help pierce problem

[calabo05]

i'm running a thermal dynamics 52 with my plasmacam and everythings runs fine... except you can see the pierce hole on my final piece. i'm using a 60amp tip for thin material 18g.-1/8" steel. should i use smaller amp tips? any advice will be appreciated.thanks in advance

[BrianMick]

From my limited experience and what ive read on this site yes a smaller tip may help...but with the p cam (i have a samson..the big brother machine) you are useing a low price machine and will never get the cut quality you would with a 100k machine.. the pierce point will always be there
Brian

[calabo05]

thanks Brian. So everyone with a plasmacam have pierce points on their finish products?

[AnotherDano]

thanks Brian. So everyone with a plasmacam have pierce points on their finish products?

You can't blame PlasmaCam for pierce points. It's the cutter that makes them.

PCam can be set to minimize them, though. Start your cut at a corner, beyond the finished area, for outside cuts and for inside cuts, extend the lead-in and set it to angle into the cutline.

[elkriverfab]

AnotherDano is right........

You can adjust the settings to help keep this from causing you problems.

I have found that if you angle the pierce points and make the lead in longer, it will help on some cuts.

If the lead in is too short, you are asking it to pierce and than cut the shape too fast ( pierce point distortion).

You want it to pierce the metal, lead in to the point where the cut starts (shape, part and so on) and than start to cut the shape.

Kerf width is important also.

You want the machine to know how wide your plasma kerf is so it will compensate.

These settings will differ with different material thickness and you may have to adjust accordingly as I do at times.

It is not the table it is the table settings along with the plasma torch.

Once you start playing with the speed, pierce point lead in and kerf....You will find the sweet spots.

Heavy plate is a whole differnt story, over 1/4 inch thick.

[jimcolt]

The proper terms, as crude as they sound, are dings and divots...these are the anomalies that show up often at the beginning and ending of holes cut with plasma, laser, and water jet processes. While some associate these with piercing, in reality the pierce should occur on a long lead in in scrap material, so the dings and divots are usually related to where the cutting process enters the cut path, and how well the motion control and torch height control controls position of the torch in these areas.

If the torch moves out of the pierce area and lead in onto the cut contour path, then dwells while making a turn, expect a divot in the cut path. The motion slows or dwells while the torch is cutting will cause the torch to erode a lerger kerf width. To fix this.....increase accleration rates of the machine, smooth out the part program with a radial or angled lead in, and make sure there is no slop or backlash in the cutting machine drives (backlash in rack and pinions, gearboxes etc can cause motion overshoot).

The ding in the cut is often caused by the ending of the part program, especially on holes. If the motion stops at exactly the same time that the plasma shuts off....then there will be a ding in the cut at this point. This is due to the fact that plasma, especially when cutting steel is partly a burning (exothermic process) that continues for a few miliseconds after the eklectrical power is shut off. The best way to solve the end of cut ding is to program your holes with an overburn....staying on the same radius, travel past the lead in point for approximately .200", but shut the plasma process off at 360 degrees. This allows the torch to fully extinguish while the machine is still moving, and extinguishes the arc.

The same issues occur with laser, waterjet and to some extent with oxy-fuel cutting. It is solved with better part programming, better torch height control, better machine motion control.

Jim Colt Hypertherm

[calabo05]

thanks guys!