No question, stump grinding is a brutal application. Ever consider the wear and tear on a stumper wheel and its teeth spinning at hundreds of RPM’s having to impact thousands of times just to remove a single stump? It’s no wonder that wheel occasionally needs some TLC. Signs of wear usually appear randomly around the perimeter as traces of the wheel’s base metal peek through the hard-face weld. All of our wheels are hard-face welded and made from A514 steel. The special-composition, hard-face weld dramatically slows the wearing process from reaching the base metal. A key question: What welding wire to use? While stump grinding involves both abrasion and impact, the teeth do most of the work. Factoring that in when selecting the wire to use for hard-facing your wheel, I believe the wheel undergoes more abrasion than impact and have found the following formula to be highly effective when welding an A514 steel wheel or A36 mild steel: Mechanical Properties of about 50-60 Rockwell and a Typical Weld Metal Properties of: C 5.30; Mn 1.6; Si 0.80; Cr 28.5; & Fe the balance. This ratio works well for a severe-abrasion and mild-impact scenario. There is the issue of cross-checkering after welding … yes, you will hear the hard-face weld cracking. However, that’s good and stress relieving. Remember, you’re not dealing with a 70,000-80,000 lb., tensile-strength weld joining two pieces of metal, rather a hard protective weld offering your wheel Kevlar jacket-like protection … and a longer working life. [Sidenote: I prefer to use MIG flux-cored wire when possible and have found Hobart 255-O; Lincore 60-O; & Cor-Met 92FC-O to be very effective.] All that said, before any electrical welding on the wheel takes place, it’s vital not to overlook two, pre-welding procedural steps:
Remember to place the welding ground on the wheel to be welded not nearby, otherwise your bearings will most likely be arcing (no bueno!).
Turn off master at the battery, and unplug the computer.
The possibility of inadvertently doing extreme irreversible damage to the machine in a few seconds—if these steps are overlooked—is very real. Also, while two weld passes (or layers) are typically possible, there is also a likelihood of weld chunks flying off if the first pass isn’t sufficiently burned into the parent metal. To avoid this, be sure to clean the wheel surface well before welding. No guarantees, but hope you find this information useful and it helps your CMI stump grinding wheel add to your operation’s productivity and profitability.
John Gossett Bucktooth Grinding Co. LLC