Troubleshooting
Sectioning
| Problems | Probable causes | Possible solutions |
|---|---|---|
| Frequent wheel breakage. | -Chisel effect. -Loose specimen clamping. -Excessive initial force applied. -Missing blotters. -Warped wheel. -Incorrect wheel selected. -Sample moved during the cut. | -Ensure coolant is flowing evenly on both sides. -Rigidly clamp specimen. -Reduce applied cutting pressure. -Insert blotters. -Clean flange of surface corrosion. |
| Short wheel life. | - Wheel is wearing down too fast. | -Select the harder wheel. -Reduce applied cutting pressure. |
| Wheel not cutting | - Slow wheel breakdown. | -Reduce coolant rate. -Choose a harder or softer wheel. -Use swaying stroke. |
| Burning of a sample. | -Incorrect cutting fluid. -Insufficient coolant. -Improper Cut off-wheel. -Excessive force applied. | -Increase coolant rate. -Check for the proper direction of the coolant. -Reduce applied cutting pressure. -Select a softer wheel. |
| Curved cut. | -Excessive cutting force applied. | -Reduce applied cutting pressure. -Clean hoses thoroughly of all residues. |
| Non-uniform wheel wear. | -Flow of coolant is not uniform. | -Clean hoses from cutting debris. |
| Motor stalling. | -Sample being cut is too large. | -Decrease sample size. |
| Excessive blade wobble | -Excessive initial force applied. -Missing blotters. | -Reduce applied cutting pressure. -Insert blotters. |
| Burr formation. | -Excessive vibration. -Excessive initial force applied. -Missing blotters. | -Reduce applied cutting pressure. -Insert blotters. |
| Specimen chipping. | Too large in abrasives. | Use a finer grit wheel. |
Copression Mounting
| Problems | Probable causes | Possible solutions |
|---|---|---|
| Shrinkage | - Poor adhesion to sample surface. | - Decrease molding temperature. - Cool mount before ejecting sample. |
| Mold cracking | - Powders absorbed moisture. - Entrapped gases during molding. - Sample too large for mold area. - Samples have sharp corners. - High internal stress due to rapid cooling. | -Preheat powders. -Release pressure for a moment during the flow stage. -Reduce the size of the specimen. -Clearance between sample and mold should be approx. 1/8". -Reduce specimen size. -Allow mounts to cool more slowly. |
| Top die damaged | -Not enough mounting powder added. | - Add sufficient mounting powder. |
| Mold blistering | -Not enough applied pressure. -Curing time is insufficient. | -Increase pressure and curing time. |
| Mounts are sticking to mold cylinder | - Mold temperature is too high. | - Reduce molding temperature. - Apply releasing agent. |
| Staining and dull surfaces | - Mold temperature is too high | - Reduce molding temperature. |
| The color of dye in the mount bleeds while rinsing in alcohol. | -Molding temperature is too low. -Insufficient curing time. | -Verify temperature and adjust if necessary. -Increase curing time. |
| Unfused mount | - The Molding temperature too low. - Insufficient curing time. | -Verify temperature and adjust if necessary. - Lengthen curing time. |
| Cotton ball effect | -The molding temperature has not reached the required maximum. -Polymerization time is insufficient. | - Verify temperature. Adjust if necessary. - Increase curing time. |
Ambient Mounting
| Problems | Probable causes | Possible solutions |
|---|---|---|
| Air entrapment | - Agitation of blend between resin and hardener is too rapid. - Improper degassing of the specimen | - Gently blend the resin and hardener. The alternative is to use a pressure vessel or vacuum system. |
| Mold cracking | - The proportion of resin and hardener is incorrect. - Insufficient air cure. - Oven curing temperature is too high. | -The reaction between the resin and hardener is too exothermic. -Measure accurate proportions of resin and hardener. |
| Mounts are soft | -An incorrect proportion of resin and hardener was used. -Poor mix between resin and hardener. | -Increase hardener proportion to resin ratio. -Homogenize more thoroughly the mixture of resin and hardener. |
| Mounts sticking to mold | - Mold temperature is too high. | -Use a mold release agent. -Decrease the volume of hardener. |
| Staining and dull surfaces | - Incorrect proportion of resin and hardener. - Oxidized hardener. | -Measure accurate proportions of resin and hardener. -Seal the hardener container. |
| Top of mounts sticky | - An Incorrect proportion of resin and hardener. - Poor mix between resin and hardener. | -Measure accurate proportions of resin and hardener. -Homogenize more thoroughly the mixture of resin and hardener. |
| Poor adhesion between resin and specimen | - Not using the appropriate medium for mounting specimen. - Samples were not cleaned before mounting the sample. - Mounting shrinkage. | -Clean samples thoroughly before mounting the sample. -Use a mounting medium that has good adhesion and no shrinkage. |
