Tech Talk
Please explain the differences between "Conventional Grinding, Creep Feed and HEDG Grinding"?
Until recently the difference between conventional grinding (pendulum grinding) and creep feed grinding was for horizontal surface grinding only. Today a new beast has been introduced that, as of the writing, it is still in its infancy. Known as HEDG (High Efficiency Deep Grinding) this process shows great promise with cylindrical grinding as well as surface grinding.
In cylindrical grinding this process is being utilized for making formed parts like crankshafts with point to point traverse and plunge grinding and punches utilizing planetary motion. With the machining and finishing in one operation, and in a fraction of the time of today’s technology.
Normal grinding regardless of application, works on a process that you can only infeed a relative percentage of the abrasive diameter per down feed of the wheel or rotation of the part. Even in creep feed you are removing with a similar stock removal rate per minute. But, with HEDG grinding you pass the boundary of mechanical interpretation and into a New World of a form of plasticity. This is not a small leap in wheel speeds but a major jump. In surfacing you are going from 6000 to a minimum of 16000 SFPM. Some speeds in Germany have been reported at 100,000 SFPM (500 m/s). I am only aware of speeds of less than or equal to 40,000 SFPM (200 m/s).
Present problems are limitations of the wheel manufacturer for developing product that will not burst at those speeds. For example the highest speed I am aware of utilizing vitrified BCN is on a graphite/epoxy core and can only be rated at 40,000 SFPM. Most companies in this country are topped out at 30,000 SFPM (assuming they are testing each wheel on a speed tester at 1.5 times the recommended operating speed).
Manufacturers are confident that in the future this process will gain acceptance and the present problems will be worked out. The stock removal rates are so great this will open even more doors for what is being called abrasive machining. The competition between conventional cutting tools and the abrasive cutting tools continues to battle. The only winner will be the productivity of the user.
