It is very rare to find an injection mold making shop that does not have at least one machine for CNC grinding. At the least there is a large, automatic surface grinder with flood coolant and a CNC controller. This is basic CNC machining.
Besides the basic surface grinder, often find an ID/OD grinder to make all those fancy core pins and other round components. Some shops have a CDC Ded-Tru or other centerless grinder, but these are not so common.
Global competition forces shops to think in terms of automation in an almost industrial manner. CNC grinding fits in very well with this approach. After all, you really can set it and forget it, which makes it perfect for the mold making process.
The better manufacturers include Mitsui, Elb, Brown and Sharpe, and Okamoto. Other brands include Kent, Harig, Chevalier, Walter, and a host of other brands
Grinding is a dying art
Just how many apprentices are there going into mold making and how many of those are learning the time-honored skills found in the grinding department? Once the old-timers are done and gone, who will be there to do all that fussy work?
The ID/OD grinder is a great tool, but mastering the set-ups and fine tunings can take years. The software and diamond wheels can at least partially compensate for this learning curve.
Get a medium sized grinder
For some reason, most likely cash, many shops have large automatic grinders and small manual grinders. They do not have many medium sized ones though. This is unfortunate because most toolmakers are reluctant to grind a small workpiece on a huge automatic grinder and are thus forced to work with a dry, manual grinder.
This is a waste of time. Everyone knows how hard it is to keep things flat and accurate without coolant, but this goes on year after year in shop after shop.
Try grinding D-2 on a manual surface grinder. This material works great in the mold, but is a headache for the guy grinding it.
Custom machine shops have some of the coolest CNC grinders on the planet. These wonders are so fast and deadly accurate that it is scary to watch them in action. There is just one big catch: they are wicked expensive.