MP & P FINDS
WINNING FORMULA FOR BETTER ROLL
GRINDING;
"MORE FORGIVING"
METHOD EXPANDS CAPABILITIES,
FLEXIBILITY
Do you do a lot of cylindrical
grinding and wonder whether to
switch from hardwheels to belt
grinding? Just look at the
experience of Mirror Polishing
and Plating Company (MP&P),
Waterbury, CT and make up your
own mind. All the new machines
are by
Ecotech.
 Twenty
hours a day, 5 days a week, the
company grinds, polishes
and plates industrial mill
rolls - including challenging
thin-wall rolls
-- for the paper and film
converting market. MP&P has
earned
such a reputation for quality,
turnaround time and good prices
that
it is in a constant state of
expansion - especially for
thin-wall
work. In response, the 40 man
shop just started up one more
cylindrical grinder, has another
on order and plans
to buy two more over the short
term.
Moving
To Belt Grinding
"All the new equipment has belt
grinding attachments," says Rich
DuPont, vice president and
general manager at MP&P.
"Compared with traditional
hardwheels, belt grinding is
more forgiving and cost
effective. With it, we turn out
quality work more consistently,
and with less skill dependency.
Put another way, more of our
people, of varying skill levels,
can productively turn out
quality work. With such
flexibility, we balance the
workload better and improve
deliveries."
Mr. DuPont's experience can also
give you peace of mind about the
"quality issue" with some
grinders coming in from China.
Their last two belthead machines
have been
Ecotech
model H-147s. Same
machines, different nameplate.
The one on order is the same
machine but with a new brand
name:
Ecotech H-147/4000. The
additional two machines will be
Ecotech
grinders as well.
"At first, we had the same
misgivings about Chinese
equipment as the next guy," says
Mr. DuPont. "Support, spare
parts, workmanship, we'd heard
the horror stories. But we
decided to take a closer look
anyway. Frankly, at a 20-30%
price differential vs. similar
equipment, we couldn't afford
not to."
Obviously, Mr. DuPont is glad
they did. Taken together, the
switch to belt grinding on the
Ecotech
machines has cut MP&P's
grinding costs about 20%. It
also opened up an emerging roll
market, simplified operations,
reduced risk and enhanced
flexibility in scheduling.
After a year's running with the
first
Ecotech grinder
and a couple of months with the
second, the quality has been
"excellent," Mr. DuPont states
flatly. The machines come so
fully equipped, MP&P starts them
up the day they arrive. He also
rates
Ecotech's support
outstanding. “Quality and
'over-the-pond' support may be
legitimate issues in equipment
coming from Mainland China,” he
adds, “but not with
Ecotech
grinders."
Small
Shop, Global Thinking
"Don’t get me wrong," says Mr.
DuPont, "this isn't a commercial
for a particular brand of
machine. Rather it's a
suggestion to not be controlled
by rumors or prejudice when
shopping for capital equipment.
Look into each offering case by
case. It's a big, competitive
world out there. It offers even
the small job shop a lot of
sourcing options, provided you
think globally and keep an open
mind."
Belt
Grinding Principles
In principle, belt grinding is
much like belt sanding but a lot
more accurate and
sophisticated. An abrasive belt
running on very precise rubber
drums replaces the traditional
hardwheel and wheelhead. Moreover,
the rubber contact drum
'cushions' the operation, making
the process more reliable and
forgiving. There are fewer
things to go wrong. And if
something does go amiss because
of a renegade grit or operator
error, the damage is less
serious and easier to fix.
Case
In Point
A typical MP&P job is
refurbishment of a 12-in. dia by
5-ft long chromium-plated steel
pressure roll for a film
laminator. Purpose: restore
accuracy and mirror finish to
the worn rolls. Hardness is
Rc64. The process involves
stripping off the chromium
coating ("pre-grinding"),
re-plating and finish grinding
("post-grinding.") Specs
are +/-0.0002 in. on
diameter and roundness. "Two
tenths round and straight, as we
say," adds Mr. DuPont. Spec on
finish is 4Ra or better.
