Choosing an annular cutter
- July 28, 2015
If I had a nickel for every time I was asked, “what type of material are you drilling?” and received the response, “steel,” I would be sitting on a beach and enjoying the rest of my life. In today’s environment, the word “steel” is a loose term and often misunderstood. It is not just something that a magnet sticks to anymore. There are more different types of alloys and materials than ever before. When it comes to holemaking, understanding what type of material is being drilled is important because of the many options for choosing an annular cutter.
When looking for an annular cutter, the type of material being drilled is the key factor in knowing which cutter to select. Find out what material you are drilling before purchasing an annular cutter. There is everything from mild steels such as A36 and aluminum to armour plate and stainless varieties. Even much of the structural steels today are harder and more flexible depending on chemical composition. AR (Abrasion Resistant) steels have become increasingly popular and can be challenging to drill. If you don’t know your material, find out.
Annular cutter types
The days of grabbing a magnetic drill and plowing a twist drill through the steel, blue chips flying, are gone. Annular cutters are the standard for holemaking with mag drills. These cutters make the job easier, more efficient and save shops money.
Here is a quick basic chart (at right) to reference when deciding which cutter to use.
Another factor in the annular cutter equation is tooth geometry. Cutting multiple plates at once does not use the same tooth angles as when cutting a single sheet. There are different geometries and features companies put on annular cutters to help ensure the most success.
And don’t forget coatings. Manufacturers can apply a variety of different coatings to increase the tool life in harder materials. Remember, you get what you pay for. Also, look for annular cutters that can be re-sharpened. That will save you even more money in the long run.
Other important factors
After you choose the proper annular cutter, there are other factors to help lead you to greater success.
1. Always use coolant and use the machine's thru-the-spindle coolant whenever possible. Cutting tools love coolant.
2. Use good steady feed pressure. Make sure you are pulling a good chip.
3. Aim to get close to the recommended RPM for the cutter and material. Your tool life will thank you.
4. Use a sharp annular cutter, because sharp edges just cut better.
5. Ensure the arbor and mounting system holding the tool is rigid and secure otherwise you can quickly dull or break a cutter.
6.Always use the pilot pin. Slugs must be ejected.
When in doubt, call the manufacturer and ask questions. Your supplier is the expert and can help guide you in your hole cutting decisions. Whether it is sheet metal or thick plate, annular cutters are incredible tools that make it much easier to drill holes. Choose wisely and there is almost no “steel” you can’t drill. SMT
Allan Powers is technical specialist with Hougen Manufacturing Inc.