Wiper Inserts for face milling brass

Is it worthwhile to use a wiper insert to improve the surface finish of brass when doing a facing operation.

I have a 3" face mill, and would like to get the best face finish possible. I am using sharp, positive rake Iscar inserts currently, but wonder whether adding a single wiper to teh cutter would result in a better finish.

If the answer is yes, what is the incremental finish quality one can expect (some experiences would be nice - ie Ra finish before and after)

Reply to
Robert Salasidis
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I guess you already tried taking half the inserts out.... Isn't brass better suited for a negative rake and a real sharp edge?

Reply to
Kathy

My understanding is that all ferrous metals are better with sharp inserts, and positive rake (which I am doing)

Howeever I would like to improve the surface finish further, and that's why I would like to know if a wiper inserty will help, or in the case of brass would amke no difference I have not tried is as the cutter I am using uses APCR1003 inserts, and no wiper is available for that cutter body - so I would need to get a different cutter, new sharp inserts and 10 wiper inserts (sold only in that quantity)

Reply to
Robert Salasidis

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Reply to
PrecisionMachinisT

What kind of finish, are you getting now? How are you measuring it now, and what type of finish are you trying to achieve, reallisticly?

Reply to
Garlicdude

Robert Salasidis wrote: SNIPPED

- all

Get your local, pick a major brand rep, to come out and demo before you buy. Most good ones will do that if your serious.

Reply to
Garlicdude

Sorry it was a type - as I was discussing brass, I should have said NON-ferrous metals

So the wiper insert - does it do anything for quality of finish (or does it just allow faster feed rates - at the same level of quality)

Reply to
Robert Salasidis

I wish I had a profilometer, but I am just using the feeler type gages, and can estimate I am getting about 0.4 um (about 16 u in).

I would like to double that if possible.

Reply to
Robert Salasidis

Improved finish at same rates....

Chipload per tooth being pretty much the same, difference being that one "wiper insert" has a "flat" bottom.......

Reply to
PrecisionMachinisT

ummmm....brass is non ferrous

Reply to
fulliautomatix

sorry...already done

Reply to
fulliautomatix

Brass is better with zero or even negative rake, not positive, which tends to dig in too much, unless the machine is *really* rigid.

I've got no experience with wiper inserts, but I suspect that they might prevent dig-in just as zero rake does.

Good Luck, DoN.

Reply to
DoN. Nichols

I have most of that info in the form Kennametal literature--rarely needed here though.

A fairly simple explanation ( though not entirely complete--DOC and nose radius comes into the picture too ) is that your IPT times your number of teeth cannot be greater than the width of the "flat" on your "wiper tooth".

Reply to
PrecisionMachinisT

Robert, I checked my Machinery's Handbook, Surface Roughness Produced by Common Production Methods, and IF your presently achieving a 16 finish by milling your doing pretty well. I think to get a MEASURABLE 8 finish would require a good machine, especially the spindle, and a solid setup. Having said that wiper inserts, button style cutter, or a larger radius on your present cutter insert will all help to give you a better finish.

Reply to
Garlicdude

One buys the 70$ surface roughness "feel" gages and compares - strictly a qualitative measurement.

The exact details of my cut are

I am using an ISCAR HM90 F90AP 3" cutter with APCR1003 inserts

There are 11 insert position on the cutter, with a nose radious of

0.02"

I am cutting at a depth of 0.01", 1300 RPM at an 8"/min feed rate (very slow to minimize the ipt)

When I speed up the feed rate, I get a worse surface finish.

My machine has a BT30 spindle, so a 3" cutter is tha largest that I can use.

Reply to
Robert Salasidis

Mine was a free sample from a machine tool manufacturer - but if you were to buy one they do run up to 70$.

Reply to
Robert Salasidis

Right out of Bill's calculator, copied from Sandvik technical help:

F = finish requirement represented as non decimal integer i.e. 32 or 63. R = tool nose radius.

SQR((F*(8*R))/(10(sixth))

Can also be used for calculating step over amount when kellering with a ball end mill.

Reply to
Bill Roberto

0.01" - iscar told me to try a DOC that is at least the nose radius (0.02") deep, so I will try that

The iscar tools have a nose radius, but also have a short flat area (0.047"). Therefore the classic formula for ball cutters and scallop height would not apply.

My main reason for thinking a wiper would give better finish, is taht it would eliminate the small diferences in insert size/mismatch, and seating mismatch within the cutter body.

Having a single wiper would eliminate all differences between the inserts, and then the main problems would be rigiditiy of setup, as well as the "flatness" of the flat area on the wiper.

Howeever, I don't really want to buy 10 of them to see if it will work.

Reply to
Robert Salasidis

See if you can convince your rep to give you one as a try-out, promise to buy 10 if it works.

-- Cheers,

--Mitch

Reply to
Mitch

Here is the link to the actual insert

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I have an indicator that is able to indicate at 1/20 of a thou - I will try seeing what the mismatch between teh inserts in the cutter is

(I know my spindle runout is about 2/10 ths)

Reply to
Robert Salasidis

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