Published 01/07/2026

Why Mold Builders Must Embrace On-Machine Deburring

Q: What CAM features are worth evaluating to maximize efficiency when analyzing deburring toolpaths?

A few additional CAM features are worth evaluating to maximize efficiency when analyzing deburring toolpaths. For example, connection movements should be automatically generated to lessen the programming load and keep the cutting tool from traversing to unnecessary safety positions that increase cycle times. The goal is to optimize cutting time and negate all extraneous moves by the machine tool. Another critical consideration is the CAM system's ability to recognize cutting flute length. For example, if a lollipop cutter's flutes don't wrap all the way around the globe, the CAM system must be able to automatically adjust tilting parameters to compensate. If the CAM system can't automatically adjust, too much burden is placed on the programmer to iterate to success. Ramping out of, and then back into the inside corners is desired regardless of whether the toolpath is fixed-axis or five-axis simultaneous. To continue with automatic programming, this ramping out and in should be routinely handled by the software and fully collision checked against all adjacent geometry.

Advancements in tooling and CAM make automated on-machine deburring essential, improving mold quality, repeatability and easing skilled labor shortages.

Brad Rooks, Application Engineer, OPEN MIND Technologies (hyperMILL®)

CAM Considerations

The first and most foundational factor is CAM programming, which dictates both the toolpaths and the tooling required. The essential tooling should be discussed for each specific programming application. For example, a modern CAM system should provide a comprehensive set of strategies to deal with all deburring situations. Programming options must include deburring accessible edge breaks, deburring drilled cross-hole intersections and the ability to implement hole brushing techniques.

CAM programming for accessible edge breaks will use two cutting tools commonly employed by mold builders: a ball-nose cutter and a lollipop cutter. The key in this case is the simplicity of toolpath programming for the user. For example, if the CAM software is suited to the task, the programmer simply needs to pick which edges they wish to deburr.

Also, toolpaths are defined by their tool axis behaviors, characterized by three-axis vertical, 3+2 fixed inclinations and five-axis simultaneous movements. The CAM system's ability to determine the necessary approach for each deburring application is vital for enhancing efficiency and saving time at the machine tool. Plus, this sorting must occur without any programmer intervention.

Users should also be cautious because some CAM systems generate excessive rotary motion that is not needed. This extraneous five-axis motion only leads to extended cycle times and inferior cutting quality. Fixed inclinations are always preferred, while five-axis simultaneous paths should be used only when necessary to complete the task.

Another critical consideration is the CAM system's ability to recognize cutting flute length.

Lollipop Cutter for Cross-Hole Deburring

Building on these accessible strategies, more challenging geometries such as cross-hole intersections demand specialized approaches. For example, in most cases, cross-hole deburring requires the use of a lollipop cutter, as reach and access are extremely limited. CAM software can make machining the difficult deburring details of cross holes very easy. In addition to the curve geometry of the cross-hole, the only additional input needed from the programmer is to designate the primary hole from which the cutter will approach. Using these two pieces of information, a modern CAM system can generate a sophisticated toolpath that is gouge- and collision-free.

The quality of cross-hole deburring achieved on the machine will always be superior to manual labor processes. The difficult hand tools, coupled with problematic geometries, render cross-hole deburring an inefficient process when done manually. To label it as a labor-intensive procedure when done by hand-finish is an understatement, yet the machine tool can execute the task in seconds. To ensure consistency and speed across parts, manufacturers must transition these operations from the hand-finish department to CNC machines.

Benefits of Hole Brushing

Cross-hole machining is performed using a standard
lollipop tool to achieve precise internal features.

An alternative or complementary technique for tackling these cross-hole burrs is hole brushing, a crucial task in moldmaking. The brushing tool can stroke both up and down while engaged. The tool can also be re-dressed and reused to extend longevity. Standardized hole brushing tool diameters range from 1.5 mm to 40 mm. Secondary burrs are eliminated when hole brushing is implemented properly. The burr is truly cut and not pushed or smeared, leaving nothing residual that can hinder flow or access through the channels.

Programming a hole brushing tool should be considered similarly to programming other cutting tools. There are dos and don’ts, feeds and speeds, and best practices. CAM software must have dedicated paths to program the brush to the exact specifications required by the manufacturer’s application.

Spindle direction, coolant, feed, rpm and dwell must be specific to each phase of the operation. Phases include entry and exit, entering and exiting cross holes, stroking up or stroking down and out of hole conditions.

When programmed properly, a hole brushing tool can be an extremely valuable addition to any mold builder. The primary hole is the entry point and many cross-holes can be deburred using a single toolpath axis. Hole brushing tool lengths are also measured in the same manner as traditional tooling. Nothing new needs to be implemented for machine tool procedures.

When programmed properly, a hole brushing tool can be an extremely valuable addition to any mold builder.

Final Considerations

Beyond these core strategies, a few additional CAM features are worth evaluating to maximize efficiency when analyzing deburring toolpaths. For example, connection movements should be automatically generated to lessen the programming load and keep the cutting tool from traversing to unnecessary safety positions that increase cycle times. The goal is to optimize cutting time and negate all extraneous moves by the machine tool.

A hole brushing toolpath is shown, with process tab options available to define parameters for each machining step.

Another critical consideration is the CAM system's ability to recognize cutting flute length. For example, if a lollipop cutter's flutes don't wrap all the way around the globe, the CAM system must be able to automatically adjust tilting parameters to compensate. If the CAM system can't automatically adjust, too much burden is placed on the programmer to iterate to success.

Ramping out of, and then back into the inside corners is desired regardless of whether the toolpath is fixed-axis or five-axis simultaneous. To continue with automatic programming, this ramping out and in should be routinely handled by the software and fully collision checked against all adjacent geometry.

Summary

Embracing CNC machine deburring through advanced CAM strategies and specialized tooling like ball-nose and lollipop cutters, alongside innovative hole brushing techniques, empowers moldmakers to overcome labor shortages, boost operational efficiency and deliver superior part quality with unmatched repeatability. By prioritizing intuitive programming that minimizes manual intervention — while optimizing toolpaths for fixed inclinations, collision-free cross-hole access and seamless connection movements — shops can transform a once-daunting process into a streamlined, automated powerhouse. As the industry evolves, investing in CAM systems that intelligently handle these nuances isn't just a competitive edge; it's essential for future-proofing mold production against rising demands for precision and speed.