Important reminders relating to the proper operation of an XPR system.
Cutting speed and ramp down error protection
An important new capability incorporated into the XPR systems is ramp down error protection, which enables the power supply to determine when a uncontrolled arc termination (ramp down) is about to occur and initiate an automatic rapid ramp down sequence that protects the electrode from unnecessary hafnium erosion and significantly extends electrode life.
Primary enablers of this are the extremely fast response time that is built into the XPR chopper control technology and the plasma control valve located in the torch receptacle. Together, these deliver very rapid response times. But there is a point where cutting speed can overwhelm these response limits, such that the positive effect of ramp down error protection is reduced or lost entirely. This starts occurring at around 3550 mm/min (140 ipm). Below this speed, the power supply can perform a controlled ramp down process before the arc is terminated by running off the plate. Little or no unnecessary electrode wear occurs. Above this speed, the response time of the power supply is not able to achieve a completely controlled ramp down, and so some excess hafnium is ejected, and electrode life is negatively impacted. At roughly 4060 mm/min (160 ipm), the ramp down error protection process does not have time to respond and create a controlled ramp down, resulting in a significant ejection of hafnium.
XPR’s Category 1 and 2 processes fall in the range of where the power supply can perform a controlled ramp down. Some Category 3 processes go beyond the speed limits described above.
If a customer must cut above speeds where ramp down error protection works and they can’t program the arc to terminate on the plate, then a possible approach to reduce the impact of the ramp down error would be to program a slowdown in the last 25 mm (1”) or so of the part.
Tightening an XPR electrode
XPR introduced QuickLock electrode technology, which reduces the time and effort needed to insert an electrode from multiple turn threading to a simple quarter turn. It is so easy to insert that someone who is not trained could assume that it is enough to simply hand-tighten the electrode. But this is not true. The XPR electrode requires the use of a tool to ensure a properly tightened fit. Otherwise, arcing may occur which can damage the torch.
Each consumable parts starter kit contains a tool, part number 104119, that will ensure proper tightening when used.
For those who want to ensure even more certainty around proper electrode insertion, we make available an optional torque wrench, part number 429013, that is pre-calibrated to the proper tightening force. This shouldn’t be needed if an operator is properly trained on how to use the standard tool, but if an end user has high operator turnover and non-structured training practices, it may be a helpful precaution.
It is critically important to train operators that they need to use one of the two tools we provide for this purpose. (See attachment).