Home Forums General Discussion Shot Peening Process, Intensity, Coverage Peening 2 different intensities

Hi guys,

I'm peening a HPC vane with a indexing machine. Higher intensities required on the root and shroud portion (10-13N) , the blade portion requires 4-7N. The root and shroud portions are peened using fixed guns at a higher pressure while the blade body itself is peened at a lower pressure using vertical motion guns,. No maskings are to be used. There is a tendency for the vertical motion guns to sweep hit the root and shrouds as well at low pressures after

I m thinking that I should hit the higher intensity portions first at higher pressure followed by sweeping the blade body at lower pressure. My question is

1)Should I do it the other way round or does it matter at all?
2)If a part is peened at high pressure and then is peened again at lower pressures, Would the intensity remain the same if things were done the other way round

Performing the high intensity peening first is the way to go. How are you preventing the high intensity peening from hitting the airfoil if you are not masking?

The low intensity can overspray onto the high intensity but not the other way around.

Hi Walter,

Thanks for your reply. The high intensity portions are at the top of the shroud and the bottom of the root. So basically it s just doing a lot of angling of the fixed blast guns. I have to admit , it is a pain and sometimes part of the high pressure blast stream does stray at a slight angle to hit the low portions. We still manage to get the low intensities though when this happens.

I do feel that maskings should be used, but it s not exactly part of their requirements, and I suppose it s a situation where "thats how this process have always been done" . The process is required to conform AMS2430. Unlike AMS2432 this spec doesn't say much about multiple intensity locations and what is acceptable. If I remember correctly AMS2432 requires the intensities to be within 0.0015 of each other within the specified range. So does the mean that under AMS2430:

It s acceptable to get 4N,5N,7N for 3 almen locations in the low range(requirement 4-7N)
?

The "No Masking" rule could be related to the surface tension that can be caused as a result of the masking. Dr. Kirk had an article on this that was printed in The Shot Peener several years ago.

Adam,

When you say " No maskings are to be used" is this a customer requirement or are you just stating that you are not masking the part?

Hi Walter, Jack,

It s the customer s requirement. Its shown on their process requirements drawings that no maskings were used. Hence i think it s an issue of "how it s always been done".

But my other concern is how interpret intensity within the tolerance range for multiple almen holders (as acceptable) under AMS2430. Change of process engineer , change of intepretation. If the required range is 4-7N

1)you get 4N, 5N,6.5N for 3 almen holders , Is that considered all within range and to spec

2)You have to get 3 intensities that's 0.0015inches of each other within the tolerance range.

Number 2 is probably the best way to go, but just wondering if number 1 is considered wrong?

Please see SAE J443 Section 7 below is basically a copy of what it says. Each intensity verification location has it's own unique saturation point. Run all the intensity verifications to longest saturation time of the group of holders, record your results. These resulting numbers are now your "target arc height". Now when you are in production all you do is run the holders to the "target arc height" time and compare them with your original "target arc height" results. As long as these numbers are within +/-.0015" you are good to go. Important! The resultant arc height readings do not have to be within the intensity tolerance band since the single verification time at a given location may be substantially less than or greater than T (saturation point)

Thanks for pointing that out Walter. Appreciate it