PCS Increases Accuracy, Reduces Time & Labor
For almost 20 years, Production Cutting Services, Inc., East Moline, Illinois, has been
a machine shop, specializing in processing tube, pipe and structural. In 2002, the
company installed a 2500w, 4' x 4', 3D rotary laser (SpaceGear-U44). Bill Duy, owner and
president, discusses two parts in which the 3D rotary laser was able to increase
accuracy, cut down on cycle time and costs and eliminate errors.
What is this first part?
It's a tubular component for a piece of farm equipment. The part is made from 4"
x 4", .25" wall, rectangular tube. It has holes on all four sides, and the position
of these holes in relation to each other must be held to within ±0.010".
Before installing the rotary laser, how were you making this part?
It was a very complicated part to process manually. First, we'd cut it to length.
Then we'd bring the pieces to the machining center where there were two vices. Each
vice held the part for two positions, and the machine was programmed to drill a
side for each position. After each side was finished, the operator had to stop and
turn the tube to the next side. So he had four setups per piece. Once all the holes
were drilled, the operator deburred the inside edges of the holes with a hand tool.
Overall, it was time-consuming and labor intensive.
Besides the setups and labor, what problems were you having fabricating this part?
We had several. Operator error was a big one. The operator had to pay close attention
to make sure he was rotating the part the right way. If the holes ended up on the
wrong side, the part wouldn't be any good. The machining process also caused problems.
If the operator clamped the part into the vice and machining debris from the previous
process was caught in between, this would skew the dimensions. This meant the operator
had to blow all the chips off the work area each time the tube was rotated, adding
more delays. In addition, vibrations can be very problematic. Once the drill makes
contact with the tube, the walls start flexing and vibrating. This can cause burrs
and greatly affect accuracy. I've actually seen a round drill cut a rectangular
hole. Plus, vibrations can ruin tooling very quickly. A $500 tool can be damaged
in a matter of seconds.
What sort of difficulties could these problems cause your customer?
We could have ended up with a lot of parts that didn't meet the dimensional specs.
And it's hard to spot them. Even an experienced operator has difficulty looking
at a bunch of parts in a bin and seeing which ones aren't right. He would have to
check each one individually - which, again, is costly. But if we don't check, and
we send it out to the customer, he could weld it into an assembly and then realize
the holes were on the wrong face or don't meet the dimensional tolerances. Then
he might reject the whole weldment. So, in addition to having to replace the bad
part, we would be responsible for all the other pieces included in the weldment.
How are you processing the part with the rotary laser?
We put a 10' tube into the rotary chuck, and it does all the work. The laser is
programmed to cut the right holes in the right face. The rotary chuck automatically
rotates the part, so there's no more manual turning. And, with our laser, we don't
have to be concerned with debris or grinding of burrs. After the holes are cut,
the laser cuts the part off at the correct length and starts the next part and so
on. So not only is the process reduced to one operation and one setup, but we're
now getting ten parts per chucking.
How did this solve the problems you were having?
Since we started using the rotary laser, we've dramatically reduced lead time and
labor costs, and we haven't made a single bad part. Not one. Operator error has
been eliminated and hole placement has been extremely accurate. There are no vibrations
with a laser so that's another reason the quality has been so much more consistent.
And, we're not risking an expensive tool to machine something that wasn't very "machinable"
to begin with.
In addition to accuracy, the machine gives us incredible time savings.
We've gone
from three operations - cutting, machining, and deburring - down to one. This has reduced
cycle time by 40%. At the same time, we're making ten parts per cycle instead of
one.
What is this second part?
This part is also used in a piece of farm equipment. The part has holes on three
sides and on the fourth, there is a cut with a beveled edge that the customer welds
to another part.
How were you previously making this part?
First, we sawed the tube to length and then drilled the holes in the three sides,
which required two setups. The top and bottom holes need to line up exactly, so
we drilled right through the tube. Then the operator would turn the part, and the
machining center would drill the four holes on the back. Next, the part would be
taken over to a different machine so the beveled edge could be cut. Finally, an
operator would remove the burrs on the inside and outside of the part caused by
drilling straight through the tube. It was very time consuming.
How are you able to cut this part on the laser?
We attach the tube to the rotary chuck and do it in one setup. Once again, no need
to manually turn the part or deburr. We cut out the extra step for beveling, too.
So we
went from four operations to one, and the cycle time was reduced by about 50%-60%.
Was it difficult for the laser to accurately cut the holes on the back side, which
extend over the radius of the tube?
No. The laser handles the curve and thicker wall very well. In the programming,
the speed and pressure are adjusted to ensure the hole dimensions are kept. No accuracy
problems occur at all. In fact, the laser is much more accurate than the machining
center. Again, that's because vibrations can affect accuracy during machining.
What future opportunities do you see for your company?
We are currently working on some sophisticated parts that will use the laser's 6-axis
capability, and we're also working on getting more 6-axis jobs. Our laser has 2D
capability too, so we could also do sheet and thick plate parts. It's a new market
for us, and we'd be very effective in it. |