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Acrylic
Laser Cutting Machines: Purchasing pre-requisites, a case study
Part 1: History... why purchase a laser
machine?
Part 2: Preliminary purchasing criteria
Part 3: Additional purchasing criteria
Part 4: Workflow analysis
Part 5: Comparison of various Machines
Part 6: The smart purchase order
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To
download or view a Windows Media Player version of our video click
here.
History:
We
are a national point of purchase display fabricator with an emphasis on
fabricating acrylic displays. In January, 2002 on a whim we purchased
our first laser cutting and engraving machine. This was a Universal Laser
(www.ulsinc.com) with
a 100 watt laser tube (actually two 50 watt laser tubes with combined
beams) and a 32" wide by 18" cutting bed costing us $XX,175.
Although we based this initial purchase on the premise that we would primarily
be engraving signage plus some small lot cutting of "odd shaped"
pieces, our personnel quickly recognized the benefits of laser cutting
versus routing various other shapes that we had been mass producing in
our shop for years. The laser benefits versus the router were: 1) dust
free pieces, especially when we transferred parts into our silk-screening
department for printing, 2) eliminated a second work step of flame polishing
the edge of the acrylic to achieve an optically clear sheen, 3) possibility
of faster output (this document will spend time analyzing this parameter),
4) elimination of router bit sharpening expense, 5) potential of "bulk"
peeling of the film masking found on the acrylic sheet when purchased
from the manufacturer.... If you could bulk peel one large sheet in advance
prior to fabrication you would save much time versus peeling individually
fabricated pieces downstream of the routing process. A second advantage
of peeling the acrylic in bulk (and being able to process the acrylic
with its film masking de-peeled) would be the capability to silk-screen
or imprint multiple images in one labor effort on one large piece of acrylic
and then laser cut into multiple final shapes downstream of the silk-screening
process. Our traditional process of routing had to occur upstream of the
silk-screening process, because of the dust and scratches that would be
prevalent if we tried to route de-peeled material after the silk-screening
process. The only disadvantage that we could see cutting with the laser
versus router cutting was that we could not gang stack multiple pieces
together (cut multi-up). With hand held routers and good templates we
often cut 6 to 8 pieces of .080 thick acrylic in one pass.
Our most example piece is an acrylic brochure holder, our model
code LH40. This is a literature display that has an irregular shape in
"the flat" and then is bent into a three dimensional shape with
heated line benders as a secondary operation after the machining of the
flat shape. See the shape and dimensions of the LH40 piece below:
Our personnel quickly took this LH40 piece, drew a multi-up pattern of
six pieces which was optimized for the Universal Laser machines 32"
x 18" cutting bed. (See LH40-6UP).
They were off to the races attempting to cut 10,000 pieces on the first
laser cutting production run. The following are results and observations
from trying to run production quantities on the small Universal Laser
platform:
1. The fastest cycle time for cutting the 6-up LH40 file that could be
achieved was 2 minutes and 15 seconds.
2. We could not cut the acrylic with the film masking side peeled off
one side of the acrylic exposing the raw material, but had to leave both
sides of the acrylic with the film masking on. The Universal machine left
much "hazing" or cloudiness on the surface of the acrylic with
the film masking peeled off. This "hazing" is a result of heating
of the raw material and the residual gases from the laser cutting process
falling onto this heat affected zone prior to its cooling. The result
is a cloudy scar or marring of the material called HAZ or HAZING.
3. Loading and unloading the machine was slightly cumbersome or inefficient,
although in retrospect it was nice to handle such a small sheet size (15"x32"),
we had to lift the Class 1 lid and place material down into a bed, and
conversely we had to extricate (6) finished pieces, (6) scrap drop outs,
and a scrap trim perimeter piece. We quickly jigged up a "slide tray"
and utilized the side door of the machine so that we could operate it
a little bit more like cookie trays in an oven, sliding batches in whole
and extricating them in whole batches.
4. There was considerable down time for the operator, although they had
to collate and peel the film masking off the (6) extricated pieces that
had just been cut they still had over 1.5 minutes of extra time to stand
and watch the laser cut during the 2 minute and 13 second cycle. If we
had a second machine we could run reciprocating machines at the same time
to double our output.
5. The final result was the achievement of 1100 to 1300 pieces cut per
day; our shop operators were simultaneously achieving 1800 pieces per
day by hand routing these same LH40 pieces in multi-up jigs plus one additional
effort of polishing the edges which they could do at a secondary
rate of 6000 pieces per day. It was simply more efficient to do it the
old fashion way of hand routing versus laser cutting.
The Universal Laser was not appropriate for our mass production style
of cutting (although this is a great little machine for model making,
engraving signs, or just to get your feet wet without spending much...
see further review below). We however could see the benefits of laser
cutting and knew there must be a better way, a better laser cutting machine
with a faster cutting process and more appropriate cutting bed size. The
machine we had was the largest machine that the Universal Laser Company
offered, thus the search began for a more optimal Laser cutting system.
The first vendor we came across was advertised in "Plastic Fabricators
& Distributor" magazine (www.plasticsmag.com).
