Why Use Indexable Cutting Tools?
An indexable endmill making its way through a pocket…
Large endmills can remove a lot of material, but they’re also very expensive. It didn’t take the machining world long to decide they’re too expensive and to come up with indexable cutting tools as the answer. With indexable tooling, the cutting edges are removable carbide inserts. Most of the tool lives on when the cutter dulls, and only the inserts need to be replaced.
Even then, most inserts have multiple cutting edges that can be “indexed” into place to provide a fresh edge. Hence the name Indexable Cutting Tools.
The companion to indexable endmills are called “face mills” because they’re used for “facing.” Facing is surfacing a large flat area, typically the top of the part.
Here’s a typical face mill with 90 degree inserts…
it’s possible to do more than just surfacing with a face mill, so sometimes they’re referred to as “side and face milling cutters.”
If you’re going to be purchasing a face mill, it’s worth looking at our article that compares the insert angles to see which is best for your application.
Face mills can be sensitive to how they enter a cut, especially with tough materials that can chip the inserts. Be sure to check out the tips in our toolpath article on how to optimize your face mill programming.
Indexable End Mill / Insert End Mill
Indexable end mills are used in lieu of solid end mills. For efficient roughing, it’s convenient to have an indexable endmill that are at least 5/8’s to 3/4 inches in diameter. That’s the size where buying solid endmills starts to be expensive, but it is small enough that what’s left for smaller solid endmills to clear is little enough that they can do that job quickly. So, you rough with the indexable and finish with the solid endmill.
Depending on the jobs you have, larger indexable endmills may make sense too. It’s basically a tradeoff between your machine’s capabilities, how tight the confines of your workpiece are, and the cost to keep a bunch of indexable tooling and an inventory of suitable carbide inserts for them.
Indexable End Mills come in many shapes and sizes and with many different insert shapes as well. Here are some of the specialized sub-types:
Button Cutters, Copy Mills, and Toroidal Cutters: Round Insert Milling Cutters
Indexable End Mills with round inserts are often called “Button Cutters”, “Copy Mills”, or “Toroidal Cutters.” They have a number of advantages:
- Their large radius creates a great surface finish.
- Their round shape makes them very strong, so they’re well suited to materials that are hard on cutters.
- The round shape creates forces that are more axial than radial. For light machines, this is their stiffest direction for resisting cutting forces.
We’ve got an entire article on these versatile cutters:
OSG Indexable Drill…
Given just how often our machines need to make holes and the advantages of indexable tooling for end and face milling, it should come as no surprise that indexable drills are available too. These are generally best used for larger holes. Not a lot to know here at the basic level other than to keep in mind that they exist and can save you quite a lot of time on a job.
A Few Words About Indexable Tooling Economics
There are some great deals on indexable tooling and inserts on eBay…
Indexable Cutting Tools will help you save money over running solid end mills all the time. They have many other advantages too. But all indexable cutting tools are not created equal when it comes to saving money.
One thing that’s important to keep in mind is whether the indexable milling cutter uses a standard insert shape available from many manufacturers, or a proprietary shape you can only get from one manufacturer. The latter may be capable of higher performance that may justify its price, but you can be certain its price will also be higher.
Managing indexable inserts is another cost saving opportunity. The more insert types you have to stock, the more expensive the inventory. Look for opportunities to standardize on multiple cutter types that all use the same inserts and you’ll save on inventory at the very least.
For individuals and smaller shops, I want to pass along perhaps my best tip for saving money–you can buy a lot of great indexable tooling plust the carbide inserts on eBay at bargain prices. I’ve put together an article for you on just that topic:
It’s also easier than you’d think to make your own indexable tooling. Here’s a dovetail cutter I made that uses TPGB inserts:
TPGB dovetail cutter goes to work…
I made it in just a few hours on my manual mill and lathe before I had CNC. With CNC, it would be even faster to make one.