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Machining a large
polycarbonate plate wasn’t the problem for this shop, it was how to hold it in
place. Taping it down worked, but entailed after-work cleaning. Then the shop
found the answer in a vacuum.
What do teenagers know? Sometimes
quite a bit. Two teens – best friends Carlos Barrientos and Lino Covarrubias –
had an interest in machining and decided to turn it into careers. They began
their own business, and today, with 30 years of machining experience between
them, own Motiv Design Group, Inc., in San Jose, CA.
“We knew how we wanted to run our
business and we are proud that we are still running it the way we want,”
Barrientos said.
As with many start-up shops, there
is the desire to own every piece of equipment available. Realizing it is easy to
get overly equipped and deep into debt, the two co-owners were careful to buy
only the machines and tools that would keep them competitive and benefit their
shop’s bottom line.
During their experience, they
learned what would work for their business and what would not. They had
experience with CNC mills, so they purchased a CNC lathe to make their business
more competitive.
“We learned that the best way to go
was to keep work in-house,” Covarrubias said.
Soon after they bought the lathe,
they purchased a CNC horizontal milling machine to expand their shops
capabilities and respond to customer demands. They realized that the worst reply
they could make to a request for a quote was not to bid because they didn’t have
the capability to do the work.
Besides the machine tools, the duo
realized that an integral part of their capability was proper workholding. For
their work, they chose the
Mitee Bite VacMagic vacuum chuck.
Going to Tape
Before buying the vacuum chuck, they tried different hold-down methods, such as
tape-down, thinking that a vacuum chuck would cost too much, considering the
extra investment needed in a compressor or pump. They knew a vacuum chuck would
be the ideal solution, but they considered the investment too daunting.
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The VacMagic workholding system allows pieces
to be held for machining without the use of clamps
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One of Motiv Design’s continuing
orders was for one of its major customers and involved tooling a 3/16"-thick,
18½"×27½" polycarbonate window. Quality was a major priority. Using the
tape-down method to hold the piece for machining caused problems. It required
applying alcohol to the tape – which would get on the part as well – using a
scraping tool to remove the piece from the work table, then removing the
protective paper which had tape stuck to it, and reapplying a new protective
paper.
If the alcohol smudged the window,
they needed to wipe it clean. Sometimes they would scratch the polycarbonate
while trying to pry the piece from the work table, reducing it to scrap.
The use of tape wasn’t as
inexpensive as they thought at first, since it involved purchasing the two-sided
tape, alcohol, and protective paper.
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Where Motiv Design once had to use
double-sided tape – and the mess involved with its use – it now uses a
vacuum workholding system to keep polycarbonate workpieces stable during
machining
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A visit to a machine tool
distributor during an open house familiarized Barrientos and Covarrubias with
VacMagic’s vacuum holding system and convinced them it was the way to go. With
the next order of the polycarbonate windows, they purchased the system. Their
biggest concern was the system’s ability to hold the 20"×30" subplate.
“I spoke to tech support at the
company and they suggested a few ideas about how to make it work,” Barrientos
said. “But, they told me our needs might be beyond the limits of the system.”
Customization
Working with technical support from Mitee Bite, Center Ossipee, NH, they made
their own subplate out of ¾” thick aluminum, following the specs for hole
locations and slot locations. They planned to use the rubber gasket that came
with the VacMagic, but it didn’t fit the perimeter of the plate, but to their
surprise, the vacuum held the material while cutting without the gasket. They
used pins to position the material in place and then remove them once the vacuum
seal is established. The VacMagic holds both the subplate and the material. The
vacuum workholding system works without the gasket.
Compared to using double-sided tape
and all that entails, using the vacuum workholding system is cost-free after the
initial investment.
The system made the job easier,
cleaner, and faster. One area where they gained efficiency was not having to
take the time to let the alcohol soak the double-sided tape to make it easier to
remove, then cleaning the subplate of tape and alcohol. It’s about 90 percent
faster to remove a finished part and load a new piece of material.
With the tape-down method, the
finished part was removed from the machine, and then placed where the tape
wouldn’t stick to anything. It required a lot of table space to keep parts from
touching and sticking when there wasn’t time to peel off the old protective
paper and apply new protective paper.
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Carlos Barrientos (right) and Lino Covarrubias
were teens when they opened their shop, Motiv Design
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Now that tape is no longer used,
parts can be stacked on top of each other without worry. Also, there is much
less part scrap since completed parts don’t have to be pried off the work table
which resulted in occasional scratches, ruining the piece. Original protective
paper stays on the piece from the start until the customer removes it, insuring
there are no scratches, fingerprints, or smudges on their parts.
The VacMagic system resulted in
about a 40 percent savings for the job. Not only has it made the work more
profitable, it lets anyone, no matter what type of experience they have in
machining to setup – and run the job. Clamping the VacMagic to the machine table
and connecting the air supply is quick and simple.
“The VacMagic paid for itself within
a couple orders,” Covarrubias said. “With it we can respond to an RFQ for a part
that can’t be clamped in a vice. Though we’ve only used the VacMagic for the one
job, we plan to build more fixtures to help speed up production of our aluminum
jobs.”
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