Tool Bit or Toolbit? Let's Clear the Air and Talk Performance!

Is it “toolbits” or “tool bits”?

ProFace1 tool bits

It’s always bothered me not knowing whether it’s “toolbits” or “tool bits”. I finally looked it up, and the grammatically correct term is “tool bits”. Since we are in the world of precision machining, I wanted to make sure our terminology is precise also.

I wanted to write about our tool bits :) and why we think they are the best out there, as well as give out tips on how to use them properly to get the best life out of them.

The Unforgiving Challenge: Facing and Squaring Stainless Steel Tube

Working with stainless steel tubes, especially for high-purity applications, presents a unique set of formidable challenges. This material is chosen for its exceptional corrosion resistance, particularly against chlorides and acids, thanks to its molybdenum content. However, these same properties also make it difficult to machine.

Here’s why Stainless Steel demands specialized attention:

• Work Hardening: Stainless steel, especially 316 SS, has a strong tendency to work harden rapidly when cut. The material becomes harder as it’s machined, leading to concentrated heat at the cutting edge, accelerated tool wear, and a higher risk of built-up edge formation.

• Poor Machinability: With a machinability rating of only 36% compared to free-machining steel, 316 SS requires approximately 25% slower cutting speeds than 304 stainless steel. This translates to more frequent tool changes and higher processing costs.

• Stringy Chips: Its inherent toughness causes 316 SS to produce long, ductile, and stringy chips. Without proper chip control, these can re-cut the workpiece, get entangled, or damage the surface finish or tool.

• High Purity Imperative: For industries like pharmaceuticals, food & beverage, and semiconductors, a perfectly square, clean, and burr-free tube end is non-negotiable, especially in preparation for defect-free orbital fusion welding. Burrs can detach, contaminating sensitive process lines, damaging downstream components, and compromising the integrity of critical orbital fusion welds. This means deburring as a secondary operation is often unacceptable due to contamination risks.

• 
  

Donut Tools ProFace Tool Bits: Engineered for Elite Performance on Stainless Steel

Our ProFace line of tool bits (what we used to call the TB-1506-LC, TB-0202-LC, TB-1515-LC and TB-1518-LC) are specifically engineered to conquer the challenges of 316 stainless steel and deliver the burr-free, square cuts demanded by high-purity applications and orbital fusion welding preparation. Here’s why the ProFace stands head and shoulders above the competition:

The Powerhouse Core: M42 High-Speed Steel and Carbide

We make our ProFace tool bits from M42 High-Speed Steel. M42 is a high-cobalt HSS (containing 8% cobalt) renowned for its superior “red-hardness,” meaning it retains its hardness and cutting ability even at elevated temperatures. This is crucial when machining heat-generating materials like stainless steel. M42 offers an excellent balance of high working hardness and exceptional toughness, making it robust enough for demanding applications like interrupted cuts.

We also make ProFace Carbide tool bits which offers superior hardness and exception wear resistance. We recommend carbide for cutting exotic materials like Inconel and Hastelloy and can be operated at 3-4x the RPM of M42 HSS

The Unseen Shield: Advanced AlTiN PVD Coating

The ProFace tool bits are further enhanced with a Physical Vapor Deposition (PVD) AlTiN coating. This isn’t just any coating; AlTiN (Aluminum Titanium Nitride) is a premier choice for stainless steel applications, offering exceptional heat and wear resistance.

Here’s why AlTiN is critical for high-purity facing:

• Superior Hot Hardness: AlTiN maintains its hardness at temperatures up to 900°C (1400°F). This is vital for dry machining stainless steel, where heat is concentrated at the cutting edge.

• Self-Regulating Thermal Barrier: AlTiN forms a protective aluminum oxide layer during cutting that actually increases in hardness as temperatures rise. This layer acts as an active thermal insulator, transferring heat away from the tool and into the chips, preserving the cutting edge and contributing directly to burr-free results.

• Dry Machining Compatibility: For high-purity applications where lubricants are avoided to prevent contamination, AlTiN’s ability to perform exceptionally well in dry conditions is a critical advantage.

• 
  

5 Tips for Maximizing ProFace1 Life and Performance

To get the absolute best out of your ProFace tool bits and achieve consistent, burr-free, square cuts on your stainless steel tubes for orbital fusion welding, follow these critical guidelines:

1. Optimize Cutting Speed (RPM): For 316 stainless steel, slower cutting speeds are recommended to manage heat and work hardening. Do NOT run at high RPM or at full speed!

2. Master Your Feed Rate: This is arguably the most critical parameter for surface roughness and burr control. Consistent Feed: Maintain a consistent feed rate to ensure the tool continuously cuts through the work-hardened layer and avoids dwelling or rubbing. Sufficient Chip Load: Avoid “baby cuts” or excessively light feeds, as these cause rubbing, rapid work hardening, and burr formation. The adage “twice the feed and half the speed” highlights the importance of sufficient chip load.

3. Strategic Depth of Cut: Ensure your depth of cut is sufficient to penetrate past the work-hardened zone, which can be 0.003 to 0.005 inches deep.

4. Correct Position of the Tool Bit: For best results, we want as much tool bit material behind the cutting point as possible. The optimal place to cut on the blade is closest to the middle of the tool bit.

5. Screws on the Back Please: Finally, please make sure that you install the tool bit so that the set screws are on the back. We get it wrong too while testing facing machines, and it will still cut going the wrong way, but the back is dull and has a negative rake angle so it’s not going to be pretty!

   
   

By combining the advanced design and materials of our ProFace tool bits with these optimized machining practices, you can consistently achieve the burr-free, perfectly square tube ends essential for the most demanding high-purity orbital fusion welding applications.

Try our tool bits today! Please reach to us at info@donuttools.com or at 916-573-7800 if you have any questions or to order!

Thanks and I hope you have a great day!

Ky-Won