Thread: considering a waterjet machine - some questions

We often get work that involves machining thin (say 1/8 -3/8) plates that are max 7"x5" squares. Usually this requires fixtures and seemingly simple parts become compete PITAs and take far longer than they should. There is enough of this stuff generally in Al, but also a lot of SS that we do and I am thinking that it may be easier to do these on a waterjet. Before I call my local sales rep I would like some oopions from anyone else. Should I keep doing what I'm doing with the mill?

A cursory research has shown me that thin flat pieces are what are done on these machines. The videos I watched show profile cutting, but it doesn't look like there is any vibration problem, such that the part falls out complete (no tab fixing it to the material). How is this possible? The accuracy +/-0.003 is way more than what is needed for these parts.

What I like the most is the material savings and the ability to cut out 2-D parts complete. No tooling costs is also kind cool. This would be perfect for my application and also let us add additional capability. What is the ballpark cost of these machines? Something on the order of 10' x 5' table.

I would think a laser would be a preferable solution. Cheaper simpler and faster. If you pieces can have a little hardening on the edges.

when you are comparering brands, check what the cost of spares are, the water pump need regular replacment parts to keep the pressure up. make sure that it has quality hyd pump gear, a cracked oil cooler gets $pendy real quick.
Set up off material is real quick, often just some weights or a G clamp or 2
You need good service and parts backup.


Jake.

I thought about the laser also, but from what I understand that it is not good with Al as it reflects a lot of the light and is really limited to aroud 1/4" thickness. Although that would work for the parts I have in mind, future work should be considered. While I'm on the topic, how does finish compare between laser and water?

Most people find that a waterjet is not financially feasible unless you can run it at least one full 40 hour shift a week, and, preferably, two.
They are pretty expensive to buy, but also expensive to run- the hourly costs are high, with abrasives that are usually consumables, and pretty high parts wear issues as a normal matter of course- hoses that need regular replacement, regular and expensive rebuilds on pumps, and just, in general, expense.

Find a good local shop and send it out.

Around here, anyway, laser machines usually cost about double what an equivalent waterjet machine does, and laser cutting costs by job shops are always quoted to me as MORE than waterjet, but with better finishes and tolerances, especially on thinner materials.

You can get a waterjet for less than $100K, I cannot find any laser for anywhere close to that. Waterjets are maintence hogs. They do *lovely* work on a *very wide* variety of materials. I think they're like a big boat - you don't want to own one, you want a good relationship with somebody who owns one.

Think about plasma or high def plasma.

By the way - the "conventional wisdom" is that laser should be cheaper on a per part basis for thin stuff, Ries seems to have experience to the contrary (which I believe.)

I think that laser versus waterjet job shop prices are variable, depending on where you live- if there are a lot of laser shops competing, prices come down, same thing for waterjet.
Up here north of Seattle, I have consistently gotten laser quotes at 30% to 50% higher than waterjet- but that could be totally different in other parts of the country.

Also, I have more experience with waterjet because I am often needing things cut like 1" stainless, which are beyond the capacity of most common laser machines.

Here in tucson Lazer is half the cost of water jet I get all my parts lazer cut I have done some water jet but the cost always kept me away. The shops that own water jets are always messing with the thing, tons of mess and tons of maintenance. I am glade other people want to own them and do work for me because no way in hell would I want to monkey around with one.

We run a 4.5kw laser. Its kinda hard to see how water jet can touch us for price? All of the you tube videos shows the heads barely moving. Our laser cuts 10mm alu at more than a meter a minute. Same for stainless. Our problem is 4.5Kw of laser limits you a max of 25mm mild steel, circa 15mm stainless and around about 12mm in alu. We are one of the few that can also cut brass and copper, but are limited to circa 6mm. Above these thickness's and water jet really starts to shine. Its more or less the only common way of cutting thicker stainless and such.

Water jet and laser are the same. If your cutting almost a whole shift a week you need your own. Anything less and farming it out makes a hell of a lot of sense. They both take a lot of power, need a lot of space and sheet material how ever you handle it also takes a lot of space.

Your example of 5x7" plates, assuming a few holes - slots in each you would be needing in the order of 10's of thousands a week to keep a laser busy. More or less regardless of steel, stainless or alu. Our laser will cut a 3x1.5m sheet of 10mm into several hundred parts full of holes slots and curves in less than a couple of hours. Whilst there's no or minimal consumable costs, its by no means free to run. Gas costs, both oxygen and nitrogen add up. Lenses and mirrors don't last forever, but will do several months. Nozzles can last a day or 2 of solid use just depending on the material. Then there's the electric. A 4.5kw class laser will take 125 amps of three phase at 415 volts. Its chiller unit will want another 80 amps and about another 16 or so for the extractor. If your cutting alu on air, your going to keep a 20hp screw compressor in solid use too! The electric meter little flashy light can cause epileptic sezuers in meter readers at these current draws! SO whilst you might not be ordering cutters and drills, its by no means cost free cutting.

Thanks for the answers. They really gave me an idea on the practicalities of owning both of these types of machines. I never realized that the operating costs would be so much. And I didn't realize that there would be so many pieces that you would need to make just to stay profitable. Looks like I'm going to hunt for someone with a laser/waterjet ths week.

water jets are so maintenance intensive. Thae last place I worked we had a O-max 10 feet from a Mori NH4000 and more times I got sprayed by that thing I hated setting up the mori. They are very dirty machines to run. The cost per hour for elec, abrasive, water was around $28.00 an hour. We went through more mixing tubes, nozzels ect......That machine cost around $240,000 because it had the taper compensating head on it.

The only time I liked that thing was when I was making vacume fixture gaskets made life so easy.

Sometimes I think of getting a small waterjet for my shop but I would rather add another turning center and VMC and just keep farming it out.

Jason,

Water jet will cut materials that a laser will not. I get 1" plastic cut by W J, laser will not do that. W J will cut glass, wood, thick ss, brass, most anything. They cost a lot more than 28.00 / hour to run. The local W J shop charges 220.00 / hour.

Originally Posted by moonlight machine

They cost a lot more than 28.00 / hour to run. The local W J shop charges 220.00 / hour.

$28.00 was just for abrasive,electric and water per hour on average. To turn a profit on that machine it had to run at $250 an hour.


Jason,

Like that other thread mentioning the late model Flow with the ultra high pressure pump, that eats $4000 worth of plumbing on a regular basis, there's a lot the manufacturers leave to the machine owners to figure out.

If your business is cutting 2" steel all day, you need its features and can keep it busy for most of one shift, a 90K psi machine with 5 axis tilt/taper compensation and a large work envelope may pencil out as your best long term investment. After you've paid back the $450K capital cost etc.

Someone who buys that machine and runs it at 90K to cut sheet metal will learn real quick about metal fatigue in the plumbing, and how much higher the true operating cost can be than what is typically claimed. I have a feeling some job shops lose money on a lot of jobs, because they don't appreciate what drives their maintenance costs and so don't properly price their work.

At the other end of the spectrum, for a lot of simple work, someone can buy the sub $100K machine, run it at below its rated specs to even further reduce the maintenance costs, and have a cost per finished part of maybe 1/4 the shop that operates the half $mil machine. Parts per $, its meaningless to compare $/hr rates because the machine capabilities vary over such a wide range.

I think the typical owners of the half $mil machines are big corporations with accounting methods that hide the ultimate per part cost.

Yes depending on the machine, your direct consumables cost starts at around $30/hr, plus maybe $10/hr for maintenance & parts, plus your capital cost/depreciation/overhead however you figure that. For a high performance machine, maybe double the above.

Of course what the machines do is pretty cool. Its a fascinating business.