In the field: Need to Punch (or Drill) 400+ 9/16 in Hastalloy

[racookpe1978]

Working in the field, inside a turbine exhaust (so the work will be on scaffolding: overhead, sideways, and underfoot).

Need to punch some 400x 9/16 dia holes, each hole 33 mm from the side of a plate; plus 50x 7/8 dia holes, also 33 mm from the edge of the plate.

My planner wants me to use a hand drill - drilling a 1/4, 7/16, and finally the 9/16 holes. For the 7/8 dia holes, he wants me to use a hydraulic (Lamina) drill - which will need to be hand-clamped to the Hastalloy plate since the plate is NOT magnetic. (Weight of the Lamina and hand-punches will be about the same.)

I don't.

Due to fitup problems, some of these holes will need to be slotted as well - doubling the amount of drilling (or burring them out wih hand (Dotgo) air grinders and burr bits.)

I want to use a hand-held punch (35-45 lbs) to make the holes.

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Anybody have experience punching (small) holes in 1/4" Hastlloy plate?

Anything I need to worry about?

Any work hardening or stress cracking (later) when a punched (rather than drilled) Hastalloy plate vibrates under exhaust air dynamic loads and heat?

 

[ornerynorsk]

http://www.inkosas.cz/download/htafab.pdf

Here's some info, don't know if it's useful to this app or not.

 

[CoryPad]

A quick calculation shows that the force required to shear a 14 mm (9/16 in) diameter hole through 6 mm (1/4 in) plate in Hastelloy is ~ 200 kN. This will not be possible for human-powered devices.

 

[ornerynorsk]

Portable hydraulic c-frame punch.

 

[racookpe1978]

"A quick calculation shows that the force required to shear a 14 mm (9/16 in) diameter hole through 6 mm (1/4 in) plate in Hastelloy is ~ 200 kN. This will not be possible for human-powered devices."

"Portable hydraulic c-frame punch."

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Concur with above: I need to address the worries (of my planner and back-at-the-home-office designer) about stress cracking from the hole being punched. Above link to the Haynes specification site seems to answer that : Haynes "expects" their material to be cold-punched, and does not require tempering or annealing after punch operations.

Lifting the hand-punch (hydraulic c-frame punch) overhead and aligning to the marked holes will not be simple, but it the same operations and alignment problems that I will face using the "no-longer-magnetically-based" Lamina drill that is my only other option..

 

[TVP]

Keep in mind that nickel-based alloys like Hastelloy will work harden significantly on the surface during drilling, and that subsequent drilling to create a larger hole will likely have problems with lubrication and tool wear. I expect that tool breakage will be a significant problem as well.

 

[dvd]

Before I bet the farm on this one, I would investigate the die roll, breakout and burr formation/deburring requrements on the punched holes. It may not be so great.

 

[racookpe1978]

True. I had already directed my fitters to "test-drill" 3x of the 9/16" holes in a cut piece of the Hastalloy X that had been removed for weld repair access. Your caution (about work-hardening) had not occurred to me - I wanted a time/hole measurement for the planner's 1/4", 7/16, 9/16 series of holes.

If they are going to face work hardening y drilling - in addition to the "simple" problem of drilling three holes per hole x 350 holes .... Makes punching - even with the (probable) need for cleaning up the back of the punched hole with a grinder - even more attractive.

 

[EdDanzer]

You may want to try Roto Broach type cutters to do it in one pass, these should cut through the misaligned holes. Making a clamping fixture for a drill motor from a magnet base drill with power feed may be required.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[ornerynorsk]

Rotabroach can also assist with your oblongation of holes to eliminate so much die grinding. Boy am I glad this one is on someone else's plate. Work hardening will still be an issue. Are you allowed cutting fluids? If so, there are several very good compounds that will help with the inherant difficulties of high nickel content. Buttercut is just one.