Mold Material Idea - D2 Tool Steel?

[mfraser264]

Have had many thoughts also about the best mold material over the years which has lead to interesting discussions with my father. We both are engineers involved in many aspects of tooling.

No need to rehash all the available materials but a thought came to me that may be worth looking into. As the person who design the gauges at work, material choice is critical. Need a material that is easy machined, can be heat treated, is tough, reasonable in cost and lasts. Settled on D2 which is a high grade tool steel.

Being steel is will transfer heat. In the softened state machines well both turning, milling & grinding. It can be heat treated to Rc 58-62 and holds it shape well after hear treat. Many of the gauges I design are heated treated and shipped as less than .001" distortion is measured after HT.

Lead casting temp's are 300-400 below the min for tempering D2 so no issue there. Would use a softer material for a sprue cutter. The rule of thumb in engineering for moving or sliding parts is never the same materials together. Softer material on the less critical surface.

This metal is tough, holds up the best we have and have had 250,000 castings checked and the gauge is going great. It's resists rust too!!!

Most metal suppliers can locate or stock D2 McMaster Carr www.mcmaster.com
www.MSCDirect.com also stocks it.

Another interesting project if someone is up to it. My time is limited and perhaps someone has approached shops already with different material and has someone willing to give it a try.

I'll supply the material if someone has a shop willing to give it a try. 3 times the charm and I'll supply enough for three single cavity molds.

Markus

Engineers are not good spellers!!!

[Greg5278]

I wouldn't use D2 because it is tough on your tooling, and tends to chip when milled. It grinds well, and is semi-corrosion resistant. You would be better off with Durabar cast iron, grade 65-45-12. It is available in easy to machine sizes. The other problem with D@ is the continous chips. Cast Iron machines into powder, which is easier to deal with. D2 will tend to ball up in the cavity being machined, and reuire high pressure coolant to force it out. In extreme cases, the chip can push the cutting tool to the side, and they will cut oversize.
Greg

[scb]

Most moulds are cut with high speed steel cherrys. I don't believe that you would get many cavities / cherry if you were cutting d2. Out of curiosity why do you think the mould requires heat treating anyway? Some of the best moulds I own are aluminum and brass.

[xr650]

I am in agreement with the two previous posters. Not a tooling/machine friendly material.
What looks good on paper doesn't mean it works well in the shop. [smilie=1:

[Red River Rick]

Simply put, D2 or any other Tool steel just don't make good mould block material, because of the difficulty in machining. If it did, why aren't all the commercial mould makers using it?

RRR

[MtGun44]

+1 on no need for a material that expensive or hard to machine. If dead soft
dirt cheap extruded aluminum will make a mold that will last for many years with
good care, and soft cast iron will last darn near forever if not rusted or beat on,
there is not a lot to be gained from such a hard and expensive to cut material.
Not that it wouldn't be one heck of a great mold, but the cost would be unnecessarily
high.

Makes GREAT knife blades, tho! :-D

Bill