Few steps in the machining process are as important as proper end mill selection. Complicating the process is the fact that each individual tool has its own unique geometries, each pivotal to the eventual outcome of your part. We recommend asking yourself 5 key questions before beginning the tool selection process. In doing so, you can ensure that you are doing your due diligence in selecting the best tool for your application. Taking the extra time to ensure that you&#;re selecting the optimal tool will reduce cycle time, increase tool life, and produce a higher quality product.
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Knowing the material you are working with and its properties will help narrow down your end mill selection considerably. Each material has a distinct set of mechanical properties that give it unique characteristics when machining. For instance, plastic materials require a different machining strategy &#; and different tooling geometries &#; than steels do. Choosing a tool with geometries tailored towards those unique characteristics will help to improve tool performance and longevity.
Harvey Tool stocks a wide variety of High Performance Miniature End Mills. Its offering includes tooling optimized for hardened steels, exotic alloys, medium alloy steels, free machining steels, aluminum alloys, highly abrasive materials, plastics, and composites. If the tool you&#;re selecting will only be used in a single material type, opting for a material specific end mill is likely your best bet. These material specific tools provide tailored geometries and coatings best suited to your specific material&#;s characteristics. But if you&#;re aiming for machining flexibility across a wide array of materials, Harvey Tool&#;s miniature end mill section is a great place to start.
Helical Solutions also provides a diverse product offering tailored to specific materials, including Aluminum Alloys & Non-Ferrous Materials; and Steels, High-Temp Alloys, & Titanium. Each section includes a wide variety of flute counts &#; from 2 flute end mills to Multi-Flute Finishers, and with many different profiles, coating options, and geometries.
An application can require one or many operations. Common machining operations include:
By understanding the operations(s) needed for a job, a machinist will have a better understanding of the tooling that will be needed. For instance, if the job includes traditional roughing and slotting, selecting a Helical Solutions Chipbreaker Rougher to hog out a greater deal of material would be a better choice than a Finisher with many flutes.
One of the most significant considerations during end mill selection is determining proper flute count. Both the material and application play an important role in this decision.
When working in Non-Ferrous Materials, the most common options are the 2 or 3-flute tools. Traditionally, the 2-flute option has been the desired choice because it allows for excellent chip clearance. However, the 3-flute option has proven success in finishing and High Efficiency Milling applications, because the higher flute count will have more contact points with the material.
Ferrous Materials can be machined using anywhere from 3 to 14-flutes, depending on the operation being performed.
Traditional Roughing: When roughing, a large amount of material must pass through the tool&#;s flute valleys en route to being evacuated. Because of this, a low number of flutes &#; and larger flute valleys &#; are recommend. Tools with 3, 4, or 5 flutes are commonly used for traditional roughing.
Slotting: A 4-flute option is the best choice, as the lower flute count results in larger flute valleys and more efficient chip evacuation.
Finishing: When finishing in a ferrous material, a high flute count is recommended for best results. Finishing End Mills include anywhere from 5-to-14 flutes. The proper tool depends on how much material remains to be removed from a part.
High Efficiency Milling: HEM is a style of roughing that can be very effective and result in significant time savings for machine shops. When machining an HEM toolpath, opt for 5 to 7-flutes.
After specifying the material you are working in, the operation(s) that are going to be performed, and the number of flutes required, the next step is making sure that your end mill selection has the correct dimensions for the job. Examples of key considerations include cutter diameter, length of cut, reach, and profile.
The cutter diameter is the dimension that will define the width of a slot, formed by the cutting edges of the tool as it rotates. Selecting a cutter diameter that is the wrong size &#; either too large or small &#; can lead to the job not being completed successfully or a final part not being to specifications. For example, smaller cutter diameters offer more clearance within tight pockets, while larger tools provide increased rigidity in high volume jobs.
The length of cut needed for any end mill should be dictated by the longest contact length during an operation. This should be only as long as needed, and no longer. Selecting the shortest tool possible will result in minimized overhang, a more rigid setup, and reduced chatter. As a rule of thumb, if an application calls for cutting at a depth greater than 5x the tool diameter, it may be optimal to explore necked reach options as a substitute to a long length of cut.
The most common profile styles for end mills are square, corner radius, and ball. The square profile on an end mill has flutes with sharp corners that are squared off at 90°. A corner radius profile replaces the fragile sharp corner with a radius, adding strength and helping to prevent chipping while prolonging tool life. Finally, a ball profile features flutes with no flat bottom, and is rounded off at the end creating a &#;ball nose&#; at the tip of the tool. This is the strongest end mill style. A fully rounded cutting edge has no corner, removing the mostly likely failure point from the tool, contrary to a sharp edge on a square profile end mill. An end mill profile is often chosen by part requirements, such as square corners within a pocket, requiring a square end mill. When possible, opt for a tool with the largest corner radius allowable by your part requirements. We recommend a corner radii whenever your application allows for it. If square corners are absolutely required, consider roughing with a corner radius tool and finishing with the square profile tool.
