AEC Colortronic MSH Series 2039 - Manual (Page 32)

C Series Granulators Maintenance 32 of 53
Bed Knives
We recommend that the same screws and washers be re-used only when the bed knives have
been repositioned or re-ground. When blunt knives are discarded and replaced with new
knives, use new screws and washers. This will reduce the risk of screw failure due to their
overstretching. Screws and washers must be replaced with the type specified in the Spare
Parts List.
1. Access the cutting chamber as directed in Section 3-6 on page 16.
2. Loosen and remove the bed knife screws with a 30 mm socket mounted on a breaker
bar. Make sure you have solid footing while you apply the breaking force.
Note: These screws are tightened to a torque of 640 Nm (472 lbs./ft.), so make sure
you have the proper breaker bar. We suggest a four foot long (1.2 m) bar with a
3/4” (19 mm) drive.
3. Remove the downstroke bed knife shield and the upstroke bed knife clamp. Hold
them in place while removing the last screws to prevent them from slipping off the
inclined mounting surface. Keep the screws for reinstallation or use new factory-
supplied screws of the same specification.
4. Remove the screws holding the bed knives, and remove the bed knives.
5. Thoroughly clean the knife seats with a stone or other non-marring tool.
6. Replace each half of the upstroke bed knife, making sure to install it with the knife
edge on the lower side.
7. One half at a time, place the upstroke bed knife clamp over the knife and hold it in
position until you fasten the first two screws and washers. Hand-tighten the mounting
screws and washers.
8. Replace each half of the downstroke bed knife, making sure to install it with the knife
edge on the upper side.
9. Place the shields over the downstroke bed knife, and hand-tighten the mounting
screws and washers.
10. Remove the rotor locking pin, and use the adjustment screws to set the knife
clearance to 0.15 mm – 0.20 mm (0.006” – 0.008”). The clearance should be
measured with a feeler gauge at the ends of the knife, by rotating the rotor sheave
backwards by hand. The clearance is slightly greater at the center of the knives.
Check both the upstroke and downstroke knife gaps.
11. Position the downstroke bed knife shield so that it sets back from the bed knife edge
about 1/32” for film and 1/16” for thicker materials. Use a plastic or leather mallet, if
necessary, to tap the shield or knife.
12. Tighten all of the mounting screws to a torque of 640 Nm (472 lbs./ft.), and re-check
the knife gap.