Understanding Two Key Milling Techniques

Climb Milling vs. Conventional Milling

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Summary

In this informative video by Toms Techniques, the intricacies of climb milling versus conventional milling are explored. Addressing common concerns from machinists, the creator explains the differences between these two techniques, highlighting that both have their unique advantages and applications. He provides demonstrations of how each method interacts with the material, the effects they have, and their potential pitfalls, particularly focusing on the flexibility needed to prevent equipment damage when using climb milling. The video aims to arm machinists with the knowledge needed to harness both techniques effectively while avoiding common mistakes.

Highlights

Climb milling against the cutter’s rotation gives a better surface finish but can cause the workpiece to pull into the tool, risking damage. ✂️
Conventional milling feeds against the cutter’s rotation and is ideal for preventing workpiece movement on light machines. 🚜
Use climb milling for a finishing pass to achieve a smoother finish, using conventional milling for rough cutting. ✨

Key Takeaways

Climb milling offers a superior surface finish compared to conventional milling due to its cutting dynamics. 🎨
Conventional milling is safer for heavier cuts on lighter machines as it doesn’t pull the workpiece into the cutter. 🛡️
Understanding the interaction between cutter rotation and feed direction is crucial to prevent accidents. ⚠️

Overview

Climb milling and conventional milling are often confused but serve important, distinct roles in machining. The video by Toms Techniques clarifies misconceptions and highlights when each method should be used for maximum effectiveness and safety. He dives into the mechanics behind each method, explaining how the direction of feed relative to the cutter's rotation impacts the final surface finish and machining dynamics.

Climb milling is the tactic of feeding the work with the cutter's direction of rotation and is noted for resulting in superior surface finishes, albeit with the risk of pulling the workpiece into the cutter if not controlled properly. This is why it’s recommended primarily for finishing rather than heavy cuts, especially on light equipment, to avoid damage to the tool or workpiece.

For roughing or heavy cuts, conventional milling is better suited as it pushes the material against the cutter's rotation. This provides better control and stability, especially on lighter machines, preventing the undesirable latch-on effect of climb milling. The video emphasizes the importance of selecting the right milling technique to match the task, ensuring both efficiency and safety in machining.

Chapters

00:00 - 00:30: Introduction to Climb and Conventional Milling The chapter introduces the topic of climb milling versus conventional milling. It mentions that the author receives many questions about these milling techniques, indicating a common interest or concern among people. The chapter aims to explain what climb milling is, why people might be apprehensive about it, and what conventional milling is, along with guidance on how to perform it.
00:30 - 05:30: Climb Milling Explanation In this chapter titled 'Climb Milling Explanation,' the speaker addresses the common confusion surrounding two milling techniques: climb milling and conventional milling. The chapter emphasizes that both methods are valuable to machinists, with the key being to utilize them to one's advantage and avoid common pitfalls that can arise from misuse. The speaker intends to demonstrate both climb and conventional milling, highlighting their pros and cons. Additionally, practical demonstrations, including intentionally crashing a part, are planned to illustrate the functioning and challenges of climb milling.
05:30 - 09:30: Conventional Milling Explanation The chapter discusses conventional milling, starting with an informal introduction noting the challenges it poses and a hope to effectively demonstrate the process without damaging parts. The speaker describes their setup, which involves using a 7/8 diameter four-flute end mill held by a collet, and points out that the grip on the endmill isn't very firm, indicating potential instability in the setup.
09:30 - 19:00: End Milling Considerations This chapter discusses considerations when using large endmills, particularly those with a Welden shank designed for holders with set screws. It highlights a challenge with the proper fitting of large endmills into holders, noting that while they typically have a rigid setup when the holder extends down to the flute, in some situations, like in this case, an endmill extending further than usual can be beneficial.
19:00 - 28:00: Surface Finish Comparison The chapter 'Surface Finish Comparison' discusses different machining techniques and their impact on surface finish. The speaker introduces a demonstration using an aluminum bar and describes the concepts of climb milling and conventional milling. The chapter emphasizes the flexibility of the cutter and the preference for it to bend rather than break during machining. The practical application of these techniques is highlighted in context of achieving precise and finished surfaces.
28:00 - 30:00: Conclusion In the chapter titled 'Conclusion,' the discussion focuses on the concept of climb milling in machining. Climb milling involves feeding the workpiece against the cutter's direction of rotation, which in this case is clockwise. This method results in the cutter climbing up onto the surface of the material being cut. The summary highlights the significance of the cutter's rotation direction in this process.

