Wiper Inserts for face milling brass

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

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)

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?

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.

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)

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.

Improved finish at same rates....

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

ummmm....brass is non ferrous

sorry...already done

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.

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".

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.

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

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.

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

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.

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.

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

-- Cheers,

--Mitch

Here is the link to the actual insert

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)