Manufacturer Onsrud suggests. This works particularly well for routers. Optimizing feed rates and speeds: 1. Start off using an RPM derived for the chip load for the material being cut (see charts). Increase the cutting speed (feed rate) until the quality of the part’s finish starts to decrease or the part is starting to move from hold downs.
- Cnc Router Feeds And Speeds For Cutting 2.5mm Thick Aluminum Sheet Metal
- Cnc Router Feeds And Speeds For Cutting 2.5mm Thick Aluminum Steel
When I built my first router in my dad’s garage, I was really excited to make all kinds of things with plastic and aluminum. I went to school for machining, and I worked in shops with some pretty high-end CNCs.
- AlTin is an aluminum based coating, highly inappropriate for cutting aluminum as the material tends to weld itself to the end mill. A 2 to 3 flute end mill is ideal for milling aluminum, air blast will work fine to prevent recutting the chips.
- Toolroom vs Manufacturing Feeds and Speeds: Do you know the difference between toolroom and manufacturing feeds and speeds? Coolant and Chip Clearing: Best practices for coolant and chip clearing on the mill. What Now: My CNC Won’t Go Slow Enough or Fast Enough? CNC Router and DIY users especially, check this one out.
After the fourth snapped endmill, something dawned on me:
![Feeds Feeds](/uploads/1/1/8/5/118541732/176755355.jpg)
Routers are totally different animals.
Let me share what I’ve learned about how to cut aluminum with a CNC router.
Lubrication
You’re going to want to use some kind of lubrication for aluminum. You can get by without anything for a short amount of time, but it’ll be riskier the longer you go without. If you’re planning on letting your router buzz away for 4 hours unattended, don’t expect your cutter to still be in one piece when you get back if it’s run dry.
There are a lot of websites and forums that say that oil mist is required for cutting aluminum.
Casio fx 880p programs. It’s not.
![2.5mm 2.5mm](http://www.carbonfiber-composites.com/photo/pl14539475-professional_carbon_fiber_parts_cnc_cutting_router_carbon_fiber_sheet.jpg)
It’s really not a bad idea, though. If you want to do the upgrade and have the resources to pull it off, I’d definitely recommend installing one. I use mine all the time for plastics and metals.
![Cnc router speeds and feeds aluminum Cnc router speeds and feeds aluminum](/uploads/1/1/8/5/118541732/742130914.jpg)
They’re not hard to set up. All you need is a kit, compressed air and a bit of oil. The whole package will cost you under $100 (assuming you have an air compressor), so if you use your router reasonably often it’s a really smart upgrade.
While it definitely is my preferred way to cut it, there are a few alternatives that also work great.
Probably the simplest is just hanging out while it’s cutting and giving it intermittent sprays of WD-40. It you’re like me, you’ve probably already got 6 or 7 half-full cans of the stuff on your shelves and in your toolboxes. No reason to overcomplicate this.
There is an area where this doesn’t work the best: if you have a router with a downwards exhaust. I mean like those big Porter-Cable types of wood routers that have lots of power. They’ll blow a ton of air all around the tool, without actually getting air to the tool. It can be pretty tricky to get a decent spray around that air blast.
Not impossible, though. You can use those little red extension tubes that come with the can to help get the oil right to the tool. It’s just a little annoying because the air will blow away any oil that’s more than an inch or two away from the tool so you have to monitor it closely. I have a water-cooled spindle so it’s no problem for me, but it depends on your setup.
Another great option is to use a cutting wax. However, this works better in some application more so than others.
Cutting wax can be smeared all over the top surface of where you want to cut, and it’s great because it sticks on – even a downward exhaust won’t take it off.
This works amazing for work that will be done at a single or shallow Z depth, like when you’re working with sheet metal or engraving. If you’re doing deeper work with lots of Z levels, wax will do a better job of lubricating just the first pass.
To get it to lubricate further down, you need to reapply it in that recently-cut channel. Not the end of the world, but I always like to let machines run without me babysitting them.
Small Tools
For the heavy duty CNC milling machines at work, my go-to was a 1″ diameter solid carbide roughing endmill for tough alloy steels.
Obviously, that wasn’t going to work for a little hobby router.
Small tools work much better – but even still you need to know what kind of tool to use for aluminum. They’re different from plastic-cutting tools.
