How To Grind D2 Tool Steel On A Manual Surface Grinder

D2 tool steel is a lot like bad tasting medicine that is good for you: you hate it, but you need it. So, how can you grind D2 tool steel on a manual surface grinder, with precision and economy?

Suppose you are using a typical surface grinder, such as a Mitsui, Brown and Sharpe, Okamoto or Harig 6x12 or 6x18. It has no flood coolant, and you prefer not to use some kind of spray mist coolant; you are going to be dry grinding the steel.

A typical injection mold or stamping die component could be 2x6 x1/4 in in size, and you might have 4 of them to grind together. If the milling machine operator or CNC milling department left a lot of stock, you have a problem that will take some time to fix.

If there is too much stock left for grinding, which seems to often happen, you could try hard milling the excess material off in a manual milling machine, such as a Bridgport or Deckel, using a solid coated carbide end mill. Usually there are plenty of good used carbide cutters left over from CNC precision milling jobs in the shop. If you find one with a radius on the corners, it will hold up much longer. Do not use a ball end mill, but a bull nose cutter, with a .010 in. radius. OSG makes a great coated carbide end mill for D2.

Once you get to the point where you are ready to grind, use a Norton 5SG-46 grit wheel. This is a blue, gel seeded ceramic grinding wheel that is made especially for tough materials, such as D2 and H-13. For the cost, you will get more than your money's worth. These ceramic grinding wheels work much better than your common aluminum oxide gray wheel.

Dry grind, do not wet grind.

Some toolmakers have good results with a hard wheel, such as an H or I from Norton. The softer wheels seem to break down too quickly and waste a lot of your time with constant dressing.

One trick is to take a dressing stick, such as a Norbide or carborundum stick, and carve out a groove in the center of the wheel, in order to reduce the heat build-up. You can plunge grind quite well using this wheel, just do not get too aggressive.

If you have a lot of grinding of these tough tool steels, A2, D2, H-13, or DC53, you might consider investing in a CBN grinding wheel. These super abrasive grinding wheels work wonders on the toughest hardened tool steels, but cost much more, of course! You will, however, quickly recoup your investment just by saving time dressing the wheel every few passes.

D2 also has a tendency to expand and twist after a lot of grinding has been done. It is advisable to let it settle down overnight before taking your finish passes. Once you do get this stubborn material finished, it will be like that nasty tasting medicine and work well in your injection mold or stamping die.