December 2004 •  January 2005 • Vol. XXIII No. 3 • An Arnold Publication

Cutting the Crust

Switching to an Iscar Heliturn 907 Insert Allowed Techni-Cast Corp.
to Double Its Parts Per Insert Corner While Slashing Cycle Time 33%. 

Story and photos by C. H. Bush, editor

Techni-Cast Corp. is a 50-year-old South Gate, CA-based company that uses state-of-the-art centrifugal casting techniques and CNC machine tools to produce bushings, cylinders, washers, flange castings, gear blanks, rings, and solid bar stock in sizes up to 50” O.D., lengths up to 10 feet and weights ranging from 1-4,000 pounds. For specific applications the company will modify its standard tooling to incorporate flanges, cams, hubs, off-set steps or other shapes to meet customer requirements. Its customers include aerospace, marine and the military.

“Centrifugal casting is the rapid solidification of molten metal under extreme pressure,” explains Mario Teran, programmer, scheduler and 10-year Techni-Cast veteran. “We produce our castings by pouring molten materials into a mold that is spinning at speeds up to 2500 rpm. The result is a highly refined and high-integrity casting with very low scrap rates. When people need castings that deliver strength and long service life in tough applications, centrifugal casting is often the most cost-effective answer for them.”

According to Teran, Techni-Cast is somewhat unique, particularly on the west coast, where there aren’t many competitors. The company, is a privately held corporation with 90 employees working in a 42,000 sq ft facility.

“Producing our castings is hot, dirty work and for that reason a lot of people don’t realize that it is really high-tech, too,” Teran says. “Our engineers and metallurgists are experts in producing alloys to meet almost any need our customers have. We work with aluminum, nickel, cobalt, stainless, iron, copper, basically any materials that can be combined into pourable alloys. Plus, if you need a custom material, our people can come up with it. Our quality control program is based on the requirements of MIL-I-45208 and MIL-Std-45662. With 50 years under our belts, there aren’t too many problems we haven’t seen and solved.”

How Castings are Made

The steps in producing a finished Techni-Cast product are fairly standard, according to Teran.

“Let’s pick a bushing for illustration,” he says. “Basically, the process begins when a customer tells us the alloy they want to use and gives us a spec. For instance, the finished part might have a four-inch I.D., a five-inch O.D., and will be two-inches long. So, with that in mind we’ll pick out a mold that will produce a cylinder with an I.D. smaller than four inches and an O.D. larger than five inches. We have a huge selection of stock molds to choose from, but if we don’t have one that works, we can make a new one.”

The type and size of mold chosen is dictated by the size and number of parts to be made. Techni-Cast’s standard mold is 13” long, so the number of bushings the customer wants will determine the number of pours that will be required. Meanwhile, the molded parts are placed to one side to cool.”

While parts are being cast, Teran receives blueprints with finished part dimensions and mold-size information, which lets him get to work writing a program using either SmartCam or GibbsCam software.

“Whenever I write a program, based on the dimension of the casting I get, I have to figure out which machine I'm going to use to finish the parts. I have a lot of different machines with different capabilities to choose from.”

Programming

Techni-Cast actually maintains two machine shops with a lot of modern equipment.

“Most of our machines are turning centers, since all our castings are cylindrical or ring configurations. We have several Okumas and Mori Seikis. The machines in the back shop are for the big stuff. We have a really big Warner & Swasey back there, too. Several of our machines have double turrets and several have live tooling to cut down on the number of setups. We also have a new Haas mill for other types of machining.”

Once Teran select the machine he wants to use to produce the part, programming is fairly routine.

“My program has to make sure to get enough material to machine the number of parts that I need from each casting,” he says. “Plus I allow for every cut off, depending on how wide the blade I'm using. I allow for metal stock at the end so I'm able to grab the last part before I part it off. It’s really no different than any other turning shop does.”

Cutting the Crust

If programming the machines is fairly routine, so is the turning process, but not until the problem of scale is solved.

“Our parts come out of the mold with a very thick scale on them,” says Teran. “Before we can even begin to cut metal, we have to cut through that scale and in the past, until we found the right cutting tool, that gave us a lot of headaches. That scale costs us a lot of time and money.”
Teran cites one particular part made of 316 stainless that was tough problem for a long time.

“I’m not allowed to tell you what the part was or who it was for,” he says, “but I can tell you that when we first started, cycle time for the parts was about twenty minutes. Then we started working trying to bring that down. We changed to another insert which we ran at about four hundred surface feet per minute with a .012 ipr on a half-inch cut. That insert used to give us about two or three parts per corner with a cycle time of six minutes a part. And we were pretty happy about that, because it was quite a bit of improvement.”

But then one day the Iscar regional manager asked Teran if he would like to try out new tooling in return for feedback on the new tooling’s performance.

“I told him I’d like that,” he says. “We were using a lot of Kennametal, Sandvik and Iscar tooling, and we had been really pleased with Iscar in the past. I remember the day when he showed up with their new HeliTurn system, which were double-sided inserts with four cutting edges. I took a look at it and thought, ‘This is a weird looking cutting insert.” But I decided to give it a try. Originally they only made the HeliTurn in grade 1025, which is a good grade, but my favorite Iscar grade is their 907, which we use a lot at Techni-Cast. So I asked him, ‘When are you going to make these HeliTurns in grade 907?’ He said, ‘As soon as it’s ready, I’ll bring it to you.”

Benchmarking the HeliTurn

Even though the HeliTurn was not his favorite 907 grade, Teran decided to test it against his existing tooling.

“I noticed right off the bat that I was able to make the part in 4-1/2 minutes,” he recalls. “That was a 25% reduction in cycle time, so I’m saying, ‘Hey, that’s pretty good.’ But I still wasn’t satisfied. At least I wasn’t amazed, but I did realize we could get more, if we had the right tool.”

In 2003, Teran finally received a 907-grade HeliTurn.
Teran: “The regional manager said, ‘Let’s give it a try, but let’s speed up the process. Let's go faster and feed it faster.’ So, we took the machine to 650 surface feet per minute, feeding at seventeen thousandths per revolution at the same depth of cut. The cycle time came down to four minutes per part, which is basically two thirds of what we were getting with the tool we were using before HeliTurn.”

But there were even more gains with the grade 907 HeliTurn.

“With the other inserts we were making 2 to 3 parts per corner at a higher price per insert,” Teran says. “To our surprise, with the new HeliTurn we getting five or six parts per corner, so the savings we achieved is really significant. A lower price insert, a third less cycle time and more than double the parts per corner. I’m not sure why that insert works so well, but I think it’s a combination of grade and geometry. It’s really an advanced cutting tool.”

Teran says he uses the HeliTurn for both turning and facing now, and that he looks forward to all the company’s new product announcements.
“These people spend their lives trying to make my life easier,” he says. “I’d be a fool not to listen to them.” 

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