Milling 101: What are the considerations when it comes to milling operations, and how can operators reduce vibration in milling? Read on. Article by Sandvik Coromant.
Milling has been evolved into a method that machines a very broad range of operations. In addition to all the conventional applications, milling is a strong alternative for producing holes, threads, cavities and surfaces that used to be turned, drilled or tapped.
There are different types of milling operations. They are:
Groove milling and parting off
Holes and cavities/ pocketing
The following are the initial considerations for milling operations:
The milled configuration
The features to be milled have to be carefully considered. These can be located deep, requiring extended tooling, or contain interruptions and inclusions.
Workpiece surfaces can be demanding, with cast skin or forging scale. In cases of bad rigidity, caused by thin sections or weak clamping, dedicated tooling and strategies have to be used. The workpiece material and its machinability must also be analyzed to establish optimal cutting data.
The choice of milling method will determine the type of machine needed. Face/shoulder or slot milling can be performed in 3-axis machines, while milling 3D profiles require alternatively 4- or 5-axis machines.
Turning centres today often have milling capability due to driven tools, and machining centres often have turning capability. CAM developments mean that 5-axis machines are increasingly common. They offer increased flexibility, but stability can be a limitation.
How to Reduce Vibration in Milling
Milling vibration can arise due to limitations in the cutting tool, the holding tool, the machine, the workpiece or the fixture. To reduce vibration, there are some strategies to consider.
Sandvik Coromant has introduced a new collet for its CoroChuck 930 high-precision hydraulic chuck. Designed to suit Weldon shanks, the new collet features a mechanical locking interface to prevent tool pull-out or movement when producing expensive components and/or machining with challenging cutting data.
“Being 100 percent assured of zero pull-out for Weldon shanks when producing high value-added parts, such as aerospace frame and engine components, is paramount in the highly competitive manufacturing arena,” says Mats Backman Global Product Manager at Sandvik Coromant. “Production engineers and managers are under constant pressure to minimise scrap and maximise bottom-line profitability. These thoughts were the driver for developing the new collet.”
The mechanical locking interface acts between the collet and chuck, and between the collet and shank. Having confidence in no pull-out when both collet and chuck are locked enables increased productivity in heavy-duty applications. Further benefits include easy assembly into CoroChuck 930 chucks, both slender and HD versions, while high run-out accuracy is assured with cylindrical clamping of Weldon shanks. In addition, coolant supply through the collet provides secure and reliable coolant delivery to the tool.
Ultimately, this new solution will benefit any machine shop seeking trouble-free machining in heavy applications. No pull-out or tool movement protects against the potentially sizable cost of reworking or scrapping an expensive component. Pull-out effectively changes the gauge length of the tool mid-cut, leading to the generation of features with incorrect dimensions or crash marks.
To provide an example of the potential gains on offer, a customer case trial saw CoroChuck 930 (featuring the new collet) used for a milling operation on a CNC turn-mill machine. The objective was to produce a twin-screw from 42CrMo4 alloy steel. At cutting data of 3220 rpm spindle speed, 1500 mm/min (590 in/min) feed speed, 10 mm (0.394 inch) axial depth of cut (nominal), and 20 mm (0.787 inch) radial depth of cut, the mechanical locking interface generated a stable process with no pull-out. In addition, productivity increased due to longer tool life.
Celebrating its 63rd year in business, MESCO Inc. has been leading and aiding the growth of the Philippine metalworking industry. Allen L. Lee, president, tells us more about the company and his outlook for the country. Article by Stephen Las Marias.
Allen L. Lee
Manufacturers’ Equipment and Supply Co. (MESCO) was founded in 1956 by Peter N. Lee. Together with his wife, Mercy, they started out of a small apartment in Manila, Philippines, at the time that the country had begun to rebuild after the Second World War.
MESCO was the first to introduce several significant machining technologies into the Philippines. In fact, the company introduced the first CNC machine tool in the Philippines in 1973. It was also during this time that MESCO was incorporated to MESCO Inc.
The company successfully brought more machining technologies in the country, such as a CNC milling machine, a CMM, a vertical machining centre, and a CNC lathe machine, among many others. (The very same QuickTurn 10 CNC lathe machine that Peter brought in 1981 is now on display in the lobby of the MESCO building as a tribute to his visionary force.)
At the recent PDMEX 2019 tradeshow in the Philippines, Allen L. Lee, president of MESCO Inc., speaks with Asia Pacific Metalworking Equipment News (APMEN) about how the company has been leading and aiding the growth of the country’s metalworking industry.