| Time for polymerization is too long. | -An incorrect proportion of resin and hardener. -Exothermic temperature is too low. -Oven polymerization temperature is too low. | -Measure accurate proportions of resin and hardener. -Homogenize more thoroughly the mixture of resin and hardener. |
Grinding and Polishing
| Problems | Probable causes | Possible solutions |
|---|---|---|
| Scratches. | -Sharp abrasive particles are released from the material being used to grind or polish. -Contamination of the previous steps in grinding or polishing. | -Repeat the step until all scratch lines are uniform. -Increase the preparation time for the current step. (Not the pressure) -Verify that the cutting edge of the abrasive being used is effective. If necessary, change. -Change polishing cloth. Use a more thorough technique in cleaning between steps. -Clean samples thoroughly in between each step. |
| Smearing/Buffing | -Surface of the specimen is not being cut. -The pH of the alumina suspension is too high. | -Increase the quantity of applied lubricant. -Use a less napped cloth. -Use a coarser diamond grain particle. -Decrease the pH of alumina suspension. |
| Staining | -The pH of alumina suspension is alkaline -Mounting does not adhere to the specimen. -Incomplete penetration of cracks or pores. | -Neutralize the pH of alumina suspension. -Select resin with little or no shrinkage. -Use pressure vessels or vacuum systems. |
| Grain Pullouts. | -Insufficient steps between grain sizes. -Type of polishing cloth used. -Polishing time is too long or too short. -Excessive use of lubricant. | -Increase grain size steps. -Use a napless polishing cloth. -Decrease the polishing time. -Depending on the application may have to increase the polishing time. -Reduce the quantity of lubricant used. -Moisten cloth with lubricant before applying diamond abrasive. |
| Rounding of the edges. | -Samples were not mounted. -An incorrect mounting medium was used. -Polishing times were too long. -Excess pressure was applied to the specimen. -Type of polishing cloth used. | -Mount the samples. -Use a mounting medium that has good adhesion. -Keep polishing time to a minimum. -Use shorter and tighter weaved polishing cloth. |
| Polishing relief. | -Too much speed. -Excessive rotation. -Mixing different hardness of materials while polishing. | -Reduce speed. -Use a lower fiber-napped polishing cloth. |
| Cracks. | -From cutting the specimen. -Clamping of the sample. -The wrong mounting medium was used. -Shrinkage. | -Use the appropriate cut-off wheel. -Use a protective layer between the sample and clamp from cut-off equipment. -Use a cold mounting system with a vacuum system or pressure vessel. -Use a mounting medium that has the least shrinkage properties. |
| Porosity. | -Worn out abrasive. -Type of polishing cloth used. -Type of mounting medium. | -Change abrasive discs more often. Alternatively, use diamond discs. -Use a shorter nap polishing cloth. -With cold resin, use vacuum or pressure vessel systems. |
| Embedded abrasive. | - Excess pressure was applied to specimen. - Type of polishing cloth used. - Excessive use of polishing abrasive. - The lubricant has low viscosity. | - Reduce pressure applied to specimen. - Use a shorter nap cloth. - Decrease the amount of polishing abrasive, especially for soft metals. - Use a higher viscosity lubricant. |
| Comet tails. | -Too much pressure. -Too much speed. -Over-polishing on worn grinding cloths. -Use of the same orientation during all polishing steps. -Scratches from embedded abrasives. | -Reduce pressure applied. -Reduce speed. -Change the grinding cloth more frequently. -Change the orientation of the sample for every step. -Use the same direction in rotation for the head and base. |
| Scratch lines are long and dull. | -Sharp abrasive particles from the material being used to grind or polish. -Contamination of the previous steps in grinding or polishing. | -Repeat the step until all scratch lines are uniform. -Increase the preparation time for the current step. (Not the pressure). -Verify that the cutting edge of the abrasive being used is effective. -Change polishing cloth. Use a more thorough cleaning technique between steps. -Clean samples thoroughly in between each step. |
| Machine vibration. | -Too much pressure. -Speed is too low. | -Reduce pressure applied. -Increase grinding speed. |
| Uneven grinding across the specimen and mount. | -Inappropriate choice of resin for the sample to be prepared. -Improper tracing of the specimen over abrasive discs. -Different head/base speed. | -Select a resin that is comparable to the hardness of the sample. -Orienting is the hardest part of the sample to cover the abrasive discs. -Match head/base speed. |
| Gaps | Mounting does not adhere to the specimen. | -Select a very hard resin that has good adhesion, is wear-resistant and has low shrinkage. -Clean sample. -Select resin with little or no shrinkage. -Use a pressure vessel or vacuum system. |