On The Wire -ARC Cutter Review

I got the arbors OK and another arrived a few days ago. There is still a full range of R8 and ISO 40 available from existing stock and cheaper too.

Actually the review was done a while back as the full complement of new arbours were due well in time for Xmas stocking fillers but have been held up hence the "coming soon", Hopefully Ketan will post an update

Yebbut they're not what I wanted!

Andrew

I am tempted to go with the 50mm shell mill, a 2 inch cut width would be useful but I think I will resist temptation. I think my SX2 would cope with a 50mm cutter providing I kept the DOC down but I try to keep the mill within its limits and dont push it beyond.

The 25mm end mill works great so will continue with that and save the 50mm for when I upgrade to a larger mill.

Hi Andrew,

Apologies for the delay. The new arbors are due in around 22nd January 2020.

The main difference between the new and the 'reduce to clear' rage is that the reduced to clear range have specially made screws to secure the shell mills to the arbors, rather than socket cap head type screws being used on the new range. Please see link to the spare screws.

The arbors in the 'reduced to clear' range will fit the shell mills, but in certain cases, the flange type screw head may need to be turned down, or you can replace it with 'normal' socket cap head screws.

Generally, makers of the shell mills are totally different from makers of the arbors. Makers of arbors really have no idea about which type/maker of shell mill is going to be used with their arbor. Both items being generic in their own way... to a certain extent. So, most of the time, the locking screws are either the flange type or general socket cap head screws.

With the new range, we managed to make the new arbor making factory 'talk - discuss' with the shell mill maker. The idea being to try and match the arbor screw fit with the shell mill. Although this is a new product range for us, long term aim is to try and get consistency, so we also got the shell mill maker to 'work - discuss' with the factory from whom we buy the inserts.

Ketan at ARC.

In some way, you are correct in your understanding Ron. On the tests I did, the 50mm cutter worked fine on the SX2P with low DOC due to the higher torque setting/programming used for that particular brushless motor, at the higher speed range. Great for one pass light finishing/face mill cuts on materials which are less than 50mm wide.

In this respect, the key advantages of using the 50mm diameter shell mills for shallow/light cuts on the SX2P would be that as the shell mill has carbide inserts, it can be run fast, and with there being 4 inserts means you can feed upto 4 times faster than a single point fly cutter.... provided you can handle the faster manual feed rate... or run it on some kind of power feed.

For higher DOCs... say upwards of 1mm (based on material being cut), the 25mm end mill would be more useful for regular use on the SX2P.... generally using 1/2 the diameter of the cutter depending on DOC and material being cut, as discussed elsewhere by Jason and others. If the 50mm diameter shell mill is used for greater DOC, I would experiment with using 20% to 30% of the diameter, on this machine.

Fortunately and unfortunately, due to the higher torque programming, the 50mm cutter 'may do the job - based on material being cut' for DOC greater than 1mm on the SX2P. However, this could result in increased forces loosening various mechanical parts, which in turn could mean re-tightening gibs/spindle nut/s, or damaging machine/material being cut.

Using the full diameter of the 50mm cutter is definitely not recommended for the DOC greater than 0.5mm to 1.00mm on the SX2P.

Ketan at ARC.

There is a rule of thumb that says a width of cut of about half the cutter diameter is bad; it shock loads the teeth/inserts. Better to use less than a third, or more than two thirds.

Andrew

Thank you Andrew... learned something new today

Ketan: Thanks for the update on the shell mill arbors. I'll wait until the new arbors are in stock. The inserts are supposed to be generic. Does this mean I can buy them from elsewhere (an industrial supplier) and they'll fit?

I plan to buy a 40, or 50mm, body for use on the Bridgeport and a 63mm body for use on the horizontal mill. I've already got an 80mm indexible shell mill for the horizontal. The mill has a 5hp motor so I hope to give the cutter a run for it's money in terms of DOC, WOC and chip load. The only limitation is that maximum spindle speed on the horizontal is 1200rpm.

Andrew

Thanks Ketan,

Thats interesting and I think I will keep the 50mm on my current shopping list. I would be happy with 0.25mm cuts in using the full 50mm and it sounds as if the SX2P will be handle that, its the increased feed rate that appeals especially on larger jobs.

Ron

Andrew: Yes, the inserts are supposed to be generic, and you can buy them from elsewhere, and they will fit. In the past we paid limited attention to 'indexable carbide endmills' as a product range.

There used to be a consistency issue because the previous maker insisted on supplying their indexable carbide endmills WITH inserts obtained by them. Sometimes the pockets in which the inserts sat were different from one batch to another, and to accommodate, the indexable carbide end mill maker would change the insert/source slightly, to accommodate. At the same time, the inserts which were sold separately, also changed slightly in dimensions from time to time. This was specifically the triangle type of inserts which were clamped, rather than the ones with a hole through the centre. So we discontinued that range about three or four years ago.

Thereafter, we went on a journey to source a better - consistent package. We settled on a specific maker of inserts who makes to international standards. It was interesting to see how they were made on the latest state of the art Swiss machines. The room in which these machines are housed is spotless, and one could eat off the floor. The only problem I found in this place was the toilets....eastern squat rather than western sit.

