Damage to the tool is breaking the rules

Damage to the tool is to break the rules.

Although this maxim seems to be contrary to intuition, it is a successful way to increase the rate of titanium removal. Titanium, like Inconel and other special materials, is widely used in aviation and military fields. Michael Allawos, president of Mikana Manufacturing, Inc., in San Diego, Calif., knows very well: “Our company was founded in 1985 to serve the aviation industry,” he explained. “We strive to find a unique material that makes parts that are difficult to machine from those that are difficult to machine.”

In the past few years, the price of aerospace metal materials has skyrocketed, making material costs more and more important in the profit-loss equation. To reduce costs and remain competitive, Allawos found that Mikana must speed up production. He had to cut titanium and Inconel more quickly, which meant that reforms had to be made.

Allawos knew that machine tools and machining processes were the only solutions. He started looking for a tool company and hoped they could help him create a new way to cut titanium. In the end he found a perfect partner: Hanita cutting tool dealer, Jonathan Saada of Thousand Oaks, California and his partners.

“This is a tripartite partnership!” Jonathan Saada said loudly, referring to his three companies, his company, Mikana and Haas Automation. Saada offers innovative tools and Mikana provides the platform and expertise to test these new ideas. Thanks to the stability of the Haas machine itself and the support from the Haas maintenance engineers and the Haas plant, a Haas VF-2 with a high tension lever became the test machine. The result of their collaborative innovation has overturned the cutting theory of many difficult materials.

Most of Mikana's workpieces are made of hard Inconel or Titanium, which are traditionally processed at lower feed rates. “The rate of removal of processed materials is measured in cubic inches per minute,” explains Allawos. “This is often used as a measure of profit or loss. Faster cut rates and longer tool life mean higher throughput, and some of the parts we produce need to cut a lot of material. These are all related to reducing cycle time. ”

So how much material is removed? Allawos lifted a large piece of titanium 6-2-2-2-2 and a hollowed out titanium box. “Have you seen it?” he asked. “This thin piece of work was machined from this big guy. As you can see, 90% of this big guy was cut off, and Titanium 6-2-2- 2-2 is harder than other types of materials.” But it is incredible that the feed rate of the cut material is unimaginable to most mechanics. Most of the cutting is done at a feed rate of 80 to 90 inches per minute!

Saada and Allawos decided to use a practical approach to solve the problem of slow feed rates. “When we started the project,” Saada said, “I promised Michael that he didn’t have to pay any tool costs until the tools proved their worth. But we wanted to know the limits of the new tool, so We brought it to Mikana's production manager and asked him to break it. We did this for every new tool we tried, recorded the results, and reached a higher feed rate."

“I encourage my staff to come up with new ways and new experiments,” Allawos continued. “If we find a good result, then the cost savings can make up for the entire process. We record everything, and We have achieved amazing results. We now have mastered this technology, which allows us to achieve excellent results using cutting speeds and feed rates that are much higher than the cutting tool manufacturer's recommendations, especially in cutting Inconel and Titanium. aspect."

“There are three factors that make an excellent titanium cut,” Saada said. “The first is the tool. To eliminate the noise, we use a variable helix angle tool called Varimill to break the resonance. It has an aluminum nitride titanium coating that dissipates heat.”

“The second factor is the use of copy milling,” Saada continued. “Using the tip of a spherical end mill to machine the radius. Third, we use the thinning chip effect.” Thinning chips mean most of it. The cutting edge makes light contact with the workpiece to achieve a large depth of cut.

“By using coated tools, we were able to cut 80 to 90 inches per minute for titanium 6-2-2-2-2,” explains Saada's companion, David Buchberger. “When you say that people who are used to machining titanium at a speed of 4 inches per minute, they can process up to 80 inches per minute, he will definitely go backwards and wave his hands and say it is unbelievable. Then you go to him. Show, in fact, can do this completely, he will be deeply shocked."

Saada solves the work embrittlement caused by work hardening by practice. “In most cases, work hardening is caused by the pause of the tool,” he said. “People are afraid to process titanium, so they only cut 0.01 feet at a time. When they are machined to the corner, they slow down. So where is the heat? Going into the part! The work hardening becomes localized, so you have to move the tool without stopping and keep cutting. We use the method of thinning the chips, so the heat is transferred to the chips instead of the parts."

Titanium 6-2-2-2-2 is very hard and difficult to cut. The same is true for the 635 Inconel. It is the most difficult to machine metal and the tool damage is very fast. Saada took a spiral plate and a piece of Inconel on the table. “You can see how we machined this part from this alloy,” he points out. “About 95% of the alloys have become chips. We have tried carbide milling cutters, ceramic inserts and cobalt-containing tools. They wear very fast – basically no life. We finally try a powder high speed steel tool with 12% cobalt, 6% vanadium, with an aluminum nitride titanium coating, which is the best combination.” “All other End mills are extremely fragile, and cemented carbides are too fragile and fragile, so that the edges are broken,” says Buchberger. “They can only process about 635 Inconel for about 20 minutes. Now we can use more than one tool per tool. Hours, and the tool does not need to be re-coated after regrind. At Mikana, we used the same 1-inch tool to cut Inconel for up to 3 hours, most of which was full-cut."

The separate use of the tool and feedrate override does not result in efficient performance. “One of the most important factors is the high tension tension lever of the Haas VF-2,” explains Mikana product manager, Ed Lujan. “The tension of the tie rods removes all the possibility of tremors. The tremor is a headache for the mechanics when cutting materials. It is not a malfunction of the machine itself. If you are going to cut a variety of metals, then You'd better have a diverse machine tool that, like us, allows Haas machines to machine any kind of metal."

The ability to process a wide range of metals is critical to Mikana's production and future. “Although we produce parts for the F-18, F-22 and Joint Strike Fighter, things have become more and more commercial,” Allawos points out. “We work with commercial customers like Lockheed, Boeing and JPL. We probably There are 108 Rover parts that are now on Mars. Most of them are produced on our Haas machine."

Mikana's 50% products are made of titanium and inconel, they also process plastics, foam and aluminum. “It’s these tools that cut aluminum,” says Buchberger, holding a large-diameter 3-toothed edge milling cutter. “Second micro-grain cemented carbide. Some people feel that it is not necessary to cut aluminum, but its tool life and cutting speed will return its cost ten times.”

“We even use this tool to cut the floor,” adds Lujan. “We can cut floors up to 6 inches square and weigh 0.045 inches – the error is controlled within 0.005 inches. Some tools can cause cracks on the floor. This is my unique 90-inch tool per minute.”

Almost half of the processing in the Mikana workshop is in aluminum. “We want to do this with our Haas machine, because it works well on Haas machines,” Allawos commented. “It's a sturdy machine that is better suited for machining hard materials.”

Lujan says one of the biggest advantages of Haas machines is that “Haas machines operate the same. If you operate VF-2, then you can operate VF-4 or VF-8. Their controllers are the same. The factors that will have different effects on machining are feedrate override and read-ahead. The Haas controller makes difficult work easier."

“We are testing the limits here, and then we can see how fast we can achieve cutting speeds, where are the limits of these tools, machine tools and processes,” Saada said. “We support each other and then get from each other’s ideas and innovations. beneficial."

Allawos agrees. “Our innovative spirit has brought benefits to all three companies – and ultimately, it has brought benefits to the entire industry.”

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