Saying goodbye to lead: How industry is learning to machine lead-free brass

Why lead-free brass is now gaining importance

Lead-free brass is no longer a marginal topic in machining. Stricter requirements, increasing demands from OEMs, and growing expectations along the supply chain are forcing manufacturing companies to reassess familiar processes. At the center of this is the move away from lead-containing brass alloys such as Ms58. 

If you ask the experts why lead-free brass is gaining so much momentum right now, they all cite the same starting point: legislation. Hermann Reinhardt, Head of OEM2 at Paul Horn GmbH, puts it directly: "Lead-free brass is currently becoming more important primarily due to legal requirements - in my view, that is the main driver." The revised EU Drinking Water Directive further lowers the permissible lead values and, for the first time, creates uniform hygiene standards for all of Europe - these requirements will apply to new installations from the end of 2026. In addition, there are REACH, RoHS, as well as particularly strict substance bans in electronics that leave the industry hardly any room for maneuver.

Stefan Thoma, Industry Driver Small Parts Machining at Walter Tools, classifies the situation similarly: "The current momentum is an interplay of three factors. Primarily, the topic is driven by regulation - especially in the area of drinking water regulations and by international chemicals directives such as REACH. At the same time, however, we are feeling massive market pressure: Many OEMs, fittings manufacturers, and system suppliers are already proactively converting their materials today in order to obtain long-term legal certainty." Thoma adds that this development is also driven by strategic considerations regarding product liability and ESG goals.

Christian Erb, Application Engineer at the Wieland Group: Direct requirements from end consumers have so far played a rather subordinate role - the topic of lead-free materials is rarely consciously perceived by consumers. At the OEM level and in the processing industry, however, a different picture is emerging: inquiries, trial orders, and series launches with an explicit demand for lead-free materials are continuously increasing. New products are now often designed to be lead-free from the outset. "Overall, the growing importance of lead-free brasses is less a short-term trend than a long-term, regulation-driven development," says Erb.

Which industries are under pressure with lead-free brass

The strongest pressure to act is currently being felt by companies whose products come into direct contact with drinking water or other sensitive media. "Components such as fittings, valves, or fittings are directly connected with water. Accordingly, the requirements here are correspondingly strict. Many of our customers therefore started a long time ago to switch specifically to lead-free alloys. In some cases, new products are even being developed only on this basis," Reinhardt describes. The same applies to areas in which hygiene is particularly important - food and beverage technology as well as parts of medical technology.

For Index, a manufacturer of CNC automatic lathes, the issue directly affects classic customer segments. "Particularly strongly affected are the sanitary and fittings industry, hydraulics/pneumatics, connection technology, automotive suppliers, as well as electrical engineering and precision mechanics," explains Rainer Gondek, Head of Global Marketing. The company's machines predominantly produce rotationally symmetrical precision parts made of brass in large quantities - threaded parts, valve components, connectors and screw fittings - and these are increasingly being manufactured in lead-free alloys. Specific projects, such as the machining of lead-free brass in cooperation with material manufacturers such as Diehl Brass Solutions or Wieland, showed that the trend is already taking place in real series production environments.

Walter expert Thoma adds further fields to the list of industries: automotive, medical, electrical engineering and connection technology were also placing more and more focus on lead-free materials. And Wieland observes in its customer base that the changeover is no longer only arriving in sensitive core areas, but increasingly also in broad industrial applications.

The missing lead: what changes in machining

Anyone who wants to understand why the switch to lead-free brass is no small matter must realize what lead actually accomplished in the alloy. In lead-containing brass, the metal acts as an embedded lubricant - the so-called lead nests promote chip breaking, ensure short, easy-to-remove chips and protect the tool from excessive friction and thermal stress. The result: high-quality surfaces, long tool life, a process that forgave errors.

"Compared with Ms58, cutting forces increase, chip control becomes more difficult and the tendency toward built-up edges as well as burr formation increases significantly. In addition, lead-free materials react much more sensitively to tool geometry and process parameters," explains Walter expert Thoma. The classic Ms58 - CuZn39Pb3 - was an extremely forgiving material with excellent chip breaking. This forgiveness disappears completely with lead-free alternatives.

Reinhardt from Horn describes the consequence vividly: "Lead-free brass, by contrast, is more demanding. Without the lubricating effect of lead, cutting forces and thermal stress increase. With the same tools, the chips are longer and tougher, which makes process control more difficult." This effect is particularly critical in internal machining - drilling, grooving operations, deep grooves - because continuous chips can wrap around, ruin surface qualities or, in the worst case, damage the tool.