Here are the basic qualities you want out of a cutting tool for aluminum:
- Great chip clearance – aluminum is gummy stuff that loves to plug up cutters, so the best way to handle it is with cutters with a lot of space between the flutes for the material to clear out while cutting.
- Strong tool – aluminum isn’t a hard metal, but you can still easily break a cutter on it. The 1 flute endmills that are popular for plastics often aren’t strong enough for aluminum
- Smooth – since aluminum likes to friction weld itself on to cutters, it’s better for the surface finish of the cutter to be as smooth as possible to reduce the likelihood of something bad happening.
- Up-cutting (higher helix) – for plastics, it’s common to see down-cutting tools, or tools that have a downwards cutting pressure. Aluminum will just gum up if you use that. Straight-flute bits don’t work so great either – the whalloping impact as it cuts just makes for a nasty looking cut. The best one to use is a cutter with a solid angle on the flutes that will lift the chips up and away from the cutter and gives a smoother shear to the cut.
This is why I really like using carbide 2 or 3-flute endmills whenever possible; they have enough chip clearance to reduce the chance of the aluminum welding itself to the cutter through friction, but they’re much stronger than the 1 flute endmills. Your cuts will look cleaner, and the tool won’t break as easily.
Typically I’ll use a 1/4″ endmill since my machine can handle it well; I’ve done a few mods to make it a bit more rigid. If your machine is really little, you might want to use a 1/8″ endmill for cutting profiles.
Here’s a link to the 1/4″ endmill for aluminum. If you have a decently rigid home build, it should work fine. If you have a small machine, then you should start off by trying a 3/16″ or 1/8″ cutter. Those all have a 1/4″ shank so you don’t need to change your collet when swapping them.
Another factor is your RPM – larger tools need a lower RPM, so if you can get down to 15,000 RPM then the 1/4″ endmill will generally work well. If you can’t go less than 25,000 or 30,000 RPM then you might not want to use anything more than a 1/8″ or 3/16″ cutter.
Rigidity
The cutting parameters and quality of cut will depend a lot on how rigid your machine is. Small hobby routers and the big $100k machines are very different.
Aluminum needs a lot more rigidity that wood or plastic. If you push it too fast, you might actually be able to see your machine flex under the load, if not rattle loose.
Here are some tips for dealing with a machine that’s not too rigid:
- Use stubby tools. The longer the bit, the more leverage the workpiece has. When you’re buying bits, keep an eye out for “stub end” endmills. Keep them nice and short in the collet.
- Use a really small depth of cut. For my first machine (before I did a bunch of upgrades to make it more rigid) I could only go down about 0.010″ per pass in the Z when cutting aluminum. The nice thing about using small Z depths is that you can usually crank the feed rate.
- Consider taking measures to boost your machine rigidity. I used aircraft cable and steel pulleys to add some tension to the bridge (mostly ‘cuz I’m cheap). It worked, though – that really made my machine less prone to issues with flexing and vibration. Some people have added extra ball screws and bearings to make their machine more rigid.
I’ve always found that the more you do to deal with rigidity issues, the better the job will go.
Speeds and Feeds
This is usually the first question asked, but the least likely to get a straight answer.
CNC mills and lathes are generally very predictable in how rigid they are. That’s why we can calculate optimal speeds and feeds without too much testing.
How to open ips files. Then click 'Open with' and choose an application.Programs that open and convert IPS files:. If you cannot open your IPS file correctly, try to right-click or long-press the file. (Windows 10) or ' Windows cannot open this file' (Windows 7) or a similar Mac/iPhone/Android alert.
Not so with routers. They’re way more finicky, and since each machine is a bit different, it’s almost impossible to know beforehand what the “sweet spot” is unless you know your machine well. A homemade hobby router will be very different from a large router that’s professionally built for aerospace composites.
Either way, there are a few starting points that might work for you.
The textbook cutting speed for aluminum using a carbide tool is about 1,500 surface feet per minute at the high end, and 1,000 at the lower end. That’s not to say that you can’t spin it slower – you definitely can. But usually you don’t want to go faster than that.
So here’s how that translates to endmill RPM:
1/4″ carbide endmill | 24,000 RPM max, 16,000 RPM ideal |
3/16″ carbide endmill | 32,000 RPM max, 21,000 RPM ideal |
1/8″ carbide endmill | 48,000 RPM max, 32,000 RPM ideal |
1/16″ carbide endmill | 96,000 RPM max, 64,000 RPM ideal |
Now it’s pretty unlikely that you have a 96,000 RPM machine, but this should give you an idea of how cutter diameter affects RPM. If your minimum speed is 30k RPM, then you might want to shy away from 1/4″ endmills for aluminum in favor of something 3/16″ or 1/8″.