Climb Milling vs. Conventional Milling Transcription

00:00 - 00:30 [Music] so I answer a lot of email on questions from people on various topics and one common topic I hear about all the time is is climb Milling versus conventional Milling people want to know what this climb Milling thing is and why should they be afraid of it and what this conventional Milling thing is and how do they do it and there's just generally a
00:30 - 01:00 lot of confusion about the two techniques in reality though climb Ming and conventional Ming are both very useful techniques to The Machinist the trick is just learning how to use them to your advantage and how to prevent them from using you to theirs so uh what I'm going to do today is uh just do a quick demo on what is cim milling and what is conventional milling and go over a little bit over the the positive points and the negative points of each and I'll probably even uh crash a part or two just to show you how how climb
01:00 - 01:30 Milling in particular can bite you in the ass so uh let's get going um make some chips and hopefully I'll figure out a way to crash apart without breaking something that that's always a challenge but I think we can work something out okay before we get started here let's talk about my setup a little bit um I'm using a a 7/8 diameter four flute endmill double n and as you can see it's not gripped very well I'm using a collet to hold on to it and I don't use
01:30 - 02:00 endmills this large so I don't really have the proper holder for this big of an endmill um this endmill has what's called a Welden shank on it you see it has a flat that Flat's meant for endmill holders with set screws okay um normally the holder would come like all the way down to the to the flute so it' be a nice rigid setup in this case it won't fit all the way into the CET some kind of it's kind of extending farther than it should but that's actually a good thing in this case because it if it's
02:00 - 02:30 extending farther it means it's flexible and I'm going to be doing some nasty things to this cutter and I'd rather have it Flex than break so uh that's enough about that let's talk about uh our demonstration here here I have a piece of uh aluminum bar okay let's say I wanted to side Mill the end of this bar this is just a belt sanded surface here let's say I wanted to machine it make it nice and precise there are two ways I could go about it I could climb Mill it or I could conventional Mill it now what's the
02:30 - 03:00 difference now let's talk about climb Milling first okay climb Milling is when you feed the work against the cutter in the direction of rotation okay rotation has you know has everything to do with it in this case the cutter is rotating clockwise so if I feed my work against the cutter like this it's feed being fed in the direction of rotation of the cutter okay and what the cutter is going to want to do when it starts cutting is is climb up on the on this surface that's
03:00 - 03:30 where the the term climb Milling comes from okay now that is both advantages and disadvantages the advantage is climb Milling gives you a much better surface finish I'll explain that a little later but gives you a good surface finish the disadvantage is if you try to climb Mill take a heavy cut climb Milling on a light machine you're going to be in trouble because what it's going to do it's going to bite into the work and it's going to either pull the work out of the vice or it's going to break the cutter one of the two so climb Mill is
03:30 - 04:00 generally not a good idea on light machines for heavy cuts and let me let me demonstrate that okay what it can do it's a big heavy machine but I can still get this cutter to grab this metal and pull the table into it and I'm going to show you how that what that looks like actually let me slow this down it's easier to see when it's going slow let's just run it slow okay so let me touch the end of the part here
04:00 - 04:30 okay we'll move in about uh oh I don't know 80,000 okay now Watch What Happens here when I start feeding with the direction of the cutter taking an 80,000 steep cut okay see it see the uh work getting pulled into it and that loud clunk that goes with it okay that's uh what you're looking at is the part grabbing the work
04:30 - 05:00 and pulling it um pulling the table toward it from the uh it's hard to explain here from the the backlash in the lead screw is allowing the table freedom of movement and the cutter is actually pulling the table independent of the lead screw okay this machine doesn't really care but if I was using a smaller endmill or a lighter machine this this would cause problems
05:00 - 05:30 okay so that's that's a that's a negative of uh clim number all right so let's talk about conventional M let's go down here at the other end same depth to cut difference is we're feeding in the other direction we're feeding against the rotation of the cutter
