I'm rebushing a machine I just purchased which is a large mini or small full size excavator IHI 80. I've priced out the pins and bushing at the dealer and can't believe what some of the cost. I think I'm going to bite the bullet and buy most of the bushings from the dealer but the pins I'm probably going to have made up at a local machine shop. What's the best material to use for this? I would imagine you want something harder than the bushings. The good thing as all the bushings are solid, meaning they don't have any grease passages through them. Some of them will just need a hole drilled through them or a small plate welded on. I'm hoping to get away from any material I have to heat treat. Want something that can just be turned down on a lathe. Any help would be appreciated.
Stressproof.
Yair . . . I always though 4140 was the go to grade for pins. For new construction we designed around standard ground finish sizes and turned the bush to match, its always better to avoid drilling if possible and, as giannid mentions put the lube in through the bush. Cheers.
Here's a another vote for 4140-ht (pre-hardened to Rc28-32 or so) The bushing is probably going to be "glass hard" BTW, and the pin will not be.
Check with a hydraulic shop. I have had pins rechromed or built out of cylinder rod stock for less than half.
Never seen chromed pins, new one on me, how do they hold up ?
You want the pin SOFTER than the bushing, so the pin wears, but the bushing does NOT. The problem is that if you use a HARD enough bushing, it cannot be impact driven, but must be chilled and pressed. 4140 is a mid carbon stainless. Personally, I would think that a HIGH carbon, like a 1090 bushing, machined BEFORE final heat treat, and a lower carbon, like a 1060 machined and drilled for lubrication, then heat treated. Perhaps a final lapping to the bushing prior to final installation, with one end with a ground bevel, and adequate provision for end play adjustment. Not that I have EVER spend time in a machine shop...(PS: I became personal friends of the LeBlond family, while living in Cincinnati, while working on my PhD in Industrial Engineering) Howard
"final lapping " ? Uhm no, most places I've seen leave copius* amounts of clearance as the bushings wiggle around bit if welded in. * being gross fit to a toolmaker.
You want the bushing to fit very tightly in the hole, to the point you freeze the bushing and heat the hole with a rosebud...then you want the pin to be a "tight running fit" or about 0.002" clearance. Once installed, I expect minimal heat, and the clearance is needed for the grease to form a film. However, the close the fit, the higher the cost, and the mechanic isn't going to be the one operating the machine. Howard
I plan to use case pins and bushings. It took 21yrs and 3900 working hours for some to wear so for replacement I will use factory parts.
Yair . . . Slightly off topic but over the years for various pivot assemblies I have used sections of (or complete) 'dozer pin and bush assemblies . . . D9 pins and bushes worked real good on loader arms. Cheers.
When I can get it I use ETD150 which is even better, Stressproof (1144) is good, decent hardness without heat treatment, machines easily to size, and can be welded if you preheat well. Since you have a metric machine, you either have to get them all machined to size, or go to some outfit like www.metricmetals.com . 4140 is fine, but usually requires heat treatment after machining to get decent hardness. If you can find it prehardened and ground in the metric sizes you need, it would be fine. :my2c
I dunno, haven't had to monkey with them yet so they must be ok. I don't know if it is actual chrome (it is not shiny) but they send them far away to some special metal shop that dose amazing things cheaper than oem. Most operations if they have time go that route around here.
I'm hoping I can find something that I can get off the shelf and have machined to size. Think if I have to buy the rod, have it machined, then heat treated and machined again, it's going to cost as much as the oem pin. Is there any material that I can use for the pins and bushings like this? Obviously I don't know my metals well and am not a machinist either. I do know these pins don't have any chrome plating on them.
That's why I suggested Stressproof, it's medium hard as is, but still machinable with using special cutting tools. Or ETD150 as I said my favorite. There are probably dozens of options. Try this place, call them up tell them what you're doing, give finished diameters and lengths, see what they recommend, they may have the exact metric sizes you need in a TG&P which is Turned, Ground, and Polished ready made carbon or alloy steel material. http://www.metricmetal.com/products/round.htm They're even in Ohio.....
A few points. OEM pins and bearings are in the 58 to 62 Rockwell hardness. That is both about the same as a roller bearing. Pins are normally induction hardened 4140 or similar. Bushings are case hardened EN14 or similar. Pin to bushing clearances are normally around 8 to 10 thou depending on manufacturer. If you run an O&K RH200 they will be half that. That sorts out the line borers I have successfully made bushings from 4140. Machine oversize,heat red and quench in oil and final size with a ceramic tip. I often machine pins from 4140 and take them to a shop with an induction hardener. Its not all that expensive. With a small digger that the OP has 2 thou crush is good and they will pull in with a couple of washers and a threaded bar. We'll take it for granted that the bores are in spec.
Have just read this old thread and just wanted to add 2c worth: Regarding chromed pins, it's my understanding that the chrome element of " chrome plating" is the hard surface, and is clear. The shining silver colour on your wing mirrors is most likely nickel plating, with thin layer of clear chrome on top to protect it. Chromed pins are not necessarily shiny, but they are hard and remain hard surfaced until lack of lube/ dirt ingress tears a strip of surface off, etc. Cheers!