Jet J-4421-2, Инструкция по эксплуатации и каталог запасных частей, Страница: 12 / 20

12
Silicon carbide
While discs may be available for 20 inch grinding,
this material is not recommended for use on the
ModelJ-4421 because a water coolant/lubricant is
typically required for effective use of this material.
Application tip
While the 20 inch grinder can mount the full range
of grits available – from 24 to 400 – the most
efficient production and the longest abrasive disc
life can be achieved when the production manager
is aware of the capabilities of the grits offered. If
you start with a workpiece which has been rough
cut with an 80 grit wheel of some type, and you
eventually want to achieve a finish at the 400 grit
level – don't go directly from the 80 to the 400 disc
machine. The 400 grit wheel will eventually do the
job, but it will take an excessive amount of time
and the disc will have a short service life. Plan your
surface finishing to take advantage of the full range
of grits available to the shop.
9.0 Maintenance procedures
9.1 Removing and replacing grinding
discs
CAUTION: The gap between the abrasive surface
and table edge must not exceed 3/16". If it does,
loosen the four motor mount bolts and move the
motor forward to minimize gap.
Grinding discs are secured to the aluminum drive
disc using an adhesive on the grinding disc
backing. To remove an abrasive disc:
1. Turn the ON/OFF switch OFF.
2. Disconnect the machine from its power source
to prevent accidental start-up of the motor.
3. Move the table to the bottom of its travel using
the table raiser mechanism. (See sect. 7.3,
Raising and lowering the table )
4. Tilt the disc guard to the rear to expose the top
of the drive disc.
5. Pull at the edge of the mounted grinding disc
to pull it away from the drive disc, then pull it
completely off of the drive disc.
6. Be certain the drive disc surface is clean. If
necessary, use a cleaner which dries film-free
(such as naptha) to remove any old adhesive
(or dust) which might adhere to the drive disc.
7. Remove a small portion of the protective cover
from the back side of the new grinding disc
you are mounting on the drive disc. A typical
amount to remove is about a third of the
protective cover. See Figure 12.
Figure 12: Replacing a grinding disc
8. Put the exposed edge of the new grinding disc
against the drive disc and center the grinding
disc carefully on the drive disc. When you are
certain it is accurately centered, press on
grinding disc so the exposed portion of the
adhesive anchors the grinding disc to the drive
disc.
9. Rotate the drive disc 180 degrees. See Figure
13. The part of the grinding disc which is
attached to the drive disc will now be at the
bottom of the drive disc, and will be slightly
hidden behind the table.
Figure 13: Replacing a grinding disc
With the components in this position you can keep
the grinding disc accurately centered while
reaching behind the grinding disc to remove the
rest of the protective backing and progressively
pressing the grinding disc against the face of the
drive disc. The reason for this care is that a
grinding disc, once firmly pressed into position, is
often extremely difficult to remove. In other words:
Once it is down... it is down to stay.