There was an advertisement for lasers with 51"x31" and 51"x51"
cutting beds, laser power from 50 watt to 500 watt. We introduced ourselves
by sending our LH40 6-up file to the vendor along with a supply of .080
thick film masked extruded acrylic. We requested a through-put speed for
cutting the file. The new vendor claimed their machine could cut our file
in 1 minute and 10 seconds on an equivalent 100 watt machine, a major
improvement over the 2 minute and 13 seconds we were currently were currently
cutting at on our Universal machine. We were initially impressed and went
to witness this cutting speed with our own eyes. Sure enough, it cut the
LH40-6UP file in 1 minute and 10 seconds. We extrapolated a cut time for
20 pieces that would fit in the 51" x 31" bed and calculated
that one operator could easily run two machines simultaneously. We calculated
that we would achieve 3200 pieces per day by alternating two machines.
The quotes came back and the two 100 watt machines, 51"x31"
cutting beds, with chillers cost $XX,000 each. We were so sure this was
going to bring us to the next level that we told the vendor to also quote
an additional 200 watt machine so that we could also cut some thicker
materials (1/4" and up) without having to push the limits of the 100
watt machine. The price of the (2) 100 watt machines and the (1) 200 watt
machine with chillers was $***,000. We fine tuned the quote and extrapolated
a purchase order from the vendors phraseology found on their quote. We
were within 24 hours of sending a 60% deposit off, when common sense hit
us. With such a large deposit we had better slow down and do a little
bit of due diligence... We had better check some references, check a Dunn
& Bradstreet report, and see if there were any reviews on the internet,
etc.
You'll never guess what we found out. We found an internet website pertaining
to granite rock engraving that had many chat threads pertaining to this
vendor, the writers of these chat threads were trying to organize a class
action law suit against this particular vendor. I dug deep, and was able
to make actual contacts with some of the entities whom were writing these
chat threads. One entity actually had a law suit pending pertaining to
the delivery of a new laser machine that was defective and the vendor
had refused to service or mitigate. The Dunn & Bradstreet report was
fairly clean, but buried deep was a reference that the vendor had filed
Chapter 11 a few years back. Imagine sending off a $***,000 deposit and
having the company file Chapter 11 after receiving your good funds..
THE MORAL OF THE STORY IS: DO YOUR PHONE CALLS, DON'T GET LAZY, AND GET
GOOD and CURRENT REFERENCES!
We were frustrated because the rug had gotten pulled out from underneath
our feet. We had to start our purchasing due diligence process again from
scratch. But this sure was better than our hard earned money being thrown
down the drain. As it turns out, the laser machine we almost purchased
would have been considered a toy in comparison to the machines we inevitably
purchased.
Defining Our Initial Purchasing Criteria:
1. Speed or Throughput: We would not measure the speed of a laser cutting
machine by inches per minute, laser tube wattage, and acceleration specifications.
These are all miss guided criteria:
a. Inches per minute are in general theoretical, if you were
cutting a long straight line without any curves, and you were cutting
a material substrate that had zero resistance than perhaps you could look
at this specification. But a laser cutting system can cut only as fast
as a compilation of many variables including the following:
i. Laser Tube strength, nominal wattage
produced after it exits the nozzle (not at its exit on the tube)
ii. The thickness of the sheet or
substrate material being cut
iii. The type of sheet or substrate
being cut: extruded acrylic, cast acrylic, ABS, with paper masking, with
film masking, etc.
iv. Your quality tolerances pertaining
to edge finishes (the polished sheen for acrylic edges).
v. The file drawing should be clean
with curves drawn with arcs versus a lot of tangent points, a lot of tangent
points will force the motion software to have to slow down and read more
data. Have you "step and repeated" segments or components in
you file to create its final version or has it been drawn as one (or the
minimal number) continuous lines which would be interpreted more optimally
by the motion control software.
vi. The amount of curves in your cutting
file, as the laser must de-accelerate when it approaches a curve and re-accelerate
when it exits the curve:
1. Does the
laser system have "look ahead" algorithms built into its motion
software to recognize curves in advance?
2. What acceleration
speed can your gantry mechanism actually run at?
vii. Type of motor; stepper versus
servo versus linear plus the "slew" speed which is the speed
the motor travels it when it is not actually cutting but traveling between
"cut" points or returning to "home".
The only sure measurement of speed that we could objectively measure was
to cut our common LH40-6UP file on extruded film masked acrylic with one
side of the film masking peeled off and use this as our baseline index
to measure the different types of machines and their actual cutting speed.
The time to cut this file with acceptable edge quality would be the actual
measurement of the laser cutting system or its throughput with regard
to our needs. Do not look at specifications in pretty marketing brochures!
Set up a file and supply same-type material that is indigenous to your
business to the laser machine vendors and make them prove themselves.
2. Fume Free Cutting; Exhaust System: To put it bluntly, cutting acrylic
stinks. We even had trouble with our Universal Laser system smelling up
the environment (clean production room with 40 persons working, air conditioned).
We had to tweak the exhaust piping making sure every seam was duct taped.
