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Wear Liners
Rolls
RPM and Associates has 25+ years of experience rebuilding existing coal pulverizer rolls. We
also manufacture new rolls from cast steel cores.
All of our rolls are surfaced with a CP3 chrome carbide overlay to ensure the
roll has a long production life and are machined to a unique profile that
minimizes the possibility of spalling.
Click on one of the links below to proceed to your particular area of interest.
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We rebuild existing coal pulverizer rolls at our facility in Rapid City, SD. Worn
rolls are shipped to our shop, inspected, scanned with a CMM, preheated,
and welded under strict parameters with our CP3 chrome carbide overlay. Roll
bores are checked again following the overlay process, then, if necessary, finish-machined
to provide a perfect fit. Each roll is assigned an RPM number with which wear
and rebuild data is recorded for future reference.
Following is an overview of the process that we follow for a typical roll
when it arrives and is rebuilt at our facility.
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- Inspections of Worn Pulverizer Rolls Received at RPM
- Metal Template Fit To OD Profile
- Visual Inspection of Wear Profile/Anomalies
- CMM Inspection of ID Bore and OD Profile
- Die Penetrant Inspection of ID Bore
- All Rolls Are Assigned an Identification Number
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Typical Worn CE 1043 Roll
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Template Inspection of
CE1003 Roll
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Template Inspection of
CE1003 Roll
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Template Inspection of
CE1003 Roll
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CMM Inspection of
MPS89 Roll
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CMM and Die Penetrant Inspection
of CE863 Roll
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RPM Identification Number
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- Pre-Repairs Performed Include Air Arcing of OD as Required
- ID Bores Machined as Required
- Rolls Are Preheated and Rebuilt Using Automatic Welding System
- Rolls Are Allowed to Slow Cool
- Metal Template, CMM and Die Penetrant Inspections Are Performed Again When
Welding is Complete and Roll is Cool
- All Data is Recorded on Job Sheets and May Be Used in RPM “Pulverizer Wear Parts
Monitoring Program”
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Automatic Air Arcing
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Machining ID Bore
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Pre-heating
Roll
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Rebuilt CE1003 Roll With Hardfaced Heel
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A number of different roll profiles are available. The table below describes the key features for each.
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ORIGINAL STYLE
- Very durable
- Low wear resistance
- Does not crack
- NiHard sometimes spalls off cast iron
- Cannot repair bore
- OD is rebuild/welder friendly
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ONE PIECE
- Typically a high chrome material
- Sometimes cracks even when new
- Wear is a little bit better than NiHard
- Not very rebuild/welder friendly
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ONE PIECE
REDUCED WEIGHT
- Same properties as One Piece
- Higher chance for breakage
- Not very rebuild/welder friendly at all
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CAST STEEL CORE
HARDFACED OD
- One-time forever purchase
- Chromium Carbide hardface overlay has 2-3 times wear life over any other options
- Will not break or crack
- Bore can be repaired
- Be careful to get enough overlay on new rolls
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RPM and Associates manufactures new coal pulverizer rolls from Pulvco cast steel cores. The
cores are machined to fit the profile of the roll being replaced and a hardfaced
surface is added to improve wear-life.
Cast steel cores have many advantages.
- Cast Steel Parts Will Not Crack or Break
- Cast Steel Alloys Resist Heat Better Than Cast Iron Parts
- Cast Steel is Weldable – ID, OD, Anywhere!
- Cast Steel Cores are “Forever Purchases” as They are Always Repairable
Typical cast steel cores are shown below along with
photos showing transformations of a cast steel core into a CE1043 and Foster
Wheeler MB 23.5
rolls.
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Machining ID Bore of CE1043 Roll
New CE1043 Cast Steel Roll
Rebuilt Cast Steel
Foster Wheeler MB23.5
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Cast Steel Profiles
Cast steel core rolls have a standard profile and an optional profile.
Place your mouse over the profile to see an expanded view.
Standard Steel Core Profile
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Optional Steel Core Profile
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The following alloys are available for hardfacing rolls.
- Standard High Chrome Carbide Such as Stoody 100HD
- Standard High Chrome Carbide with Molybdenum Such as Stoody 100HC
- Micro-Alloyed High Chrome Carbides Such as RPM-CP3 Which has ~30% Increased Wear
Life Over Standard High Chrome Carbide Alloys
- Continuous Wear Band of Tungsten Carbide Chips Embedded in High Chrome Carbide
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In addition to the standard overlay profile, two other overlay options are
available.
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Option1 - Ribs
Chrome carbide traction ribs perpendicular to the travel direction keep rolls
from skidding in the mill, which can cause increased amperage draw and uneven
wear.
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"Ribs" added to standard profile
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Option 2 - Continuous Tungsten Carbide Chip Wear Band
RPM & Associates can apply a tungsten
carbide chip wear band over the high-wear areas of rolls to extend the performance life.
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Continuous Tungsten Carbide
Chip Wear Band
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A gallery of miscellaneous photos relating to rolls is shown below.
Place your mouse over the smaller image on the left to show the larger image on the
right.
Cast Steel with Tungsten Carbide Wear Band
Cast Steel with Tungsten Carbide Wear Band
HP863
MPS 89
MPS 89
Spalling Example
Badly Worn CE1003
Modified Profile Reduces Spalling Potential
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