probably this is the best way to go, but then again, I might not learn anything from the process. The intent of making postings on newsgroups is to explore the possibility of doing this. Sure, a consultant would be the best way to go, but it is still interesting to discuss how this might be done, and what resources to use.
So, what does the board look like that we're building this box around. Since you're insisting it will be hand held, you must know the size and approximate volume, maybe even the location of most inputs and outputs? What will power it, i.e., how much power does it require? Hand held, to me, means anything from a battery powered cell phone to a chorded, 5 pound machine controller with 30 buttons. The cell phone has a nice plastic case, the machine controller, plastic over sheet metal. Handhelds come in a thousand different sizes, shapes, weights and complexities. Again, it's a very loose definition of a requirement. You can help us help you with something more precise, more exacting.
Thanks again for your response. We're looking at a PCB that is slightly larger than 9 cm by 15 cm by 2 cm. The transducer assembly is located at the front of the case. The inputs (power plug and USB) will be situated near the back of the case. The circuit will be powered by a Li-Ion battery pack placed inside of the enclosure. Preferably the circuit will have a plastic case. I'm thinking of using a rapid prototyping machine to produce the case.
OK, I'm not going to try to figure out your board/circuitry. After all, I'm a mechanical guy. But even I have trouble with inputs that include a power plug (plus a LI battery?) and USB plug (with no signal inputs from anywhere?) and a transducer? on a board?, also with no input (or output).
But it sounds like you'll be using board connectors. Much smarter than jumpering wires all over the place. It also sounds like the stack up of battery, board, connectors and transducers will make this almost the full height of 2 cm, IOW, a simple cover over the top of your box. No draft on the walls as no split down middle of box. You've indicated no environmental/EMI/RFI requirements so really simple ~ a screw at each corner.
So, it sounds like you need a couple openings in your case in the back, some standoffs for mounting the board and some standoffs for mounting the cover. The best method would be FDM. Find an RP outfit with a Stratasys Dimension 'printer'. They use ABS plastic, the parts are fast and accurate and usable out of the machine.
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