05:30 - 06:00 okay notice you don't see any of that jerkiness it's not trying to hold the work into it what it's trying to do is trying to push the work away but it can't because there's there's no backlash in the lead screw it's trying to it can't you know it can't grab it and you know the table is not floating when you're feeding in this direction you're feeding right directly against the the screw itself
06:00 - 06:30 so this is what you should be doing if you have a light milling machine for heavy Cuts is conventional Milling all right let's bring this thing up to speed and we should be running this is like a 7/8 cutter this should probably be running 4 500 RPM okay so let's finish this up at proper speed here you can see
06:30 - 07:00 what one of the disadvantages of climbing on you can see it leaves a pretty crappy looking finish okay see let's let's feed this whole thing clean this whole thing okay I just climb no this entire end of this part you can see it's pretty nasty finish there's chips hanging on it
07:00 - 07:30 so now let's say uh that was that was conventional Ming now let's move it in another 5,000 and take a a light finish cut back the other direction climb up look at the difference okay that's the advantage of climbing Le a really nice surface f
07:30 - 08:00 so that's you know that's generally what I do I'll take a rough cut conventional milling and I'll take a finish cut fine millon these are these are really really nice finish okay so let's talk about endmilling um you know a machinist always has to be aware of what the cutter what effect the cutter is going to have when it contacts the work you know how it's going to how it's going to move the try to move the work so you
08:00 - 08:30 always have to keep that in the back of your mind so you can make sure that if you if you think that you know if if the cutter is going to be climb Milling for an instant when you start a cut you have to lock your table down or remove the backlash from your lead screw so it can't grab the table and move it unexpectedly you always got to keep that in the back of your mind so let me show you how climb Milling applies when you're end Milling instead of side Ming okay so let's talk about climb
08:30 - 09:00 milling and conventional Milling as it relates to uh to end Milling okay let's say I want to end Mill the top surface of this part okay there are a couple ways I can go about it I can I can conventional Mill it or I can climb Mill just like I did on the side let me show you what the difference is right okay if I start here on the back side and bring the work toward the
09:00 - 09:30 cutter okay kind I'm going against the RO the rotation of the cutter I'm conventional Milling in this back side okay see the cutter is wanting to move the part into it in that direction okay but if I come over on this other side start that if I go to the front side and I Mill the same direction
09:30 - 10:00 I'm climbs the table see now the the cutter is trying to push the work away from okay now this it doesn't seem like much but I'll tell you what I I get a lot of people pointing out when I'm I'm Milling when I'm squaring up stock like I had video out on squaring up stock on
10:00 - 10:30 the milling machine I'm constantly getting critiques from people saying hey you got to you got to use a file to remove those Burrs before you turn the part over so those there's all kinds of Burrs there you can't you can't set a a part on a burr and expect it to be square well let me explain what's what's going on here I'm using climb Milling to my advantage okay if I climb mil all around the outside of the par like this for my first
10:30 - 11:00 cut all way around it doesn't create a bur so I can say myself a lot of time by not having to remove that bird see there's nothing there okay nothing I mean normally You' slice your finger open doing that but not if you climb a little around the outside first and once you get that once you get the
11:00 - 11:30 outside done then you can go back in the middle and finish up there they have a nice inmed surface with no filing required so there I'm using climb Milling to my advantage okay all right now let me show you how clim Milling can cause you some major grief let me switch setups here
11:30 - 12:00 okay let's say we have a part clamped in the viice like this and let's say I want to Mill a step in this thing let's say I want to Mill a step out of it like that okay so throw the part in the vice going to going to side Mill it okay I'm just going to run up against it should be an easy thing right let's see let's see how it works out for us okay just tucks front of the
12:00 - 12:30 part move in a little bit I don't know however deep your your slide is let's see what happens okay well what happened is we uh we just scrapped our part up okay CU climb Milling caused the End Mill to bite into the work and being gripped sideways in device like this it wasn't a very substantial grip and it moved apart okay
