I just got off the phone with Lovejoy customer service. I asked why, after many years of buying their unbored UJ's by the dozen for my products and easily machining them, that I'm burning out tooling on what appears to be hardened nodes inside the part. They responded that they have changed their production supply to obtaining the yoke blanks offshore and their own shop is experiencing problems with them. I said, "so you're selling unbored UJ's that your customers won't be able to bore, mill and tap?" After the expected hemming and hawing she answered yes.
It appears to me that their heat treament process is faulty, leading to inconsistent hardness.
Ex 1: boring a 5/8 UJ with a 3/8 drill and plenty of lube. It went in fine 1/2" before burning out the HSS drill. I tried a HSS reamer, wasted that too. Finally I took a 1/4 carbide lathe bit, ground it to be a mini boring bar, and completed the hole. This was 1 bad bore out of 6 on 3 UJ's.
Ex 2: slotting the UJ with a 7/16 HSS end mill, I got down 1/4" before suddenly burning the tool. This was on my 2nd piece.
I've done this exact work on dozens of these with no problems, the steel was more like cast iron with small chips. Now I've got a 2 out of 5 failure rate.
Lovejoy's best suggestion was to buy extras of UJ's & tooling, since the guys in their shop didn't think switching to all carbide tooling would be very successful. Nice huh, a real win-win for them, at $25 per piece.
It appears to me that their heat treament process is faulty, leading to inconsistent hardness.
Ex 1: boring a 5/8 UJ with a 3/8 drill and plenty of lube. It went in fine 1/2" before burning out the HSS drill. I tried a HSS reamer, wasted that too. Finally I took a 1/4 carbide lathe bit, ground it to be a mini boring bar, and completed the hole. This was 1 bad bore out of 6 on 3 UJ's.
Ex 2: slotting the UJ with a 7/16 HSS end mill, I got down 1/4" before suddenly burning the tool. This was on my 2nd piece.
I've done this exact work on dozens of these with no problems, the steel was more like cast iron with small chips. Now I've got a 2 out of 5 failure rate.
Lovejoy's best suggestion was to buy extras of UJ's & tooling, since the guys in their shop didn't think switching to all carbide tooling would be very successful. Nice huh, a real win-win for them, at $25 per piece.
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