Wedges: Brass vs Aluminum Bronze

[markbugno]

I am a union millwright and brass wedges are very handy for disassembling machinery due to their softness. They are also expensive to purchase. Ampco makes many "non sparking" wedges that are an aluminum bronze alloy. These are cheaper and come in a better selection of sizes. I am curious if they are comparable to brass when used to wedge apart machined pieces of steel. I know bronze is stronger, but will it damage steel if you say used it to split a flange or coupling?

Thanks,
Mark

 

[PugetDude]

Just need to look at the Rockwell Hardness scale. The wedges obviously need to be softer than the steel you're trying to wedge apart.

1018 Steel runs around 85 Rb
1045 CRS runs round 100Rb

Aluminum Bronze C95400 runs around 87 Rb
http://www.dura-barms.com/bronze/aluminum-bronze/c95400.cfm

You're going to want a softer alloy to be safe...a lot of die blocks are 1018 CRS, for example.

Here's a handy conversion chart fro hardness scales:
http://www.steelexpress.co.uk/steel-hardness-conversion.html

 

[OutsideMachinist]

I would say verify that they are non sparking if that is a requirement. I use aluminum wedges all the time and they never mar anything from what I have seen.

 

[Mohawk Dave]

Just curious....but how would Delrin fit the bill for this stuff?

I got Delrin round stock I cut up into different lengths to use for punches. We use Delrin on the race truck and it holds up to torsional loads.

EDIT: Wow. Am I reading this right? 94 or 120 rockwell what is "M" vs "R" ? .......https://www.google.com/webhp?authuser=0#authuser=0&q=delrin+rockwell+hardness

 

[OutsideMachinist]

Just curious....but how would Delrin fit the bill for this stuff?

I got Delrin round stock I cut up into different lengths to use for punches. We use Delrin on the race truck and it holds up to torsional loads.

EDIT: Wow. Am I reading this right? 94 or 120 rockwell what is "M" vs "R" ? .......https://www.google.com/webhp?authuser=0#authuser=0&q=delrin+rockwell+hardness

Yeah definitely. I have used similar stuff. Depends what you are doing. You wouldn't want it to fray or chip and contaminate the system. Depends what you are working on.

 

[2oolhound]

Some aluminum alloys are harder than some steels. The bronze alu alloys are typically harder so I'd stay away from them. A lot of times the hardness factor doesn't enter into to it. You only need enough force to split the casings or lift the weight of the piece. Having wedges that have a very low angle will help not damage the edges of mated surfaces. I use a lot of mild steel wedges, even on aluminum casings and most times you can find a good spot where the mating surfaces are wide enough that you won't cause any damage by starting a wedge. I find my mild steel wedges are what gets damaged and I have to grind them after use. Once the seal is broken start another wedge in the opposite side to prevent binding.

Google "set up wedges" for a good variety.

Here's a shot showing chisels on the left and actual wedges on the right. Note how thin or fine an angle some of these steel wedges are.

 

[pauls_workshop]

I'm pretty familiar with aluminum bronze and have designed some bushings of this material. It is stronger and harder than normal bronze, but there are many grades of it. Some harder than others. I would be surprised if it damaged anything made of steel. You might have to get a sample and try it to be sure. - Paul, ME on the side

 

[kd3pc]

I have a couple of monel wedges, but I am no expert on the hardness. They were cut from some prop shafts years back and they have held up very well.

Have not seen similar ones for sale, though, so I assume they were machined for a specific purpose originally.