Generic Chassis Design Issues

The vendor should bring up any issues that are missing from the chassis specification. But the vendor doesn't know the system requirements. So all the requirements need to be spelled out in the requirements, or something going to end up missing in the finished chassis.
1. No EMI protection; Openings in the chassis walls, un-shielded wires within the chassis, no fan grills
2. Power Supply to small to drive all card slots. Size the power supply so that the supply can drive all available or usable card slots. Size the power supply so that it output the required current at the maximum temperature after it has been derated.
3. Not enough air flow inside the chassis. Insure that there is sufficient air flow within the chassis, and that the air flows over the components that require cooling.
4. Missing warning stickers: ESD Labels, Two man lift, High Voltage warning. [Warning Signs]
5. Running spare wires.
6. Wire color coding for internal cables.
7. The minimum required wire gauge.
8. Any vibration requirements that require cable attachments.
9. Connectors no longer working well.
Connector Savers - Although most electrical connectors are considered to be durable, each of them has a finite life. During testing and system checkout, certain connectors may be subject to frequent mating and demating. When this situation exists, wear and potential damage can be reduced by the use of connector-savers.

Connector-savers transfer the wear from the 'finished' connector to the jumper harness connectors. It also prevents uncontrolled (and possibly damaged) test equipment connectors from mating directly with the cable or harness assembly connectors.

The use of connector savers is recommended. A connector saver can be a short harness jumper that has a mating interface connector to engage the unit. The other end of the harness has the same interface as the unit.

10. Equipment power switches should be selected and located so that accidental contact by personnel will not operate the switch.

These are just a few of the possible issues that may arise while designing an Electronic Chassis. Each of these potential issues are covered on the page that covers the topic in greater detail. Use the Index page to see the contents in this section.

What does a Chassis Cost

The price a vendor will charge for a chassis will depend on a number of factors, including completion. An off the shelf [OFS] chassis which is already designed may not have a published price, so the vendor may have to be contacted. However when the cost of a OFS chassis is published, than there are no cost issues, the price is already known and can be used as a comparison with other chassis products from other manufacturers. For what ever reason some companies use the term OFS; however the much more common phrase is Commercially available Off-The-Shelf [COTS].

A custom chassis is a different issue and depends on what the chassis consists of. Some vendors may not even bid on producing the chassis which they don't offer as a product.
Assuming a chassis vendor will take the work they may charge a Non Requiring Engineering [NRE] fee.
There also may be some kind of Setup fee.
A separate fee may also be charge for any cabling required in the chassis. Some vendors may out source cable work.
Some vendors may also charge a different cost depending on the number of chassis produced. That is, the more equipment you purchase the less it will cost, and you can spread out the set-up few over more gear.

Check all the different vendors, there are dozens that do this type of work. Just be sure to only include items in the specification that are required for the chassis. Any additional items may increase the bid. However, if the vendor already has a ready-made design which include features not required, you may want to accept those if they don't impact the design. That way the company does not have to change the design which in turn increase the cost.

Don't forget to ask about the delivery dates, or dock dates when the bid comes in.

Index Page; How To Specify a Equipment Chassis, this section.

MIL-PRF-55339-55; SMA Connector saver, RF coaxial adapter. Frequency range; 0 to 27GHz.

PC motherboard

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