Weld repair of product in CNC machines 1

[bumpjones]

I am having trouble convincing the machining manager that weld repair of castings and forgings while still chucked up in CNC machines during machining is causing damage to the computer boards in the CNC machines. I think that the high freq electromagnetic pulse used to start the welding process is damaging the circuit cards in the CNC machines. I need some ammo to stop this practice. Can any one point me to the right source.

Thanks,

Bumpjones

 

[Rich2001]

It is very probable that the welding is causing problems/damage to the circuit boards. A typical CNC machine installation does not have a shielding needed to prevent damage nor is the grounding of the equipment itself generally good enough.

The first thing that I would do if you can not change the process is to install at least one (1) 8'x 1/2" UL listed ground rod within 5 feet of the machine. (Two rods might lower the ground resistance by 40%, 3 rods by 60%, and 4 by 70%, separate rods by 6ft.) Use # 4GA minimum welding cable for the ground leads. (I learned this the hard way.)

Here is a link to an article though not directly related to CNC machine, nor welding, does have some ammo for you.

http://zdnet.com.com/2100-11-515644.html?legacy=zdnn&chkpt=hpqs014

 

[gbent]

The welding current is also probably damaging your precision bearings in the spindles and ballscrews. Ask a local precision bearing supplier if they have any literature about welding assemblys with precision bearings. The ground path the current takes thru a machine is unpredictable. The only lathes that are fit for welding are the old ones with sleeve bearings.

 

[jlhmaint]

I completely agree with you. we never weld on our cnc lathes or mills take the part out or take the panel off. if the cnc doesn't have a really great ground you will more than likely damage something. its not worth the risk.

 

Get your operators some professional mental healthcare . . .IMMEDIATELY !!!!!!!!! Even welding NEAR a cnc can cause the control to pick up stray RF and EMF. This is an absolute no-no.