Some say that to reduce the “required” RPM, you need to use a HSS cutter. This is incorrect.
You do not need to run carbide at a minimum RPM.
Usually where people get confused is either one of two possibilities:
1) The machining handbook recommends a minimum RPM, so some people assume that the tool needs to be run at that RPM. That’s not what it means. It just means that you’re not achieving maximum efficiency for the tool. Not a big deal.
2) Some cutters do need a minimum RPM to properly use their features. For example, you need to run some coated endmills at a minimum RPM to “activate” their coatings. You will not likely be entering this arena of high performance machining with a router.
Basically, low spindle speeds are not a good reason to switch to HSS cutters. The only time that this makes sense is if you’re just starting out and you’re afraid of breaking a tool – Carbide is more expensive, but they work better and last significantly longer.
HSS is cheap but not really all that great. That’s why you usually see a lot of HSS in high schools – when the students mess something up, it doesn’t cost the school as much (they’ll break the tools before they get a chance to wear), and nobody really cares how fast their cycle time is.
Now for feedrates: This is a bit of a juggle with your Z depth of cut and XY stepover.
In general, you’d want to keep your chips small – something like 0.001″ per tooth for a 1/4″ endmill, and less than half that for a 1/8″ endmill.
So here are some possible starting points:
1/4″ carbide endmill, 2 flutes | 16,000 RPM | 32 inches per minute |
3/16″ carbide endmill, 2 flutes | 21,000 RPM | 21 inches per minute |
1/8″ carbide endmill, 2 flutes | 30,000 RPM | 18 inches per minute |
1/16″ carbide endmill, 2 flutes | 30,000 RPM | 10 inches per minute |
This may or may not work. It’ll totally depend on how good your machine is. If your machine is home-made and reminiscent of a wet noodle, you might want to cut those feed rates down by half. If it’s a $100k machine, you could probably double it if you want to push it.
For Z depth of cut, just test it. This will be a balance of machine rigidity vs tool size.
For a 1/4″ tool on a rinky dink machine, try starting of at a depth of 0.010″ and go up in 0.010″ increments. For the same tool on a solid machine, try starting at 0.050″ and going up in increments of 0.025″. Listen for when the machine seems to be under load, or when the cut starts to look ugly.
Here’s a little chart that will help you identify what the “sweet spot” is:
Honestly, you’re just going to need to play with it. That chart should give you an idea of what to look for to adjust the feeds and speeds to something that suits your machine.
Don’t get too worked up about this. If your router is fixed RPM (or very limited) then just adjust based on feed rate and depth of cut. It ain’t rocket science, just make it work.
Cutting Strategies
Toolpaths are actually pretty important for routing aluminum. Here are some tips.
Avoid plunging down into the metal whenever possible. Some tools are better designed for this that others, but it’s generally best avoided entirely. Unless you’re dealing with very thin sheet metal, that is. Then it’s not a big deal.
If possible, get to your Z cut level off the workpiece, and then start cutting. That’s not always possible, though. Sometimes you need to get the tool in from the middle of a thick sheet.
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If it’s heavy aluminum, try not to just jam the tool straight down. What works way better is a ramping motion to get down to the required Z depth for the cut.
![Router Router](/uploads/1/1/8/5/118541732/558467486.jpg)
Generally, there are two common ways of achieving this: A ramp-on-shape type of engagement, or helical interpolation.
For a ramp on shape motion (some CAM software might call it something different) you’ll trace the profile that you’re wanting to cut while the tool slowly descends. It’s typically something like a zigzag motion. For most CAM software, it’s just a matter of checking a box and punching in your ramp angle. I usually go with something around two degrees.
For helical interpolation, you’re just making a spiral instead of a zigzag. This works well for holes, or when you’re making a pocket.
If you really have no choice and you have to plunge straight into the material, cut your feed rate waaaay down. Like if you’re running the profile cuts at 20 inches per minute, turn the plunge feed rate down to 4. Even then, pay close attention to see how it goes.
When disengaging from the workpiece (like when the profile is cut and now it’s time to get the tool out of there) a straight retract usually works fine. The only problem that’s common is to have a notch on the part profile where the tool retracted.
