First cylindrical grinding topic- plunge or in-feed grinding

One method of cylindrical grinding is plunge machining. I suspect it is restricted to short workpieces often for form grinding to impart a particular shape. An example of this might be an NTBA 40 or 50 arbor or adaptor.

One application is to machine a taper or even two adjoining tapers of different angles (again requiring the wheel to be modified for a form grind).

In the case of my Russian universal cylindrical grinder the specifications say that the standard wheel is 350mm maximum diameter by 40 mm wide (again maximum so that probably answers one question). So plunge grinding is limited to 40 mm wide. If you want a taper wider than that is it possible to fit a wider wheel so the taper can be plunge ground? The manual says that the wheel guard is 50mm wide inside.

Plunge grinding a form can be good, depending on specifics. It's done quite a lot.

The major first thing to think about is uneven wheel wear. For example, if you begin grinding a straight cylinder into a taper, the first part of the wheel to touch will get more wear than the last part. If that wear exceeds the part tolerance, you may have multiple dressings per part...

In short. There is no pat answer to the general question.

Many standard wheel sizes can be bought with a pocket recessed in one face to accommodate mounting hardware. You may or may not find a suitable match. Whether you should or not is debatable. Safety issues come to mind.
Also keep in mind that any imperfections in your wheel dress is transferred directly into the workpiece. Any void in the wheel periphery results in a "hump" in the work. If you were grinding a male taper (with a said hump in the middle) to match a perfectly formed female part they would never lock up.

Damien W said:

So plunge grinding is limited to 40 mm wide. If you want a taper wider than that is it possible to fit a wider wheel so the taper can be plunge ground?

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Plunge grinding on a cylindrical grinder IS NOT limited to short parts. I grind lots of different steps in machine tool spindles. Some are plunge ground, some are traverse ground. Sealing areas on spindles I always plunge grind. Plunge grinding assures there are no spirals that can move oil past an oil seal. As fine as grinding may seem, traverse grinding still leaves a spiraled surface that when a seal is rubbing on it, it can cause oil to weep out.

Why would you want to go through the hassles of plunge grinding a tapered part that's wider than your wheel? Can't you move your table to the angle you need to grind, and just traverse grind the taper. Of course if you had a grinder like I just bought with a SIX INCH wide 36 inch diameter grinding wheel, your problems might be solved. Although I wouldn't want to remove the material from it to plunge some angle unless I was doing a lot of them!

The other alternative of course is to plunge your angle twice after moving the table of the machine. If the part's tolerances aren't super tight, blue your first ground finish, then proceed to grind your second step, with the wheel just overlapping your already ground surface.Grind until the bluing just starts to get ground off. Just a thought.