Home Forums General Discussion Ask Dr. Peener lance peen saturation curve

hi
i am trying to lance peen a.500 hole wity an intensity of 12-16a. i want to make a correlation chart.can some one explain what it means to make curve for the lower range and then the upper range. why cant i make a curve between 12-16a and then run shaded strips to correspond. how do i know what angle to set the nozzle to?
thanks for help

You can, as you say, run a curve in the 12-16 range and then get the corresponding shaded strip response. But, when you run shaded strips later, how will you know how close you are to the limits? If you always get exactly the shaded arc height response you correlated at some value in between 12-16 then everything is ok. But in practice you will get varied readings of shaded strip arc heights. You need the upper and lower responses to verify that you are withing the tolerance band.

do i run the curve for the low range (12) the same as i would to get between 12-16a. if so would my t1 be the low limit for the shaded strip? i am a little confused i am relativly new to shot peening and have never done lance peening
thank you for the help

Adjust your machine and run 4 (or more) full-size strips with standard nozzle. Hopefully you will land at intensity of 12 (using 10% rule). Keep adjusting air pressure until your graph shows intensity of 12. Then, blast your shaded strip at the T1 time derived from this test.
Re-adjust the machine until you are at the 16 intensity (again using 4 or more strips and the 10% rule). Then, blast your shaded strip at the T1 time found from that test. The arc heights of the shaded strip are now the boundry conditions for your production runs.
Lance peening and shaded strips are challenging (difficult). Let me know if you need more help. You might also check out this article by Bill Barker from Progressive Surface: http://www.shotpeener.com/learning/hole.pdf

when i blast the shaded strips i get.0089-.0128A.the problem is i can't get the lance peen to shoot that high using an A strip. what should i do?
thanks again

Your range of 12-16A for a small hole is very large. You may not be able to achieve that intensity unless you have a large lance. What size media are you using? What air pressure are you using? Your procedure so far is correct regarding the strips since you peened the shaded strip with the regular nozzle and then peened the shaded strip with the lance nozzle trying to get the same arc height.

Are you sure that this intenistiy is required inside the hole?

hi
the 12-16a intensity in the hole is correct. the rest of the part is 8-12a intensity.i am using cut wire sccw 20 shot with an air pressure of 60 and shot flow of 2 which is max shot flow.
would i be violating the rules if i used n strips with lance peen? i know this isn't best solution but i have only one lance
which has an opening approx .250 wide .500 long.
thanks for help

Using an "N" strip would yield a higher arc height but that doesn't change the intensity capability of your lance or solve your problem. If your lance can only develop an intensity of 9-13 on the shaded "A" strips then you are at the limit of the set up capability. I think we need to get some others involved with this dialouge. Would you want to post this at the LinkedIn web site?

yes you can post on the other site
thanks

CCW-20 is a bit on the small side for an intensity of 12-16A. The velocity needed to yield this intensity is very high and you may be abusing the part surface rather than peening it. CCW-28 or larger would be a better choice. A 12-16A in a 1/2" hole is rather strange to begin with.