Using Tools From Iscar, Easily Machine Lead-Free Brass Lead-Free Brass: Really Nice, Short Chips

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International regulations limit the lead content in copper alloys. This is positive for health and nature but presents manufacturers and machinists with significant, or perhaps better, lengthy challenges. Without lead in the alloy, long chips often form. Together with experts from the Wieland Group, tool specialists from Iscar have addressed the issue. At the Techcenter in Ettlingen (Germany), they jointly developed a wide range of drills, mills, turning and grooving tools that allow lead-free brass to be machined without problems.

Originating in 1820 from a bell foundry in Ulm, the Wieland Group is now an internationally operating provider of copper alloys, copper semi-finished products, as well as component and system solutions.

Wieland: 10,000 employees—80 production sites

With a global network of over 80 production sites, service, and trading houses, as well as around 10,000 employees, the company offers a broad product, technology, and service portfolio. From prototype to series production, Wieland develops solutions for the automotive, aerospace, electronics, refrigeration, and air conditioning industries, among others.

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Wieland: Developed Lead-Free "Ecoline Series"

REACH Annex 17, RoHS, DWD, and ELV—numerous international regulations limit the lead content in copper alloys. Previously used and proven materials are thus only conditionally usable in the long term. Therefore, Wieland has developed a family of lead-free products with the "ecoline series" to replace these.

However, their machining presents new challenges, as lead imparts specific properties to lead-containing brass alloys, for example, improving their machinability and tool life.

Low Lead Content—Great Challenges

Industrially important machining brass contains, for example, between 0.5 and 3.5 percent lead in small particles as chip breakers. The element is present in the material structure in finely dispersed particles. The more lead it contains, the better the material can be processed. Lead provides a certain lubrication during machining and results in short chips.

"The challenge is to ensure these characteristics even without lead," explains Angelos Tanios, process engineer at Wieland. To make these properties available in lead-free brass, Wieland uses silicon and phosphorus in its "ecoline alloys," such as "eco SZ3."

Phosphides in the Alloy are Similar to Lead Particles

The forming phosphides are distributed in the alloy similar to lead particles and serve as predetermined breaking points for the chips. This allows the new materials to achieve very good machinability. Nonetheless, low-lead or lead-free materials pose challenges to the machining process to achieve the exceptional performance of lead-containing materials.

"During tests, we observed increased wear on the cutting edges and burrs forming on components in some areas," says Christian Erb, application engineer at Wieland. "It is also critical that long chips can form, which can wrap around tools, clog the process space in the machine, and eventually make chip removal from the system more difficult."

Lead-Free Material Must be Process-Reliable to Machine

The team around Christian Erb and Angelos Tanios was aware that the lead-free material would also need to be economically and process-reliably machinable—with the right tool.

Therefore, they turned to their longstanding tool partner Iscar and described the issue to Florian Schöffler, consulting and sales, and application engineer Martin Staudacher. Since not many companies are yet working with the new lead-free brass, the tool specialists also lacked experience for recommendations.

"But we have an ace up our sleeve for such cases—our Techcenter in Ettlingen," says Florian Schöffler. At the well-equipped "playground for big boys," Iscar tests its own products on the one hand, but primarily solves the technical problems of its customers on the other. "So we invited the Wieland team to Ettlingen to work out solutions together," says Martin Staudacher. "In the Techcenter, we were able to try out what works best. As experience shows, trying out is better than studying."

The Tech Center Provides the Solution

In the "ecoline family" from Wieland, there are alloys with very different properties to meet the various requirements of users. For the trials at the Techcenter, the material experts from Ulm provided three-meter bar stock from eco SZ3 (CuZn40SiP) in diameters of 26 and 38 millimeters (approx. 1.02 and 1.5 inches). "We chose this alloy because its properties are closest to the widely used brasses CW614 and CW617," says Christian Erb. "This allows us to cover a wide range of applications."

For lead-containing material, extremely sharp tools, such as aluminum geometries, generally work best. "In SZ3, however, exactly these tools led to extremely long chips in our tests," says Werner Lederbogen, work preparation at Wieland. "We therefore switched to less sharp steel geometries with a protective chamfer. That worked great." Marco Huck, Application Engineer at the Techcenter at Iscar, adds: "Especially cutting materials with a suitable C-chip former and a very smooth and polished coating allow for good chip flow." Which coating will ultimately prove to be the best for lead-free materials can only be determined when it comes to the tool lifespans in a specific application case.

Tests on Long and Short Lathes

The 26 material was to be machined on the long lathe. To replicate typical industrial machining processes, a component resembling a connector was created—in one go and almost exclusively with standard tools.

For cutting off and grooving, the Techcenter team used the resource-saving "DOGRIP" with a cutting insert only one millimeter wide. They performed drilling with a "SOLIDDRILL solid carbide (VHM) drill" and with "SUMOCHAM exchangeable head drills" with diameters of 32 and 4 millimeters (approx. 1.3 and 0.2 inches). For turning and pre-turning, "ISOTURN tools" with "F1M chip former" served well. With the new three-edged "PICCO3CUT," they applied chamfers and smoothed the internal corrections; they milled key surfaces with a four-edged "MULTIMASTER VHM cutter" in the wear-resistant, TiAlN-PVD-coated fine-grain grade IC908.

The thread with a 1.5 pitch was cut by the machinists using an "IscarTHREAD thread mill" with ISO indexable inserts. Only for the form groove was a special tool used: it was set with a precisely tailored five-edged "PENTA-27 insert" with a laser-engraved chip former. "The entire process from bar to finished part takes only about two minutes and delivers very good results," says Thomas Eiberle, setup operator at Wieland.

Test Object Plain Bearing Bush

The material with a diameter of 38 millimeters approx. 1.5 inches) was machined by the tinkerers on a short-turn lathe. A plain bearing bush was produced as a test object, modeled after actually existing components. The bar stock was roughed with the new three-edged "QUICKTLOCK" with extremely stable clamping and finished with the "LOGIQ6TURN," the positive indexable insert with six 55-degree cutting edges. A four-edged "MULTIMASTER VHM cutter" created the key surfaces. With a "DR-TWIST drill" with a 32-millimeter (approx. 1.3-inch) diameter, the team created an end face hole and turned it out with a "WHISPERLINE boring bar."

For the groove, the machinists also used the "DOGRIP" with a cutting width of only one millimeter here. "The successful processing on this machine was also supported by the quick-change system 'Varia-VX' from our partner EWS, which reduces setup time and safely transmits torque. Additionally, there is the collision-optimized tool adapter 'SPANNTOP mini 65' from our partner Hainbuch, which allows us to get very close to the chuck," explains Jörg Huber, Application Engineer at the Techcenter at Iscar.

It's the Tool: Consistently Nice Short Chips

The test results on both machines were convincing. With the tools used, the expert team can produce the components both on the long and short lathe in a process-reliable manner and in one go.

"We have consistently nice short chips and the surface quality is also right," says Christian Erb, satisfied. Angelos Tanios summarizes the findings: "With the right tool, lead-free material can also be machined without any problems."

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