|
Is
it tough enough for you?
Click here for a PDF
version of this article.
Can a new tool steel that machines like butter
really be tough enough to withstand the pounding that a
Tier One automotive stamping plant will put it through? We
ask an "old D-2 boy" what he thinks.
By Chris Cummings, 2001
issue of Canadian
Machinery and Metalworking
 Like most
toolmakers, Marty Puncheon of Ajax Precision Manufacturing
Ltd. in Toronto, is a skeptical man. As the toolroom
supervisor of this Tier One automotive parts supplier,
he's been around the block and knows his tooling business
as well as anybody. He is a self-confessed "old D-2
boy," loyal to the tool steel that is considered the
industry standard. So when asked to check out a new kind
of tool steel said to be easier to machine--and yet
provides a longer tool life than conventional tool
steels--he was, naturally, skeptical.But Puncheon ensured Ajax was the first Canadian plant to try
DC53 tool steel in production. He says he was as surprised as
anybody to find it significantly outperforms alloy tool steel
D-2--long the standard in the industry--in the applications in
which he has tested it.
Because of the steel's ability to withstand compression and
shock, this Toronto stamping plant reports it is getting 10
times more hits, double to triple the tool life, 30% less
machining time, much faster grinding time and 30% less downtime
when used in its progressive dies.
REDUCES CRACKING AND CHIPPING
The steel sharply reduces cracking and chipping and the
number of processes involved in the stamping industry, and
provides better hardness after heat treatment. Moreover, unlike
competing die steels, it is inexpensive, costing between D-2 and
the powdered metal steels.
The plant, one of three operated by Ajax Precision
Manufacturing Ltd., mainly makes automotive parts for the Big
Three car companies. A Tier One supplier to General Motors, Ajax
is currently making almost 70 parts for the new smaller version
of the Hummer vehicle manufactured by GM in the United States.
For more than 20 years, Ajax has also made brake shoes for rail
cars. The plant has 32 presses and 24 robotic and spot welders;
it employs 205 people.
LONG-LASTING STEEL
DC53 is particularly effective in applications where
long-lasting tool steel able to take shock and not crack is
called for. Although Ajax has so far used it in several
applications, including cutting, DC53 is a general all-purpose
tool steel that can be used in forming and coining operations as
well. The steel is now being used in about 20 other
manufacturing plants and shops in Canada.
Puncheon was skeptical about DC53 when Titus Steel of
Mississauga, Ont., offered it to him several months ago. It had
no track record in Canada and he doubted anything could
outperform familiar tool steels such as D-2, which has been the
industry standard for decades.
"I was hesitant to try something new. I'm an old D-2 boy
and I'd never found anything else around. I didn't believe it
would do what they claimed it would. I was given some sample
DC53 to try out. At first, I was reluctant to say it was any
good because I watched how easily it machined; it cut like
butter. I said any steel that machines that easily couldn't be
any good. But we finished the part, had it heat-treated and
installed it in the die. I had egg on my face because it worked.
I couldn't believe it. In my 30 years in the business, I've
never seen a steel do what it did."
Chris Martin of Titus Steel points out several more
advantages of DC53 compared to other tool steels. The material
has less residual stress after EDM wire cutting. You can heat it
to 63 HRC without losing its toughness and without it becoming
brittle. You don't have to pre-heat treat or post-harden DC53
when coating using CVD (chemical vapour deposition) or TD
(thermal diffusion). DC 53 does not "move" as much as
other tool steels during these hot coating processes. So you
don't lose as much hardness. And you can save money on your
heat-treating and post-hardening processes. Welding and general
repair is much easier with DC-53 than with other tool steels.
100,000 HITS VS. 10,000 HITS
Puncheon notes that, in one particular application with D-2,
he gets 10,000 hits on the stamping press. Both DC53 and Vanadis
4 give him more than 100,000 hits but DC53 costs less.
"And it's not just the ease and speed of machining I
like: It cuts down on maintenance; you're not wearing out as
many cutters and it gives longer life to grinding wheels."
DC53's molecular construction is what makes it perform
efficiently. Its carbides are one-third smaller and more rounded
and uniform than D-2's. Because D-2's carbides are bigger and
more angular, kick-back is more likely to occur when machining
or grinding.
"With D-2, your grinding wheel will wear down faster
because of the sharp carbides in the steel," Pucheon says.
"You get heat when you start grinding on a taper. DC53 does
not destroy the wheel as fast; you still have that leading edge
which gives you a narrower cutting face, and, obviously, less
heat. So it's much better grinding. It's also easier on the
cutters when you machine it; you're not breaking up cutters or
making the cutters dull."
CAN BE HARDENED UP TO 63 HRC
DC-53, made by Daido of Japan, can be hardened up to 63 HRC
without losing its toughness or becoming brittle.
Puncheon was particularly impressed by how the steel worked
on one "nasty" 18-year-old die that has always been
awkward to work with.
"The die takes a lot of pressure: It draws about 470
tons. One small round station about 3-in. diameter takes about
400 of those tons. I hadn't found a steel that would stand up to
it. I'd used D-2, Vanadis 4, H13, S7. I've tried them all and
nothing worked. The best was Vanadis 4; I got about 100,000 hits
with it but I had to stress-relieve it all the time. It's hard
to grind or machine because it's a very tough material. DC53 did
the job," but it does also need some stress relieving, he
adds.
The steel has helped Puncheon overcome other problems.
"I have a couple of dies with developed holes. The
sidewalls are extruded but it's an irregular shape. The two dies
are the same: If they get a little dull where the flanges are
extruded, the part rips and I get rejects from the customer.
Before getting DC53, I had to sharpen the dies every two runs
maximum with D-2 punches and die-sections. So I put the DC53 in
and one die has been in and out of the press eight times and
it's still running. The parts aren't cracking; it's holding its
edge. It's giving me a better cut.
"I don't build dies, I repair them. I have presses of up
to 600 tons. The number one consideration for me is that they
have to run. When I have a breakdown it has to be repaired fast
due to the customer's needs and press scheduling. Equally
important is the quality of service; it means more than cost.
The supplier who can get the steel to me in an hour, even though
he's more expensive, is better than the supplier who takes two
days."
EXPERIMENTING WITH COATINGS
He hasn't yet tried the tool steel with protective coatings,
but plans to. "If I see a die design that looks
problematic, I'll try it (a protective coating). I'd try DC53 in
almost any application in the stamping industry. I will
experiment with coatings. I have some dies that require a
difficult draw. It doesn't matter what steel I use, the die
requires a special coating on it. D-2 moves after being
reheat-treated after coating. I can save money on the
heat-treating cycle with DC53." The steel can be coated
with PVD, CVD (chemical vapour deposition), TD and other
coatings, extending tooling life.
Ajax, a recently incorporated company, has other plants
besides the stamping plant, the firm's original site. It has a
plant nearby in Mississauga and a new 100,000-ft2 corporate head
office and stamping facility in Brampton, northwest of Toronto.
Ajax was started in a Toronto basement in the 1930s,
manufacturing compact cases and drafting equipment. During World
War II, it made munitions for the war effort, and, afterward,
began stamping automotive parts. The current owner, Bruce
Mitchell, acquired the company in 1976. The steadily growing
company employs more than 500 people.
Chris Cummings is a
regular contributor to Canadian Machinery and Metalworking.
Copyright by © Rogers
Media, Publishing, Legal Notice
|
