How Chipbreakers Save Your Parts

by Aaron-Michael Eller, Product Manager - ISO Turning & Advanced Materials, Seco Tools

Chipbreakers make critical contributions to machining operations with turning inserts in ways that shops often overlook. First and foremost, chipbreakers focus on the safety of everyone who works with or near machining equipment. Long, stringy "bird's-nest" chips carry edges as sharp as razor wire and can cause severe injuries to anyone who touches them, let alone gets caught up in them. With the right chipbreakers, these hazards never develop. Ideally, chips form tight conical curls about 1 inch long to create maximum compaction in the chip hopper as they fall away from the workpiece, into the evacuation system and away from the machine.

The right chipbreaker means fewer insert changes, less rework and fewer opportunities for chips to make damaging contact with a workpiece. Proper chip development and management eases the operator's task and leads to longer tool life, which in turn promotes efficiency, productivity and profitability. The right chipbreaker also enhances part quality and can deliver a substantial cost savings. Which of these two parameters matters more to an individual shop? That depends on workflow, job selection and part quantities.

In a facility that focuses on aerospace, medical or automotive parts, with high finish requirements on every component, part quality becomes the primary concern, even more than tool life, because of the high value of each individual workpiece. Conversely, in a shop that produces higher-quantity parts that demand less in terms of surface finishes and specification tolerances, longer tool life equals fewer tool changes and longer production runs for greater profits.

The reality of modern machining is that specific jobs require equally specific tools, chipbreakers included. Consider the fundamental differences between chipbreakers on roughing tools and finishing tools. On a roughing insert, the chipbreaker sets slightly back of the cutting edge to add strength and support heavier depths of cut or higher feed rates. At the shallower depths of cut used in finishing processes, the chipbreaker sets closer to the cutting edge to direct the chip off the workpiece and make it form from the chipbreaker instead of burnishing the cutting edge of the insert.

New developments in machine tools, materials and parts mean new challenges for chipbreakers. High-speed machining prompts an overall push to higher cutting parameters. Greater depths of cut and higher feed rates also mean greater tool pressure, which raises machine load. Optimized lead angles increase the engagement of the insert and raise metal removal rate at the same time that they add security to the cutting edge. All of these considerations increase the average thickness of the chip and make it easier for the chipbreaker to do its job.

Increased feed rates, along with heavier depths of cut, assist mechanical chip breaking. Engaging the entire edge of the insert helps reduce a common failure mode called depth of cut notching, in which repeated cutting action on one area of the insert creates a notch in the cutting edge and drastically shortens tool life.

Abrasive materials, including workpieces produced through additive manufacturing, also pose challenges for tools and chipbreakers. Turning hard materials with the right chipbreaker causes few problems because the material is easy to manage. By contrast, workpiece materials with transitions between hard and soft surfaces can create bird's-nest chips at the transition. All of these situations call for careful chipbreaker selection in consultation with the manufacturer of the tools.

To achieve ideal results from chipbreakers, try new technologies and don't hesitate to look beyond familiar chip breaking solutions. For example, on our Secomax CBN inserts, Seco Tools offers a flowing radii chipbreaker, which is laser machined to the cutting edge to allow for a continuous flow of material off the insert and onto the chipbreaker. If we had ground the chipbreaker instead of laser machining it, the process would require approaching the workpiece from multiple angles to achieve the right profile, which causes sharp edges and corners that don't allow for free chip flow. Before you begin your next cut, let us help you think through your tooling and your approach. Seco Tools Technical Sales Representatives can help customers solve their chip breaking challenges, often over the phone.