High speed milling has been with us for a while now. However, it hasn’t quite had the impact it could have had. Matt McDonald looks at why a lot of manufacturers are still wary of high speed techniques and what can be done to ease their fears.
High speed milling isn’t the easiest concept in the world to define.
“There are a lot of factors going into it,” Prashant Gokhale, CNC Machine Tools Manager at Applied Machinery told Manufacturers’ Monthly. He explained that having the right machine and spindle are parts of the equation, but not the whole story.
He added that high speed milling also involves using software with a ‘look ahead function’. This enables the machine “to read multiple lines ahead to be able to perform those operations smoothly.”
“And you need to have the right tools for it as well and the right cutting conditions including your coolant.”
So high speed milling involves several components and, in its early days, was seen as complicated. In fact, according to David Morr, Technical Manager at Seco Tools Australia it was over-complicated.
“The high speed milling strategy promised a lot of things to a lot of people,” he told Manufacturers’ Monthly.
But, according to Morr, people have now realised the concept is really about things like small actual cutting depths which produce small chip thickness.
“And when you produce a small chip thickness it comes back down to using your milling tools in an appropriate fashion,” he said.
“When you’re actually side-milling, using only say five per cent of the cutters width or even two per cent of the cutters width, you really can begin to start using the milling cutters into the high cutting speed strategies.”
By using such a technique, he explained, you can actually start to increase cutting speed and feed to compensate for that average chip thickness being reduced to such a small level.
In addition, there’s more contact time and therefore it is possible to increase the cutting speed to ensure that there is enough heat in the cutting zone.
“I think the strategy behind high cutting speed milling is really about reducing your chip thickness,” Morr said. By reducing chip thickness you can improve efficiency and productivity.
High speed milling does involve a lot of components and you need to know what you’re doing to successfully use the techniques, but it doesn’t have to be over-complicated. Since the early days, it has become a lot simpler and it shouldn’t be approached with excess caution.
Nevertheless, a lot of businesses that could be using high speed milling techniques aren’t. And they are missing out. And, in addition, a lot of manufacturers just aren’t getting the best out of the machines they have.
The issue of cost
According to Gokhale, the major reason for this is the initial cost. He explained that, given the difficult times manufacturers are now facing “...the initial costs of these machines and tooling them up properly is high. People are using yesterday’s technology to do today and tomorrow’s job. And a lot of people are using second hand machines.”
“People can’t justify buying a good machine,” he said. And they can’t justify buying the correct tooling and software to go with it.
However he believes that, while the initial costs may be slightly higher, in the long term the benefits will outweigh the costs.
And on top of costs, said Gokhale, it is also a matter of education.
“A lot of customers aren’t aware of Trochoidal milling or high speed milling team strategies or push-pull strategies. There are a few different ways of high speed milling and unfortunately a lot of people aren’t aware of these things,” he said.
Morr expressed similar views. Though in his opinion, price is less significant.
“I think price is always a factor in a lot of new technology but I think it really comes back down to what the customer is actually machining. If they’re just doing some basically ordinary skills, to be honest the price shouldn’t be a factor. I think it’s the concept of actually how to do it is the real factor,” he said.
For Morr, education is the big issue. “I think there’s a technology gap,” he said.
The technology is out there and there are users out there who have expertise and knowledge to share. But too many businesses are not up to speed. They are not aware of the technology and are not aware of the techniques.
Morr sympathised with those who find themselves in this position.
“They don’t get the opportunities to meet and explore different opportunities and different possibilities in tooling and machining. And that technology gap does tend to grow...these days more than ever,” he said.
Citing metal cutting as an example, he said, “People are doing it all day. They’re always cutting steel, turning, milling, drilling, whatever, but nobody’s really given the time to sit down and explore what’s actually happening and the fundamentals of metal cutting behind the process.”
Morr explained that education and training are available. And you don’t have to go back to uni or TAFE to get it. For their part, Seco Tools runs the Seco Technical Education Programme (STEP), a practical programme designed to familiarise users with the latest tooling systems and metal cutting techniques.
It aims to address the ‘technology gap’ and help participants improve their machining productivity; and to keep them up-to-date with changes in the industry. It is recommended for machine operators, manufacturing engineers, programmers, and company owners: anyone who stands to benefit from an improved understanding of tooling and machining strategy.
Topics covered include machining language, concepts, and terminology; cutting tool design, selection and application; as well industry-specific components.
The good news is that there are many such courses appearing on the scene. All will surely go a long way to ensuring that some light is shone on hard-to-define concepts like high speed milling; and that more businesses start taking advantage of them.