This aluminum motorcycle wheel hub starts out as an aluminum casting and is processed completely in house by Ward Corp., which machines more than 300,000 lb of aluminum a year. Coolant is CIMSTAR® 3800 by Milacron, Cincinnati (OH).

You invest in the best machine tools and tooling. You exercise dogged control over each process parameter.You meticulously monitor the materials you machine. And yet you still have an annoying scrap rate that seems without cause. What do you do?  Try changing your metalworking fluid.

FORT WAYNE, IN — Fairris Dean is Machining Division manager at Ward Corporation, a major supplier of aluminum parts and components to the automotive, marine, motorcycle, recreational equipment and heavy truck industries. The company is entirely vertically integrated (there are four divisions — pattern/engineering, foundry, machining, and heat-treat), allowing complete and total control over process and quality. Raw ingots literally come in one end of the company and finished aluminum parts and assemblies go out the other.

So when Dean attempted to fix a persistent  — and erratic — tapping problem (resulting in an unacceptable level of scrap), he found himself searching for, and not finding, a cause.

“I looked at everything,” Dean says, “all the process parameters, and not only did nothing jump out as a cause of the problem, there appeared to be no cause whatsoever.  There was no discernable pattern, no rhyme or reason.”

Fairris Dean (center) and two Milacron representatives discuss a part with the erratic threading problems.

Beginning at the beginning

Dean says that annually some 300,000 lbs. of aluminum are machined by the division, which employs 50 and runs three shifts, five days a week. Machining takes place in 100,000 sq. ft arranged on three floors of a five story 80 year-old building. As many as 486 different part numbers are machined each year in runs ranging from 200,000 pieces to 100 pieces. Process operations include milling, drilling, tapping, reaming, finish turning and form tapping.  Actual stock removal varies up to 0.750″. Typical materials are 356 and 319 cast aluminum.  Tolerances are consistently tight, in the 0.0007″ to 0.0005″ range.

There were four jobs where the erratic tapping problem occurred.  A gear housing, two fuel filter heads and a transmission case. All four of the parts had numerous threaded holes and tight tolerances on true position.

“On the gear housing,” Dean says, “we were holding 0.0007″ true position off a 2″ datum bore over a length of 14″.  Holding 0.0007″ on a piece that long is really very tough: the aluminum tends to stress, to warp and to bend, and to spring back from the hydraulic fixture. Fluctuations in temperature can radically affect it, too.  This is an expensive part, and a six to seven percent scrap rate just was not acceptable.  To try to get at the root of the problem I had to begin at the beginning, at the base line, and work backward.”

Dean notes that the nature of the tapping problem was particularly frustrating: they would run three good threads, and then the fourth would rip out. Then numbers five, six, seven and eight would run fine, only to have number nine rip out or go over-size.  Then ten and eleven would be okay, but twelve would fail. And every parameter checked seemed to be exactly as it should: the tooling was fine, the tapping feeds and speeds were fine, the fixture and machine were fine, the coolant flow was fine — and yet the rip-out or over-size problem kept occurring, with no predictability.

Out of the box

Dean says that with a tapping problem in aluminum it’s natural to look into the mechanics of the process for a cause.  But when that failed to produce a result, he began to “think out of the box” for an answer. The alternative — accepting the scrap rate and living with it — was a position Dean was unwilling to accept. He began to suspect that the tooling was gumming up and sticking, resulting in torn and oversize threads. His focus now became the metalworking fluid used in all four jobs.

The unexpected

“I contacted our local industrial supplier, Specialty Tool a Milacron distributor, and asked if there wasn’t a fluid with better lubricity than what we were using, that was designed for aluminum work and specifically tapping,” Dean says. “They said that Milacron in Cincinnati (OH) was just then bringing a CIMCOOL® metalworking fluid product out of R&D, a new addition to its 3800 Series, CIMSTAR® 3890, which might fit the bill.”

Milacron paid Dean a visit and introduced him to CIMSTAR 3890, a biostable, chlorine-free, high-lubricity fluid specifically formulated for aluminum machining, threading and finishing applications.  The two agreed to a controlled test on a single machine.  Nothing was changed for the test — same machine, fixture, tooling, speeds, feeds — except the fluid.  The results, Dean says, were nothing short of remarkable.

“I’ve been in the trade for 25 years,” Dean says, “and during that time I’ve had people try to sell me everything from allen wrenches to multi-million dollar robotic systems. But whatever the product, the proof has always been in the performance, and that’s what we’re now getting with CIMSTAR 3890.”

The aluminum gear housing being machined on a high-precision HMC. The fluid is CIMSTAR® 3890. The thread problem disappeared and the scrap rate fell to nearly zero.

Dean reports that his scrap rate for the gear housing has fallen from six to seven percent to less than one percent.  The thread problem has simply disappeared.  Tool life has increased a full 12 percent.  And he’s seen a significant increase in productivity.  “I’ve been able to increase my feeds and speeds,” he says, “where before, because I was ripping out threads, I had to slow the machines down.  Now we’re running up where we should be.”

Dean also notes that he’s able to “recycle” the CIMSTAR 3890, which saves time and money.  “I can just keep making up the system,” Dean says.  “Usually the water evaporates before I have to do anything.  Then, we just add more water and concentrate, then adjust the fluid concentration to the proper refractometer reading.  We don’t have to completely flush the entire system as we do with other fluids — disposing of the spent fluid, cleaning out the sump, adding new fluid and recharging the system.  With the CIMSTAR 3890, we just recycle and add makeup with no resulting loss in fluid effectiveness.”

The aluminum gear housing where threads erratically tore out or ran oversize, resulting in an unacceptable scrap rate. But, what was the cause?

Paying for itself

“Our customers are pretty intolerant of defects, and very understandably so,” Dean says.  “They’re pushing for 100 parts per million — not just for the Machining Division but for the entire corporation, and for a foundry, heat-treat and machining facility, 100 parts per million is a very big issue. Everything we do has to work toward eliminating any potential for error, and that includes even the seemingly small stuff — like solving what appeared to be an unsolvable thread tapping problem.”

Dean notes that the Machining Division is today entirely a Milacron shop.  He uses CIMCOOL CIMSTAR metalworking fluid 3800 on all the other machines and the CIMSTAR 3890 on three high-precision horizontal machining centers that run the tough threading jobs.  And even though the CIMSTAR 3890 costs more than the CIMSTAR 3800, Dean says it’s completely worth the investment — in fact has more than paid for itself in extended tool life and the elimination of thread-related scrap.

“You know, it takes just as much money to run bad parts as it does to run good ones,” Dean says.  “Same operating costs, same labor costs. But no one wants to run bad parts.  In this business you get the performance you pay for.  We buy top of the line machining centers, fixturing, tooling and fluids.  And the proof is down on the floor, with the operators.  Their reaction to the change in fluid?  ‘Wow.  No odor, no skin irritation, no spotting or finish problems — and no more torn or oversize threads.  Wow.’

“That’s all the proof I need.”

Note: For more information, contact Milacron at 1-888-CIMCOOL or visit www.cimcool.com