When used in the correct application, a coated tool will help to boost performance by providing the following benefits:
Harvey Tool and Helical Solutions offer many different coatings, each with their own set of benefits. Coatings for ferrous materials, such as AlTiN Nano or TPlus, typically have a high max working temperature, making them suitable for materials with a low thermal conductivity. Coatings for non-ferrous applications, such as TiB2 or ZPlus, have a low coefficient of friction, allowing for easier machining operations. Other coatings, such as Amorphous Diamond or CVD Diamond Coatings, are best used in abrasive materials because of their high hardness rating.
There are many factors that should be considered while looking for the optimal tooling for the job, but asking the aforementioned five key question during the process will help you to make the right decision. As always, The Harvey Performance Company Technical Service Department is always available to provide recommendations and walk you through the tool selection process, if need be.
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Harvey Tool Technical Support: 800-645-
Helical Solutions Technical Support: 866-543-
Harvey Performance Company&#;s team of engineers works together to ensure that your every machining challenge &#; from tool selection and application support to designing the perfect custom tool for your next job &#; is rectified with a thoughtful, comprehensive solution.
As has been said step one is to get a reliable brand. I tend to buy mid range industrial ones as my machine is a Bridgeport.
Step two is to make best use of what you have bought within the limitations of the machine. My Bridgeport is a monster compared to your X1 but its still only specced for endmills up to 1" diameter!
There is much more to be gained by setting into a proper technique to get longest life than by stumping up the extra ££ for a super duper extra quality cutter costs over decent mid range.
Coatings are generally thermally sensitive and usually need to get hot to work properly. No point in paying the extra if you aren't going to see any real benefit because your machine cannot work them hard enough to heat up. However even if the coating doesn't get into working range the cutter may still last a little longer but this is usually more due to the base cutter being of higher quality than a simple mid range one. If a good maker is going to go to the trouble of coating it makes sense to start with a high quality cutter.
If buying off brand a certain care and feel for prices is needed to avoid the low end cutters dressed up with a pretty coating for showroom appeal. Rather like the pretty TiN coated drill sets in the bargain bin.
Normally too messy for us but decently arranged coolant, either mist or flood, is probably the best way of extending cutter life. On my Bridgeport decent but inexpensive with mist is about the equal of good (mid range industrial) dry for lifetime.
The big neophyte error is babying the cutter with tiny cuts rather than letting it cut. For best results and life you need to get close to book values. Oh and use the sides, book says depth same as diameter at 1/4 diameter width for endmilling and 1/2 diameter depth for slots so get as close as you can given the job and machine specifications. I can just follow the book, you will need to be more circumspect with larger cutters.
Fundamentally the cutter lifetime is defined in number of turns and number of passes. Crudely twice as many passes at half the feed means 1/4 as many jobs per cutter. Keep the chips clear, recutting chips still counts and conditions are unfavourable.
Don't go mad as you are machine stiffness limited but it's well worth sacrificing a cutter or three just to get a good handle on what works for you. When you have found out the best settings, whether by experiment or inadvertently mid job write them down.
The advice against carbide cutters is primarily against the insert kind. Generally the holder diameters are too large and the inserts designed for heavier cuts at higher speeds than your X1 likes. But, as with lathe tooling, there are a fair number of inserts that work fine in lighter machines at well below book speeds and cuts. There are also some that will leave a ploughed field finish if used off book. Experimentation is expensive!
Normal endmills in carbide will be fine. Handle with care as they are very sharp. They don't like vibration which can lead to edge chipping. Given the much greater durability of the sharp edge relative to HSS this is the one time where going light on cuts may be an advantage with a small machine which doesn't have the mass to tamp down vibration.
Carbide shanks are "more slippery" than steel ones so they don't hold as well in collets. Collet needs to be pulled up well. ER are better than Morse or 5C but you should use book torques. Don't even think about bodging one into a drill chuck to save changing the chuck out. It will walk straight out under cut! Learned that the hard way many years ago when I "only wanted a quick counterbore" on a drilled hole. My carbides are weldon flat types.
Clive
PS Sorry for repeating some previous advice. Slow typing. + 1 Andrews recommendation for Cutwel, a very good supplier.
Edited By Clive Foster on 29/03/ 10:13:58
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