A turn for the better

Turning technology is set for some big changes. The regulatory environment is expected to transform manufacturing, with environmental considerations resulting in new practices. At the same time, the turning technology of tomorrow will be responding to industrial pressure, with specific sectors forcing advances in cutting tools and materials, much as they do today.

One example is the diesel engine in the auto industry, which has increasingly demanding standards.

“Dump trucks and semis aren’t allowed to send out as much black smoke as they used to,” says Don Graham, a manager with Seco Tools. “The grey iron engines currently in existence can’t run at a high enough combustion pressure in the cylinders.”

As a result, Graham expects higher auto sector demand for compacted graphite iron, given its greater strength and lower weight. These two issues – strength and durability – will also be at the fore of innovation in aerospace, which will rely on more thermal resistant materials.

“When you look at aerospace, you can see increased interest in burn-resistant titanium alloys, as well as gamma titanium aluminides,” says Graham.

There will be a much higher use of composite materials in aerospace, too, particularly ceramics and metals. These are difficult to turn, and the challenges will only increase. A good example is Boeing’s 787 Dreamliner, in which the fuselage is assembled using composite barrel sections instead of multiple aluminum sheets.

“The Boeing 787 has a much higher component of composite materials, with graphites for the primary structure combined with a lot of titanium,” says John Sullivan, director at the Center for Advanced Manufacturing at Purdue University in West Lafayette, Indiana. “There will be a lot of ceramic/metal composites – we’ll see them in commercial engines in the not-too-distant future.”

Sullivan says that in a decade’s time there may actually be a reduction of machining requirements.

“As things progress, there may be less machining, but the machining that will be there will be more intricate,” says Sullivan. “When you look at turning operations, it’s been around for an awfully long time, and we are still making improvements. Traditional approaches will evolve to address hard materials.”

These tough materials will require better carbides and coatings to support faster speeds, meaning that the reliability of tool materials will be challenged. At present, there are still challenges with chipping upon contact with titanium. One expected solution: increased use of ceramics. Tool makers, already integral to addressing the challenges faced by new materials, will have increased significance as we enter this new era.

“I think toolmakers will be even more relevant in the future,” says John Reeb of SMTCL Canada. “The materials will be more exotic, and will require more specializations.”

To address the tooling challenge created by these new materials, academic institutions like Purdue are working with some of the bigger tooling companies to look at coatings. They are bringing some incredible scientific advances to the table. The result will be more coatings designed for more precise applications, like Seco’s Duratomic technology, which arranges aluminum and oxygen atoms for better toughness and abrasion resistance.

“Structured coating at the atomic level is analogous to a piece of wood – it is easy to split along the grain, but if you tilt it will resist,” says Graham. “This is called anisotropy, wherein materials have different properties in different directions. We can tilt aluminum oxide to make it harder and tougher – actually 15% tougher and 10% harder than the previous generations.”

Advances like these, wherein coatings and materials are addressed at the level of nano-technology, will result in more application-specific tools.

“It was a black art to put these together twenty years ago, but now coatings are advancing at the atomic level,” says Sullivan. “The result is that we can move to more and more specific coatings.”

This is true in medical applications, for example, where there is a lot of pressure to extend the life of surgical implants and where turning small, hard parts is crucial. At present an artificial knee will only last 10 to 15 years, which means that some people will have to go through more than one procedure. Here too ceramics will be important, and difficult to machine, which will inevitably result in more innovation on the cut.

“From a tooling perspective, people are looking at machining ceramic bearings, as well as other components, by utilizing laser-assisted machining,” says Graham.

As it stands, super-accurate cutting with wire or water, and on more than one axis simultaneously, is already an advance on the past, when several different machining operations were required. There will always be limits to how fast a piece can be turned without risking throwing the part. That’s why multi-function capabilities, usually within a machining centre, will only be more popular in the future.

Green machines

Though many CNC turning machinists and business owners think that environmental concerns are something of a fad, the side-benefits of increased efficiency and material retrieval, as well as a more strict regulatory environment, will change the look of turning in the future.

“We will see more dry machining, with no coolant whatsoever,” says Graham from Seco. “In Germany, Austria, and parts of Italy they have pretty much banned the use of coolant. Our new tools have dry machining in view.”

The two motivations for getting rid of coolant are cost – from 15% to 25% of the cost of a finished part can be attributable to coolant – and the environment. Many people believe that tremendous changes with coolant over the years, and the shift away from soluble oils, have created coolants that are environmentally sound. But the cost argument is still a factor.

“A lot of new coolants are environmentally friendly,” says Graham, “but there are costs associated with monitoring and disposing: in California it costs $3,000 for a 55 gallon drum, and in Michigan $1,200.”

So, one way or another, we can expect dry machining to be part of our future, though that future is some years out. And we can expect the supply chain to force changes on smaller suppliers.

“Green can help with the cost side of things, and reducing waste along the supply chain,” says Darryl Short from Karma Machining & Manufacturing Ltd. in Edmonton, Alberta. “Companies are taking it upon themselves in order to be more strict internally so that they can satisfy external clients.”

Go big or go home

In the future, turning will have to functions at extremes – in very small applications, such as are found in the medical industry, and with large parts in aerospace, wind, and oil and gas.

“Oil field applications call for larger diameters, and longer lengths,” says Short from Karma Machining & Manufacturing. “There are people who specialize in gigantic vertical applications – we are going to have to get into longer pieces and bigger diameters.”

And though vertical turning is seen as something of a niche market, it may have an important role to play as the future demand for large parts grows.

“When you have a heavy part that has to be turned you are better off on a vertical axis,” says  John Reeb from SMTCL Canada. “The weight is more evenly distributed – it is much more stable on a vertical axis.”

Wind is another industry that is growing, and that points to future demand in large, high value parts.

“Wind relies on big, heavy gears,” says Graham from Seco. “We work with the wind industry using cubic boron nitride (CBN) tools and composites for the blades. It is so expensive to build those things, and so expensive to get the turbines in the air – you don’t want to do any repair work up there.”

There are even people who are building lay-up machines for very large structures, in which a composite – basically a liquid cloth – can be used for wind turbines and even aircraft. Clearly, the need to address size issues, both big and small, and a new era in materials, will put pressure on multi-function machines to perform more varied tasks faster. What that will look like, only the future can tell. CM

Tim Wilson is a freelance writer based in Peterborough, ON and a regular contributor.