Magnetics question; and I don't have more info than presented

steveT1968

Joined Aug 18, 2018
10
The fake-it had the wrong part number too. On top of all that, the plater's cert had the right part number and revision but someone changed it with a pen and a strikethrough of the (what was the) correct rev and hand wrote in the wrong.
Sounds like time someone checked all sub contractors had all the ECN and BOM up to date. If the paperwork is wrong, the product will never be right.

Done a little MOD assembly, it makes IPC-610 class 3 look easy. Even had a weight spec for completed product.
 

profbuxton

Joined Feb 21, 2014
419
I doubt that ONE extra lamination on a contactor core will make a significant difference to its operation. BUT it may depend on lamination thickness and how it affects the fit into coil bobbin. Will it be too tight to fit properly and will it cause problems with expansion when coil is energized and hot. Will it make to hard to remove coil. The fact that the supplier can't seem to make it to a MIL spec should be enough reason to reject.
As far as building stuff for the military, I recall some time ago looking up into the bomb bay of a B52 and seeing bundles of cables draped through holes along the length the fuselage and thinking "well that's not meant to last. But I guess they were built for one purpose anyway.
Makes me wonder how well built other aircraft and such equipment is(military or civilian).
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,128
That's why MIL-SPEC's came about. 610, 620, J-STD and the myriads of other standards one has to cross reference can make it rather daunting. Looking at the stuff we build, one must admire how much detail goes into just the wire routing alone. Some of it is pretty damned high voltage (not at liberty to say exactly), but it can become apparent why things like a small burr can be a huge reason to reject something. Especially when it's noted on the print to break all sharp edges. Not just because they're sharp but also because of the potential haloing that can occur.

The contactor? Well, it's not high voltage but it IS pretty heavy. Almost need two hands to lift one out of the box. And just 5 in a box can be close to the OSHA allowed weight limit for a single person to lift. They're big. 2% difference might not be a problem. But again, I'm not an engineer. It's up to them to decide. And I may be wrong, but with magnetics, half the distance is four times the pull. That's why it's nearly impossible to get a magnet very close to another and hold it apart. Slightly closer and the attraction is anything BUT slightly stronger. The extra lam ? ? ? There may be specs that I'm unaware of, like how quickly this has to release when de-energized. We tend to think of lights and motors, but this is a lot more than just that.

Ever see that video of a rail gun (not advocating building one, to do so is a violation of the community guidelines). Imagine all the relays that have to fire simultaneously. Or in a specific sequence. Coil operation can be extremely critical. To my knowledge we're not building such things, but I suppose there COULD be a case where the time it takes for a contactor to operate could be critical.
 

Reloadron

Joined Jan 15, 2015
5,107
Never heard that one before, but I like it. Plenty funny.
It can be changed to MIL-T-D41 to omit the vulgarity. :)
Something we could do was if we changed a procedural method we could mark up a drawing or test procedure and initial the changes and date it. Following a revision you had thirty days to get the new rev and changes into things. The fraud link I provided was one of our suppliers. :)

Ron
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,128
Yeah, we have red line drawings too. But to make them legal there's an ECO that goes with it. Without the ECO the red line is invalid.
 

Reloadron

Joined Jan 15, 2015
5,107
Ever see that video of a rail gun (not advocating building one, to do so is a violation of the community guidelines). Imagine all the relays that have to fire simultaneously. Or in a specific sequence. Coil operation can be extremely critical. To my knowledge we're not building such things, but I suppose there COULD be a case where the time it takes for a contactor to operate could be critical.
Setting aside the rail gun but what if we could apply the same principal of operation to a catapult? A catapult like those used on an aircraft carrier to launch aircraft. That would save countless gallons of fresh water.

Yeah, we have red line drawings too. But to make them legal there's an ECO that goes with it. Without the ECO the red line is invalid.
ECO is what? Engineering Change Order? WE called them an ECN (Engineering Change Notification). Anyway, I recall it was 30 days for a marked up copy or something like that. Wow, only 5 years since I left for retirement and it is amazing how much I have forgotten or simply choose not to remember.

Ron
 

Thread Starter

Tonyr1084

Joined Sep 24, 2015
4,128
ECO Engineering Change Order

The ECO is an order to change the part mid production without having to wait for the final print to come out. This is so they can evaluate the production and make further changes if need be. Sometimes a part already being installed can be pulled and reworked to a higher revision. This is also considered authorization to move forward with the rework.

Yesterday I investigated a part that has been on our inspection shelves with no documentation. Apparently there was an ECO that changed the size of a slotted hole. The part is revved up from A to B and directs the proper paperwork to make, track and approve the modifications. That document is missing and now, those who made the changes will have to create the document after the fact (called "Late Entry").
 
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