laser vs. waterjet

jdm61

jdm61

itinerant metal pounder
Joined
Aug 12, 2005
Messages
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I am trying to figure out which would be better for a mid tech project. Water jet blanking does not leave a heat effected zone, but how does the edge finish left by laser and waterjet compare? My primary problem with waterjet is the kerf. I have people tell me that the newest machines compensate for it and then they show me an example and it is not even close to being straight. What is a poor boy to do? I know that wire EDM is the most accurate and can leave the best finish, but it is probably quite pricey especiually if you have to drill holes ahead of time so that you can do interior cuts.
 
What are you having cut?

I use waterjet now and then for large runs, I only make fixed blades.

I have never considered laser for my application because of the heat.

My waterjet blanks come out with what could be called "textured" edges(much cleaner than a bandsaw), but the remedy for that is a couple passes on a 220 grit belt.

For me, it is a huge time saver and saves money in belts as well.
 
The kerf can be compensated for with a newer machine. The thicker the stock the more of a kerf you get. The advantage of waterjet is no heat, no slag or scale to remove.
 
I'd say go water jet. My dad had a small run of folders done using the laser to cut out blanks and spot holes, the result was a lot of destroyed taps and drill bits.
 
Laser is great if your making sheetmetal components, waterjet with Dynamic head = lot less headaches on precision details /edges and holes not harder than woodpecker lips:)
 
Go with waterjet. If I remember corectly, the kerf is only a 1* deviation from square. It also leaves a very clean edge finish. Something like 120 grit paper in feel.
 
Kerf refers to the cut width and not the cut taper, although most people treat the two terms as synonyms. I agree, the dynamic head (tilting head to compensate for cut taper) technology is not perfect. Furthermore, your edge squareness can only be as good as the parallelism between your steel and the waterjet table, and that is only as good as the sturdiness of the table, and the squareness of the table to the machine axes. In other words, if your bar/sheet is warped or bowed (they usually are), then the cut will not be square regardless of machine precision. Waterjet and laser tables are sacrificial and get beat-up a lot - loading/unloading a 5,000 plate isn't exactly a gentle process.

Laser edge perpendicularity and edge finish can be great. It can also be terrible with a lot of slag. There is a wide range of quality and price across various vendors. Lasers can be very finicky machines and the quality from batch-to-batch from the same vendor can vary. The same is true with waterjet quality. Both machines have consumables (lens and nozzle for laser, orifice and mixing tube for waterjet) whose service age is directly related to cut quality.

Lasers really make things ROCK hard and can do a very poor job on holes. A laser is usually a terrible machine for skeleton-izing handles unless you're cutting 0.06" stock.

As far as pricing goes (you suggested this was an issue), I would say get a few waterjet quotes. You should be able to find a laser quote for 1/3 to 1/8 the price of waterjet.

So you probably need to experiment and do the cost analysis for your application.
 
the shop i work at has two water jets, and a wire EDM. The owner is old school, and does not like the idea of a laser cutter. We have fantastic results, and see little reason to spend the $$$$$$$$$$$ on a laser cutting system. I dont even think its a competition. for a small to medium size shop, the water jet is the clear cut winner. As for the wire EDM, im not as knowledgeable about that. All i know is it sits most of the time and looks good. We do have specific cuts that require the precision that you get on the EDM, but for the money i dont think its the way to go.
 
I run an industrial cutting laser. For a customer and for myself, I have cut blanks from 1075, 15n20, and some stainlesses. It does leave a nearly full hard heat affected zone, but in my blanks, by the time I smoothed the edge length wise, the haz was gone.

I've cut some knives with skeletonized handles from 7g and quarter inch. It worked great.

The biggest differences that I have seen, is that waterjet won't leave the haz, but is slow. Laser is much faster. It depends on the application.

The cutting knives I cut for a company did a batch anneal afterwards, so the haz wasn't an issue. I've worked with hardened steel before, so I just used the proper techniques.

There are differences between vendors and machines. I've cut parts for waterjet places that weren't able to cut parts as efficiently and I've farmed out some of my stuff to have them do it.

What are you wanted cut, from what material and what thickness?

Jamie
 
To put it simple, spyderco and benchmade use lasers for their speed and accuracy. Lasers can only cut about 1" steel and .5-.625" alum. Where as a waterjet can cut up to 6" of steel. I used to work in a metal fab shop and we looked at lasers and wsterjets. Laser wad our choice but only because of speed.
 
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