The new maker of the indexable carbide shell mills/end mills wanted to also supply us the carbide inserts.... in the same way as every other factory maker we visited. Their buying power from carbide insert makers is automatically high, so prices for inserts/replacements from them is lower than what I pay. Secondly, they will never buy from the manufacturer we use, because our makers prices are generally high in the market place, as they cater for the higher end industrial CNC production market. Generally, most shell mill/end mill makers will go for the cheapest insert supplier at the time of order.

So, even though inserts are generic, based on past experience, I insisted that the shell mill/end mill makers just make the product they are good at, being fully aware of the insert maker we are using, so that they can make sure that their pocket/mount is not deviated in any way, and so that there is no doubt about what we expect.

For the rest of what you have said, it will be interesting to see how you get on with the products once you get a chance.

Ketan at ARC.

I certainly found that the ARC inserts performed far better than ones I had bought in the past complete with a 50mm head and also cheap boxes form the same marketplace. Even the standard APMT ones looked sharper.

Ketan: Thanks for the notes on inserts. The more I look at it the more I'm put off buying. I've been looking at inserts from Cutwel made by Korloy. They seem to measure insert length in a slightly different way so it's hard to compare like with like. Even in the Arc calalogue the length and width of the two inserts on offer are different. How does that work in the machined pocket?

Cutwel do inserts that almost exactly match the Arc part numbers, but are specifically for the Korloy Alpha Mill series. They also do ISO standard inserts. In this section the inserts are stated to be generic but the part numbers differ from Arc in the detail. Specifically what is the significance of the PDFR and PDER parts after the style and size code?

I apologise for being a pain but as always in engineering the devil is in the detail and I don't want to waste my money!

Andrew

Funny enough having seen your earlier post this morning I tried some inserts by both YG-1 and Korloy via Cutwell and they fitted OK, possibly taking a little more pressure on the screw to seat then down into the pocket but no visible sign of any gaps. I've only got 4 of each type so not easy to try in the 63 and 80mm heads but could try three in the 80mm to see if they cut OK.

Those 4 letters may describe shape of insert for a particular metal (angles, chipbreaker etc), the bright Aluminium one in the head from YG-1 is PDFR as are the ones from ARC. The grey Korloy is PDTR and a different shaped cutting edge to the ARC PDER

Edited By JasonB on 02/01/2020 13:06:51

I have just compared the PDER and PDFR inserts I have with the 25mm end mill (both from ARC) and the front face (cutting edge) to rear face (seat) dimension is greater by 0.52mm on the PDER. The sides and ends of the inserts taper inwards down to the rear face where they must be the same dimensionally as they both fit the pocket perfectly. With the inserts having a different thickness and the same tapered sides the length and width dimensions at the front face differ, the PDER being thicker having the larger dimensions.

Well thats how I see it.

Well spotted that man, there are also other differences such as the length of the lower cutting face as arrowed and the Korloy ones certainly come with different angles too

Ha ha, you are not the only one Andrew. I was put off buying for two to three years!... It has been difficult to find a reliable and consistent source... especially for the inserts. Add to this, every manufacturer of shell mill wants you to buy inserts only from them for their holders... as explained before. I have gone through this several times, even with Sumitomo. To get a shell mill from them costs a small fortune... although it is high end CNC production stuff.

On our website, the dimensions given for the APMT and APKT inserts relate to the cutting edges, not the back of the insert (or pocket size).

Any variation in the geometry of the insert, i.e. relief angles, chip-breakers etc., as you would expect from inserts designed to cut different materials, would result in different dimensions. Still, all classed as ISO generic.

PDER – PDFR (ISO codes):
P = 90°
D = 15°
E = Rounded
F = Sharp
R = Right hand feed direction

The thickness can and will be different as you can see in this picture:

Ketan at ARC.

Ron... agreed.... and that difference in thickness is also shown on our site, and it is as provided by the manufacturer we use. thank you. Hope it also comes across in the pictures shown above.

Ketan at ARC.

Jason/Ron: Thanks for the information and practical results.

I'm not worried about variations in thickness, but inconsistencies in length/width do worry me. It's good to know that the inserts fit anyway. Looking at professional tool suppliers the insert side angle seems to be 11°, although I don't think that's set in stone.

I looked up the coding for inserts. The PDER and PDFR decode as follows, basically in accordance with what has been previously posted::

P - cutting edges are at 90°

D - Wiper relief angle is 15°

E/F - Cutting edge condition, E is rounded, F is sharp

R - Cutting direction, right

Man, this stuff is complicated. I'm concerned because I got done on the 80mm face mill I've previously alluded to. It was very expensive but the range is now obsolete, as are the inserts. I've been buying up inserts on Ebay. I've got about 50 now, and with 4 edges per insert that should see me out.

The Arc part number misses out the corner radius, although that's not an issue as they only supply one value.

Andrew

Beaten to it again - must learn to type quicker!

Edited By Andrew Johnston on 02/01/2020 16:15:10

Andrew, when I was looking at the Korloy catalogue earlier they do the same, only adding the corner radius code to anything over what seems to be the standard 0.8mm so possibly an industry standard way to write the insert codes?

I was looking at the Cutwel site. Oddly the Korloy specific inserts don't include a radius, but the ISO inserts do include a two digit radius size, after the insert code.

Andrew