Helical milling is an important CNC machining process to make complicated profiles and accurate holes. Compared to conventional methods it gives better surface finish, more precision and longer tool life. In this blog post you will learn the working principle of helical milling, its technical details, advantages, & typical applications. You will also learn its basic challenges and how it differs from other hole making processes.
What is Helical Milling?
Helical milling uses a CNC controlled end mill moving along a helical or spiral path. The tool moves in three axes i.e., X, Y and Z to make bores, accurate holes or contours in workpiece. It is different from conventional drilling which moves vertically down. So you can make holes of any diameter with extraordinary surface finish using helical milling.
Also See: What is CNC Milling?
Technical Factors of Helical Milling
Here we will see some factors which make helical milling adaptable and precise in modern machining.
Toolpath Generation
In helical milling toolpath follows a spiral shape generated by precise CNC programming. Cutter moves down along the Z axis while tracing a circular path in the X‐Y plane. Customized algorithms and modern CAM software like Archimedes helical‐interpolation are needed to produce these toolpaths within tight tolerances.
Tool Selection
You can get the best results in helical milling if your selection of tools is right. Usually tool diameter should be more than milling size and the workpiece’s helical radius by about 40 to 60%.
Solid carbide tools are good for holes less than 20mm. For larger hole diameters you should use indexable tools instead.
Chip Evacuation and Cooling
Chip removal is important in helical milling to stop overheating and tool wear. High helix tools are used to aid chip evacuation. Coolant systems or air blasts through the spindle are recommended particularly when machining hard materials or deep holes. These clear the chips from cutting area and keep the tool running optimally.
Cutting Parameters
You need to select and fine tune cutting parameters to make helical milling both precise and proficient. Usually feed along the Z axis is about 20% of standard cutting depth. And ramp angles depend on the material you are machining. For example harder steels need ramp angles between 1 to 3° and softer metals can use angles from 3 to 10°.
See Also: Feed Rate & Cutting Speed in CNC Machining
Helical Milling Benefits
1. Better Hole Quality & Precision
You can get tight tolerances of up to IT7 and surface finishes as low as Ra 1.25 μm with helical milling. Mostly this eliminates secondary operations altogether. This method minimizes vibrations because of controlled engagement of the tool. You get precise, straight and round holes even on tough materials such as composites or titanium.
2. Lower Machining Temps
Cutting action in helical milling is intermittent so heat can dissipate quickly. Peak temperatures at the cutting edge are lower. Lower temperatures protect both the workpiece and tool. You can not only use minimal lubrication but dry machining in some cases too.
3. Less Tool Wear & Cutting Forces
Helical milling disperses cutting forces along the edge of the tool. In comparison with traditional drilling, axial load can be reduced by as much as 30%. Less axial load means less tool breakage and longer tool life. It is particularly valuable when machining abrasive or hard materials.
4. Better Chip Evacuation
In helical milling the tool only occupies part of the hole diameter. This gives more space for chip removal. You can clear chips with air blasts or coolant. Better chip evacuation improves hole quality and limits clogging.
5. Less Burr Formation
Gentle cutting action of helical milling produces cleaner hole edges. You’ll see fewer burrs as compared to traditional drilling methods. So secondary deburring works are less necessary.
6. Versatility in Hole Shapes and Sizes
With one endmill you can interpolate holes of multiple diameters and at the same time make non circular shapes. This reduces the number of setups and tools. It is particularly useful for small batch production and prototyping as well.
7. Longer Tool Life
Helical milling tools have reduced and predictable wear rates so you get longer tool life as compared to traditional drilling methods. You can regulate toolpaths and track tool wear accordingly. This helps you get the most out of your tool.
Helical Milling Uses
Helical milling’s precision and usability in multiple fields make it favorite for manufacturers to use it in many demanding industries.
Automotive
In automotive industry helical milling is used broadly for engine blocks, steering system parts and transmission components. It’s great for machining complicated geometries and hard materials. Not only does it support high volume production of standard parts it also allows custom manufacturing for purpose‐built vehicles or motorsports too.
Aerospace
Aerospace companies use helical milling to produce precise threads & holes in carbon‐fiber reinforced plastics (CFRP) and titanium alloys. Extraordinary surface finish and tight tolerances are necessary for landing gear, engine components as well as structural parts. In aerospace manufacturing hole quality directly affects general reliability and safety.
