The PACER Method of
Paper Mill - Roll Grinding

- a system approach to easier grinding and better finishes -

This is a summary of the Pacer four page "Operating Instructions" booklet for roll grinding wheels. These recommendations are for PM or cork wheel use mainly on chilled iron. For more details, refer to the Operating Instructions booklet. For it, other technical literature, any operating questions or sales, call 1-800- 225-0315.

For proper wheel performance, the machine settings, coolant, dressing, etc. should be as stated. The operator, however, may find other ways for wheels to work as well or better. If the machine does not display roll and wheel speeds, the operator should have a tachometer available and also a refractometer to check coolant concentration.

Pacer manufactures new technology grinding wheels that have earned a wide reputation across North America for stock removal, easier use and roll quality. Operators have seen advantages over shellac wheels and belts. Considering the shorter grinding time, longer life and moderate price, these wheels are a good way to reduce overall costs while achieving higher surface quality.

PM (Paper Mill) resin bond wheels are for fast roughing of all roll types. They self dress, cut freely and have very little chatter tendency. They operate well at high or low amps. Cork filled, rubber bond wheels are for fast finishing of hard rolls. The new Cl2OA3RC formula is a recent improvement. The new wheel removes stock easily and polishes better. Cork wheels reduce the difficult and time consuming job of roll finishing to a matter of hours.

PM Roughing Wheels (.001" to .003" /hr removal)

Wheel specs.- C6OH7PM or C46H7PM (or harder I)
Roll speed - 60 sfm (13 rpm for 18" roll. 8 rpm for 28")
Can try 75 sfm later if 60 sfm works well.
Decrease to 45 sfm if wheel seems to "sing"
Wheel speed - 3200 sfm (600 rpm for 20", 400 for 30")
Lower the speed if wheel acts hard.
Traverse speed - 2-1/2" per rev. for 3" wide wheel.
Wheel amps - 10 to 15 over idle. Infeed across roll.
(auto or manual). Can go to 25 over idle.
Coolant - Full flow. Decrease if wheel acts hard.
Use RollCool or equal low-lubricity synthetic.
A common cause of roll grinding problems is coolant related. Many types have mineral oil, soap, paraffin or silicone lubricants. These can slick the hard roll and load the wheels. RollCool has no Iubricants. Its job is to inhibit rust. Non-foaming. Clear and clean on the roll. Long tank life. Settles fines. Better environmentally.
Dressing - Use DiaNib or equal coarse impregnated nib for sharper dress than by a dulled single point. A single point often wears flat. DiaNib has many chips imbedded in a metal block. As it wears, sharp points surface. No need to rotate as with single point nibs. It works well on PM and cork.

Miscellaneous - Wheel must break down well in order to cut well. Should be able to see and feel some grit on roll surface. Keep amps up. A new wheel may act harder for an hour or two. If using cork next, make some light passes. 60 or 46 grit PM can finish although cork wheels often finish faster and better. Use 100 or 80 grit PM if same wheel roughing/finishing is wanted. Total time, however, will be longer than with 60 or 46 PM and cork.

60PM works well on all hard rolls such as iron, stainless, granite, stone-like, hard rubber, etc. Use 30 grit PM on soft rolls (over 10 P&J). Rubber (except poly) can be ground dry. PM cuts rubber coolly and should not load.


Cork Finishing Wheel - roughing phase (9/12 passes)

Wheel specification - C12OA3RC Cork
Roll speed - Same as for PM wheel.
Wheel speed - 2100 sfin (400 rpm for 20" 275 rpm-30")
If wheel breaks down little or some chatter
appears Increase wheel rpm about 25%.
Traverse speed - Same as for PM wheel.
Wheel amps - 10 to 15 over idle. The new formula does require
auto or manual infeed to hold amps.
Coolant - Use moderate to low flow. The flow must cover
frill wheel face to avoid dry-grind pattern. 1% to
2% (100:1 to 50:1) RollCool ratio will prevent
rust. Use Pacer filter if low Ra finish is needed
or if coolant is contaminated.
Bypass during roughing and use just during finishing. 18" high
2.5 dia, 25 micron cartridges are replaceable. Housing bowl
unscrews for easy cartridge replacement. If possible place
not far from discharge nozzle. This type filter prevents swarf
or oil in coolant lines from scratching roll or loading face of
wheel.
Dressing - Same as for PM. Should not need redressing. Stop
wheel edges about 3/8" off roll ends. Leadlines erase faster
if edges are chamfered.

Miscellaneous - Like the PM, cork wheels must break down well in order to remove all roughing wheel marks The use of low lubricity coolant is very important. New formula cork wheels can remove stock (.0003" /hr) and improve profile. Cork leadlines erase in next phase. For a Farrel grinder use Pacer crane to make changes from roughing to finishing wheels quick and safe No lifting.


Special base bolts to the swingrest corner - about 3 ft. from the spindle end. The 65 lb. mast/boom/handcrank assembly drops into the tubular base. Mast swivels in the base so as to swing wheel/mount from the floor up and near to spindle. Wheel/mount slides onto short spindle extension. Boom then can fold or swivel out of way. Secure. strong chain sling.

Cork Finishing Wheel - finishing phase (12/15 passes)

Wheel specs. - Cl2OA3RC or C24OA3RC Cork
Roll speed - 90 sfm (19 rpm for 18" roll, 12 rpm for 28")
Increasing to 105 or 120 sfm can brighten the
roll more while reducing finishing time.
Wheel speed - Low. like previous phase, usually is best but
25% higher rpm may improve finish.
Traverse speed - Increase if roll speed was increased. It may
not be necessary to then gradually decrease.
Leadlines may erase easier at high traverse
speed (2-1/2" for 3" wheel)
Wheel amps - allow to drop only about amp per pass to
eventually 4 over idle If auto infeed is used
gradually decrease and then turn off.
Coolant - Same as above.
Dressing - Should not need redressing. Stop at roll ends.

Miscellaneous - Removes marks from roughing phase. If amps drop too fast, deeper scratches and leadlines will remain. Make sure each pass removes leadlines from previous pass. If it doesn't, add an amp or two and make pass again or try a wheel speed change. Finish should be 5 to 8 Ra - with no leadlines. If using a 240 grit, start it after the 120 roughing phase. Finish should be 2 to 5 Ra.

Improper use of grinding wheels can he dangerous. Follow the instructions set forth in the ANSI B7.1 American Standard Safety Code for "The Use, Care and Protection of Abrasive Wheels".


pacer@pacergrindingwheels.com
1-800-225-0315
610-383-4200      Fax: 610-383-4239 
200 Red Road, Coatesville, PA 19320
 


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