This is because the tool is no longer under cutting pressure to stabilize it, and the vibration and runout cause the tool to make a slight gouge.
To counteract this, use an “arc-off” motion. Basically, instead of just having the tool stop on the part profile, add an extra little arc movement in the XY that will get the tool away from the finished geometry when it’s no longer under cutting pressure and free to leave a mark.
Over time, there will be dozens of tips and tricks that you’ll pick up. This should be enough information to get you started with some pretty cool projects.
Have you done anything interesting with your router? Do you have some tips to add? Share them in the comments!
The first question that most people ask when using carbide mini and micro tools to cut wood (and other soft materials) for the first time, is, 'What are the best speeds and feeds?'. What they really want to know is, 'How fast I can cut without breaking a bit? What are the optimum cutting conditions with my equipment?' If you are primarily cutting metal, in most cases, the process of selecting the proper speed (RPM) and feed-rate is relatively straightforward. If you are cutting woods or plastics, the world is not so kind. Nonetheless, it is possible to arrive at an optimum combination of speed and feed reliably and repeatably without experiencing too much brain-death.
The following discussion assumes that:
The following discussion assumes that:
- SPEED always refers to spindle RPM
- FEED always refers to how fast the cutter moves through the material or how fast the table moves during a cutting operation (also referred to as 'feed rate')
- you have measured the backlash on both the X and Y axes of your CNC router and both are less than 0.001' (0.025mm)
- material density and abrasiveness
- material homogeneity (consistent density and cutting properties from point to point)
- feedrate ramp (or acceleration)
- feedrate
- spindle RPM
- spindle TIR
- Clean the spindle bore and collets with ColletCare
- Measure the TIR of the collet you will be using for the test
(measured as far down on the calibration blank as possible) - Use the controller interface to set the acceleration on each axis
(excessive acceleration may break the tool prematurely) - Determine the highest RPM that you can use to cut the material you are testing with this tool
- Record this data for later use
Over the past 20+ years we have gathered a LOT of data cutting specific materials. You can find the information at:
- FR-4 / G10
We consider the feedrate (FEED) and the spindle RPM (SPEED) together because, in the case of cutting soft materials like wood and plastic, it is their combination into a single parameter known as 'CHIPLOAD' that matters the most. As the name suggests, chip load is the amount of material (load) each flute cuts during each revolution (every chip). Another way of looking at it is how far the bit chews into the material every time it rotates one full turn. As the chip load increases (bigger bite per revolution), the transverse stress on the tool increases. Clearly it is important to keep the strain, that results from this stress, below the breaking point of the tool (Transverse Rupture Strength (TRS). On the other hand, at very low chip loads, not much material is being cut so there is nothing to carry heat away from the cutting edges. Below a certain limit, the tools gets too hot and abrasion rolls away the cutting edge, rendering the bit useless. In the case of machining thermoplastics, feed rates that are too low also inevitably lead to the swarf (stuff that you just cut) melting together, which can clog up the flutes and break the bit. Usually the breaking point is preceded by the chips melting and packing together in the kerf as the bit moves on. There is another aspect to chip load that is often overlooked. As the bit turns and starts to cut, material 'flows' across the outside and inside faces of the cutting flutes. If this material 'flow' is too high on the outer surface (low chip load) the cutting edge rounds over from material abrasion. If the material 'flow' is too high on the inner surface (high chip load) the cutting debris cannot be evacuated quickly enough causing it to back up and pack. With nowhere to go, the impacted material seals off the flute and the bit breaks. When the outside and inside 'flow rates' are balanced, edge erosion is symmetric and the bit stays sharper longer. We call this the 'Sweet Spot'. This near mystical combination of FEED and SPEED is exactly what we are trying to find. The strategy that we will employ is pretty simple-minded. Using the SPEED determined above, we will make a series of cuts at gradually increasing FEED rates and examine the chips and kerf produced at each step to find the sweet-spot. The characteristics of the sweetspot in both woods and plastics share some common features.
- If your feed to too low for the spindle speed, the chipload is too small. In most woods, the swarf will be a fine powder that will tightly pack the kerf and have to be picked out by hand. You might also see some burning in the corners where the bit changes direction. In a thermoplastic, this is the region where the chips are so hot that they melt together and weld back to the parent material basically ruining the workpiece. There is also a VERY good possibility that you will break the bit.