Hint: you cannot overbuy on the exhaust motor, spend the extra $150 and
go one model up from whatever you calculate to be appropriate cfm for
your laser system. Acrylic that has been laser cut reeks by itself, just
the stacks of acrylic after cutting... excluding any fumes from the process
itself. There is a residual odor to the acrylic edges. We knew we could
not do anything about this residual odor, but we definitely had to mitigate
the process odors resulting from the actual cutting cycle. We had to have
a Class 1 type of enclosure on our machine with a real efficient exhaust
system. We needed both top side extrication of fumes as well as a bottom
side draw down of the fumes. The top side extrication implies a hood and
lid system which typically comes as class 1 safety enclosures. There are
systems however, that have this Class 1 safety enclosure with top side
exhausting but can operate as a Class 4 machine by having secondary vertical
sliding doors below the topside lid enclosure. This way you do not have
to open the topside lid each cycle or more importantly close the lid in
order to activate each cutting cycle. See Beam Dynamics ( www.beamdynamics.com)
machine design and to a lesser degree the design of the SEI Mercury (
www.seispa.com) system.
This fume extrication is a must when cutting acrylic, although some shops
have had luck simply building a "none enclosed" hood over their
cutting tables we think that a complete enclosure is necessary for optimal
fume exhausting. A lot of larger sized laser machining centers have an
open table format. How one can cut acrylics without mitigating the process
fumes on a large open table system baffles me? One side note: cutting
cast acrylic (if you can afford it) smells half as bad as extruded acrylic.
3. Haze Free Cutting: This may be a-typical for your business as you may
be satisfied laser cutting acrylic with the paper or film masking applied
to both sides. We however perceive many benefits to peeling at least one
side of the film masking off (usually the top side being cut, the bottom
side will have more exposure to flashback and scratches from material
handling). By peeling one side of the film masking off the acrylic prior
to cutting we benefited by:
a. We averaged 6 seconds for peeling one individual piece
after cutting; the individual piece was the LH40-1UP approximately 9-1/8"
x 9-1/8" in dimension. Our yield for this piece from a 48" x
49" sheet was 30 pieces. When our operators were able to peel in
advance one 48" x 49" bulk sheet (equaling thirty LH40-1UP pieces)
in 20 seconds or less, resulting in less than one second per individual
piece versus the six seconds per individual piece when peeled individually.
b. By peeling the larger 48" x 49" in advance we
were able to avoid added time in the unloading cycle. The unloading cycle
is where our operators would individually peel the film off each individual
piece that had just been cut. Peeling (30) pieces individually at 6 seconds
each is equivalent to 3 minutes (180 seconds). This burdensome peeling
time had a negative effect on any type of aggregate laser cutting cycle
we tried to implement.The alternative would be to set up a second workstation
(additional labor effort) for peeling the individual pieces downstream
of the laser cutting cycle.
c. We could now imprint larger sheet sizes with multi-up yields.
We could imprint 4, 6, 8, or even 10 units at a time in the same pass
of the silkscreen machine prior to laser cutting process (upstream)...
versus individually silk-screening pieces downstream of the laser cutting
effort. Labor and OH costs were reduced due to multi-up screen printing
capabilities.
The problem with peeling film or paper masking off the acrylic and laser
cutting with the acrylic surface exposed is that the laser beam heats
both the inside molecules inside the kerf of the cut and some area on
the surface near the cutting line. Prior to this heat affected zone cooling
gases being released during the cutting cycle land or brush this heat
affected zone leaving a permanent scarring or cloudy marking primarily
on the exposed surface area. The challenge for which most laser machine
manufacturers have not conquered is to readily remove the gas from the
kerf area during cutting so it cannot accumulate on the heat affected
zone. These gases must be forced down through the cut line and extricated
quickly and exhausted rapidly from the top side of the surface being cut
(removal from the immediate laser head). This procedure is easier said
then done. It often involves:
1. a forced gas assist pushing air through the kerf,
2. a custom nozzle so that the air circulation pattern that
occurs upon the exiting of assist gas from the nozzle is controlled for
irregularities in its circulating pattern.
3. this custom nozzle is coordinated to work with travel direction
of the laser head (in all its directions).
4. a specialized vacuum pump riding on the laser head and
connected to a laser head enclosure that traps topside gas prevalent when
cutting and extricates this gas rapidly..
The half ass solution provided by many laser manufacturers involves cutting
sub surface templates approximately 3/8" deep and shaped exactly
the same as the pieces being cut except a few millimeters smaller in perimeter.
Each of these template shapes would be jigged leaving a kerf or crack
between the individual templates, this crack would be thick enough for
the force gas to easily travel through after exiting the kerf of "live"
pieces being cut. The theory is that the gas continues straight through
the cut piece into a secondary templated "channel" or "kerf"
and is forced out the bottom side of this template (through additional
vacuum holes). This creates unidirectional downward air travel eliminating
residual air above the surface of the material being cut. Making these
complex templates (the templates pattern is identical to the primary pattern
being cut) for every job could be considered onerous depending on the
length or run-time of each job. Sliding pieces or moving pieces that have
just been cut over an irregular table surface (which is what you get when
you cut on a template that looks like a jig-saw puzzle) can also be onerous,
especially as the size of the piece being cut gets smaller creating a
more complex (multi-part) template..
In summary, our initial purchasing criteria were these three criteria:
1) indexed speed or throughput,
2) fume free cutting, and
3) haze free cutting. During the evaluation process we evolved our
thinking and expanded our purchasing criteria. Following are two more
added pre-requisites from which our purchase decision was derived.
