Gland Machining
The best gland finish is achieved by using the single-point method of machining. Alternately, form tools may be used but care must be taken to prevent chattering. If form tools are to be used, they should be of the “coated” variety. With either machining method, finish quality depends on a variety of factors including machine speed, condition of the cutting tool being used, lubricants and the type material being machined.
Machining Notes:
- 16 Ra finish minimum on both tooth faces. No machine marks across tooth. Annular machine marks OK.
- 60° included angle tooth is preferred, although sharper angles may be used to decreased penetration force.
- H-Seal gland teeth can tolerate misalignment of up to .015" , as shown in the adjacent drawing.
Mechanical Polishing
Avoid mechanically polishing the tooth because this type of operation is generally done by hand, making it difficult to control the amount of material being removed. The tooth must remain sharp, and an overly aggressive polishing operator can unknowingly remove 30-40% of the tooth. Even penetration of the tooth into the H-Seal requires that the apex of the tooth have minimal waviness.
Electro-polishing
Electro-polishing of the tooth is permissible providing the amount of material removed is in the range of .0003" or less. For conditions where other areas of the component must be aggressively electro-polished, the tooth should be masked. Also, avoid surface pitting which results from overexposure to the EP process.
Alignment Tolerances and Gland Clearance
For clearance purposes, the OD of Standard and Zero-Clearance H-Seals has been designed to be .015" smaller than the corresponding gland OD. For similar reasons, the step ID of the H-Seal will clear the inside base of the tooth by .004", even when the H-Seal is pushed completely to one side or the other of the gland.
Handling
Care should be taken to protect the apex of the tooth from damage. Because the tooth is below the free surface of the part, casual scratches from being placed on an assembly table are usually avoided. However, if damage from impact with tools, other parts or other objects is likely to occur, the tooth should be protected with a nylon cap. |
