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ChipWright
08-06-2003, 02:19 AM
I have a subcontractor that dropped the ball. We're now coordinating their faceplate subassembly between a graphic overlay shop and a cutter.

REQUIREMENT:
The have a graphic faceplate that fastens over our front panel's buttons and obstructions in general. Graphic overlays are typically 5mil thick but we require the to be affixed to a thick polycarbonate plate. Due to the tricky cutouts, the selected material, and its depth, waterjet cutting is appropriate.

Due to aspects of the cutout, the plate needs to be pre-cut with some cutouts that don't correspond with cutouts of the graphic overlay. We also include some pilot holes so that the waterjet doesn't have to punch through during the second cut pass.

After the precut, the graphic overlat is affixed as a signle sheet of NxM panel graphics aligned loosely on the underlying precut holes. The overlay includes some cutouts to coorespond with the pilot holes.

Next the plate and overlay and run through the waterjet cutter. Because the overlay and plate are cutting individual faceplates at the same time, there is no problem with the overlay registration not matching. The only issue is how well the waterjet cutter can get his registration from the overlay pattern to cut good parts.

The relationship between the precut holes and the 2nd pass is non-critical. The relationship between the overlay graphic and the plate 2nd pass cut is critical.

When we have our circuit boards cut, we use certain type of registration marks so the robotic chip placement can maintain high tolerances.

What do waterjet cutters use? Can I key each faceplate to a mark on its graphic?

By the way, We use the pilot holes so that the water jet doesn't have to punch-through when the overlay is affixed. the pilot hole allows it to start with blow through and then edge into the material. Punching through might flow into the laminate between the plate and overlay reducing its adhesion.

DR
08-06-2003, 01:35 PM
Hmmm....."What do waterjet cutters use? Can I key each faceplate to a mark on its graphic? "

Not with the water jet guys I've used. In your case, most likely you'll have to position off the edge of the object if possible.

A good many laser/water-jet shops have minimum wage people feeding their machines. The positioning system should be as fool-proof as possible, stopping off an edge is.

There may be shops with ways to quickly indicate off a registration mark, I haven't run into any yet. My guess is any kind of manual positioning to your marks would be expensive given their high hourly rates and time needed to do the indicating.

Everytime I've had an idea for the laser shop to cut something based on indexing off existing features they talk me out of it. Their preferred method is to cut the whole part from randomly oriented stock and let us finish the piece by indicating off their cuts.

The best answer to your quetions will come from your water-jet guys, they know their machines.

ChipWright
08-07-2003, 12:19 AM
Doing 3x3 foot plates would yield 50+ faceplates. The 1st pass cutter would cut a clean 3x3 outline, precut and pilot holes and rectangluar cutouts in the border for aligning the overlay manually.

The precut plates could be placed over a fixture wherein edges would protrude through the border cutouts along the top, bottom, left and right. The edges of the cut overlay (single sheet of 50+ faceplate graphics) would be butted against these protrusions and then affixed to the plate. As the adhesion starts to set, the plate could be pulled from the fixture and allowed to cure.

The waterjet cutter would later take a plate with overlay affixed and butt it against the edges of his cutter workarea and clamp it. As long as the plate is not wrongly rotated, it should yield good registration of overlay and cutout.

Sounds like a solutions. I'll see what the waterjet contractor adds. It would be nice if we could cut some registration notches that match his machine... we'll see.

> The best answer to your quetions will
> come from your water-jet guys, they
> know their machines.

I agree with you on that. I've been impressed with the agility of the WJ cutters I've worked with. I attribute it to their business being a lot of prototype work and short run work... they are used to doing new things and have to know their machine.

All this talk about G-Code and automated machines is getting me hungry for one to play with. I think a Waterjet cutter would be the best machine for my company to buy... they're versatile and would really help with development prototypes.


[This message has been edited by ChipWright (edited 08-06-2003).]

Thrud
08-07-2003, 01:13 AM
A laser could do this easily. Plastics are no trouble, glass is (with either Laser or WJ).

alumtuna
08-07-2003, 01:33 AM
Only some to add, i had a prof who was specilizing in water jet cutting. Showed his lab to us in class one time, and went though the whole manufacturing process. Very interesting.

To add this, WJC does not have distortion like a process involvin heat does, does not puts any forces on the plate (being cut) and cuts ANY material (including ceramics). They could also add abrasives to water to cut faster also. Pressures could be well over 100,000 psi. Said that the hoses to handle this pressure were revolutionary to adapt this process to many more applications.

About registering the parts i would go w/ DR and basically ask the WJ guys. They will do whatever they need to do to do the job.

Regards

Evan
08-07-2003, 01:49 AM
Yeah Thrud, like we talked about a while ago an excimer laser would work except on glass. Might even work on glass, the instantaneous power is really high for an excimer and glass does absorb UV.

OlKeith
08-07-2003, 11:06 AM
If you decide to use a laser to do this job here is what I do in simular situations.

Using a product called Laser Lignts (colored plastic 0.004" thick/adhesive backed) I adhere it to a plastic material the approximate size of the project. Adjusting the drawing to separate the vector lines (to be cut) from the raster lines (engraved areas) I send the drawing to my laser. The laser will engrave the text and graphics then cut the interior holes before the outside perimeter. The result is a perfect faceplate ready to mount.

There are plenty of other plastic/acrylic engraving materials available in most standard thicknesses that could be used in the same manner without using an adhesive plastic piggybacked on acrylic. These are avaialble in almost any color combination.

Hope this helps, feel free to contact me if I can provide any information or links to material suppliers.

keith@workshoptreasures.com

ChipWright
08-08-2003, 12:38 AM
> The laser will engrave the text and graphics
> then cut the interior holes before the
> outside perimeter. The result is a perfect
> faceplate ready to mount.

That's a nice technique.

20 years ago I had a faceplate made out of a plastic material with two color layers. The faceplate contracted routed the company logo, accent lines and then the cutouts and perimeter. It was very nice!

The face plates I'm trying to get manufactured are a little more trouble. We have a multi-color graphic overlay with a window insert to allow the LED displays to shine through. I just got a SAMPLE insert from the overlay company and its light gray since we have multi-color LEDs. The problem is that it uses a strange diffusion pattern that makes the alphanumeric display fuzzy beyond all hope of comprehension. http://bbs.homeshopmachinist.net//smile.gif

I don't think I can sell that as a "feature".