Tool Holder material

[z1]

Hello,

I've designed a tool holder and a tool for a cutting process in a CNC lathe (using tip insert on the tool).
My problem is to select the best material for the tool holder, and for the tool.

Can anyone give an idea of what type of material should I be looking at?

I need to avoid vibration during the machining. What type of parameters should I look in the steel properties ? Enlongation ? Rm ? density ?

Thanks,

Rjl

 

[metman]

Number one property requirement for the holder is Modulus of Elasticity. You want maximum regidity possible unless the workpiece is light metal and you are taking light cuts and the function is not boring a hole with a large depth/dia ratio. Solid Carbide has the highest MoE for tool holders that I am aware of. Next would be probably Molybdenum but not commonly used in this applicaation so I know not about availability. Steel is probably next and very likely best choice unless you are boring deep/(small-dia) hole in which case you might need Carbide.

The second property requirement is compressive strength since the insert will impart compressive stress to the holder. Cabide has good compressive strength but if your regidity reqirements allow Steel it can be heat treated to very high compressive strength. Keep in mind that the heat treatment will not alter the MoM.

One needs to know the geometry of the holder and cutting function to give a more difinitive answer for material selection.

For the insert, I recommend you take that question to the Machines & Machining forum under Industrial/Manufacturing Engineers heading. When you post your question there, give them all the details of geometry, material and conditon (heat treat, form, i.e. forged-rolled-cast-etc) and provide specfics of the cutting operation(s), tolerances, and surface finish requiremnts.

There a lot of beautifully designed inserts out there today so you will likely want to also talk to a vendor to help choose a good insert.

 

[tomwalz]

The braze alloy and joint design can make a huge difference in the performance of the finished tool.

We do a great deal of this. If you want to contact me directly I would be happy to talk to you no charge.

We do the tool design free so we can either build the tools or sell the materials for you to build the tools.

Tom

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

 

[z1]

Thanks Metman for your technical answer.

Tom:

In this case the tool design is complete, just need the material.

I'm located in Portugal, if we buy the material, would you send us the right spec. for surface treatment/ heat treatment?


Rjl

 

[BillPSU]

4140 heat treated to 28-32 Rockwell C. Machine holder in the hardened state. Enough hardness and strength for most applications and still have enough elongation to flex under roughing cuts and not be brittle.

 

[EdDanzer]

You may see more vibration from heat treated materials used for tools. All carbon steels have a nearly identical rate of deflection with a fixed stick out and load. The amount of spring back and, or natural frequency will affect chatter (that is why cast iron is a good machine bed material). We experimented with different materials for long stick out boring bars, the worst is induction hardened C1040, then 4140 HT. For Cat 40 and 50 holders, 8620 works about the best, a good combination of strength, machine ability, and low vibration. For boring and turning tools if wear is not a concern, 12L14 has the lowest chatter of all, then 8620 is next.

 

[ornerynorsk]

We make custom toolholders from time to time, I've always used 4140 prehardened to around 30c as BillPSU stated. Never any problems with rigidity or chatter.

 

[arunmrao]

BillPSU,
I was all along waiting for someone to come out suggesting 4140. But when it didn't I began to woder if I was wrong. I go along with BillPSU's suggestion for most common tool holders.

 

[unclesyd]

We use 1020 CS for tool shanks if we are going to braze on a carbide tip and 4140 or 4340 if the carbide attachment is mechanical.
All our long boring bars are made from Maxel 3 1/2 and are very old.

 

[z1]

Thanks you all for the information !!

Now I just need to find the equivalent standards for the steel, here in Europe (I'm in Portugal).