Over the last 80 years that grinding has become a very documented and researched manufacturing method, it has grown quite popularly with ID or Boring Grinding. Using a relationship between spindle speed, tool diameter, and crystal size/chip depth. Typical jog grinding happens with a spindle speed around 10,000-50,000 RPM; however, with technology advancements, we are seeing spindle speeds capable of 120,000+ RPMs. This has allowed jig grinding to gain some ground, being able to run your tools at much higher spindle rpms and SFPM, allows for higher in-feed rates, reducing overall cycle time for the operation.
When running a DPM Mandrel, we recommend a SFPM of around 7,500, with in-feeds around 3-8″ Per Minute. Depth of cut, somewhere in the 0.100″ range depending on the P-Line or Surface contact on the tool. We recommend per 0.25″ of contact, reduce infeed by 0.010″ This is due to tool pressure and deflection. If the user has a very stiff shank and large crystal sizes, they can run in-feed and depth outside this range. Our Jig Grinding mandrels are capable of sizes from .0080” to 20.000”. Our mandrel size is limited by our tanks. We do have partners that can plate over a 20″ piece.
Now, these speeds and feeds that were listed above are general in-feeds for HSS with a 40-60 Grit Mesh. Running Diamond on Carbide or PCD is a different story. We recommend running the same Surface Foot Per Minute, but reduce your in-feed rates by about 40%, this will help the crystal load and heat build up from the Carbide or PCD. They tend to make a better or easier chip to deal with, but also require quite a bit of force to cut resulting in high temperatures.
Lets talk oscillation, we recommend a cross-feed or oscillation rate of 0.010″ Per 0.50″ or P-line contact. This will help keep your hole more concentric and hold a tighter tolerance to your desired blueprints than running a straight bore or wipe/drag feed method.
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