It’s no secret that tooling is important, but can the right tooling really have a profound effect on a shop’s competitiveness and future growth? Absolutely, say the veteran machinists and manufacturing professionals at CMG Precision Machining Co. Inc. in Romeoville, Ill.
For CMG Precision Machining, discovering the particulars of this case was a sort-of detective story that centered on a vital oil field flow part and involved calling in a skilled “investigator.”
CMG Precision Machining is a family-owned, woman-run shop south of Chicago that’s been supplying high-precision parts and assemblies, in an array of metals and plastics, worldwide for nearly three decades. It provides a variety of capabilities, starting with turning, milling and grinding—holding tolerances to ±0.00025" (0.00635 mm)—and extending to tapping, reaming, sawing, deburring, shrink fitting and polishing. It also offers welding, plating and heat treating and can chrome and anodize. It deploys these capabilities in production and prototype work, engineering and reverse engineering, programming and designing.
Still, despite this formidable list of capabilities, CMG was severely challenged by the oil field flow part. This 500-lb (226.8-kg) workpiece made alternately from 17-4 or F-22 stainless steel with a hardness of HRC 30, requires several holes, most importantly a main chamber measuring 3.75" (95.25-mm) wide and 11" (27.94-cm) deep.
Few shops are equipped to successfully complete this job. CMG Precision Machining, which worked on these parts, was compelled to contract out some of the work, including the difficult main chamber operation; this, of course, took time and cut into its profit margin. That’s when the investigator, Daniel Sanchez, was called in.
Sanchez is a field sales engineer for tooling specialist Walter USA, Waukesha, Wis. His entry into the case wasn’t as dramatic as that of Sherlock Holmes into an investigation that has Scotland Yard stumped, but for CMG Precision the effect was just as powerful.
Sanchez surmised that a new type of Walter anti-vibration boring bar might provide the answer CMG Precision Machining was looking for. But it should be noted that Sanchez was no stranger to CMG Precision Machining.
“We’ve worked with Walter and with Dan for many years,” said Ragina Crim, vice president of CMG Precision Machining. “He has built up a knowledge of our operation and our issues that has been very beneficial and has proven to be a good ‘go-to-guy’ when we have difficult tooling and machining questions.”
Observed Sanchez, “Every company is different, with its own challenges and talents. You can’t take a cookie cutter approach to shops and still help them find the right solutions to their particular needs.”
In this case, Sanchez felt the right solution was the Walter Accure·tec A3000 boring bar. Why? “Conventional steel or solid-carbide boring bars are often ineffective at length/diameter ratios beyond 6 × Dc,” said Sanchez. The new Accure∙tec A3000, on the other hand, with its vibration dampening system, excels at length/diameter ratios beyond 6 × Dc. That’s the point, claims Sanchez, where conventional steel or solid-carbide boring bars often prove less capable.
Because shops are often worried—and justifiably so—about time-consuming “fine tuning” of the dampening function, Walter’s anti-vibration feature is preset at the factory, so the tool is ready for quick application. In addition, the new boring bars feature compact QuadFit precision quick-change exchangeable heads, designed to boost versatility and decrease downtime. Internal coolant delivery for optimum chip removal is another Accure∙tec A3000 feature that aims to speed production while improving surface finishes, the latter being crucially important in many oil and gas flow parts.
The Walter tools CMG planned to employ in this application included a Walter 3.75" (95.25-mm) indexable insert drill. The indexable carbide inserts featured Tiger·tec Silver coating technology designed to boost performance through its optimized microstructure and reduce residual and thermal stress wear.
First the main chamber, measuring 3.75" wide and 11" (27.94-cm) deep, was roughed out using this indexable drill, after which hardness had risen from 30 HRC when drilling to 40 HRC.
“We were then ready for the boring operations using the new Walter boring bar,” noted Crim. “We were ready to run this on our Doosan Puma 300L CNC turning center and put the proposed new application, which we had worked out with Dan, to the test.”
Lights ... camera ... action, like they say in the movie business, but this scene, like many, wasn’t about to be wrapped up in one take. Noted Sanchez, “This was a prime example of not using a conventional or cookie-cutter approach. In this case, we had to adjust running parameters (speeds and feeds) to fit the machine capabilities. The machine didn’t have enough horsepower to run at ‘recommended’ speeds and feeds, and that’s why we had to dial it back, through trial and error.
“Our first try wasn’t the success we had hoped for, so we dialed the parameters back a little bit to make it work,” Sanchez continued. In the first test, as he related, the machine was run at 335 sfm at 0.0038" (0.09652 mm) feed per revolution. It resulted in a spindle overload alarm (130 percent).
For the second test, speed was 458 sfm at 0.0038" feed per revolution. The same spindle overload resulted.
In the third test, sfm was kept the same but feed per revolution was dialed back to 0.003" (0.0762 mm). The result was “no overload alarm, but it was at about 90-95 percent spindle load.”
The fourth test was run at 458 sfm at 0.0015" (0.0381 mm) feed per revolution. “Success!” Sanchez exclaimed. It was a process and produced results everyone was happy with. The four iterations, he recalled, took less than a day.
“Now,” said Crim, “we can machine these vital parts without having to farm out so much of the work. Of course that impacts our bottom line and reduces our turnaround time. Perhaps equally important, though, is the fact that with our advanced boring capability we can now attract an exciting array of new jobs that we couldn’t compete for in the past. This puts us in a whole new competitive position.”
For information on CMG Precision Machining, visit cmgprecisionmachining.com or call 630-759-8080. For information on Walter USA LLC, visit walter-tools.com/us or call 800-945-5554.
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