Need Advice on buying EDM

Guys, new to the site as a member but have been trolling for a few years.

I am looking at bringing into the shop a used EDM machine and wanting some advice on what the costs would be and any pitfalls to avoid (brands, etc). Currently we go through 3-4 tons of aluminum round bar a month that requires a holes of varying sizes to be cut out of the middle. A good example is the following: 9.5” OD, raw stock with the final dims on the parts at 9.350”OD and 7.5” ID. In this size we will go through 24-36’ of this material each month, cut into 12” pieces. My thought is that I can use a wire EDM to rough out the material and also get a roughly 7.250” piece of material to use for other parts that I need it for anyway. I can also take the material out the middle of that 7.25” part and use it again for other parts that I need to make monthly.

The EDM would need to support 12”x12”x12” material. Speed it not a huge factor since I can put it into the production schedule pretty easily, but being able to run lights out would be a HUGE addition. The machine time and material savings this could offer seem to be significant, especially since we are essentially cutting circles that are not required to be exceptionally accurate.

What would you advise on this? I anticipate that the machine would work 20-30 hrs per week. I am especially needing ideas on running costs, both monthly and annually (such as how much wire would be used to cut the slug out of the 9.5" piece above, and how long it would take, etc).

Thanks for your help with this.

Sounds like wire edm isn't for you...you would need to make a hole in the middle or somewhere within the id and cut the slug. This will not give you a solid piece as the wire will have gone through some part of it. Your cut time would be multiple hours, think 10+. Then you have to worry about rethreading if the wire breaks. And the biggest concern is dropping that slug onto the lower head, that's a quick way to fuck things up. Not to mention operating costs as aluminum plays hell on the filters.

Sounds more like you need to invest in some trepanning gear.

If you're using similar sizes regularly, look at getting custom extrusions made. Price is a lot more reasonable than I thought it would be. A friend's company has custom extrusions made that look a lot like 80/20. The die was a few thousand dollars and I think they need to order 2-4000 pounds at a time. With your example piece, for one month you're buying 2500# of aluminum and turning it into 900# of parts. If this is a regular need, it may pay back really quickly.

This would also drastically cut down the amount of machining you need to do. It's also going to make your material handling much easier. Each blank is going to be 30# rather than 85#

I agree, one of the biggest eye-openers I've ever had was the first time I had a custom extrusion quoted. Shockingly cheap and then you are only paying for material in the places you need it.

plastikdreams said:

Sounds like wire edm isn't for you...you would need to make a hole in the middle or somewhere within the id and cut the slug. This will not give you a solid piece as the wire will have gone through some part of it. Your cut time would be multiple hours, think 10+. Then you have to worry about rethreading if the wire breaks. And the biggest concern is dropping that slug onto the lower head, that's a quick way to fuck things up. Not to mention operating costs as aluminum plays hell on the filters...

Click to expand...

2nd that. Wedm is great at making accurate cuts but it is the slowest operation for material removal.

If is any good.

https://www.practicalmachinist.com/vb/machinery-for-sale-or-wanted/edm-m55k-356301/