Having problems with machining H13 casted steel

[Camelot]

I programmed a huge mold made out of cast H13 and I'm finding no success with tool life.  20 minutes and tool is done.

I programmed a similar mold a few years ago with the same parameters with no problem.  Tooling lasted 2 hours minimum.

Does anyone have any thoughts what I can do to improve my tool life?  It just seems like I'm dealing with a very difficult scale.

Cam

[Matthew Hajicek - Singularity]

7 hours ago, Camelot said:

I programmed a huge mold made out of cast H13 and I'm finding no success with tool life.  20 minutes and tool is done.

I programmed a similar mold a few years ago with the same parameters with no problem.  Tooling lasted 2 hours minimum.

Does anyone have any thoughts what I can do to improve my tool life?  It just seems like I'm dealing with a very difficult scale.

Cam

I think in order to help you, we need to know what you're doing.  What exact cutters are you using, what holders, what machine, what cutting parameters?

[crazy^millman]

On 2/17/2024 at 1:26 PM, Camelot said:

I programmed a huge mold made out of cast H13 and I'm finding no success with tool life.  20 minutes and tool is done.

I programmed a similar mold a few years ago with the same parameters with no problem.  Tooling lasted 2 hours minimum.

Does anyone have any thoughts what I can do to improve my tool life?  It just seems like I'm dealing with a very difficult scale.

Cam

How was it tempered? I was machining some 440 Stainless Steel Casting years ago and about every 4th batch would be impossible to machine. I reached out to the casting house and asked them what was the tempering process on the lot that was giving us the issue. He said they were taking them and quenching them in the snow. I asked him to review what was to correct tempering process for the Rockwell specified. He reviewed and said hum I guess we are incorrectly cooling them and making them about 25 Rockwell harder than the spec. I would have the parts Rockwell tested by a lab and see what they come with. i would then go back and review the supplied specifications and see if they are correct. If they are not then all work ha to stop and this has to be sent to the end customer for approval before wasting any more time on the work. They are not to spec then go back to the supplier and ask them how they want to cover the overages on the tooling cost and run time because they are not within spec.

[cruzila]

14 minutes ago, crazy^millman said:

I reached out to the casting house and asked them what was the tempering process on the lot that was giving us the issue. He said they were taking them and quenching them in the snow. 

I spit out my coffee, Thanks Ron for a laugh!!

[CEMENTHEAD]

Did some work for "a biG powEr plant". they outsourced the castings from India. There were noticeable ball bearings and other unconfirmed hard spots inside. Nightmare to machine. NDT failed all 6 parts. These were Ø4' X 5' long, bosses on ends were Ø2' X 8.0".  We kept the snake we found in one of the crates in the programming office ( in a terrarium) for like 3 months before the office girls found out. 

[Camelot]

On 2/19/2024 at 10:53 AM, crazy^millman said:

How was it tempered? I was machining some 440 Stainless Steel Casting years ago and about every 4th batch would be impossible to machine. I reached out to the casting house and asked them what was the tempering process on the lot that was giving us the issue. He said they were taking them and quenching them in the snow. I asked him to review what was to correct tempering process for the Rockwell specified. He reviewed and said hum I guess we are incorrectly cooling them and making them about 25 Rockwell harder than the spec. I would have the parts Rockwell tested by a lab and see what they come with. i would then go back and review the supplied specifications and see if they are correct. If they are not then all work ha to stop and this has to be sent to the end customer for approval before wasting any more time on the work. They are not to spec then go back to the supplier and ask them how they want to cover the overages on the tooling cost and run time because they are not within spec.

Hi Ron,

I talked to the casting house and their process seemed sound.  They shot blasted the scale after tempering. 

We did send out the raw molds to get annealed again.  Got the rockwel C down to 20, but we may have shot ourselves in the foot to do that as the scale wasn't blasted after this.  

I ended up using a 2" high feed face mill cutter from Kennametal to get rid of most of the skin with SFM of 450 and this got me some good tool life.  I then used a 3/4" endmill to rest machine.  But I had to decrease SFM on this endmill to 250 to get any good tool life.

Thanks for your input Ron!

[Camelot]

I most always use a 3/4" V7 end mill from YG-1 to rough out our molds.  Using the parameters of 700 sfm, 10% step overs at 121 IPM.

But with this same endmill, I ended up going to 250 sfm with 50% step overs at 26 IPM.  This took a little longer but the end mill looked great after 3 hours of cutting.

[crazy^millman]

1 hour ago, Camelot said:

I most always use a 3/4" V7 end mill from YG-1 to rough out our molds.  Using the parameters of 700 sfm, 10% step overs at 121 IPM.

But with this same endmill, I ended up going to 250 sfm with 50% step overs at 26 IPM.  This took a little longer but the end mill looked great after 3 hours of cutting.

This right here is what most managers don't get. Every part tells it own story and it up to us to figure out what that story is.

Excellent problem solving skills and work on this one. Thank you for reporting back faster is not always better. The turtle can still win the race after all.