The sidewalls of the kerf will probably show a fair amount of chatter (if you can remove the debris) - If your feed/speed combination is just right, wood and plastic swarf will come out as nicely formed chips with little or no packing in the kerf. You should be able to blow out any debris with low pressure air.
The sidewalls and top edges of the kerf should be fairly smooth showing only minor tool marks. - If your feedrate is too high for the spindle speed, resulting in a chipload that is too much for your cutter to accommodate, the bit will start to chatter as the flutes become filled with swarf faster than it can be ejected. You can usually see this happen quite a while before the lateral forces break the bit.
The sidewalls and top edges of the kerf will start to show significant chatter marks. In the case of brittle plastics, you might also witness material being fractured out of the top edges.
To make sure that we choose a safe starting place, we always some empirical 'rules of thumb' to set the depth of plunge, initial feedrate and feedrate increment. In the list below, D is the diameter of the bit being tested.
Cnc Router Feeds And Speeds For Cutting 2.5mm Thick Aluminum Sheet Metal
Plunge Depth (Z)- Softwoods like pine or fir (Janka < 1,000): Z = 2 x D
- Hardwoods like birch, cherry, maple or rosewood (1,000 < Janka < 2,500): Z = 1 x D
- Extreme hardwoods like ebony and ipe (2,500 < Janka < 5,00): Z = 0.5 x D
- Composites like G10, paper phenolic or carbon fiber: Z = 1 x D
- Thermoplastics like PVC, ABS, acrylic or polycarbonate: Z = 1 x D
- Softwoods like pine or fir: F = 0.03 x D x No. flutes x RPM (3% chipload per flute)
- Hardwoods like birch, cherry, maple or rosewood: F = 0.03 x D x No. flutes x RPM (3% chipload per flute)
- Extreme hardwoods like ebony and ipe: F = 0.03 x D x No. flutes x RPM (3% chipload per flute)
- Composites like G10, paper phenolic or carbon fiber: F = 0.007 x D x No. flutes x RPM (0.7% chipload per flute)
- Thermoplastics like PVC, ABS, acrylic or polycarbonate: F = 0.08 x D x No. flutes x RPM (8% chipload per flute)
- Softwoods like pine or fir: ΔF = 20 IPM (0.51m/min)
- Hardwoods like birch, cherry, maple or rosewood: ΔF = 10 IPM (0.25m/min)
- Extreme hardwoods like ebony and ipe: ΔF = 10 IPM (0.25m/min)
- Composites like G10, paper phenolic or carbon fiber: ΔF = 5 IPM (0.13m/min)
- Thermoplastics like PVC, ABS, acrylic or polycarbonate: ΔF = 5 IPM (0.13m/min)
For the sake of simplicity, and uniformity in data collection, all of our testing will be done with the plunge depth specified above. Before you cry foul and point out that most 'real world' machining involves much deeper material removal, keep in mind that our goal is to investigate as many feed / speed combinations as possible WITHOUT breaking the bit. By plunging D deep into the material under test, we minimize the stress on the bit and reduce the chance that it will break. Of course, in actual practice, you can plunge much deeper but, you should keep in mind that the relationship between feedrate and depth of cut is often VERY non-linear. You may find that is it much faster to make a lot of shallow, high-feedrate passes than to make a single deep pass. It is definitely much kinder to your bit and spindle bearings.
- Program a set of parallel slots 1' long and spaced apart at least 2 times the diameter (D) of the bit that you are testing (S = 2 X D) using the test FEED determined above as a starting point.
- Set up your router/spindle to the 'quiet' SPEED also from above.
- Plunge the bit 1 diameter (1 X D) deep (e.g. plunge a 0.0625' dia. tool, 0.0625' deep)
- Cut the first 1' slot.
- Pick up the tool, move to the top of next slot.
- Increase the feedrate by ΔF:
- ΔF = 5 IPM (inches per minute) for tools less than 0.0315' (0.80mm)dia
- ΔF = 8 IPM (inches per minute) for tools greater than 0.0320' (0.81mm) but less than 0.1181' (3mm).
- ΔF = 10 IPM (inches per minute) for tools greater than 0.1250' (3.18mm) dia.
- Note: As you gain experience, you will probably select different ΔF values to more precisely determine the best FEED to match your SPEED. We typically run a test with a fairly large ΔF to isolate the general neighborhood of the sweet spot, then set a lower ΔF to home in on the best operating point.