12:30 - 13:00 so what we would have done is if you used a using a smaller endmill you probably would have broken your endmill and we also scrap the part up so let's see uh what a better way to do this would be okay first of all holding apart like this and Milling it so that the the the end Miller wants to move the part sideways is generally not a good idea um you just
13:00 - 13:30 saw why it's not a good idea for climb Ming I mean I I can get away with uh conventional Milling without a problem okay if I do the same thing I come over on this side and I Mill against the rotation of the cutter I'm probably going to be okay okay if it does grab it might move the car a little bit but it's not going to it's not going to crash like it did the other way then I can come back and take my finish cut the other way light good okay a better way to do
13:30 - 14:00 this would be to rotate the part this way okay and do your Machining on the Y AIS instead of the X okay and now the cutter is trying to push the part against the solid jaw of the device and there's no way no way going
14:00 - 14:30 if you take too heavy a cut it might Mudge the part sideways away from the end though but it's not going to grab it and it's not going to you know crash on you so that's that's a good example of how F knowing can bite you if you're not paying attention remember I said machinist always has to be aware of how the cutter is going to act on the part when it when it starts cutting so you got to keep that in the back of your mind all right so let me show remember I showed you how clim makes a much better
14:30 - 15:00 surface finish let me just explain why that is here all right so let's see if I can explain why we get a better surface finish climb Milling than conventional Milling let me do a quick sketch here in my vice dry erase board um this is looking at at a piece of uh stock from the top that we're we're this is our cutter right here okay
15:00 - 15:30 cutter rotation is clockwise and the direction of feed is in this direction so we are conventional Milling here right now what happens is when you conventional Mill your cutter starts out with uh the thickness of the chip is zero where it starts out okay and that's that's where the the bad surface finish comes from your uh cutter requires a certain amount of pressure on the work before it starts cutting so
15:30 - 16:00 before that point it's just kind of rubbing along the surface and generally just kind of smearing the metal it's not it's not cutting it nice and clean then as it travels into the work it gets a little more and more pressure on The Cutting Edge until it starts Until It Breaks through the surface and starts cutting so what you end up with is a chip that starts out with zero thickness and then as the cutter travels and rotates you end up with a chip that's shaped like this okay
16:00 - 16:30 don't forget we're feeding in this direction and there's more than one flute so as the cutter travels and rotates it creates this sort of wedge wedge shaped chip so it starts out with zero thickness ends up with some thickness depending on how fast you're you're feeding and how fast you're rotating okay this makes a crappy finish because like like I said when at the start of the cut down here there's zero thickness zero thick chip thickness and it just kind of smears the metal that's why end up with chips stuck on the on
16:30 - 17:00 the side of the part when you conventional M so now let's take a look at climb melon just the opposite okay we got a our block or block of aluminum or steel or whatever we're cutting here okay we got our cutter like that direction of rotation is clockwise and we're feeding in this direction feeding with the direction of
17:00 - 17:30 rotation of the cutter okay now as these uh cutting edges as these teeth come around with the with the cutter or the work feeding okay the start of our cut is thick okay and as the cutter rotates and feeds the chip gets thinner until it's zero going out then it makes a nice and it just kind of exits okay The Cutting Edge so we what we end up with here is a nice clean Rance and a nice clean
17:30 - 18:00 exit of our Cutting Edge so we get the same shaped chip it's just in Reverse we start out with a thick cut end up with with a thin cut there's none of that smearing going on here because the cutter when it gets to the end of the of the material it just comes out okay it releases it doesn't have to build up pressure before it starts cutting like when you conventional mil so that that's why you get a better finish
18:00 - 18:30 clim Milling over conventional Milling okay so that's all I have on that just remember keep your mind going and whenever you uh before you ever take a cut on a piece of metal have it down in your mind what's going to happen how that cutter is going to interact with the part and it should keep you out of trouble all right I'll see you next time [Music]