best way to machine 10,000 stainless steel Tee components

[SDConcepts]

I've got a customer that wants me to make some tees. the parts are 3/4 x 7/8 x 1/2 304 ss. here's what I've come up with...

1. automatic band saw saw 10000 blanks mount parts in a mill to square up saw cut, then put them on a fixture in a 4th axis to machine 3 additional sides. (holding for this may become a problem)
2. laser or water jet the blanks, put in 4th axis etc
3. don't know if I can afford this but buy a mill turn and have it spit out done parts one at a time machined off the bar automatically.

did I miss anything?

for the 4th axis fixture I'm thinking it would be about 16 inches long and could hold parts on 4 sides. may have to make 2 of these so that I can swap fixtures and load/unload off the machine. whats the best way to hold the parts down? I though about mittee bites that may grab them well enough.

the other option is to start from 3/4 x 1 stock and then mill a space between them I'd lose a lot of material this way, but it may be the most economical to save setup costs.

 

[alphonso]

A sketch would really be helpful.

 

[Bobw]

More info on the part...

If T shaped, make long ass strips, across 3 or 4 vises, add holes as necessary. At 3/4 x 1, you could split it easily with a 1/4" endmill,
losing that 1/4", which is about 1 ounce of material. If you were going to bandsaw and cleanup anyways, you would lose at least a
quarter of an ounce. So 3/4 of an ounce at even $4 a lb... 19cents in material.

That 19 cents of material saves you a saw cut, blowing the chips off the sawn piece, probably deburring the sawn piece, then handling that
little bastard 10,000 times... If you can do them even in strips of 10, your 10,000 pieces becomes only 1000 pieces of material to handle...

A job I've done quite the # of times over the years.. 3 different pieces, always sawn and then run... Multiple per button push....

Re did the whole mess this trip around to run them in long strips... It was awesome. Saw time was close to nothing, and I could walk
away from the machine for extended amounts of time.... By the time it came to do the 5th and 6th sides, after splitting, I wasn't even
sick of seeing the parts yet, I'd barely touched them...

 

[dstryr]

Make out of rectangle on a horizontal. Hit all 3 "t" sides. 2 ops.

 

[sable]

Get them investment cast?

 

[dstryr]

Get them investment cast?

The name of this forum is practicalmachinist.... Machine shops don't do that well machining castings as they do from solid .

 

[ewlsey]

Mill some long strips. Cut with an auto feed cold saw. Throw in the tumbler and call it a day.

 

[SDConcepts]

I didn't even think about running in strips in vises. would it be worth setting up fixture plates? I've got a 3016 fadal that will be doing this work.

 

[sable]

The name of this forum is practicalmachinist.... Machine shops don't do that well machining castings as they do from solid .

Oh I'm not so sure, I can think of a couple of big high level shops who source castings (mainly from the far east these days) do a bit of machining on them (here) and then sell them on for big money.

 

[sfriedberg]

Yeah, I also found his comment a bit narrow, but allowed for the smiley face.

If I had to bet a quarter, I'd bet that 80%, by volume, of all the parts ever cut on all the Warner & Swasey turret lathes set up as chuckers (rather than bar machines) were forgings or castings as blanks.

 

[scadvice]

If I understand your part right... I would consider getting the material quoted from someone who could extrude it to near or net 'T' shape in bars. May save a bunch in cutters and time that way. Hard to tell without seeing the part.

 

[rcoope]

Casting seems very appropriate at that volume. You could also then have more than the simplest rectilinear part so the final product would be potentially more pro looking. Failing that I like the extrusion, 4th axis, auto-saw and tumble. As I'm normally the waterjet lobbyist I would say if you did waterjet or laser them (and 1/2" is about the crossover), start from 1/2" plate and cut them out that way rather than step #2 in the OP. Then 4th axis and tumble. Interesting to know which method would be faster.

 

[SDConcepts]

for those suggesting band sawing these apart, every time I band saw thing I get the saw teeth striations. don't think I can tumble that out. I like the idea of milling them apart and then facing off the back.

 

[SteveinAZ]

SD, I wish I would have peeked at this before leaving the shop tonight...

We run a steel tee, usually only a thousand at a whack, but here's what works for us. Finished parts are 1" x 1.25" x 1.50" long from 1018, 5/8" thru holes connecting the dots, 0.756/0.758" x 0.200" deep C-Bores for braze clearance. We do band saw these from 1" x 1.25" stock cut to 1.6"; although we ran a batch just before getting our autosaw, so I paid my saw buddy to slice them into little chunks, and no deburr since the cut edges overhand the fixture and get cleaned up with a 1/2" end mill. We run this on our 5" tombstone on a vertical and the fixture plate is about 20" long holding 14 parts per side (just because we don't run a ton, it was fine to cut it a bit short, and only run one tombstone instead of swapping t'stones.) We use a 5/8"-3xD Sandvik 880 to drill through the 1.60" direction first, and then rotate 90 and drill the short direction breaking into the cross hole, then we drop a 1/2" vari-flute into the hole and profile the 0.756/0.758" bore, flip the t'stone and repeat until all three holes are done, profile a little step and chamfer. We tumble for a spell and then a quick dip in a rich coolant bath to prevent rust; our customer rinses them with solvent prior to silver brazing. Fixture clamping is by a single Mitee-Bite Uniforce clamp holding two parts - the only times we have had issue is machine or operator error...TSC died, forgot to torque the Mitee-Bite, misloaded the blank, etc.

