Smooth finish inside Dia 1.1mm

What is the meaning of some carry over pass on 2nd solution test ?

Is it some metallic chips / metals passing on ?

This may not be because of the finish of the holes, it will be due to drill burrs left out on the end of the drills.

No, it not a metallic chips or metal particle but after completion of the 1st test & even after rising with water before starting the 2nd test, some contamination of the solution of the earlier test is remain on the surface of inner hole because of roughness of the surface. The smooth surface required to complete dropout of earlier solution test.

I believe that he is saying that some solution is remaining in the holes after first step of passivation.

Burrs are inevitable at intersections of holes.

http://www.vectron.cc/

milo

Dear Milo,

I might not be able to explain you properly. Burrs is not our problem.

Please understand my requirement.

1. The inside path surface should be very smooth.

2. The material used SS316L

3. Passivation is done as per the ASTM A967 standard.

4. Main Requirement:- This finish component used to pass the chemical solution. It should get flushed by the followed Chemical solution. But i observed that there is a contamination of the earlier solution with the second solution.

I want to avoid this contamination. As per our observation we think it is happening because of inside surface finish. The first chemical sticks to the inside path surface and then mixed with second comes.

Kindly guide.

it is not finish that is causing this retention. The others especially sb have described this situation better than I.

milo

A) You can not totally eliminate the first chemical, especially if you are wetting the wall of the hole. The finish will only create additional wetting area. So in the first flushm the chemicals will be mixed.

b) If I understand correctly your manifold (or the component) is like this

In this condition, the most of the chemical contamibation are from the dead pockets and these can not be eliminated so easily.

In fact in components like this (if it is so), it will be difficult to even remofe the entrapped air bubble from the pocket.

You can try to get a hand reamer to the size and try to improve the finish (say drill to dia 1.0 and ream to 1.1 ) but I am not sure it will be worth it. The major effect of the surface finish for you may be in terms of the pressure losses in the capillary and the possibility of air bubble entrapment in it.

I don't what type of solution your using, but try drilling your holes over sized and then insert a glass tube coated on the outside with some epoxy glue. This will give you a smooth interior finish and not have any reaction with your solution.

I was going to suggest the same. Like a helicoil insert. You could finish and clean or maintain it out side the hole. It has not been mentioned what kind of chemicals are included in the process so its hard to say. If the part/assembly could be subjected to heat all impurities could be evaporated using heat. Need more information!

I'll get back to you once the cyclone has receded. Good luck, Ky.

If "sb's" schematic of your component is correct (answer 5), I suspect the "dead areas" each end are the main problem.

Put a new plug in each end to fill that area and much of your problem may disappear, or have I got your layout wrong?

Please advise.

To improve the finish of the holes, you could ream a light skim off the inside of each hole, but I'm not sure this will give much improvement in solving your problem.

where is OP

Have you thought about spark eroding the holes in your component, this method I believe is used extensively for making moulds, where a smooth finish is required.

The EDMs are almost extensively used as are ECMs in making this type of holes in the Blades and Nozzles of Gas Turbines. However if the problem is the one that I stated then that will not solve it.

OP is not coming back (problem resolved ? ) At least tell us what was the solution.

At a prior employer we built a cylindrical hydraulic manifold that was part of a downhole tool. All of the passages were deep gun drilled holes that intersected. One of the machine shops we used devised a method of minimizing the burrs generated when the cross-drilled holes intersected. After one hole was drilled a sacrificial rod was insertedinto the first hole, the second hole was drilled into the rod. When the rod was removed the burrs left were much reduced. We were investigating using abrasive slurry pumped through the ports to further remove the burrs when I left their employ.

As to the dead space, I have a few suggestions. Instead of drilling the block from both ends, drill a blind hole from one end. I would further suggest that the entry to the blind hole be plugged with something like a Lee Hydraulics AFO plug and have the first cross port intersect as close to the plug as possible. Another possibility that eliminates dead space all together is to instead of drilling the horizontal hole to connect the ports, you drill two angled holes that intersect in a V shape. You may have to use a larger port to give you enough room to angle the drill enough to keep the intersection point inside the block. A variation of this is to eliminate one of the two vertical drills and use the blind hole for one port and connect it to a 90 degree fitting.

One other thing you can try is to electropolish the manifold. this should improve the surface finish by about half. (I.E. if the original surface finish is 32 microinch RMS, you should get 16 microinch after electropolish.

Electropolishing is a Good answer to the finish problem Rorschach. but it wil not help with the dwell of residual fluids in the "dead zones".

milo

Understood, but the OP was not real clear on the reasons for the contamination so I was taking a shotgun approach to the problem.

Dear all,

Yes "sb's" schematic of my component is correct. Indeed there were dead pockets in my component. Now I have eliminated those dead pockets & passing abrasive slurry thru the path. It will take another 2 or 3 days for final conclusion.

Thanks to all for your valuable inputs.

I will be in touch with you very soon.

Sb will be a happy man if you do so. Take him out to lunch or something if he was right. I would, Ky.

Creature is correct word (we are hermaphrodite) and it was easy (i stay on those pockets and collect the items.

Anyway, it was an easy guess (that is how usually many blind manifolds are made isn't it ?

But I could never understand the basics

How come different types of liquids alternating through the manifold

again for nth time I miss a smiley where I am scratching my head (without hairs of course)