SPENT FUEL ROD PROCESSING (WIRE REMOVAL)


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Learning From Prototyping (10-26-06)

 Benefits

  1. Machining skills – we get ideas of how to make a workable design. It is good that we have solid models, but spending time machining helps us to see how practical designs are. We learned the importance of tolerances even on simple prototypes. For example, it turns out that the drill press and band saw are not sufficient for constructing the jaws of the Pacman.
  2. It is easier to improve on a design than it is to come up with a design from scratch, from my experience. Having a prototype revealed the strengths and weaknesses of the Pacman. For example, once we built the Pacman, it was very clear that it would need to be hardened. Applying a small force to the wire resulted in a marking on the blade.
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Semester End Reflection (12-10-06)

 
GOOD 

  1. I believe that we have enough good concepts that we can create a fully workable design
  2. Our team works well together with a variety of skills that compliment each other
  3. We will be able to start prototyping right off the bat next semester
  4. We finally got the fuel jackets!
  5. Tom seemed to like many of our concepts

  BAD 

  1. We will have to all do some design work over break to really hit the ground running next semester
  2. We didn’t produce nearly as many prototypes of the individual concepts as we would have liked
  3. As a team we all need to religiously devote time every day to work on this stuff
  4. As a project management goal we need to break down specific tasks and post them along with the job responsibility so that we are all held accountable.  Hopefully it will increase productivity.
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Lessons Learned – 3-20-07

 Lessons Learned – Tapping

 Use 1 size larger than what is on chart for drilled hole

  1. Steel – use finer thread, Aluminum/Brass – use coarser thread
  2. Bottoming Tap – for blind holes
  3. If possible – drill farther than 0.2” past the end of the threads. This gives room for the chips to pile up, plus you don’t hit the end of the hole with the tap.
  4. Start Taps with mill @ about 140 – ensures straight upness

 Lessons Learned – Vice Stop

  1. Don’t use mallet to position part with the vice stop. This resulted in a piece being about 0.020” off.

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Lessons Learned – Shear – 3-22-07

 Situation - “Get the set up right, and everthing be nice ‘n’ Smooth” – At first, Phil (our mentor) had to do a lot of “clamp chasing”. Clamps had to be repositioned multiple times on each part. The first part took about 2 hours to finish. To fix this problem we tapped the tooling plate and made holes in the stock material so that the stock material could be clamped to the tooling plate via two bolts. This new setup/part design reduced the manufacturing time/part to about 40 minutes.

Lessons Learned – Always consider placing holes in parts for clamping (via bolts), especially in smaller parts.

Lesson Learned – One good piece of advice that we were given (by Steve Byerlein our instructor) was to assemble everything and make sure it works before sending out the shears to be hardened. This will prevent us from wasting time and money hardening shears that aren’t going to work.

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Lessons Learned – Top Bar – 3-28-07

             Cold Rolled Steel

Situation -  While manufacturing the Top Bar, we ran into some trouble. While cutting out the excess material (to form the “C” shape), the excess material began to bow away from the Top Bar.

Lesson Learned  - Cold rolled steel develops residual stresses when it is processed. When we began to cut the long (36”) piece of cold rolled steel, we were relieving the residual stresses. The result was, when we placed the part on a flat table, the middle of the Top Bar was about 0.25” off of the table.

Deformation 1
Deformation 2

 We decided to scrap the part and start over with a new design. The new design does not use one solid piece. It uses 3 pieces of 1” bar stock bolted together. The design will actually be easier to manufacture and will eliminate any chance of deformation during the manufacturing process.

          Large Stock Material

Situation – The stock material for Top Bar is 36” long and the part itself is 31” long. The travel on the mill will not allow us to make all of the holes in the piece without moving it. Moving the piece would add possibility of error to the manufacturing process.

Lesson Learned ­ - The head on the mill (containing the spindle) can swivel. So we can find the zeros (datums) on one end and then drill a reference hole in the part that is relative to the datums that we set. Next, we can swivel the mill head until we have enough travel to finish the piece. At this point, we use the dial indicator to set a new zero. We can move the piece until the dial indicator shows that the hole is centered under the spindle. Then we can set the coordinates of the hole on the mill so that we are still working from the same datums.