Burrless Machining?

[m_morgan]

Firstly, hi! Long time lurker, first time posting.

Is it possible to machine components without producing burrs? What I mean is, if you use the correct cutter, at the perfect speeds and feeds, will the last piece of material be sheared free from the stock, rather than smeared over the edge, causing a burr?

I'm looking at a whole series of steel components which come in pre-turned, and have splines machined on them, before being deburred and hardened. The cycle time for cutting splines on these parts should be pretty low, but the circlip grooves and ends of the part produce pretty serious burrs which take a while to file off.

At the minute, 4 guys are having to work 12 hour shifts with deburring tools, dentists drills, etc. to remove the burrs. Not good.

Also, there's similar sized parts which have internal splines that are broached, rather than cut on a gear cutting machine. These also have serious burrs at the bottom of the broached hole, which are a nightmare to deburr.

What do you guys think? Could the burrs be resolved by a change in the cutting conditions, or do we have to live with them?

[PixMan]

Not too many options there. Of course a sharp tool will leave easier-to-remove burrs, but it won't stay sharp long. The workpiece material has a lot to do with how heavy the burr is and how hard it may be to remove it. The piece in your photo is one that would be fairly quick to throw in a lathe and recut the diameters to do the bulk of deburring, but I sense you don't have the lathe that made them.

Perhaps you can seek out better deburring tools, such as "brush technology" that you could walk around the surfaces using a vertical machining center tool path. The big burrs on broached holes are usually removed by redrilling at the bottom of the hole.

[m_morgan]

The problem with these parts is that there is literally THOUSANDS of them being made every week, and only hundreds going out after deburring. The ones that can be held in a lathe are being deburred that way, but internal splines and difficult to hold/reach components are having to be manually deburred.

I also believe that using the nylon impregnated deburring brushes is a no-no for these parts as they are aerospace, and surface finishes of the adjacent features is critical.

You say that a sharp tool will leave an easier to remove burr, but is there any tool material which could be used to provide a sharp edge for longer when cutting steel? Diamond coating maybe? I'm more used to cutting aluminium, so carbide all the way for me, with HSS when I can get away with it.

[Boots]

Burrs are a by-product of Machining and therefor very difficult to eliminate. The only machining I have seen that produces little or no burrs is waterjet and EDM. Other than that rubbing 2 pieces of metal together to make one smaller will produce a burr no matter how sharp one of the parts are. I often run lite finishing passes to eliminate burrs and change the finishing tool often. I also use a vibratory deburring machine with the proper stones, being careful not to ruin the finish. You can also use a bead blaster to remove burrs so long as that type of finish is ok at the burr site.

[beege]

How much radii are permitted on your features? I usually program a .001"-.005" radius on turned grooves, and mill a small chamfer or radius on sharp edges and corners so that burrs are next to nothing. If you have huge burrs, I suspect that your tool (the last one that influenced the feature) either didn't cut at all, or is dull. Keep your finish tools sharp as possible with as light a cut as possible to minimize burrs. Of course, especially depending on material, YMMV.

[tmbg]

is it possible to cut the retaining groove before you cut the splines? sometimes the order in which you cut your features can reduce the amount of deburring work necessary.

[norm glaser]

Try explosive/thermal deburring. The company I used to work for made gas regulators with many internal intersecting passages, lots of deburring with dental tools.

Explosive deburring worked and removed all burrs in an instant.

[RICHARD ZASTROW]

ref: #7 AKA thermal deburring. Works great on hydraulic valve bodies. Ther's also a newer method, cryogenic deburring. Freezes burrs and then brush them off while they're still brittle.

$.015 Dick Z