[xray34]

Hi everyone,

I have to machine 4 dies for cutting out biscuit (cookie) shapes.
They are from solid stainless steel 316..

Blank 120x180x45 mm

The shape is the outline of a fat snowman (not that this matters)

My problem is that the remaining wall is only 1.0mm thick !
and 18mm in height...

I am getting vibration marks and a bad finish.

My final cut is using a 4mm dia 4 flute cabide endmill TiLAN coated with 20mm flute length.

RPM 5845 FEED 0.02mm per tooth

I have to use the 4mm dia as the smallest radius is 2.2mm.

Can anyone tell me where I'm going wrong or suggest a better approach??

cutter??
Speed??
Feed??

Many thanks for any help guys. :-)

[txcncman]

500 RPM or less. 0.0005 radial DOC. 1 to 3 IPM. 3 finish passes (not spring passes) 0.0005 radial DOC.

[Shane1234]

also, do the inside profile first if possible, so that any vibration marks are on the outside of your cookie cutter, and wont affect the product as much.

another trick is to make a plug out of plastic or metal that you can wedge inside of the part after you finished the inside pocket. then you gain a little bit of reinforcement for doing the outside wall. i suppose if you had access to blocks of wax, you could heat the part while still in the jaws and force the wax into the pocket.

[xray34]

500 RPM or less. 0.0005 radial DOC. 1 to 3 IPM. 3 finish passes (not spring passes) 0.0005 radial DOC.

interesting, I will try your method.
Many thanks for your reply.
:-)

[xray34]

also, do the inside profile first if possible, so that any vibration marks are on the outside of your cookie cutter, and wont affect the product as much.

another trick is to make a plug out of plastic or metal that you can wedge inside of the part after you finished the inside pocket. then you gain a little bit of reinforcement for doing the outside wall. i suppose if you had access to blocks of wax, you could heat the part while still in the jaws and force the wax into the pocket.

Thanks for the reply 'Shane123'
I have machined a bung to go on the inside
and it reduced the marks slightly but they where still giving an unacceptable finish. ..

Thanks again guys :-)

[RICHARD ZASTROW]

Or you could fill the inside form cavity with wax or low melt temp metal. That's been done on stainless steel turbine blades for many years.

A company I worked for too long ago finish cut hardened D-2 (58-62 Rc) rotary dies with carbide burrs. Used the diamond cut pattern. Worked better than grinding. 3/8"dia.@22,000 rpm, VERY noisy. LOL

Dick Z

[Shane1234]

expanding foam for the win! joking

[Geof]

The old guy higher up (that can be taken two ways can it not?) suggests low melting metal. Try a small variation on this suggestion use 'typemetal'. This expands slightly on cooling so it will give a very firm fit all the way round.

[Shane1234]

lead would work well, correct?

[txcncman]

Lead can work, yes. But there are some even lower temperature metal products on the market that for most applications work even better.

[RICHARD ZASTROW]

See, it pays to retain some of your memory. Us old guys still have a lot of stuff in there, some of it is even usefull!! Now, if I can just remember where I put the church key.LOL

Dick Z

[xray34]

all excellent suggestions, we will find out on wednesday when I begin the machining.
Results to follow guys.
Thanks very much for the advice. :-)

Such a lot of knowledge on here.

[xray34]

Hi all , finally machined the parts..

Finish cut was with 3.5mm dia 4 flute Vari helix V4 TiAIN coated end mill
reach 20mm flute length 4mm shank dia 3.35mm.

The slow feed and RPM recommended didn't really work for me so I ended up with the following settings...

DOC = 0.15mm AP = 0.2mm

RPM = 5140 FR = 2350

It took a bit of trial and error on the first off but the other 5 worked fine

Same cutter to finish all 6 off.

Take a look.

Many thanks guys. :-)

[txcncman]

Good job. And now I hope you and others that see this can understand that machining is as much of an art as it is science.

[xray34]

Good job. And now I hope you and others that see this can understand that machining is as much of an art as it is science.

Well said my friend..Very well said. :-)

[Boltz]

Was the reduced shank a standard or custom item?

-Jim Hart

[xray34]

Was the reduced shank a standard or custom item?

-Jim Hart

Hi Boltz.

It was a standard item from our tool supplier here in the uk. :-)

(see below)