Mold and Die
You can produce deep cavities, intricate profiles and slots with helical milling in mold and die manufacturing. This reduces secondary finishing work as it machines contoured and inclined surfaces precisely. Rapid tool changes are also possible which can increase your productivity.
Medical Devices
Medical device manufacturing needs cleanliness and precision particularly when working with materials such as titanium and stainless steel. Helical milling is perfect to make bores and miniature threads in dental implants, surgical instruments, orthopedic implants as well as other important medical parts. This assures biocompatibility and homogeneous quality.
Thread Milling
For threading, particularly with extraordinary thread profiles or large diameters, helical milling is very useful. You don’t need tool changes when producing external or internal threads. It gives you more accuracy and flexibility in particular when working with difficult to machine materials.
Energy
In industries like gas, oil and power generation helical milling produces strong threaded connections for valves, pipeline fittings as well as turbine parts. Threads produced with this process not only withstand harsh operating conditions but high pressure too. So helical milling supports different energy applications covering renewable and traditional sectors.
Custom Manufacturing & Prototyping
Helical milling is great for custom manufacturing and prototyping because of its flexibility. You can produce holes of different shapes and diameters without frequently changing tools. This shortens your turnaround time and simplifies your workflow.
Challenges and Considerations
Helical milling has many benefits but you must also think about challenges & limitations to get the best results.
Programming Complications
As compared to drilling or milling, CNC programming for helical milling is more complicated as you have to control 3 axes at the same time.
Tool Deflection
Tool deflection is a basic issue specially when using slim and long end mills or high feed rates. Deflection can cause chatter or dimensional inaccuracy. This is more prevalent in deep hole machining or when machining hard materials such as titanium alloys.
Machine Needs
Every CNC machine cannot do helical milling. Your CNC machine should be able to do work in multiple axes and with rigidity. This assures the machine can handle complicated tool movements in particular when machining hard materials.
Material Limitations
Even though helical milling can work with many materials but poor thermal conductivity or excessive hardness can limit its effectiveness. Titanium alloys for example can wear out the tool faster. So you need to increase the machining parameters to avoid premature tool failure.
Best Practices for Helical Milling
Tool Maintenance
Regularly clean and check the cutting tools to remove coolant and chips. Replace or sharpen dull tools to preserve quality and functionality of parts. Adequate maintenance will prevent tool wear and corrosion.
Parameter Optimization
Adjust machining parameters like feed per tooth, cutting depth and helix angle according to your application and material. For example 30° helix angle with 0.15 mm/z feed per tooth works well with many materials.
Skill Development and Training
Provide continuous training to your team members. Assure they are proficient in programming helical milling toolpaths. Also equip them to quickly identify and resolve machining issues.
Helical Milling vs Other Hole Making Methods
| Feature | Drilling | Boring | Helical Milling |
|---|---|---|---|
| Cutting Forces | High axial thrust (4 to 7 times higher) | Average/ Normal | Low & distributed forces |
| Surface Finish | Ra 1.6 to 6.3 μm | Ra 0.8 to 1.6 μm | Ra ≤ 1.25 μm |
| Tool Changes | Multiple for large holes (4 to 6 tools) | Customized per diameter | Single tool for different diameters |
| Flexibility | Gives round & straight holes only of limited sizes | Exact for enlarging existing holes | Covers different diameters, complicated geometries and non circular shapes |
To Sum Up
Helical milling is the best for different processes and complicated holes. It reduces cutting forces, extends tool life as well as gives a better surface finish. That’s why helical milling is a must in demanding CNC machining industries.
If you need any kind of CNC machining services then Richconn is your best option. You can contact us anytime.
Related Questions
What materials are appropriate for helical milling?
Helical machining is good for alloy steels (EN353, SAE8620, 20MnCr, 18CrNiMo) and hard materials such as CFRP, Ti‐alloys or composites.
How does helical milling increase tool life?
Helical milling increases tool life because it distributes cutting forces equally. It also removes chips proficiently and reduces heat generation. These aspects reduce tool wear so you can use tools longer.
Can helical milling be done on all CNC machines?
To do helical milling your CNC machine must support simultaneous multi axis movement in X, Y and Z directions. Most newer CNC mills have this capability but basic or older machines probably do not have the required controls.
What are limitations of helical milling?
Some limitations of helical milling are that it removes material more slowly than drilling. Its programming is more complicated and precise CNC machine control is needed.
Is helical milling good for small scale production?
Yes helical milling is good for production on a small scale because it’s flexible and needs less tool changes.
