IMO the trend towards trying to find a magic bullet where it concerns tool
design when the goal is to solve basic chip control issues is unwarranted
when considering that the effective application of simple and well known
techniques like peck drilling etc generally provide excellent results given
low quantity runs such as the one time RD work.
Okay then yes molded chipbreakers definately work wonders for getting rid of
hairballs...as you undoubtedly already know, the effectiveness of any
particular molded chipbreaker geometry ( particularily the land width ) is
largely dependant upon maintaining feed /speed as well as doc within a
relatively narrow range..thinking I might even have geometry and feed speed
recommendations for sorta thing as in earlier times the tooling research
group at the lazy b had thorougly tabulated data for the turning of 7075
whereas our own cutter grinders would grind the chipbreaker in house to
spec--Ill try and check on monday...pretty sure I had cribbed a copy for
myself and if so maybe I'll scan the relevant portions.
I'd appreciate it, even if only from an academic POV.
I'd like to elaborate on this particular situation as it has me fairly
well pissed off. But I better not. I have no doubt that I can get the
chip issue under control. The machine has a 2,000 psi 8gpm coolant pump
plus a huge flood coolant pump. And it's rigid as all get out.
I already have some proper inserts coming too. They have a GP DCMT insert
in there right now so I don't know how they expected that work.
Anyway, it would be a good excuse to try out one of those nifty inserts
in the video at no cost to me. But I'd at least like some hope that they
would make a big diff.
Yup--even though your supplier will have guidelines it's interesting to see
cutting parameters charted in a tabulated format alongside the groove
location and geometry.
Well one nice thing about the molded chip breakers of today is that they
arent as finnickey when it comes to doc--the land width typically being
variable ( widening as doc increases )
Suggest supply the tooling rep with cutting data that are currently being
used--this gives you the best chance of obtaining a performance base line
and with little or no need to modify existing part program the initial
tryout is not a difficult or time-intensive task.......once reliable chip
handling is verified then perhaps tweek the insert and /or fine-tune
production rates upwards via program modification.
I haven't tried either, but that's about to change. I didn't even know
those existed. Looks like a really good thing. Most of what we do now is a
separate chip breaker. BTW, you need to make a trip south sometime :)
You can't 'idiot proof' anything....every time you try, they just make
I'd like to come down there some day. If I ever have the excuse I'll get in
Meanwhile, I saw an ad or something a short while ago. I'm about 99%
certain it was from one of the Japanese tooling companies. They were
touting PCD inserts with molded in chipbreakers. Of course I can't remember
which one or find the info, so while searching the web I came across the
two German companies and the video.
I'll see if I can get info on Monday. I'll let you know the cost, then
later if they worked for us.
Ran some parts today with the PCD inserts with the chipbreaker. We went
with the ones from Becker. We started with a DCGT32.51-CB2. This chip
breaker is supposed to be for larger DOC and higher feed rates. We were
in the sweet spot for DOC and at the low end for feed rate. It didn't
work. We had a very typical PCD chip. A long straight wire without any
curl. Kicking up the ffed rate resulted in severe wrapping of the chip
around the work. We ran a fairly large quantity of parts at 0.003" IPR
with no issues with the chip wrapping or interfering, but that really
wasn't what we were after.
So we switched to the DCGT32.51-CB1 insert. This is the finishing
chipbreaker. We were over the recommended DOC (but plenty of PCD for the
cut)for the chip breaker and were in the middle of the recommended feed
rate. The first part we made very tight spirals which were breaking at
about a 9" length. We kicked up the feed rate to 0.004" and the chips
were breaking. Very short C and S shaped chips. Except in one area with a
slightly different DOC. But we still had tight spirals around 4"-7" long
and very straight. We kicked up the rpm another 1,000 and the situation
We ran over well 100 parts and half filled the hopper with fine broken
I have to say these things really work well but are very sensitive to
DOC, feed rate, and surface speed. We are running low SFM for a PCD at
1155 SFM, bit so far so good. The parameters of the cut are 7075-T651
Aluminum, 0.06" DOC, 1155 SFM, 0.004" IPR feed rate.
Very cool product. Well worth a try. In your case you should probably try
all the styles and maybe all the vendors. I think there are three. Anyway
with some playing around you'll be breaking chips. They come out of the
conveyor like grey sludge.
Becker also offers wipers which we didn't get a chance to try. Due to the
geometry of the cut we had to use the 55 degree insert. I hope to get an
application for the wiper one of these days. If you get that to work that
would make a serious gain in cycle time.
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