If I remember, I'll take a quick photo tomorrow and post for you to see, even though I'm getting close to my thousand words.

Steve

 

[Bobw]

Casting seems very appropriate at that volume.

I'm thinking you may be wrong... Just crunching some #'s... The part is 3/4 x 1 x 1/2. That is 2 ounces of material... Add an 1/8 inch
each side and you are at 3 ounces of material. At a small qty of material that is at absolute worst $1 per part... Now its a simple T, so
basically turning the entire block to chips. Half a cubic inch... 30 seconds if you are scratching your ass and using a HSS endmill, double that
for finish passes. You are $1 in material and $1 in machine time into it. Get super fancy and deburr on the machine, 2 minutes tops.

We are now $3 per part. Holes will have to be put into castings anyways, so we could negate that, but the castings will have to have
each and every one of those bastards handled to put the holes in.... With bar stock, you could gang them in strips and knock out 30 at
a whack.... I'm assuming there are holes...

I think you would have to be well under $2 a casting to compete with bar stock. More likely a dollar once handling is taken into account.
Then you have all the lead time BS involved with that, where as bar stock is on the shelf.

An extrusion is an interesting idea, but it would have to be cheap, really cheap.

Then again, I still don't know exactly what the part looks like, so I may be miles off.

SDConcepts... When buying 304 bar stock, be aware that they like to sell garbage sheared off of a plate.

We do some parts that are 3/4 x 1/2 and we ended up having to go way oversize to make it clean up, (actually went to round)
unless we can find the "tru" bar, and even that isn't particularly square for some reason, though sometimes it is, but don't count on it.

Here is some 3/8 x 1 "bar stock" or "sheared garbage" as I prefer to call it... Its really sad when your best option is to
grab on the bandsaw cut edges. I've never ordered 1 x 3/4, so it may actually be bar.

 

[toolsteel]

I am in favor of machining the "T" shape in a strip style....then cutting multiple pieces from one "T" shaped bar. If you did them in strips tht you could cut 6 parts from....that is 1/6 as many tool changes .....10 parts / strip= 1/10 the tool changes....

 

[SDConcepts]

steveinaz, I'd love to see a pic of that fixture. I've been toying with a similar idea in my head. and while that will be good to get all the sides machined in one step, right now I'm looking at making a steel fixture plate and indexing the parts like suggested before. I've 30x16 table and a little steel plate and some mittee bites will allow me to load a ton more parts than 3 vises. I do have 3 matched vises for this machine as I needed them in the past. but right now my thought is to make a fixture plate that will run op 1 in the first row. op2 in the second and op 3 in the 3rd row. the band saw the strips apart clamp in a vise and mill off the back.

so many ways to skin a cat you could spend hours thinking and no time machining.

 

[SteveinAZ]

steveinaz, I'd love to see a pic of that fixture. I've been toying with a similar idea in my head. and while that will be good to get all the sides machined in one step, right now I'm looking at making a steel fixture plate and indexing the parts like suggested before. I've 30x16 table and a little steel plate and some mittee bites will allow me to load a ton more parts than 3 vises. I do have 3 matched vises for this machine as I needed them in the past. but right now my thought is to make a fixture plate that will run op 1 in the first row. op2 in the second and op 3 in the 3rd row. the band saw the strips apart clamp in a vise and mill off the back.

so many ways to skin a cat you could spend hours thinking and no time machining.

SD,

I took a quick photo of one pocket of the fixture with only one part (an ugly one that was sitting around for a while ) and the Uniforce clamp in place. Remember, these run on tombstone attached to a Koma 4th for rotations. I like it as every cycle we run (unattended) yields 28 parts. If this were a big runner, I'd probably still do it the same way, fixturing both tombstones on all fours sides and filling them up in X, so we would probably be closer to 72 parts per cycle, and about 3 minutes to swap a t'stone.

Steve

 

[sfriedberg]

When buying 304 bar stock, be aware that they like to sell garbage sheared off of a plate.

Boy, that's the truth. I seldom use SS, and the last time I ordered small 304 bar, it was grossly trapezoidal (like 10 to 15 degree lean, per side) in cross-section with nasty edges. I went back to the vendor and they pointed me at the applicable ASTM specs. Sad but true that the standard for small 304 bar is sheared with such gross allowances.

 

[sable]

SD,

I took a quick photo of one pocket of the fixture with only one part (an ugly one that was sitting around for a while ) and the Uniforce clamp in place. Remember, these run on tombstone attached to a Koma 4th for rotations. I like it as every cycle we run (unattended) yields 28 parts. If this were a big runner, I'd probably still do it the same way, fixturing both tombstones on all fours sides and filling them up in X, so we would probably be closer to 72 parts per cycle, and about 3 minutes to swap a t'stone.




Steve

Steve ,when you load that fixture ,do you just eyeball the position of the blank and leave a decent amount of stock or is there some kind of setting stop?