HOW WOULD YOU DESCRIBE THE EVOLUTION OF THE METALWORKING INDUSTRY IN THE PHILIPPINES?
Allen L. Lee (AL): MESCO is now 63 years old. It was founded by my parents in 1956. My father passed away in 2004, so since then, I have been running the business together with my siblings and my two sons. If I go back 20 years ago, most of the buyers were the big corporations. The past 20 years have seen a big change wherein the big names—the Toyotas and Toshibas, for example—had among their policies to outsource production, which is good because it led to the creation of several hundred new companies over the past two decades—job shops starting out as husband-and-wife, father-and-son, with five- to 10-people operations with one CNC machine, for example, and have now grown to 30-, 40-, 50-people operations with over a dozen CNC machines.
In that sense, it is good because the technology has spread all around. While it has provided employment, more importantly, it made the Philippines a potential manufacturing base for other overseas companies.
DO YOU ALSO MANUFACTURE METAL PARTS?
AL: Yes. We have our own manufacturing arm with about 80 people, wherein we produce parts not for the Philippines, but for export. We don’t sell those products in the Philippines because we will just be competing with our own customers. So, we export basically to our suppliers, including Mazak in Japan and in Kentucky, USA; we supply to a high-pressure pumps company in Australia; and, starting about two years ago, we are supplying medical components to San Francisco in the United States and in China.
The QuickTurn 10 CNC lathe machine that Peter N. Lee Brought in 1981 is now on display in the lobby of the MESCO building as a tribute to his visionary force.
FROM A METALWORKING STANDPOINT, WHAT ARE THE OPPORTUNITIES IN THE PHILIPPINES?
AL: Let’s take it from two perspectives: domestic and export. Domestic market is very strong because of the construction boom. What you will see is that local companies are investing in higher technology sheet metal systems; they are talking about automation, lasers, and so on and so forth.
The prospect for the export companies is a bit trickier. There is a very big potential, except for one issue: the Philippine government’s Trabaho (Tax Reform for Attracting Better and High-quality Opportunities) bill. If that new bill pushes through, it may cause some concerns to some foreign companies, because Trabaho bill will increase the tax rate, from five percent gross to 18% corporate income tax.
I have been talking to some auditors, and what they are telling me is that for an American company, or a Japanese company, there is a thing called worldwide taxation, which means, in the Philippines, for a PEZA company, if we increase the tax rate, they pay more in the Philippines, but they will pay less in the United States or Japan. At the end of the day, it’s just the same.
The impact of the Trabaho bill to the investors is not the tax rate per se, but the uncertainty. It is difficult for investors to consider investing in a country if the business environment is uncertain. Other investors are telling me this: if the Philippines must make the rules, it must stick to the rules. If you change the rules, it’s going to be difficult. Most likely, Trabaho bill will pass by December. But, why wait until December? Make a decision now, so that the investors will know what to do.
WHAT OTHER MARKETS DO YOU SEE DRIVING THE METALWORKING INDUSTRY GROWTH HERE?
AL: Worldwide, aerospace is the one with the biggest potential, wherein over the next 20 years, you will need tens of thousands of aeroplanes. The Philippines has a good potential for the aerospace industry; however, we do not have the infrastructure. We do not have special processes such as anodising and heat treatment. The supply chain for materials and for special processes—these are the challenges. Once we have the supply chain, I would think that the potential for growth in the aerospace industry will be exponential.
Regarding skills, there is no problem. Yes, it is not easy, but it can be developed. You must have certifications, all these things, it is a matter of spending some time, but it is not that difficult.
WHAT ABOUT THE AUTOMOTIVE INDUSTRY?
AL: Sure, but consider the traffic! A lot of people can afford cars, interest rates are getting low, and financing gets easier. But where will you park your car? Where will you drive?
HOW WOULD YOU DESCRIBE THE COUNTRY’S STATE OF METALWORKING TECHNOLOGY?
AL: As far as automation is concerned, we are way behind all the other countries. In this exhibition, we are showing two robots in two Mazak machines. To the best of my knowledge, in all the previous shows, this is the first time an exhibitor has shown a robot in a machine tool. What I gathered in MTA Vietnam—based from one of my principals—they were exhibiting perhaps 70 to 80 machines with robots. in Thai Metalex last year, there were about a hundred robots. In the Philippines, for the first time, two machines!
