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Large Part Expertise

There are many trends happening in gantry milling these days including custom fixturing, larger and larger bed sizes and, as is the case with all machine tools, innovative tooling solutions.

Larger beds invariably mean longer and heavier parts being machined and this, in turn, raises the importance of fixturing. Fixturing is a very important part of being able to machine accurately and if a part is not fixtured properly, vibration can also cause a poor finish.

"If you don't have a rigid fixture then you also don't get the tool life and you'll end up breaking tools," said Joe Lipsett, president of Quickmill, the Peterborough, Ont., gantry machine center manufacturer.

Another hurdle that fixturing face is the logistics behind fixturing large, sophisticated parts. That is where a manufacturer needs to supply engineering design solutions tailored to specific tasks.

"We've done a lot of turnkey fixturing for some really unique applications," said Lipsett. "It becomes a challenge when you have these very, very large parts. You have to find ways to quickly get a part into place, rotate it and clamp it back into place. This is where custom-designed fixturing becomes an important part of the entire application."

There is more and more sophistication going into tooling, such as the emergence of carbide tooling. These machines are also moving towards higher RPMs and faster cutting speeds. "We used to see big heavy cuts, just hogging over the material and now the idea is higher RPMs and higher feed rates," he explained. "And, of course, sizes are getting bigger. We offer cost-effective solutions on large machines so we have also seen people buying larger and larger machines."

As the beds increase in area, the parts that are machined are also growing in size. This in itself can cause problems in the machining process.

"What we've been able to do with a lot of our customers is what we call 'flip-flop' machining," said Lipsett. "On one end of the large gantry machine, you'll set-up, while the other end is working."

With a fixed table style gantry machine, you are also not limited by the weight of the part that you can put on the machine.

Whereas some of these machines that have a moving table are limited by the weight of the part that can be machined.

According to Lipsett, it is also easier to load and unload the machine when there is a fixed table.

"The key difference between horizontal and vertical machines is, of course, spindle orientation," he said. "But comparing axes travel, our gantry machines are often less expensive than horizontal machines."

The company manufactures three product lines; the Eliminator for large part milling applications, the Intimidator for heavy drilling and mid-range milling applications and the Quickdrill, a machine designed for intensive drilling. The milling machines are equipped with a Fanuc control, while the drilling machine is equipped with a PC-based control. The milling spindles are a Ram type while the drilling spindle is a quill type.

"The key thing with our product line is a large part of machining," noted Lipsett. "And that is why a gantry style machine is a real option for people who have very large parts that need the precision of machining all in one set-up."

The industries served by this type of machine are varied, being effective with machinery manufacturers, job shops and even defense and aerospace.

"One of our Quickdrills is being used to make communication towers for submarines out of titanium," he said.

Gantry machines from the company come in many sizes. Quickmill designs and builds machines from 36 to 200 inches wide and from 60 to 824 inches long. The gap from the table to the bridge can range from 15 to 72 inches depending on machine type and size.

With a wide range of sizes it follows that there is a wide range of applications possibilities. Quickmill's gantries are applied in such industries as heat exchanger manufacture, bridge, and structural steel, machinery manufacture, digital transmission poles, defense, job glass, composite materials precision equipment manufacturing and aircraft.

When dealing with parts of a large size, and particularly when you're dealing with expensive materials like titanium, the shop cannot afford to make a mistake in the machining process.

"With some of our customers, if they make an error in machining, it can create a $250,000 piece of scrap. This makes accuracy truly important," he added. "Accuracy can be achieved by a couple of different methods. We use HEIDENHAIN scales on our machines to ensure accuracy."

Once the machine is built, in order to prove the accuracy, the company uses a sophisticated laser system for leveling and compensating.

"You send the machine to a point, then check this with a laser to determine where the machine actually is and you record that, this is then entered into the computer," he explained. "We have to make these machines as accurate as possible when we build them."

Service has always been a major part of Quickmill's mission. Over the last 20 years, Quickmill has gained a solid reputation for exceptional factory-direct customer service. Our service and installation technicians also build our machines so that they are always current and sensitive to our end-user customer requirements.