> A mechanical switch is easy and cheap to fix or replace.
Not if it is in an airplane. Think of all the QC steps required to track the production, storage, shipping, installation, testing, etcetera for the replacement of a single switch. If a switch has failed it needs to be inspected to understand the reason for failure (no switch should fail; tracked to understand if it is a batch failure, plus other steps). I am only making an educated guess here.
> A switch can usually be cleaned easily, to restore its function.
Ummm, you think they put known failed parts back in planes? I think not. They do fix major parts, but the QC for that would be insane. You would make a switch to be hermetic and add anti-tampering - a manufacturer of any safety related device doesn’t want it to be “fixed”. Items are designed to be maintained (with proper schedules), or replaced.
> And proper quality switches can be actuated millions of times before failure.
On average? Or does it have a bathtub curve? Yes, quality switches are insanely reliable, but so are touchscreens.
If you have a variety of 50 switches and knobs, then the reliability is worse than 50x worse, because every item has it’s own reliability curve, and it only takes one failure to muck up your day.
OP context of this thread is touch panels in aeroplanes, not cars.
I can say that an intermittent switch failure is hard to diagnose and potentially costly. The dash on a 2007 Ford I got cheaply had an intermittent fault where the whole dash would shutdown, and headlights would go off, while driving. Switching ignition off and on would fix it, so I presumed it just needed a reset. It was actually the barrel switch of the key - intermittent enough to cause a lot of dangerous trouble but hard to diagnose.
Not if it is in an airplane. Think of all the QC steps required to track the production, storage, shipping, installation, testing, etcetera for the replacement of a single switch. If a switch has failed it needs to be inspected to understand the reason for failure (no switch should fail; tracked to understand if it is a batch failure, plus other steps). I am only making an educated guess here.
> A switch can usually be cleaned easily, to restore its function.
Ummm, you think they put known failed parts back in planes? I think not. They do fix major parts, but the QC for that would be insane. You would make a switch to be hermetic and add anti-tampering - a manufacturer of any safety related device doesn’t want it to be “fixed”. Items are designed to be maintained (with proper schedules), or replaced.
> And proper quality switches can be actuated millions of times before failure.
On average? Or does it have a bathtub curve? Yes, quality switches are insanely reliable, but so are touchscreens.
If you have a variety of 50 switches and knobs, then the reliability is worse than 50x worse, because every item has it’s own reliability curve, and it only takes one failure to muck up your day.