So, why automation in machine tools is weak in the Philippines? It is because the biggest market here are job shops. And in general, job shops’ production sizes are not really high volume. Twenty units, after two hours, they change the setup. So, it is a matter for the machining model to change. When will it come? I don’t know. But I would like to think that if it comes, it will be in waves.
WHAT TRENDS ARE YOU SEEING?
AL: What we do think is that the job shop market now is focused on a standard three-axis machining centre, and two-axis to three-axis CNC lathes. I would like to think that there are many other parts that are being done but are imported because they are too difficult to make.
But we are sensing the market trend will go up, go into multitasking machines for job shops. It is just a matter of them developing the confidence to approach the big companies and say, ‘This part that looks so difficult to manufacture, which you are importing, give me a chance to do it for you.’
In that sense, the technological level of the Philippines will go up. Once a job shop has this, the next job shop follows. It multiplies. When will it happen? The sooner the better.
WHAT IS YOUR OUTLOOK FOR THE PHILIPPINE METALWORKING INDUSTRY OVER THE NEXT YEAR?
AL: It depends upon the reaction of the foreign investors to the Trabaho bill. But whatever happens in three years after its implementation, you cannot slow down. Meanwhile, regardless of whether the business is up or down, MESCO will continue to invest not just in capital goods but in training—by sending people to Japan, Singapore, Europe, the United States, and so on and so forth.
Do you remember the Lehman Brothers’ collapse in 2008? Our sales plunged 50 percent. But 2009 was the year we had the greatest number of trips of people going abroad for training. The previous years, business was good, we have no time to send them for training. In 2009, there was no business, so, perfect timing. Around that time, some of our competitors laid off their staff, cut down in investments. For us, the policy was that, it is bad now, but it cannot be bad forever. It will pick up; so, in 2009, there’s time to train. In 2010, when the business picked up, we were ready.
Besides, we are here. We are a local company. Foreign companies, during the good times, are here. In bad times, they pull out. For us, we are stuck here, we can’t go anywhere. So, giving jobs, training and upgrading the skills of our workers, the benefits is for everyone.
From the shrink fit chuck to the presetting device, aerospace supplier Heggemann relies on consistent Haimer quality in tool management. Article by Haimer.
Anyone who concentrates on the development and production of sophisticated metallic lightweight components and subassemblies is a predestined partner of the aerospace and automotive industry. And Heggemann AG is one such company. Since the company was founded in 1962, it has been supplying these two premium industries. But most of the orders come from the aerospace industry, for which Heggemann holds all the important certificates.
“We also undergo annual audits, not only by the German Federal Aviation Administration, but also by major manufacturers such as Airbus and Boeing, as well as first-tier suppliers such as MTU, Rolls Royce, and so on,” says Dr. Christian Howe, a member of the board at Heggemann. “Our slogan is ‘360°–From Engineering to Production’. Accordingly, we support our customers in all phases of the product development—from conception and development through simulation and engineering, to prototype construction, and the general and functional testing or the production of small series.”
The intelligent NG coil and integrated contact cooling make the Haimer Power Clamp Comfort NG shrinking machines very comfortable to work with help.
Machining at the Highest Quality Level
The highest quality standards apply at all times. This can be seen in production with state-of-the-art CNC milling and turning centres at the company. Ulrich Ahlers, head of machining at Heggemann, explains, “Here we cut a wide range of very demanding materials from titanium, Inconel, stainless steel, and steel, to high-strength aluminium. In most cases, it is the individual parts and small series that have a high demand for precision and quality. Accordingly, not only the machine shop floor, but also the tools and the tool management are of great importance.”
Ahlers and Juergen Ballbach, who is responsible for tool management, have taken on this field in order to optimise it. “Our desire was to achieve the greatest possible consistency in terms of the shrinking, balancing and presetting devices used. We succeeded in doing this together with our partner Haimer,” says Ahlers.
Ballbach has been using two Haimer Power Clamp Comfort NG shrinking machines in order to shrink the required milling tools. “As the name implies, the intelligent NG coil and integrated contact cooling make these devices very comfortable to work with,” says Ballbach.
Balancing System for Tools and Flywheels
Two years ago, Heggemann invested in a Haimer Tool Dynamic Comfort balancing system. Ahlers explains, “We mill here with up to 18,000rpm and use cantilevered tools. If they show an imbalance, this puts a strain on the spindle and noticeably shortens its service life. These are considerable costs that can be avoided by the balancing process on the Tool Dynamic. In addition, finely balanced tools achieve a higher level of precision and surface quality on the component due to reduced vibrations.”
