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News
Thread grinder ensures mold shop's accuracy
B&R Grinding in suburban Chicago, IL, knows
the difference one machine can make.
"Our average job is 10 pieces, so each
piece needs to be perfect," says Rick Ruhl, a third-generation precision
machinist and B&R President.
These particular parts are steel cores for use
in plastic injection molding machines. "These threads have a tricky
lead because we have to compensate for the shrinkage of the plastic in
the molding process," says Mr. Ruhl. "We have to be accurate
in size and concentricity to one-tenth."
On some plastic closures, the thread form can
be very unusual, and beyond the capabilities of many thread grinders."Anybody
can do a 30/30 flank angle," says Mr. Ruhl. "But this Drake
CNC thread grinder is the only machine I know of that can do 45/7 angles
perfectly and is still easily set up."
Cutting time
The accuracy and repeatability built into the Drake GS:TE (Grinding
System: Thread External) aim at saving time and money. "One job
we had was a foot-long carbon rod that needed 100 grooves. Size and
spacing were critical. Our Drake cut the grinding time from five hours
to twenty minutes. And the result was perfect."
Minimizing scrap is another benefit provided
by the programming built into the grinder by Drake's Systems Engineers.
"That's important, because when you think about it, ground parts
are normally expensive parts," says Rick. "On a chuck gage,
our scrap rate was previously 2% to 3%," says Mr. Ruhl. "Now
it is 0%."
In fact, B&R performance has been so good,
some of their customers can't believe it. "Abbott Laboratories
has told us we're setting new standards for thread grinding," says
Rick. "We've made 3,000 pieces of three start screws for a laser
surgery machine. No burrs, flank angles were perfect and the finish
was incredible--an 8 micro-inch finish--6 is close to a mirror finish."
Dress for Success
"CNC contour diamond roll dressing is the way to go," Mr.
Ruhlsays. "A single point doesn't compare. When you use a square
corner roll, you can dress the root flat, flank angles and crest radius,
or angles all in one pass."
According to Mr. Ruhl, even new operators
can make perfect parts. "All they have to do, he says, is make
sure the parameters they enter into the CNC correspond to the customer's
print. It is surprising how many thread grinding secrets are already
built into the control."
Good service enhances machining advantages
at any time. This is true at B&R. "Once I couldn't get a diamond
roll for two weeks," Mr. Ruhl recalls. "Drake sent me a spare
overnight at cost. When my old J broke down, they stripped parts off
a carcass and sent them to me--no charge. That's incredible."
Buying his thread grinder through Drake's
representative--Bruders Machine Tools in Milwaukee, WI--has proven to
be a good move for B&R. But making the decision to purchase it was
tough. A year and a half later, Rick bought a second Drake GS:TE.
| Dress
for Success
"CNC contour diamond roll dressing is the way to go,"
Mr. Ruhlsays. "A single point doesn't compare. When you use
a square corner roll, you can dress the root flat, flank angles
and crest radius, or angles all in one pass."
According to Mr. Ruhl, even new operators
can make perfect parts. "All they have to do, he says, is
make sure the parameters they enter into the CNC correspond to
the customer's print. It is surprising how many thread grinding
secrets are already built into the control."
Good service enhances machining advantages
at any time. This is true at B&R. "Once I couldn't get
a diamond roll for two weeks," Mr. Ruhl recalls. "Drake
sent me a spare overnight at cost. When my old J broke down, they
stripped parts off a carcass and sent them to me--no charge. That's
incredible." |
 |
Buying his thread grinder through
Drake's representative--Bruders Machine Tools in Milwaukee, WI--has
proven to be a good move for B&R. But making the decision to purchase
it was tough. A year and a half later, Rick bought a second Drake GS:TE.
"On a conventional thread grinder,
I could aggressively grind at 9 rpm. Now with the Drake, I grind at
22 rpm. With the type of grinding I do, that's very aggressive--I still
get two-tenths on size and concentricity."
Currently, Mr. Ruhl is getting ready for a
third Drake--this time a GS:TE 12 x 45 external thread grinder to further
expand his capabilities. "This time," he says, "I won't
be losing any sleep over buying the machines or the way they perform."
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