Additional Purchasing Criteria:
We further expanded our criteria, and inevitably worked out a weighted
average for each pre-requisite in order to come up with an objective way
of selecting the best laser cutting machine for our needs:
1. The fourth criteria (in addition to speed/throughput, fume free cutting,
and haze free cutting) was vendor integrity. We knew that our final relationship
with the vendor would be critical to the success or failure of our laser
cutting center. We broke down this broad category of "vendor integrity"
into (3) smaller judgments:
a. Vendor and/or Manufacturer's track record with regard to
sales and service support: references, references, references! History,
History, History!
b. Vendor and/or Manufacturer's relationship with the laser
tube manufacturer. Since the laser tube was the most expensive and most
critical piece of the machine... how much "muscle" did the vendor
have with the tube manufacturer (Coherent, Synrad, and Rolfin)? Could
they guarantee in writing a tube replacement within 72 hours if a tube
went down during the warranty period, would they go to bat for you, was
this vendor/manufacturer an important customer of the laser tube manufacturer?
c. Vendor integrity, from visiting the various operations
(take time out to visit the manufacturer, spend $2000 to $4000 in travel
expenses which can be viewed as a small insurance policy), and from multiple
conversations, emails, quotes, etc. Are these persons of integrity, are
they honest business people? This could be viewed as a subjective "gut
feeling" rating, but most good business minded people can tell when
something is out of tilt, when someone or some entity is not on the up
and up. Sometimes you may have to peel back a few of the layers of the
onion however.
2. The fifth criteria: Workflow effectiveness! This turned out to be the
defining parameter that separated or differentiated most of the vendors.
Following is a very expansive dissertation, but the most critical to measuring
the value of your future laser cutter. There is as much as a 300% difference
between these various workflow outputs or throughputs. The following are
four workflow methodologies that can be extrapolated for either one machine
running solo or two machines running in parallel to each other. These
workflow methodologies are:
a. Standard Input-Output: pieces go in and come out the same
side of machine upon completion of the cutting cycle
b. Split Table Runaround: We divide the cutting table into
(3) sections; cutting section "A" on one side, cutting section
"B" on the opposite side, and a "Neutral Zone" between
the two cutting areas. The theory here is that can keep the laser cutting
all of the time without stopping for unload and loading efforts. The neutral
zone allows for a safe stop area prior to the laser head commencing to
the opposite side of the table and cutting the next file located on the
opposite side. The gantry and laser head stops just in case the operator
has not unloaded or loaded the next up material; he must than manually
activate a "start" button for the laser head to continue on.
c. Shuttle Pallet-Front & Rear: This methodology can be
used with machines that allow for front and rear door/table openings and
extension tables. Two pallets on sets of rollers (or conveyor) are shuttled
in and out of the cutting area. While one pallet is inside the cutting
area being cut, the other pallet has exited the cutting area on an extension
table and is being unloaded and loaded with next up material.
d. Single Sided Z Axis Loading: Two extension tables with
rollers are located one above the other (separated by only a few inches)
on a single side of the laser machine. One pallet exits the cutting area
(let's say on the bottom set of rollers), the Z axis rises vertically
to accept an inbound pallet from the top set of rollers (extension table).
The top pallet is cut, then removed on the top set of rollers, the Z axis
lowers to accept inbound material from the bottom pallet located on the
lower set of rollers (extension table)
The following is an actual time analysis of each of the foregoing workflow
methodologies depicting the individualized efforts, times, and results
that can be achieved. First let us set some parameters for the calculations:
Workflow Analysis with Various Configurations:
Parameters:
1. We are using two (2) laser machines running in parallel to each other,
see diagram for layout click here
2. Laser cutting time for 30 piece file on 48'x49" format 3.28 minutes
3. Peel film masking and load 48x49 sheet to cutting pallet= .35 minutes
4. Peel film masking and load 15"x 49" sheet to cutting pallet=
.25 minutes
5. Unload and collate (30) pieces (48x48)= 1.50 minutes
6. Unload and collate (10) pieces (15x48)= .50 minutes
7. Walk from one position to another position or around laser= .08 minutes
8. For shuttle Pallet methodology, switch or pull pallets= .17 minutes
9. We work 55 minutes in an hour (one hour= 55 minutes)
#1 Standard Input/Output Methodology: Two 250 watt machines in traditional
load, cut, and unload mode:
* First Machine "A" has (30) piece file
* Second Machine "B" has (30) piece file
* Assumes a 3.28 minute file cutting time (3 minutes and 17 seconds)
1. Start cutting "A", walk to "B" .08, unload "B"
1.50, load "B" .35, Start "B"= 1.93 minutes
2. Walk to "A" .08, wait at "A" for file to complete
cutting 1.27, unload "A" 1.50, load "A" .35, Start
cutting "A"= 3.20 minutes
3. Total cycle= 5.13 minutes for 60 pieces
4. 55 min per hour /5.13 min =10.72 cycles/hour x 8 hrs/day= 85.77 cycles/day
x 60 pieces= 5,146 pieces/day
* Advantage of Finished Goods, Raw Materials, and scrap pallets located
on one side of machine, not redundant footprints for these on both sides
of machine as per rolling shuttle and Runaround methodologies
*. Advantage is that there are 2 efforts per cycle x 86 cycles/day or
only 172 work efforts per day!
* Disadvantage: this is upper limit, improvements in unloading time will
not improve output... output controlled by laser cutting time which will
degrade over time.
