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Laser vs CNC Sheet Punch

Laser vs CNC Sheet Punch

(OP)
We are machinery fabricators. We sub out our sheet metal layouts due to lack of equipment.  I am looking to purchase either a CNC Laser or CNC Punching machine.

We process 48 x 120 sheets of 11 ga. 304-stainless and up to .500 in. mild steel sheets.

I tend to think a punch for 11 ga. would be LOUD and hard on tooling. Cost IS A CONSIDERATION, however.

We only need usage several times a month.

RE: Laser vs CNC Sheet Punch

CNC punches are not that loud and the metallurgy found in todays tooling is phenomenal. Either machine has its pros and cons.

Your bigger issue is justifying the purchase at all, if usage is only a few times per month.  It's not just the cost of the machine, it's having the electric service brought in, rigging and moving, the square footage, the cost of the material in inventory, consumables, scrap, and having a properly knowledgeable person to program and run them. Your worker comp insurance rate (if applicable to your locality) will also be affected.

I am old school, a huge proponent of in-house manufacturing, but there are situations where outsourcing is the way to go.  You need to quantify your cost to do it in-house and decide from there.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

RE: Laser vs CNC Sheet Punch

A former employer had a Trumpf Laser/Punch.  They bought it used.  The assigned operator didn't keep the machine squeaky clean; I think he is nearly blind, and just can't see dirt.  ... or is just lazy, it was never clear which.  They were not happy with the experience.

In the last year they had it, they paid something like USD 50,000 for laser maintenance by official Trumpf technicians, and got maybe ten hours of use out of it.  Basically, the laser had become so unreliable that they couldn't rely on it being available, and Trumpf laser service is not lightning quick.  So they sold it.

The replacement was a Trumpf CNC punch (only) that was twice as fast as the old punch, and to my surprise, unlike its predecessor, didn't put a lot of impact noise into the building on every hit, even when punching 1/4" mild steel.  It also had an 'engraving' accesssory, that could mark parts with closely spaced prick punch hits, applied very rapidly.  It also made a lot less noise than you'd expect.  It could rotate punches, so it did a real nice job of nibbling parts you'd expect to need a laser for.  It also took up less than half the floor space needed for the laser/punch, and didn't need gas supplies or super dry compressed air.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Laser vs CNC Sheet Punch

A laser is usually a better choice than a punch but it depends on continuing tool cost. A laser can make any configuration hole you want however a punch may need special punches. My biggest concern is your usage. Several times a month doesn't seems to be enough usage to justify purchasing this machine. I agree with ornerynorsk please review your part costs before you sign up for what may become a financial catastrophe.

RE: Laser vs CNC Sheet Punch

Punching 11ga sheet will not be as loud as punching .500 plate.  With laser you'll have to investigate the costs associated with lenses and gas, but gain freedom in shapes to be cut.  With a punch, installation costs will be more (isolated slab) and tooling dies will cost, but will usually be quicker than laser.

"Art without engineering is dreaming; Engineering without art is calculating."


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RE: Laser vs CNC Sheet Punch

Something I forgot to mention: Heat Affected Zone.

I don't know if it affects mild steel, but a laser leaves a HAZ in stainless steel that will affect a weld done with no further prep.

I.e., laser parts arrive with edges that are clean, a little (but consistently) rough, and look beautiful.  But if you just go ahead and weld on those edges, the welds will look rougher than they should, and the welder will, if questioned, report that it 'welds funny'.  Just a touch with a snag grinder will remove the HAZ, which I'd estimate at no more than .005" wide, but you do have to remove it.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Laser vs CNC Sheet Punch

The oxide layer on the edge of laser sheet parts must be removed mechanically prior to any paint work, as well.  I'm guessing the HAZ to be considerably deeper than .005, because we get much more than that on Grade 50 and A36.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

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