The Index experts differentiate further: Depending on the type of alloy, the machining behavior differs considerably. Binary alloys, meaning simple CuZn mixtures without additives, were particularly prone to the formation of continuous chips. Silicon-containing alloys, on the other hand, improved chip breaking due to the higher shear strength, but at the same time increased the dynamic load on the tool and machine. "This does improve chip breaking, but the dynamic tool and machine load increases," says Dr. Thomas Lakner, Head of Application at Index. Wieland expert Erb also emphasizes that the available database and the practical experience of all parties involved in the manufacturing environment are still limited - lead-free materials are comparatively young.

Tool, parameters, cooling: The three adjustment levers

All respondents agree that the switch to lead-free brass does not solve a single problem - but several at the same time. "There are several adjustment levers that must be turned at the same time," as Thoma from Walter puts it. First, rake angles and cutting edge preparation must be precisely matched to the respective material. For the tools themselves, Walter increasingly relies on specific coatings or, in series production, even on PCD (polycrystalline diamond) in order to minimize wear and built-up edges.

Reinhardt von Horn places tool geometry at the center: "It starts with tool selection: Suitable cutting materials, chip-breaking geometries and special coatings are necessary not only to handle the material, but to achieve an optimum result." In the standard range, Horn offers tools with sintered chip-form geometry at very low additional cost - the focus here is on the Mini and Supermini systems. In the special range, the geometries are introduced by laser, tailored exactly to the application.

An underestimated factor is cooling lubrication. Thoma explains: While Ms58 can be machined dry without problems, with lead-free materials it depends on the targeted selection of the right cooling lubricants or cutting oils and additives in order to control the thermal loads. Reinhardt adds that the machine must also be stable, provide sufficient power and offer reliable clamping technology in order to avoid vibrations. Only the interaction of all factors leads to a stable process with lead-free brass.

Index: CNC technology as the key to chip breaking

For machine manufacturer Index, the switch to lead-free brass is not a passive topic - they have actively responded to it. "It was therefore clear for Index: Our multi-spindle automatic lathes must not only be capable of lead-free brass, but must master it economically in continuous operation," explains Gondek. The strength of CNC control lies in its flexibility: Machining parameters, axis movements and machining strategies can be programmed individually and dynamically adjusted for each spindle position and tool position - a decisive advantage over cam-controlled concepts.

Specifically, Index machines offer the possibility of programming speed and feed independently at each spindle and each tool station and modulating them during engagement - in order to actively influence chip shape and chip breaking. In addition, the ChipMaster software cycle is available, which promotes early chip breaking and reliably prevents chip nests. In silicon-containing alloys, machine rigidity comes into its own in particular: The multispindle machines feature hydrostatically mounted Z-axes, while the single-spindle machines of the C series feature a patented scissor kinematics with plate guide for maximum rigidity with very good damping behavior.

In specific customer projects, Index is testing the machining of lead-free alloys under series production conditions together with material manufacturers such as Diehl Brass Solutions and Wieland. The structured approach consists of three elements: optimized tool concepts in coordination with partners, tailor-made machining parameters, and the consistent use of machine-specific degrees of freedom such as internal high-pressure coolant supply as well as special cycles for milling, whirling, and high-dynamic turning.

Wieland: Alloys that do not leave the machinist alone

On the material side, Wieland reacted at an early stage. With the ecoline product family, the company offers a broad range of lead-free alloys that are oriented toward the property profile of the lead-containing materials to be replaced in each case. The SZ alloys are specifically designed as free-cutting brasses; KS and BS alloys replace lead-containing high-performance copper alloys. The aim is to make the transition as smooth as possible for processors.

Erb emphasizes that the goal of material development is to achieve a similar level in chip formation, tool life, surface quality and process stability as with lead-containing brasses through the appropriate selection of machining strategy, peripherals and process parameters. Development has made significant progress in recent years - at the same time, the available database is still under construction. "However, those who approach the changeover in a structured and material-specific way can implement it in a controlled manner," says Erb.

Wieland sees itself not only as a supplier, but as a development partner. As a world-leading provider of semi-finished products made of copper and copper alloys - with more than 80 production facilities and service locations - Wieland contributes a broad base of application engineering know-how.

What does the switch really cost?

The question of costs is not a simple one. What is clear is this: lead-free brass is generally more expensive than classic Ms58. But Thoma from Walter makes it clear that it is not the material price that is decisive, but the total costs per component: "An inexpensive material such as CuZn37 can ultimately be more expensive due to unstable processes than an alloy such as EcoBrass, which is more expensive to purchase but can be manufactured stably and reproducibly with the appropriate tool concept." The calculation must include tool life, scrap, start-up effort and rework.