*. Disadvantage: work person cannot reach to back of 48" pallet to
unload pieces... needs to roll out the table for "walk around"
access
#2 Split Table Methodology: Two 250 watt machines, split file mode utilizing
half of each table to cut a 10-up
LH40 file (called the chicken runs around the coop methodology);
* First Machine #1 utilizes side "A" and side "B";
each side utilizes a (10) piece file LH40-10UP
* Second Machine #2 utilizes side "C" and side "D";
each side utilizes a (10) piece file LH40-10UP
* Although we have access to four sides (A,B,C, & D), through many
calculations we have found with the files being cut that optimization
occurred only using three sides of the two machines (A,B, & C).
* See Workflow Diagram below
1. Start cutting "C", walk to "A" .08, unload "A"
.50, load "A" .25= .83 minutes
2. Start cutting "A", walk to "B" .08, unload "B"
.50, load "B" .25= .83 minutes
3. Start cutting "B" (need start switch on back side), walk
to "C" .08, unload "C" .50, load "C" .25=
.83 minutes
4. Total cycle= 2.49 minutes for 30 pieces
5. 55 min per hour /2.49 min= 22.08 cycles/hour x 8 hours/day= 176.70
cycles/day x 30 pieces= 5,301 pieces/day
* Disadvantage of Finished Goods, Raw Materials, and scrap pallets necessary
and redundant on both sides of laser machines, taking up twice the footprint
* Disadvantage is that there are 3 efforts per cycle x 176 cycles/day
or 538 work efforts! It is like a chicken running around a chicken coop!
* Advantage if unload times improve then output will improve, output not
dictated by laser cutting speed, separate calculation with hypothetical
.34 minute unload time versus .50 minute unload time would increase output
to (6,197 pieces/day hypothetical)
#3 Shuttle Pallet Methodology: Two 250 watt machines, reciprocating shuttle
pallet mode cutting a LH40-30UP
file:
* First Machine #1 utilizes two pallets "A" and "B",
each pallet had has (30) piece file
* Second Machine #2 utilizes two pallets "C" and "D",
each pallet had has (30) piece file
* See Workflow Diagram below
1. Start cutting "A", walk to "C" .08, unload "C"
1.50, load "C" .35, pull "D" & commence "C"
.17= 2.10 minutes
2. walk to "B" .08, unload "B" 1.50, load "B"
.35, pull "A" & commence "B" .17 (need backside
startswitch) = 2.10 minutes
3. walk to "D" .08, unload "D" 1.50, load "D"
.35, pull "C" & commence "D" .17 (need backside
start switch) = 2.10 minutes
4. walk to "A" .08, unload "A" 1.50, load "A"
.35, pull "B" & commence "A" .17= 2.10 minutes
5. Total cycle= 8.40 minutes for 120 pieces
6. 55 min per hour/8.40 minutes =6.55 cycles/hour x 8 hours/day= 52.38
cycles/day x 120 pieces= 6,286 pieces/day
* Advantage is only 4 efforts per cycle x 52 cycles per day or 208 work
efforts versus the 538 in the walk around methodology
* Advantage if unload times improve then output will improve, output not
dictated by laser cutting speed, if unload time were reduced by 33% from
1.50 minutes to 1.00 minutes than output would increase to (8,250 pieces/day
hypothetical)
* Disadvantage need redundant finished goods, raw material, and scrap
pallets on each side of machine taking up valuable work space, twice the
footprint.
#4 Z Axis Single Sided Loading Methodology: this is ultimate solution
utilizing shuttle pallets from same side of machine using Z axis for vertical
pallet movement. Pallet "A" on elevated higher rolling track
and pallet "B" on lower rolling track:
1. Would save redundant floor space; finished good, raw material, and
scrap pallets on one side of machine versus both sides of the machine
2. Would achieve same amount of pieces per day as front/back rolling table
methodology above: 6,286 pieces/day or more as some "walk" time
is eliminated as you do not need to walk from the front to the back side
of each machine with this methodology.
Comparing Various Machines:
We ran across many brands and models of laser cutting machines during
our research. Based on the five criteria set forth above and with a special
emphasis on the "workflow" criteria, many models and manufacturers
were eliminated. Basically, we eliminated from serious consideration if:
1. The machine had a small bed or cutting area, was primarily used in
the sign or engraving industry, had maximum output of 100 watts or less,
or lower caliber motion control mechanics.
Universal Laser ( www.ulsinc.com
), Epilog ( www.epiloglaser.com
), GCC Neptune ( www.ilaserpro.com
) machines were eliminated from our selection pool. These machines are
great for their niche, but would not be conducive to our goals. Hypothetically,
we could purchase (3) 100 watt GCC Neptune machines (51" x 31"
cutting bed) and possibly sequence load and unloading cycles between the
three machines to achieve 5000 pcs per day. But we are back to a "chicken
in a coop" running around routine. The three machines would cost
approximately $***,000 in total, a full $***,000 less than our final purchase
price. Their life span would be shorter (based on the quality of the components),
but with the savings we could always buy an additional replacement machine
and still be less than our final purchase price. However there is something
said for "you get what you pay for" and we were not willing
to settle or compromise for a system that didn't totally meet our needs.