- Cut the second slot.
- Pick up the tool, move to the top of next slot.
- Again increase the feed by ΔF.
- Continue in this fashion until one of two things occurs.
- the quality of the cut starts to markedly deteriorate or,
- the bit breaks.
- Whichever happens, stop the test and record the feedrate (Fmax) where the bit started to fail.
- Multiply Fmax by 0.75 to get the sweet spot for these cutting conditions.
- Record the sweet spot information in your shop log, listing the material, tool specifications, depth of cut, RPM, and optimum feedrate.
Todd Reith (Custom Luthier / Reith Guitars) offers a very valid objection to the testing scenario above. He points out that lifting the tool between each cut does not accurately reflect the cutting dynamics encountered in most machining operations. Another problem is that it ignores the fact that, in materials like wood that have different cutting properties in different directions, the test does not accurately model what happens in a real wood cutting process. After trying a number of different cutting strategies, we have found that a simple 'zigzag' offers an excellent combination of being easy to program, accurately representing real-world cutting, and offering a clear differentiation between climb and conventional cutting.
Proceed as follows:
Proceed as follows:
Cnc Router Feeds And Speeds For Cutting 2.5mm Thick Aluminum Steel
- You will be cutting a simple zigzag pattern oriented any way you like relative to the grain (if any) of the material that you are cutting.
- The size (RUN and RISE) of the pattern that you program depends, in large measure, on the diameter of the tool you are testing. Practically speaking, we never use a pattern with a RUN (see image on left) less than 1 ' (25.4mm) wide for tools 1/8' (3.18mm) dia and smaller or less than 2' (51mm) wide for tools 1/8' (3.18mm) to 1/4' (6.4mm) dia.
- You will calculate the RISE based on your cutter diameter. We never use a rise that is less than 2 times the cutter diameter (2X dia). If the material we are testing is fairly narrow, and we want to run several different tests, we will increase the RISE so that we can interleave the patterns together in a herringbone pattern.
- Set the RPM on your router/spindle to the 'smooth' nodal SPEED found above
- As a starting point, use the test FEED calculated above.
- Plunge the bit 1 diameter (1X dia) deep (e.g. plunge a 0.0625' dia. tool, 0.0625' deep) and zig to the right and zag back to the left.
- Increase the feedrate by ΔF:
- ΔF = 5 IPM (inches per minute) for tools less than 0.0315' (0.80mm) dia.
- ΔF = 8 IPM (inches per minute) for tools greater than 0.0320' (0.81mm) but less than 0.1181' (3mm) dia.
- ΔF = 10 IPM (inches per minute) for tools greater than 0.1250' (3.18mm) dia.
- Note: As you gain experience, you will probably select different ΔF values to more precisely determine the best FEED to match your SPEED. We typically run a 'ranging' test with a fairly large ΔF to isolate the general neighborhood of the sweet spot, then set a lower ΔF to home in on the best combination of FEEDs and SPEEDs.
- Cut the next zigzag
- Again increase the feedrate by ΔF.
- Continue in this fashion until one of two things occurs.
- the quality of the cut starts to markedly deteriorate or,
- the bit breaks.
- Whichever happens, stop the test and record the feedrate (Fmax) where the bit started to fail.
- Multiply Fmax by 0.75 to get the sweet spot for these cutting conditions.
- Record the sweet spot information in your shop log, listing the material, tool specifications, depth of cut, RPM, and optimum feedrate.
The beauty of this method is that it more accurately models normal cutting modes by leaving the flutes in the material. This accounts for the heat that builds up as material is removed and reproduces many of the variable stresses that the tool is exposed to during normal operation. An added value is that the zigzag pattern isolates the effects of climb cutting around a sharp corner (left side) from the effects of conventional cutting (right side). This will be expanded upon in later tutorials where the condition of these sharp corners provides a very unambiguous sweet spot indicator.
In many materials, you will notice an obvious reduction in the quality of the cut as the feedrate becomes too high. This is because the chip load (amount of material being cut by each flute) starts to exceed the available space between the flutes, causing the swarf to pack and interfere with the cutting action.
Look for:
Look for:
- splintering / burring along the top edge
- bit chatter, especially along the climb side of the cut
- chipping of the top edges in hard plastics
- significant deflection and tip 'wander' (sometimes looks like a shallow sine wave in long straight sections)