Horn expert Reinhardt gives the all-clear for the tooling sector: In the area of standard tools, Horn offers solutions with geometries for optimized chip breaking at very low additional cost compared with variants without these geometries. In the custom area, the additional costs are somewhat higher, but manageable. "With the right tooling solution, we can counteract this economically and achieve a similar level," says Reinhardt.

Index points to the start-up phase as the biggest cost factor: Companies must first invest in trials, tool optimization, and employee training. However, once the optimization phase is complete, robust processes with cycle times and tool life quantities can be achieved on Index machines that are economically at the level of lead-containing alloys - in some cases with advantages due to reduced malfunctions and fewer chip problems. Machines such as the MS24-8 or MS32-6 can also economically handle smaller batch sizes from around 2,000 to 10,000 pieces, which is an important factor in the gradual conversion of part families.

Wieland urges patience and realism: Production with lead-containing materials was also optimized only over a longer period of time. "Here, too, this is a development process that requires time, experience, and adjustment," explains Erb.

No upheaval, but no sure-fire success either

How great is the intervention in existing manufacturing strategies actually? The experts' assessments align: the changeover is feasible - but it requires work. Reinhardt from Horn sums it up aptly: "The switch to lead-free brass is not a complete upheaval, but neither is it a sure-fire success." Existing tools and cutting values often could not simply be adopted. For simple components, adjustments to the parameters were usually sufficient. It becomes more demanding in series production of complex parts, where process reliability is what matters.

Index formulates it from a machine builder's perspective: from their point of view, it is not a break with the previous manufacturing logic, but a demanding yet manageable process adjustment - provided the possibilities of modern CNC technology are used consistently. This is precisely where the strengths of CNC compared with cam-controlled concepts lie, explain Gondek and Lakner. And Thoma from Walter gets to the heart of it: "Processes must be controlled more tightly; parameters that were previously uncritical now become factors decisive for success."

Wieland emphasizes that not all machinists initially cope equally well with the new materials. The reason is that lead-free copper alloys no longer achieve chip breaking via lead, but via other metallurgical concepts. "In many cases, stable processes can be achieved with a few targeted adjustments. In more demanding applications, however, more far-reaching changes are also necessary," says Erb.

Start early: The most important recommendation

All four companies share one core message: Anyone who is still waiting now is losing time they do not have. "Companies that are only now starting to deal more intensively with lead-free brasses are already under a certain amount of time pressure. The conversion of an entire production operation requires time, personnel capacities, and technical know-how," warns Erb of Wieland.

Reinhardt of Horn advises seeking dialogue - with the material manufacturer and with the tool manufacturer: "Users should address this at an early stage. In our experience, every challenge in this area can be solved with the right tool." For interested parties, Horn will offer a customer event on the machining of lead-free brass for the second time in fall 2026 - an event that met with strong demand and very positive feedback the first time.

Thoma of Walter recommends understanding the differences between the various lead-free alloys: "Not every lead-free brass behaves the same way. Processes must be designed consistently in a material-specific manner - simply transferring old Ms58 strategies generally leads to problems." A structured, step-by-step approach is more important here than quick ad hoc solutions.

Index recommends that companies proceed in a structured way in three steps: First, clarify the material strategy - together with material suppliers, define which lead-free alloys are to become the standard in the future, and test them at an early stage on representative machines. Second, raise the processes to CNC level - make targeted use of tool concepts, cutting values, cooling lubrication, and CNC functions such as ChipMaster. Third, understand the investment in modern CNC automatic lathes as a strategic building block in order to meet regulatory requirements and secure productivity in series production over the long term.

Conclusion: The industry is ready - if it tackles it

Saying goodbye to lead is not a question of whether, but of how and when. The regulation is clear, market pressure is growing, and the technical solutions - from specific alloys to optimized tool geometries and CNC functions for active chip breaking - are available. What remains is the need to gather experience, calibrate processes, and build up in-house knowledge.

Built-up edges, flow chips, higher cutting forces - that sounds like obstacles. But obstacles can be overcome if you know them and have the right partners by your side. Wieland develops lead-free alloys that are oriented as closely as possible to the proven material profile. Horn supplies tools that compensate for the missing lubricant through geometry and coating. Walter ensures process reliability even in large-scale series production with PCD solutions and precise parameterization. And Index makes sure that the machine itself is part of the solution - through rigid guides, modulatable speeds, and intelligent cycles.

"Even if lead-free brass is a challenge, it can be machined well with the right strategy and the right tool," says Reinhardt. That is not an advertising promise - it is the unanimous assessment of an industry that can no longer stop the change and is therefore shaping it.