2. So, the machines that we did finally focus in on were: SEI Spa Mercury
( www.seispa.com ),
Eurolaser 1200 ( www.eurolaser.com
), and the Beam Dynamics LMC5000 ( www.beamdynamics.com
). Following is our comparison data used to make our purchasing decision:
Laser Comparisons
Pre-requisites (subject to change):
1. 20%=Speed/throughput as indexed by LH40-6up file or LH40-30up file
weighting
2. 20%=Haze free cutting at full feed rate weighting
3. Workflow: Rolling shuttle pallets** weighting= 20%
** If single sided rolling pallet could be achieved, then even more value
4. Fume evacuation weighting= 20%
5. Vendor Service Record (ability to service) weighting= 07%
6. Vendor relationship with Tube Manufacturer, Credible Warranty weighting=
07%
7. Vendor integrity weighting= 06%
Beam Dynamics Issues & Negatives:
1. Tethered or cabled actuator or start buttons for front and back operation
needed to be incorporated into contract (but was easily achievable due
to control panel being connected via a simple serial cable)
2. Light system for mode indication (size equal to Europeans, multiple
modes or just stop mode) had to be incorporated into contract
3. Excludes cost of exhaust system and/or charcoal filtration system
4. Servo motor with brushes, possibility of brushes needing replacement.
Not necessarily a huge problem.
Beam Dynamics Positives:
1. Speed, was able to contractually commit to 3.00 minute cut time for
LH40-30UP file; within our acceptable rates
2. Haze; was able to contractually commit to haze free cutting at full
feed rates, had developed proprietary technique incorporating custom engineered
nozzle and immediate enclosed fume evacuation at the laser head
3. Best Load/Unload Workflow potential with a) standard mode operation...
but with the advantage of a built in slide out table for improved ergonomics
and access to cut pieces, b) Split Table operation, c) front & back
rolling shuttle pallet operation d) same side Z axis pallet operation
which would be a big bonus.
a. Single sided shuttle system utilizing Beam Dynamic's 12"
Z axis... whereby one pallet enters and the other exits above/below...
i. Would enable single sided raw material
storage, versus redundant storage on two sides of the machine
ii. Would enable single sided finished
goods palletizing, versus redundant storage on two sides of the machine
iii. Would enable single sided scrap
pallet, versus redundant storage on two sides of the machine
4. Smallest footprint
5. Best Fume extraction
6. Vendor (manufacturer) service record excellent (based on 6 reference
calls)
7. Vendor relationship and muscle power with Tube manufacturer Excellent,
enabling warranty enforcement
8. Vendor (Manufacturer) perceived integrity good to excellent
9. Includes Raster mode for engraving
Eurolaser Issues & Negatives:
a. Priced at upper limit of budget and not comprehensive,
must add additional costs for fume evacuation and roller tables (if possible),
putting costs over initial budget.
b. Fumes... must add enclosures. Upper enclosure, engineering,
sourcing of materials fabrication, exhausts, electric contractor, $3000
x two machines... add $6000. Risk and aggravation building proprietary
enclosure ourselves, not offered by the manufacturer
c. Can only achieve two out of four workflows: a) standard
mode operation retrieving pieces by reaching into 48" bed (but impossible
for operator to actually reach into 48" bed and retrieve pieces,
b) Split Table operation. Cannot achieve rolling shuttle pallet mode of
operation due to pallet table design placed within the frame of the machines
body; same side shuttle pallet unachievable... no Z axis movement.
d. Tethered on/off start actuators for front and back activation
lacking
e. Extra Lens, need both 2-1/2" & 5" lenses
f. No raster mode
Eurolaser Positives:
a. Committed speed of 3.28 minutes on LH40-6UP file
b. Haze free cutting can be achieved and was committed to.
c. Vendor & manufacturer service record excellent, excellent
references
d. Vendor & manufacturer relationship and muscle power
with tube manufacturer for warranty enforcement good to excellent
e. Vendor & manufacturer perceived integrity excellent
f. On/Off indicating light system excellent
g. Impressed with entire organization
h. Patented stainless steel belt, very nice design.
SEI Issues & Negatives:
a. Footprint larger, may be difficult in our allocated space
of 21' x 26' to set up reciprocating rolling shuttle... with redundant
finished goods, raw material, and scrap pallets for two machine operation
b. 7.54' wide (90.55") x 10.17' (122.04") long,
excluding conveyor system which would be needed to achieve optimal workflow
methodologies
c.
Tethered cable for front and back on/off actuation, not in quote
d. Light system unknown, is it as good as the Germans
e. software- can it operate a split table mode with two files running
on the same table (front & back... stopping between each file)
f. Extra lens, need both 2-1/2" and 5"... not both
included in quote
g. Will need additional cost transformer for 380v; add 2 x $400=
$800
h. Air Nozzle Adjustment?
i. How are fumes and smoke kept away from lens?
j. Questionable Chiller capabilities, should compare cfm and specs
to Remcor, basically unknown specifications
k. Laser Tube warranty is vague, is there a next day delivery replacement
policy during warranty period w/ no cost burden to customer? Need in writing
l. "Optics and consumption materials not covered by warranty"????
m. Some hedging on installation conditions in quote: "If
Laser Solutions can not handle it and the manufacturer has to come to
set it up" then we get reamed??? Limitation of set up and installation
to 2 days,is this for both machines or 2 days per machine? Why put limitation
burden on us... it is their responsibility to set up and install the machines
no matter how long it takes.