The Heggemann staff wanted to balance not only the tools, but also the special products. These are the elements for flywheels, for which the client orders the balancing including documentation. After consultation with Haimer, the strategy was to install just the large standard software package to define forbidden areas for balancing. The software tool ‘Alternative Balancing Positions’ is also required here. Appropriate holders for the flywheel elements were made by the machining specialists themselves. Ahlers sums up, “We saved the required external service and thus time and money.”
When an outdated tool presetting device was to be replaced, the staff in charge tested, amongst others, Haimer’s Microset VIO linear—a fully automated presetting device.
“Due to our small lot sizes, we have to measure tools every day. That is why we wanted to keep the effort as low as possible,” says Ahlers. “The HAIMER Microset VIO has fully convinced us with all its capabilities. Especially since we now achieve a manufacturer’s consistency for shrinking and balancing, which gives us further advantages.” Amongst other things, he highlights the completed premium maintenance service contract, which covers all Haimer devices, thus minimising effort and costs.
Fully Automatic Tool Presetting
In addition to the fully automatic operation, which ensures simple operation and process-reliable measurement, it was important for the chippers to be connected to the hyperMILL CAM system used in Heggemann. It should be possible to realise a functioning process chain from the CAM to the machine, which looks like this: The programmers create a tool list for each job based on the included tool library, which is then sent to the Microset VIO linear as a measurement job for tool presetting. The operator inserts the respective tool, selects the link to the 3D CAD tool data via the touch screen, and starts the automatic measuring process.
The Haimer Microset VIO linear receives all the required information regarding X and Z dimensions as well as the starting position through the connection to the CAM system hyperMILL. The presetting device then supplies preselected actual values in the complete tool set via post processor and network to the intended machine tool.
“Previously, we used different brands that are usually cheaper to buy, but do not have the same precision nor comparable life. We have found that if the quality is right—and at Haimer, it fits 100 percent—the extra investment will pay off long term,” says Ballbach, who now prefers to use Haimer devices, including Haimer tool holders.
Increasing Cooperation with Haimer
Heggemann and Haimer have been continuing to develop their partnership. When Ballbach spoke with Thorsten Böker, technical sales representative at Haimer, about the difficulty of special processing, he had a proposed solution. It concerned a bifurcated component into which two elongated grooves approximately 100mm apart must be inserted as fits. So far, this task was taken over by an oversized carbide end mill, which had to be ground free by hand to get through the first tab. Heggemann now manages this machining with Haimer Duo-Lock, a modular tool system with solid carbide exchangeable head milling cutters and extensions in various geometries and lengths.
“The switch to this tool has paid off in no time,” says Ahlers. The problem solver was ultimately the extension that Haimer has already delivered unencumbered. It saves the manual grinding of every single tool. All that needs to be changed is the HM tool head, which is considerably less expensive. In addition, the screw head can be changed quickly at the workplace, according to Ballbach.
“Because the Duo-Lock tools can be preselected with a repeat accuracy of 0.01mm due to their special interface, we do not even have to measure them after the change,” says Ballbach. In addition, the overall system runout of less than 5μm ensures best machining results and, according to Ballbach, tool life is three times as long as those of the predecessor tools.
Currently, further Haimer solutions are being tested and discussed at Heggemann. For example, the company is considering using the Haimer Safe-Lock system for heavy machining of demanding materials in the future. Its constructive design combines the frictional clamping forces of the respective clamping process with a form-fitting connection and thus reliably avoids the danger of tool pull out during roughing or power milling.
Focus on Quality
The process and results of the cooperation with Haimer not only satisfy the production staff and those responsible, the Heggemann management also appreciates the quality and reliability of their partner. CEO Christian Howe comments, “Thanks to the high-quality Haimer products, we have succeeded in further improving our production processes. The products perfectly match the requirements of our customers in the aerospace and automotive industries.”
600UK’s Clausing MillPWR CNC milling machine comes fitted with the Heidenhain Acu-Rite control system that offers flexibility and user-friendliness. It allows the creation and programming of complex parts to happen within minutes and can also manufacture one-offs and small batch components. Additionally, prototype and test components can be routinely milled.
The full conversational programming system is easy to utilise for swift and fuss-free cutting. It has the capacity to produce highly accurate parts the first-time with ultra-high precision 1µm resolution scales.
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