piercing heavy plate

[awjareme]

i run a koike plate pro, and find it a very easy machine to run, except for piercing. Does anyone have any tricks, ive messed with every setting possible. Its when i pierce from 1-2 inch, generally the tip has to come out after every pierce. After 2 inch forget it, i have to pre-drill.

Thanks

[xt300301nut]

What is the model of the plasma? What per the torch manual is the piercing capacity of the torch. There are very few plasmas rated to pierce above 1" material. Are you able to do "running pierce"? This allows the torch to move away from the molten puddle caused by the pierce. Are you using auto height. Typically auto-height is shut off during pierces of thicker materials and manual height control is required by the operator.

[awjareme]

sorry i forgot to mention its with the oxy/acet control whic is koike

[tinman13]

pre-heat at cutting height, pierce at 1 to 1 1/2 in. ramp in.
cross fingers!........ praying sometimes helps too!

[Dale Heart]

Use real koike tips and you will never have a problem.

[tinman13]

LOL............If only it were that simple!

[awjareme]

I use nothing but genuine, but it seems to be more then just science. The machine is also equipped with a "soft start" valve, but i just can't get the right combo.

[tinman13]

I use propane for fuel gas, it takes longer for your preheat time but in my case the cost savings is worth it.
Make sure you are preheating long enough..........
For 2" plate I have good luck with a # 4 tip (Koiki of course)
210 sec. preheat time,
1.5 sec. pierce delay,
1 1/2" pierce height,
55 to 60 psi cutting oxy pressure.
But I still cringe every time it fires!
I would love the soft start valve, I think once you get it figured out you'll be glad you took the time to do it.
Good Luck, Steve

[awjareme]

210 seconds!!! maybe thats my problem i pierce at a maximum 50-60. How high do you preheat? i preheat 3/8"-1/2" off the plate then when i hit cut, i rise to 1-1/2 - 2" off the plate.
I am running the 102 tips which are a triple seat tip #4 like you say. Its got an extra solenoid for high-preheat. I hate cleaning tips mid-cut, it takes so little to ruin a cut. I experimented with 102-D7's which can cut amazingly high off the plate at 100 psi cut, but they take even less to get dirty. I just can't believe the 6-12" thick donut shaped plates i order in from Carbon Steel that cost so little, that they must peirce to save time. I wish the manufacturer had some starting guidelines, but i was told they are not welders/fitters just machine makers??

[tinman13]

Your preheat sounds a little short to me but then I use propane..... I like to get the heat as far through the plate as I can, within reason.
Can you set a pierce delay?
Try your cut height a little higher.
Also does the plate have much mill scale on it? That can pop off and foul a tip quickly.
The cleaner the plate the easier it is to pierce.
Good luck, Steve

[m230042]

Originally Posted by tinman13 I use propane for fuel gas, it takes longer for your preheat time but in my case the cost savings is worth it. Make sure you are preheating long enough.......... For 2" plate I have good luck with a # 4 tip (Koiki of course) 210 sec. preheat time, 1.5 sec. pierce delay, 1 1/2" pierce height, 55 to 60 psi cutting oxy pressure. But I still cringe every time it fires! I would love the soft start valve, I think once you get it figured out you'll be glad you took the time to do it. Good Luck, Steve

Also look at creep time. this is the time the machine will move at 25% of cut speed and should be used on thicker plate instead of prerce time and it creates a trough for the slag to go out of. It takes a longer lead in but it saves in tips.

If you have ease-on then I would time the amount of time it takes to come from 0 to about half cut pressure set this a pierce time and creep time until it pierces through. Lead in's will have to be longer, maybe.

Koike does know how to cut steel. Most of the field techs don't have the experiance. However all new techs, start cutting steel for two weeks in the fab shop before they can start training.

[jcc3inc]

Gentlemen:

Here's what I learned about piercing form steel service centers and associates in the company we had:

For those that have to pierce thick plate, the machine is set up with "ease-on" cutting oxygen. We made a servoed oxygen regulator that started with a lower pressure than the final operating pressure. After preheating the plate, cut oxygen came on and the machine followed a lead-in and ran slower than the final cutting speed as the cutting oxygen pressure built up to the normal pressure. This resulted in a ramped-down cut that exited the bottom of the plate before the end of the leadin, at which time the cutting speed and pressure were at full amounts. With the ramped-down cut, the dross shoots out the back away from the torch, and the tips stay in good condition.

To make the servoed cutting oxygen regulator, we used a separate pilot regulator, and made a replacement "dome" top to replace the normal tee handled spring pressure part of the oxygen regulator. The pre-regulator was set to the desired pressure, and its output taken over to the servoed regulator. A needle valve was placed in the line conveying the pre reg pressure to the dome to essentially delay the pressure buildup and thus the final cut oxygen pressure.

As I recall, piercing was limited to about 5" thick plates. For thicker plates, an oxygen lance was used. This consisted of a sacrificial steel pipe about 3/8 diameter and several feet long to which an oxygen pressure source with a ball valve was attached. The operator manually preheated the surface of the plate. and when it was at kindling temperature, he heated the end
of the lance while turning on the lance oxygen. The lance was now thrust down through the plate until is exited the bottom. It makes quite a shower of molten steel, usually contained by using a 5 gallon pail over the opening.

Regards,
J C