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Annular Cutter FAQ

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What is an annular cutter?
Why use an annular cutter?
Which annular cutter do I use?
What are the parts to an annular cutter?
What is diamter and depth?

What is cutter geometry?
What is Standard vs. Stack-Cut Geometry?
Non-Coated vs. Coated Annular Cutters?
What is a pilot?
Do I have to use coolant?
What causes dull or broken cutters?
Why does my slug stick?
Why not use quick change cutters?
Is a carbide cutter better than a HSS cutter?
Aren't all annular cutters pretty much the same?
Why do I have trouble drilling stainless steel?
Can I get a custom cutter made?



 


 

What is an annular cutter?
An annular cutter is a specialized bit for drilling through steel. Like a hole saw for wood, an annular cutter only cuts the outside edge of a hole.
It produces accurate burr-free holes to close tolerances without pre-drilling or step drilling. It can drill a much larger hole and requires less force and time than a standard twist drill bit. As it turns, the cutter produces chips from the outside cutting edges and after cutting the hole a ‘slug’ (round chunk of steel from the center of the cutter) falls out.




Why use an annular cutter?
Annular Cutters offer superior holemaking capabilities. They cut faster, last longer, produce a better hole finish, a true round hole with very tight tolerances, can be re-sharpened and drills holes with less power and torque.





Which annular cutter do I use?
Use this chart to determine which annular cutter to use. The cutter you select depends on the diameter of the hole, the depth of cut and the type of material. A wide range of annular cutters are designed to cut through the following materials:
• Carbon Steel
• Stainless Steel
• Aluminum
• Hard Alloys ex: Titanium
• Hastelloy






What are the parts to an annular cutter?





What is diamter and depth?
When determining cutter size, they are measured by depth and diameter. If you look at an actual cutter the depth is actually longer than what it is rated, (a 1" cutter is really 1-1/4") because this ensures the tool can drill all the way through the hole and allows extra length for resharpening.





What is cutter geometry?
Angles on the cutting teeth make a big difference in how the tool performs. More precision angles increase the tool life and accuracy. Hougen tools have four different tooth geometries.
      • 2 angle
      • 2 & 3 angle - Hougen-Edge®
      • Stack-Cut
      • Industrial





What is Standard vs. Stack-Cut Geometry?
Most annular cutters come with Standard geometry. These cutters are designed to cut through one piece of steel. They offer the fastest, cleanest hole producing a slug that looks like a ‘Top Hat’. When the job requires drilling two or more pieces of steel, cutters with stack-cut geometry must be used. The cutting teeth cut from the inside out producing a round cylinder slug.




Standard Geometry Slug

Stack-Cut Geometry Slug





Non-Coated vs. Coated Annular Cutters?
For 80% of applications a standard HSS cutter works. Using a coated or carbide cutter in these applications offers no additional benefit. Hard materials is where the benefit of using a coated or carbide cutter will pay off with increased tool life.





What is a pilot?
A Pilot is a large nail looking object that must be used when using an annular cutter. It serves three very important functions:
       1. Locates the center of the hole
       2. Allows coolant to flow down around the slug and to the cutting teeth
       3. Ejects the slug at the end of the cut

Pilots go through the center of the cutter. They retract up into the mag drill arbor as the hole is made. Pilots last a very long time and can be used with multiple sizes of cutters.




Do I have to use coolant?
No.... BUT... Coolant increases annular cutter tool life dramatically. Hougen offers a
number of different kinds of lubricant depending on the application. RotaMagic™
Concentrated Cutting Fluid is a biodegradable coolant that is mixed with water and used with a mag drills coolant system. Slick-Stik™ is a waxy lubricant. The user applies a glob to the inside and cutting teeth. Slick-Stik melts as the hole is made. Good for horizontal and overhead holes. RotaFoam™ is a foamy spray lubricant that is sprayed onto the cutter before each hole.

For best results use the mag drills coolant system. Spraying or squirting coolant at the cutter while it is turning does very little in helping tool life. Most of the coolant is pushed aside by the chips and flutes before it reaches the cutter.

*** Note: For Hougen drills without coolant bottles... fill the coolant reservoir through the slots in the arbor. This will hold enough coolant for approx. one hole.






What causes dull or broken cutters?
The primary cause of broken or prematurely dull cutters is a feed rate that is too slow. Slow feed rates will reduce the life of your cutter. Using a firm, steady feed pressure throughout the cut will maximize performance and extend tool life. You want to hear the drill motor working & the cutter producing long stringy chips that are being pulled from the hole. Look for a bird’s nest around the cutter.

Blue Chips = Big Problem
(Something obstructing the coolant system or you’re pushing too hard)

Make sure you have the correct cutter for the material. Stack-Cut for multiple layers.

The second reason why cutters break is movement of the drill or work piece. The cutter wall can easily be snapped if the drill and material is not held rigid.





W
hy does my slug stick?
Using lubricant or cutting fluid helps the slug to eject at the end of the cut. But when
slug ejection becomes unreliable or the steel resists cutting, it probably means the
cutter’s cutting edges are becoming dull. Re-sharpen or replace your cutter. Also make sure there are no chips inside your cutter which can hold up a slug. Also periodically
check your ejection springs to maintain proper spring life.






W
hy not use quick change cutters?
Quick change cutters are nice and convenient if you need to change sizes every hole or two. But using a mag drill with the two set screws to hold the cutter in place offers a couple of advantages:
      • Holds the cutter more rigid and less opportunity for it to move and break
      • Will give up to 2x the tool life






Is a carbide cutter better than a HSS cutter?
Not necessarily. Carbide cutters are great tools and work good in most types of materials. But where they really shine is when they are used in hard or abrasive materials. They can be used in mild and structural steel but to get the best performance, carbide tooling needs to be turned at a much higher RPM than HSS cutters.






Aren't all annular cutters pretty much the same?
That would be like saying all meat tastes the same. Hougen was the inventor of the mag drill annular cutter technology. Hougen® Cutters include the most features for the widest range of materials and benefits for long tool life. It takes a lot of extra time to machine and quality check the tools to ensure the customer gets what they expect. When purchasing a Hougen annular cutter, you are buying the highest quality annular cutting tool in the market.






Why do I have trouble drilling stainless steel?
Stainless steel is a beautiful material but it can easily work harden. Meaning... if you let off your feed pressure and allow heat to build up, the material can harden up to the point that it becomes almost impossible to continue. Use solid steady feed pressure, plenty of coolant and DO NOT let up to adjust your position.






Can I get a custom cutter made?
Absolutely! Hougen can solve your holemaking problems with creative solutions to help you get the job done, complete it faster and at a lower cost. We have helped thousands of customers with unique holemaking solutions. Give us a call or send us an email with your holemaking challenge. info@hougen.com