COMPRESSION MOUNTING
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Compression mounts are quick and easy to produce, requiring several minutes at the appropriate mounting temperature. Most of the time required in compression mounting occurs in the heating and cooling stages. A number of manufacturers produce compression mounting machines with the better machines having the heater physically connected to the mounting chamber for rapid heating along with water jacket cooling. These machines vary between manufacturers and careful examination of the heating and cooling mechanisms should be noted.
Compression mounting resins include:
Compression Mounting Resin Properties
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Phenolics |
Acrylics |
Epoxy (glass filled) |
Diallyl Phthalates |
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Cost |
Low |
Moderate |
Moderate |
Moderate |
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Ease of use |
Excellent |
Moderate |
Good |
Good |
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Availability of colors |
Yes |
No |
No |
No |
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Cycle times |
Excellent |
Moderate |
Good |
Good |
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Edge retention |
Fair |
Good |
Excellent |
Excellent |
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Clarity |
None |
Excellent |
None |
None |
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Hardness |
Low |
Medium |
High |
High |
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Resin |
Phenolic |
Acrylic |
Epoxy |
Diallyl Phthalate |
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Form |
Granular |
Powder |
Granular |
Granular |
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Specific gravity |
1.4 |
0.95 |
1.75-2.05 |
1.7-1.9 |
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Colors |
Black, Red, Green |
Clear |
Black |
Blue |
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Shrinkage (compression)(in/in) |
0.006 |
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0.001-0.003 |
0.001-0.003 |
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Coefficient of Linear Thermal Expansion |
50 |
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28 |
19 |
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Chemical resistance |
Glycol, petrochemicals, solvents, some acids and bases |
Alcohol, dilute acids & alkalies, and oxidizers |
Solvents, acids, alkalies |
Solvents, acids, alkalies |
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Molding temperature |
150°-165°C |
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143°-177°C |
160°-177°C |
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Molding pressure |
21-28 Mpa |
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17-28 MPA |
24-41 MPA |
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Hardness |
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Rockwell M63 |
Barcol 72 |
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Curing time |
90-120 seconds |
2-4 minutes |
90-120 seconds |
90-120 seconds |
COMPRESSION MOUNTING PROCESS DESCRIPTION
Following cutting or sectioning the specimen is typically mounted. Mounting provides the following advantages:
- Convenient means to hold the specimen
- Provides a standard format to mount multiple specimens
- Protect edges
- Provide proper specimen orientation
- Provides the ability to label and store the specimens
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Compression Mounting Resins |
Heating (120-150° C) |
Pressure (2500-3500 psi) |
Requires compression mounting equipment |
- Clean specimens to remove cutting and handling residues
- Remove debris from mold assembly
- Apply thin coat of mold release compound to mold assembly
- Raise mold ram to up position
- Center specimen on ram
- Lower ram assembly
- Pour predetermined amount of resin into mold
- Clean excess resin around mold assembly threads
- Lock mold assembly cover
- Slowly raise ram into up position
- Apply recommended heat and maintain pressure for specified period of time
- Cool to near room temperature
- Remove mounted specimen
- Clean mold and ram assembly
- Optional
- Preheat resin and sample to 35°C (95°F) to expedite the initial heating process
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Symptom |
Cause |
Action |
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Large bubbles in acrylic resins |
Insufficient mounting pressure |
Increase mounting pressure or reduce temperature |
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Soft surfaces on mount |
Mount did not completely polymerize because of polymer incompatibility with mold release or oil on the specimen surface |
Clean specimen and mounting machine to remove incompatible coatings. Use a compatible mold release |
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Voids or cracks |
High internal stress due to overly rapid cooling |
Allow mounts to cool more slowly and longer |
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Haze around specimen (acrylic mounts) |
Specimen contains moisture Specimens contain copper or some other polymerization retarding alloy |
Use a desiccator or low
Coat specimens with an appropriate lacquer before mounting |
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Phenolic dye leaching out with alcohol rinsing |
Insufficient mounting temperature |
Increase mounting temperature or service check heater element |
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Distortion or cracking of specimen |
Autoclave pressure is too great for the specimen |
Reduce mounting pressure or use a castable epoxy resin |
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PHENOLIC RESINS |
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Description |
Quantity |
Catalog Number |
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Phenolic powder - Black (wood flour) |
5 lbs (2.3 kg) |
CM-2001B-5 |
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Phenolic powder - Red (wood flour) |
5 lbs (2.3 kg) |
CM-2001R-5 |
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Phenolic powder - Green (wood flour) |
5 lbs (2.3 kg) |
CM-2001G-5 |
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1.25-inch PHENOLIC PREFORMS |
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Description |
Quantity |
Catalog Number |
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1.25" Phenolic PREFORMS - Black |
105/pkg |
PCM-2125B-105 |
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1.25" Phenolic PREFORMS - Red |
105/pkg |
PCM-2125R-105 |
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1.25" Phenolic PREFORMS - Green |
105/pkg |
PCM-2125G-105 |
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1.50-inch PHENOLIC PREFORMS |
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Description |
Quantity |
Catalog Number |
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1.50" Phenolic PREFORMS - Black |
100/pkg |
PCM-2150B-100 |
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1.50" Phenolic PREFORMS - Red |
100/pkg |
PCM-2150R-100 |
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1.50" Phenolic PREFORMS - Green |
100/pkg |
PCM-2150G-100 |
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TRANSACRYLIC COMPRESSION MOUNTING RESIN |
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Description |
Quantity |
Catalog Number |
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| TRANSACRYLIC Resin powder (transparent) | 5 lbs (2.3 kg) | CM-2101A-5 |  |
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TRANSACRYLIC Resin powder (transparent) |
25 lbs (11.4 kg) |
CM-2101A-25 |
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EPOXY (Glass Reinforced) COMPRESSION MOUNTING RESIN |
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Description |
Quantity |
Catalog Number |
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EPOCOMP Epoxy Compression Resin powder |
5 lbs (2.3 kg) |
EP-2201A-5 |
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EPOCOMP Epoxy FINE Compression Resin powder |
5 lbs (2.3 kg) |
EPF-2201A-5 |
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DIALLYL PHTHALATE COMPRESSION MOUNTING RESIN |
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Description |
Quantity |
Catalog Number |
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Diallyl Phthalate Compression Resin powder (short-glass filled) |
5 lbs (2.3 kg) |
DY-2301A-5 |
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| Diallyl Phthalate Compression Resin powder (short-glass filled) | 25 lbs (11.4 kg) | DY-2301A-25 | ||
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CONDUCTIVE MOUNTING RESIN |
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Description |
Quantity |
Catalog Number |
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Conductive (graphite) Compression Resin powder |
2.5 lbs (1.1 kg) |
CONDUCTO-1 |
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Conductive (copper) Compression Resin powder |
2.5 lbs (1.1 kg) |
CONDUCTO-CU1 |
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MISCELLANEOUS MOUNTING ACCESSORIES |
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Description |
Quantity |
Catalog Number |
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30 ml measuring scoop |
30 ml |
MS-1000-30 |
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Mold release |
8 oz (0.24l) |
MR-1000-08 |
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