Proper tooling is the most important part of every machining process. We need to have specific functioning milling tools if we want to develop milling parts. Same goes for all other operations. Think of it as cooking; one cannot choose potatoes as the main ingredient when making an apple pie. Yep, this analogy is not far from reality.
So we have different tools for different operations in a CNC machining shop. We might reuse some particularly reusable tools, replace the old types with advanced ones, but that’s about it. True, we focus on quality and durability, something that’ll extend its working capability (and less wear and tear). But, did you ever give a thought to tool shape?
If you didn’t, we’ll tell you why you should pay attention to your tool shapes. Let’s get to the BOTTOM of the CNC machine tools world!
Key Advantages of Flat-Bottom Tools in CNC Machining:
At Machining Design, we work with a plethora of tools but flat bottom tools have definitely won our hearts (and infrastructure) over. Here’s a list of reasons why we would suggest it to you as well:
1. Lower Machining Costs
As CNC’rs, we’re all aware that machining is not cheap. Add in tool maintenance and replacement costs, and it’s going to cost us more than ever. While we cannot cut on labor and operational costs, we can definitely save some using the flat bottom tools.
Now, how do they make that possible?
For one, they eliminate the extra run-time by fitting exactly where they are required. Due to their shape, they are often sturdier when compared to traditional machining tools. Carbide fit flat bottom tools beat every other tool in terms of durability. Imagine the amount of money you’ll save!
2. They are more functional
There is a list of drilling operations where these flat bottom tools play the role of a hero. Take thin plate drilling for example. When performing this operation, regular tools often face irregularities due to pushing materials through the exit hole. This derails us from achieving the desired perfection in the drilled holes. Flat bottom drills are extremely beneficial here as due to their general geometry they even downward forces. Hence, more clean surfaces.
3. They don’t create burrs
Unlike traditional tools, using flat bottom drilling tools helps us avoid unexpected (and undesired) burrs on the other side of the material. Make way for straighter and regular holes.
4. Is fit even for angular functions
Flat bottom drills are perfect for irregular surfaces due to their geometry, especially if it’s required to perform angular or tilted operations.
5. It’s stable
When countering with a half hole drilling, flat bottom drilling is proven to extremely beneficial. This is because due to the lack of material on both sides of the drill, any other machining tool may walk to the side of the material, creating an extremely undesirable situation. A flat bottom drill works closely on the entire cutting geometry, making it perfect for drilling half holes even on the edge of the material.
When to Use Flat-Bottom Tools (Best Use Cases)
Flat-bottom tools are not always the universal choice, but they shine in certain machining scenarios where conventional drill or end mill geometries struggle. Here are the most common use cases:
1. Drilling Thin Sheets or Plates
- Flat-bottom drills prevent “walking” and wandering at the entry point.
- They also reduce burrs on exit when working with thin metals, plastics, or composites.
2. Working on Angled or Irregular Surfaces
- Traditional drills may skid off angled or curved surfaces, while flat-bottom tools provide a more stable entry point.
- Common in aerospace and automotive parts with complex geometries.
3. Interruption Machining (Cross-Holes or Partial Holes)
- When drilling across an existing hole, slot, or cavity, flat-bottom tools offer stable cutting and reduce edge chipping.
- Useful for manifolds, fluid channels, and mold components.
4. Creating Flat-Bottomed Holes Without Secondary Operations
- Conventional drills create conical hole bottoms that often require end mills to flatten.
- Flat-bottom tools save an additional step, speeding up production and improving accuracy.
5. Applications Requiring Burr-Free Holes
- In electronics, medical devices, and precision parts, burrs can cause functional issues. Flat-bottom geometry minimizes rework and improves surface integrity.
Tips for Maximizing Flat-Bottom Tool Performance
To get the best results, machinists should follow these practices when using flat-bottom tools:
1. Optimize Cutting Parameters
- Start with conservative feed and speed settings, then adjust gradually.
- Too aggressive settings may increase tool wear or surface damage.
2. Use Peck Drilling for Chip Evacuation
- Especially in deeper holes, retract the tool periodically to clear chips.
- This prevents clogging, overheating, and premature tool failure.
3. Ensure Proper Coolant Supply
- Apply consistent coolant or cutting fluid directly to the cutting edge.
- This reduces heat buildup and improves tool life.
4. Select the Right Tool Coating & Material
- Coatings such as TiAlN or DLC can extend tool life in harder or abrasive materials.Carbide flat-bottom tools are preferable for high-performance operations.
5. Check Rigidity & Workholding
- Flat-bottom tools rely on stable setups; ensure minimal vibration and secure clamping.
- Poor rigidity leads to chatter and dimensional inaccuracies.
6. Regular Tool Inspection
- Watch for edge chipping or dulling, as flat edges are sensitive to wear.
- eplace or resharpen before hole quality declines.
Common Pitfalls & How to Avoid Them
While flat-bottom tools provide clear benefits, there are potential pitfalls if not used correctly. Here’s what to watch for:
1. Using Flat-Bottom Tools for Deep Holes
- Pitfall: Poor chip evacuation and heat buildup lead to breakage.
- Solution: Limit use to shallow-to-moderate depths or combine with pilot drilling.
2. Incorrect Feed/Speed Settings
- Pitfall: Running at overly high feed rates causes chatter, poor surface finish, and tool wear.
- Solution: Follow manufacturer recommendations and adjust based on material hardness.
3. Inadequate Coolant Delivery
- Pitfall: Insufficient lubrication accelerates wear and causes thermal cracks.
- Solution: Use flood coolant or high-pressure through-spindle cooling for consistent flow.
4. Not Accounting for Tool Wear
- Pitfall: Continued use of dull flat-bottom edges causes poor hole quality and dimensional errors.
- Solution: Monitor wear and adopt preventive maintenance schedules.
5. Using in the Wrong Application
- Pitfall: Applying flat-bottom tools for tasks better suited to conventional drills (e.g., very deep holes).
- Solution: Reserve flat-bottom tools for thin plates, angled entries, burr-free applications, and interrupted cuts.
Working with flat bottom CNC tools definitely, make our lives (and machining process) easier. It’s easy to keep, light on pockets and DURABLE. Now, ain’t this what all of us need in our CNC machine shop?
Got questions? Want to go deep into the wonderful world of machining? Just drop us a line, and one of us will get back to you soon!
Frequently Asked Questions
What is a flat-bottom tool in CNC machining?
A flat-bottom tool has a geometric tip profile with a flat surface at its bottom, rather than the pointed or rounded tip of conventional drills or end mills. This geometry helps reduce burr formation, improve stability in thin plates, and maintain cleaner hole exits.
In which applications are flat-bottom tools most useful?
Flat-bottom tools perform especially well in drilling thin sheets, creating hole exits without burrs, angular or tilted surface operations, and intermittent wall contexts (e.g. half holes or edge holes).
Do flat-bottom tools eliminate burrs completely?
While they significantly reduce burrs compared to conventional tools, burr formation may still occur in challenging materials or aggressive parameters. Proper tooling strategy, feeds/speeds, and post-processing help further minimize burrs.
How should I adjust cutting parameters when using flat-bottom tools?
Start with conservative feeds and speeds to ensure stability. Use peck drilling if necessary to allow chip evacuation. Optimize coolant flow and tool coating. Monitor vibration or chatter, and tune to minimize tool movement.
Are flat-bottom tools suitable for deep holes or thick material?
They are less ideal for deep holes or very thick materials, where chip evacuation, tool rigidity, and coolant reach become challenging. In those cases, traditional drills or specialized deep-hole tooling may be better suited.