Pre- and post-grinding remove a
total of 0.020 in. on diameter
in a series of 0.0002-inch
passes, all done with synthetic
coolant. Pre-grinding takes
about six hours and finish
grinding slightly longer. Both
involve one belt change, from
rough to finish. Turnaround
time for the job, including
plating, is ten days or less.
Other jobs may involve plain
steel or ceramic coated rolls
ranging up to 25 in. dia by 160
in. long active lengths. On
ceramic-coated rolls, the
procedure is the same. MP&P is
moving toward belt grinding for
all their work.
Why Belt?
Belt grinding improves roll
fabrication and repair several
ways, according to Mr.
DuPont. "First, today's belts
are fundamentally of more
consistent quality than
hardwheels - no renegade grits
to gouge a roll surface.
Immediately that reduces risk
and rework time. On both a unit
and per-part basis, belts cost
less than hardwheels yet remove
material as fast or faster."
That plus the ease of use of the
Ecotech
grinders means MP&P can
more readily train and use more
of their people on the job.
This benefits scheduling and
utilization greatly.
Even if the operator takes too
deep a cut, the rubber contact
drum absorbs the excess loads,
protecting the workpiece, belt
and operator. All the
consequences of a damaged wheel
running out of balance or
exploding simply disappear.
"The more forgiving action of
belt grinding is especially
important on thin wall rolls,"
Mr. DuPont adds. "When the
workpiece wall is only 1/2 in.
thick and easily deformable
under overload, there's simply
less room for error,” Mr. DuPont
continues. With hardwheel
practice, he had to reserve
thin-wall jobs for the two or
three most experienced
operators. If someone was out
sick or on another shift, the
job would have to wait. With
belt grinding on the
Ecotech
grinders, the company can
turn that type of job over to
any of its operators on any
shift with complete confidence.
The company has done so on the
original
Ecotech
grinder which is set up
for belt grinding and hasn't had
to scrap a job yet, regardless
of which operator is assigned.
Belt changes also go 40 minutes
faster than hardwheel changes.
That difference alone saves
about two hours per job. At
eight to ten changes per day
shop-wide, MP&P saves 4-5 hours
per day in machine downtime and
labor vs. hardwheel grinding.
That frees enough time to start
another job each day and
complete an extra three jobs per
week. Belt changing is much the
same as on a belt sander. Slack
the tension, swap
belts, re-tension,
re-start.
Standardizing On Equipment
Mr. DuPont orders
all
Ecotech grinders equipped
with beltheads and all optional
equipment. The basic model
H-147 cylindrical grinding
machine features a 25 x 160-in.
work envelope, six-speed pulley
workhead, hydrodynamic spindle
and digital readouts. An
automatic pickfeed reverses the
feed at the end of each pass.
Behind-the-wheel dressing, wheel
balancing and manual swing-down
part gaging are built in.
Hydro-cyclonic coolant
filtration prevents swarf reflux
and extends coolant life 16 to
1. Hydrostatic lubrication of
table and wheelhead ways provide
smooth, precise, non-stick
operation.
"With such a simple machine,
even less skilled operators can
concentrate on finishing the
part correctly rather than
'driving the machine'," comments
Mr. DuPont. "For our 'one-off'
type of operation, we’ve found
the ideal balance between
simplicity and sophistication,
giving us the highest efficiency
and machine utilization for
quick job changeover. We're
making chips 20% more of the
time than on comparable
grinders, which is as it should
be."
Winning Combination, Competitive
Edge
"Belt grinding on
Ecotech
grinders gives us a
winning combination of method
and equipment for a real
competitive edge," concludes Mr.
DuPont. "That combination cuts
capital cost 25-30% and cost per
job by at least 20%, reduces
risk and enables us to handle
rolls more effectively. That
makes financial as well as
strategic sense. And whenever
you can get the job done for
25-30 percent lower capital
investment, your return on
capital and balance sheet
improve along with the P&L.
That's our case exactly.
Although I may be the guy
helping to keep this going, hats
are off to our president, Gary
Walband for his decisions to
move in the direction of
Ecotech
and belt grinding.”
For
more information, contact Curtis
Gibbs
Ecotech
Machinery, Inc.,4220 Wayside
Court, Lilburn, GA 30047. Phone
(770) 279-2001, Fax (770)
279-2102.
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