Multi-part Fixture with Single Point Clamping

[Geof]

Hydraulic brake components are being considered.

First I want to get an idea of the clamping force needed for the various parts. At the moment we use 3/8"-16 bolts that clamp two parts at a time, the bolts are torqued to something like 15 lb-ft and things do not shift during machining, but what is the vertical clamping force arising from this torque value. In between other things I am bulding a little test rig to directly measure the force.

Another thing that I have to determine is the resistance of brake system seals to water based coolants because this is what I intend to use for the hydraulic fluid. I have found some rubbers swell tremendously in the coolant.

[tobyaxis]

I have found some rubbers swell tremendously in the coolant.

I buy new shoes every 3 to 4 months because of the coolant. The oil from the swiss was a lot worse, but I no longer work with swiss.

Are you going to post your findings here or will they be Top Secret?

[Geof]

I will keep tacking things on here or my other thread or may start a new one. All this is going to take months.

[Vern Smith]

If your plan to use coolant as the hydraulic fluid is to prevent contamination due to a leak we never had one of these systems leak. I "think" most contemporary automotive hydraulic systems use Teflon based seals which will usually stand up to panther p*ss.

Testing for force requirements is an excellent idea. If I remember correctly hydraulic force is the force applied to the master cylinder times the volumetric difference between the master cyl. and the slave cyl. The only limiting factor is structural failure. Now this could lead to some serious contamination.

"my other thread" this is ungentlemanly obfuscation.

Vern

[Geof]

....."my other thread" this is ungentlemanly obfuscation.

Vern

Sorry, this is "my other thread":

Now I'm a believer; you can mill C1018 at 800 FPM

The force difference is dependent on the areas not the volumes. It is unlikely I will be able to get away with using a thing like a master cylinder because I will need a reasonable stroke on the fixture cylinders to allow easy removal of the parts and with many parts the displacement needed on the master cylinder would be very large.

What I have in mind experimenting with (of all things ) is a paint sprayer. Relatively low cost, made to pump a water based liquid emulsion, capable of developing up to 2000 psi and they turn the motor off when they reach pressure and just cycle when the pressure drops.

[One of Many]

You might also consider a system like the Kopal self compensating hydraulic vice jaw. No pump required in this captive fluid system.



You can custom create your own with a bit of ingenuity and some Screw in cylinders or create your own cylinder within the jaw manifold for a compact design.

DC

[Geof]

Yes I have seen those or something similar but we are trying to get away from reloading individual parts in the vises with the machine idle. Gradually we are moving to mini-platen systems with one being reloaded while the other is machining.

[tobyaxis]

Yes I have seen those or something similar but we are trying to get away from reloading individual parts in the vises with the machine idle. Gradually we are moving to mini-platen systems with one being reloaded while the other is machining.

That is definitely the way to go Geof. I use to do this with slide-in-vise-fixtures.

While one fixture was in the machine, the other was being reloaded by the operator at the bench. There were 50 parts being done in each load and I used a tensioned spring load on the right side to seat the fixture against the stop. The operators were slamming the fixture in so locations were being lost. The parts were for fishing reels and there were lots of 5000 per month. Brass Job!!!!

[One of Many]

I think it could still be incorporated into a palletized vise fixture. It was more the concept than any suggestion to use the pictured item(s).

Seems to me, I had also seen some 1/4 turn expanding posts that were used for palletizing bank loads of small spacer type parts. Maybe in the Reed catalog. Still rather fiddly, but 16-24 at a time could be a better cycle time over all.

DC

[Geof]

... The operators were slamming the fixture in so locations were being lost....

I learnt years ago that putting a single stop that a fixture had to be slid up against was no good, Many people cannot understand that that if you bang the fixture against the stop it bounces back. Now my fixtures have dowel pins or slots that have to register and stop it moving either way. And stop pins so it will only go in one way.

[tobyaxis]

I learnt years ago that putting a single stop that a fixture had to be slid up against was no good, Many people cannot understand that that if you bang the fixture against the stop it bounces back. Now my fixtures have dowel pins or slots that have to register and stop it moving either way. And stop pins so it will only go in one way.

LOL, yea, seems that we all learn the hard way at one point or another.

That is why we check in here to pick your brain Geof .

[Donkey Hotey]

Gradually we are moving to mini-platen systems with one being reloaded while the other is machining.

If you really have that kind of need, I'm curious why you wouldn't sell a few of the older machines and just move to a horizontal (EC series)?

• You could load one tombstone while the other is running (virtually continuous).
• You gain three sided access (or even full 4th) to your parts.
• You wouldn't have to design your own tooling.