n. Brand of laser not mentioned in quote
o. Will need power meter
p. 200 watt referenced with actual power of 270w; 300 watt
referenced with actual power of 380watt: Is this measured direct or after/through
the nozzle? What guarantee they deliver per this specification, Usually
they can only guarantee the manufacturers rating of 200 watt versus 270
watt (or 300 watt versus 380 watt); will they put guarantee these statements
into acceptance parameter?
q. Exhaust system additional $750 x 2 units; $1500 (excludes
charcoal & filter dumps)
r. Vendor & manufacturer service record unknown, no Mercury's
in US, no references, Vendor is new company, track record unknown... the
references are mostly European and appears this machine was designed for
the apparel industry.
s. Vendor & manufacturer relationship and muscle power
with tube manufacturer for warranty enforcement= unknown
t. Vendor & manufacturer perceived integrity?????
u. How can pallet/table be leveled, especially if on conveyor?
v. What kind of belt drive, Is this a closed loop system
Non-conveyor Version: can achieve two out of four workflow methodologies:
a) normal mode reaching into 48" bed to retrieve pieces but no slide
table, b) run around front & back split file chicken coop operation
(if software allows?),
a. Unknown if non-conveyor version can be fitted with rolling
table for front & back shuttle operations
i. Need machine specifications or
working knowledge of machine
ii. Engineering time, additional costs...
2 machines x $5000 each= $10,000
iii. Aggravation of developing proprietary
rolling tables
b. cannot do same side shuttle operation because Z axis movement
not applicable
Conveyor Version:
a. Footprint large
b. Priced beyond original budget
c. How does cutting table and downward vacuum integrate through
conveyor?
d. How does under-side vacuum system integrate with moving
pallet?
e. How can pallet/table be leveled, especially if on conveyor?
f. With conveyor, eliminates running in normal mode; conveyor
extensions cannot be removed
SEI Positives:
a. Speed & time to cut files excellent, committed cutting
speed of 2.85 minutes for LH40-30UP file (31 seconds for LH40-6UP file)
with 300 watt laser. Committed to 38 seconds for LH40-6UP file with 200
watt laser.
b. Haze free cutting can be achieved, although not proven
if methodology is burdensome
c. Fume evacuation unknown but assumed to be good
d. Machine is heavy duty (structurally), weight far exceeds
other machines
We'll there you have some of our internal notes and findings. In my opinion,
all three machines are credible. We probably short changed the SEI Mercury
(or they short changed themselves) because we were not able to physically
examine one of their machines (no machines yet located in the United States,
their first US sale was in transit at the time of this writing). We lost
our incentive to fly to Italy as our concerns and parameters were resolved
by Beam Dynamics. The SEI however, did appear to be large and bulky (with
the conveyor) for our operation.
The German Eurolaser was without a doubt a quality machine... the only
flaw being its limited workflow capabilities... there was no way we were
going to be able to integrate rolling extension tables with pallets to
this machine due to its structural frame design. In addition, a hood or
enclosure would have to be built for excavating top side fumes, as they
do not offer this option. If your operation is limited to the unloading
of large or medium sized pieces that are easy to grab quickly (versus
a table full of small pieces) from a 48" x 48" table bed, then
the workflow deficiencies should not be an issue for you and full consideration
is warranted for this machine
We visited the Beam Dynamics manufacturing facility twice, the second
time with one of our engineers whom had expertise in electrical engineering,
laser machine processes, etc. The more we got to know the machine, the
more we were impressed. This machine was designed from the ground up as
a true laser cutter. We were impressed especially with:
a. Attention to detail and well designed system shows through
out. Access to lighted work area is from front or back and has a pass
through design for material handling. Both front and rear have "drop
down" doors in additional to a traditional Lexan top. A curve to
the lid adds strength.
b. Proprietary laser firing circuit board independent of the
motion control board.
c. State of the art motion control with closed loop digital
accuracy. Optical linear encoders are used on both sides of the carriage
with the strips mounted on the frame. This gives an absolute position
for both ends which keeps the carriage square, self aligning, and adjusts
for wear over time. A part cut years from now will be the same as the
one cut today
d. 12" vertical Z axis integrated to lower vacuum cavity
e. Comprehensive drawing and cutting software can create cutting
paths or import other formats such as ACAD .dwg/.dxf, Gerber, HPGL, drilling
and routing files.
f. The focusing lens (more expensive) is removed from the
cutting area to the side of the carriage and an expendable window (less
expensive) is placed at the nozzle area to protect the mirror.
g. The electronics is thoughtfully laid out with the power
section on the right side of the machine and the electronics and laser
tube on the left side; both sides being isolated from the cutting gasses
and debris, also separating the heat generating power supplies from the
electronics
The Smart Purchase Order:
1. Freight Terms: Most vendors or manufacturers start out with a quote
that will exclude shipping burdens and expenses. The operative word here
is "burden". Freight On Board (FOB) the manufacturing facility
not only implies you own the shipping charges, but you are responsible
if the truck carrying the laser machine goes off Big Horn Mountain or
the Ship from Italy goes down. One can argue that their company's "in
transit insurance" will cover such an event. But do you really want
the burden of chasing insurance companies for claims and being vulnerable
to deductions. Most general property and casualty policies don't even
carry "in transit" insurance, this often times must be contracted
as an endorsement to your main policy. In addition to casualty in transit,
if the machine is coming from over seas, you should not face the burden
of expediting through the customs Byzantine. Force the vendor to include
freight charges to your door. Require this in the pre-quoting stages forcing
them to be competitive with their freight charges, as this could be (especially
from their perception) a make or break cost that could win or lose them
the order.
