Sealing System Leakage Analysis - Bore
Nicks on Bore Chamfer
| Probable Causes | Actions or Countermeasures |
|---|---|
| Mishandling prior to seal installation | Review bore/housing machining for mishandling |
| Insufficient material removal | Check casting dimensions for proper material allowance. Check machining for proper gage points |
| Tool chatter on chamfer surface | Review machining procedures for proper tool configuration, feed, speed, and coolant. |
Check for Looseness in Bore
| Probable Causes | Actions or Countermeasures |
|---|---|
| Oversized bore I.D. | Check bore machining dimensions for out-of-tolerance condition. |
| Undersized seal O.D. | Check seal OD for out-of-tolerance condition. |
| Rolling of seal into bore during installation | Review installation procedure and use proper installation tools. |
| Bore sizing | Increase bore material hardness or use bore sealant |
| Excessive shrinkage/hardening of rubber O.D. seal | Review application temperatures, and seal material specifications. |
| Deformation of seal during installation | Review installation procedure and use of proper tool. |
Measure Bore Diameter
| Probable Causes | Actions or Countermeasures |
|---|---|
| Seal loose. | Use correct OD seal, machine bore to correct size. |
| Oversize bore diameter resulting from seal press fit deformation. | Check seal to insure proper OD size. Increase housing radial wall in area of seal gland. |
| Tapered bore diameter resulting from improper machining techniques. | Specify maximum axial diameter taper. |
| Undersize or oversize bore due to design error. | Contact OEM for corrective action. |
| Oversize bore not in dimensional agreement with OEM specification. | Unit may be a rebuild. Check seal OD diameter and order proper replacement part. |
| Seal collapsed | Replace damaged seal with correct size. |
Check Bore Chamfer
| Probable Causes | Actions or Countermeasures |
|---|---|
| Chamfer lead-in not adequate to install seal due to improper chamfer angle. | Review machining practices and product drawing. |
| Deformation of lead-in chamfer edge due to chamfer diameter less than maximum OD of seal. | Check OD of seal to insure seal not oversized and check ID of chamfer to insure ID meets drawing specifications. |
| Chamfer not present due to machining or product drawing error | Review product drawing and make appropriate changes. |
| Chamfer deformed due to seal installation | Increase hardness of bore material; use rubber covered seal. |
| Chamfer too long causing insufficient flat area for seal retention | Check product drawing and chamfer angle. Measure seal width to insure proper part and fit. |
Inspect for Flaws or Voids in Housing
| Probable Causes | Actions or Countermeasures |
|---|---|
| Porosity in housing resulting from casting defect. | Review foundry practice. |
| Circumferential scratches, burns, gouges, due to machining. | Review machining techniques and specification. |
| Cracks in housing due to heat treating or mishandling. | Review material heat treating specification and handling practices. |
| Embedment of grinding media producing rough surface. | Review machining practices. |
Check for Tool Withdrawal Marks on Bore
| Probable Causes | Actions or Countermeasures |
|---|---|
| Poor machining practices. Tool in contact with surface during removal. | Review machining techniques. |
| Leakage through machine marks. | Apply OD sealant to seal and/or bore. Machine larger to OD and use larger seal. Machine bore and install sleeve. |
Check for Severe Scratches or Galling Marks on Bore
| Probable Causes | Actions or Countermeasures |
|---|---|
| Scratches and galling due to poor handling techniques. | Review handling and shipping practices. |
| Scratches and galling due to machining operations. | Review machining practices |
| Scratches and galling due to part assembly; i.e., shaft, seal, bearings. | Review assembly practices. |
| Leakage through imperfections. | Machine and use larger OD seal. Machine and install sleeve. |
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