It is no longer news that the technological innovation of CNC machines has simplified machining services. Not to mention, CNC machines are compatible with various metal and plastic materials to produce precise, quality parts.
However, machining more difficult details, such as countersunk parts, requires some important considerations and knowledge to achieve the best result.
Therefore, this guide contains everything you need to know about counterbore machining and its application to CNC machined parts.
What is counterbore machining?
Undercut machining is a machining technique that creates recessed or countersunk features on a machined part. With standard cutting tools used in most machining services, such as: B. end mills, no undercuts can be created. Additionally, designing recessed parts can be challenging to machine. This machining project mainly aims to implement suitable functionalities for various machined parts.
Additionally, producing some accurate undercutting patterns may require higher costs. This is because some of its surfaces are not directly accessible from above. There are also several recesses in which one part of the piece projects over the other. The overhang therefore creates a gap that cannot be reached with conventional tools.
Therefore, undercut machining requires special tools such as slot cutter, lollipop cutter or undercut end mill to produce undercut parts.
What is a CNC undercut?
In machining, a counterbore is a certain type of recessed surface on machined parts. Undercuts are often represented by one piece of the garment projecting over the other.
In CNC machining services, undercuts occur in different ways. Check out the details below.
Undercut in CNC turning
In turning, a counterbore is a depression in the inner diameter of the machined part. A general rule for recesses in turning technology is that they must be at least 1.5 threads long and have a diameter at least 0.38 mm smaller than the diameter of the thread core. Additionally, undercuts are often made at the end of the threaded portion of a screw or shaft. This creates free space for the cutting tool.
Undercut in CNC milling
During milling, the cutting tool is mounted on the spindle. In some cases, undercut machining experts cut a portion of the material in a direction where the feature is not visible from the spindle angle. However, this requires special tools to get behind the visible material.
Special tools for undercut processing
As already mentioned, counterbore machining is often difficult. Additionally, typical straight machining tools cannot reach the clearance created by most countersunk parts. Therefore, this machining process requires special tools. Check out these special tools below:
Slot and lollipop cutters
These unique tools have special shapes that allow you to create cuts where traditional tools cannot. Slit and lollipop cutters have a wide tip and a narrow shank.
However, they differ in the shape of the end tip. You'll notice that the slot cutter has a flatter tip, while the lollipop cutter has a more rounded tip.
Additionally, experts measure the distance between the outer tip and the edge of the shaft when machining counterbores. This allows you to determine the overhang length to cut for CNC machined parts.
The rounded tip of Lollipop cutters makes them suitable for machining curved and scalloped shapes. Lollipop cutters are also used in edge bearings to deburr a workpiece. However, this countersunk end mill offers multi-directional cutting, which makes it more expensive.
Note that clippers with thinner necks help create a more spherical undercut. This is due to the larger wrap angles, which provide more clearance. Cutters with thicker necks, on the other hand, have smaller winding angles and therefore offer less play.
Special cuts when processing recessed parts
Below are some of the different cuts you can make when machining countersunk parts:
1. T-slot
As the name suggests, this cutting tool helps you create T-shaped undercuts. T-slot tools consist of interconnected flat horizontal blades and a vertical shaft. These features allow the device to cut a workpiece and cut horizontally in both directions. This creates the T shape. T-slot cutting tools are available in standard widths from 3mm to 40mm.
2. Swallowtail
Dovetail cutting tools use angled blades to create recessed parts. The resulting cuts are trapezoidal or dovetail shaped. Furthermore, the recessed part always has a narrow top and a wide bottom.
Dovetail cutting tools have angled blades with standard 45- and 60-degree angles. However, other degrees in multiples of 10 degrees, up to 120 degrees, are used less frequently.
3. One-sided kerning
This unique cut uses a CNC undercut tool to make asymmetrical undercuts on machined parts. He cuts sideways, making additional cuts that protrude from the previous cuts.
Note that with the one-sided cutting technique, distance is an essential factor to consider. This ensures that the CNC bottom cutting tool is working properly.
Tips for CNC machined parts with undercuts
Below are some important tips to support your bottom cutting process for CNC machined parts:
1. Work with professionals
You will agree that working with experts makes your job easier. Therefore, experienced individuals or companies working in reductions will likely have the tools and knowledge needed to help you in a variety of ways. Therefore, working with experts will help you reduce the risk of errors in producing suitable recessed parts.
2. Avoid undercuts if possible
When preparing the design for your machined parts, you should avoid undercutting if possible. Because undercuts add complexity to your design. Additionally, you may need the necessary special tools, which may result in higher costs. Therefore, avoiding cuts will make your work easier and save more costs.
3. Avoid the need for a custom tool
You can also avoid the need for special tools, as they are time-consuming to produce. Additionally, these tools are intended for one-time use, and repeated need for these tools can add costs to your editing project. Therefore, the best way to avoid special tools is to design your undercut features with standard dimensions.
4. Make a shallow cut
Please note that the depth of the cutting tool blades is limited. This is because most of these blades are usually connected to the vertical axis. Therefore, be sure to only create shallow cutting depths that your appropriate cutting tool can handle – and the shallower the cut, the better.
Application of recessed parts
Undercuts cannot always be avoided. Basically, manufacturers often use undercuts during machining to give machine parts a certain functionality.
Therefore, counterbore machining is necessary for parts that require:
- Side holes: for consumer electronics
- Locking Features: For Easier Assembly
- Individual inserts: for unique design elements
- Vertical threads: for many fittings, hoses and other components
- Hose nozzles: for medical devices
University Degree
In particular, some editing designs seem easy to create, but are more difficult to implement during the editing process. Tasks as demanding as undercutting in machining require high-quality machining services to obtain the best cut parts.
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Common questions
Can undercuts be edited?
Yes, simple undercuts are usually processed with special tools. Slot and lollipop mills, also called undercut end mills, are often the first choice for undercut machining. They have unique shapes and characteristics that make them suitable for making recessed pieces.
What are the adverse effects of an undercut?
In general, undercuts cause local stress concentrations in metal parts. This adverse effect arises from the reduction in the transversal areas of the metal parts due to the depth of the recess.
Why can't the shape have undercuts?
Molds must be practically free of cutouts, as these complicate the overall project and prevent parts from being ejected. Therefore, it is best to avoid undercuts if possible.