2. Laser Wattage Guarantee: There probably will be no formal guarantee,
especially against a lot of inflated sales claims. You will definitely
hear in the bidding process "our 300 watt averages 380 watts"
or "these lasers are coming from the manufacturer really supped up,
we just sold a 500 watt that outputted 720 watts.
a. The first fallacy is whether or not that 380 watt measurement
or 720 watt measurement was an "after the nozzle measurement"
or in most likelihood a direct measurement "at the tube".
b. The laser optics for these machines usually travels from
the exit point on the tube, through a series of mirrors. There are usually
4 to 6 mirrors prior to the beam optics passing through the lens. Then
there is lens diffusion and refraction, and nozzle friction. The point
here is that most laser machines will lose between 6% to 10% of their
power between their root source at the tube and their impact with the
material on the cutting table. You may want to explore these factors with
the various manufacturers.
c. When it comes time for the manufacturer to guarantee their
inflated claims of 380 watts or 720 watts in writing, they will crawl
fish! They are not able to do this; the manufacturer from which they are
purchasing will not do this. The fact is that they may be showing you
a very hot tube that they have specially acquired from the manufacturer
for demo or trade show purposes.
d. Most guarantees for wattage will only be at the manufacturer's
rated wattage, i.e. the 300 watt or 500 watt rating mentioned above. Even
at this, this guarantee may only be upon purchase, but not for any significant
period of time.
e. The solution to working around a wattage guarantee or to
relieve the anxiety that you don't get a dog for a laser tube is the "throughput
file speed" that we have been exploring throughout our analysis.
Hold out a good size percentage of the final payment to be due "upon
acceptance" and work in an acceptance paragraph into your purchase
order. Our acceptance in our purchase order read: "Acceptance: After
delivery of machines to George Patton Associates each machine will be
run for a 2 hour period cutting 48" x 49.25" x .080 thick extruded
acrylic with the film masking peeled off one side. The LH40-30UP file
shall be cut in 3.00 minutes or less. Unload time (meaning pushing pallet
of material out of machine) shall take no more than 10 seconds. **** manufacturer
shall also demonstrate a HAZE free cutting result on these samples matching
indexed pieces previously initialized by both parties". The 3.00
minute file throughput was determined under competitive conditions as
each manufacturer was competing for the purchase they were trying to submit
their best achievable results.
f. In addition to binding the manufacturer to an "acceptance"
on file speed, we also structured the payment terms so that we would give
a second deposit upon their purchase of the laser tube from the laser
tube manufacturer and upon them faxing in writing to us "the actual
wattage outputs of those tubes in advance". Between the laser machine
manufacturer having to deliver machines that cut at certain throughput
speeds and in addition publicizing their tube wattage in advance to us,
we felt they had every incentive to give our requisition some special
attention, especially as they negotiate their purchase with the laser
tube manufacturer.
3. Payment Terms: should be tailored to integrate "e" and "f"
above, final acceptance and laser tube notification. Notwithstanding,
these two points our payment terms may have been considered liberal for
some. Our payment terms were: 40% initial deposit, 25% upon receipt of
laser tubes and power test report to customer, 20% on delivery, and 15%
Net 10 days after acceptance.
4. Machine Warranty: most manufacturers will or should warrant all parts,
materials, and workmanship for a period of one year. They however, will
subordinate the laser tube warranty to the laser tube manufacturer. Make
sure this is the only subsystem part that they are subordinating the warranty
on to an additional party. Often times a warranty will not include the
phrase "manufacturer is responsible for all freight charges, shipping
charges, and travel expensed during the warranty period". There are
often fine printed phrases to the contrary... take them out! A warranty
is a warranty, why should the customer pay for a technician to come fix
a problem that was a fault of the manufacturing process and thus the fault
of the manufacturer.
5. Laser Tube Warranty: Force the laser machine manufacturer to add an
additional page or endorsement to the purchase order from the Laser Tube
manufacturer for their subordinated portion of the warranty. You need
to determine the details of replacement in the event your laser tube goes
down during the warranty period. Is the policy "send your tubes back
to us, we will examine it for 3 weeks, and UPS back to you"? You
could be down for a month! Do they have an expedited replacement policy?
Our addendum to our purchase order from the laser tube manufacturer read
"The standard target is to achieve a service exchange within 72 hours
of notification of problem in most cases. In actual practice, **** company
has received service exchange units in 24 to 48 hours". This is not
a full blown guarantee from a legal perspective, but defines an expected
covenant between parties. The results will rely on the integrity of the
parties involved, but the basis for expectationsis set in advance.
6. Power Meter: buy one, have the manufacturer put it into the price of
their quote. You will want to monitor the degradation (hopefully limited)
of your laser tubes.
This document was written by:
George Patton Associates
55 Broad Common Road
Bristol, RI 02809
Phone: 401-247-0333
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