I use these bits in my CNC router, primarily for cutting aluminum and plastic. 610. T-65 aluminum was used, which put the drill through more stress than traditional non-hardened metals. Regardless, this punch lasted about 30 minutes in a 3 hour run. After it broke I switched to the onsrud bit and finished the job. While I don't think this bit is weak or ineffective, it does appear to be slightly weaker than Onsrud.