Standard AS568 O-ring sizes are well known in the seal industry. Generally adding the compound with a standard O-ring size creates a smart part number for identification and purchasing purposes. But how do we come up with part numbers for seals that are different geometries, hollow profiles, or non-standard sizes? The Applications Engineering team wrestles with questions like these on a daily basis. There are generally three options for a custom sized part: precision cut, cord stock, and extruded and spliced parts.
Parker refers to our extruded and cut part product line as a Precision Cut. These parts are manufactured by pushing an elastomer material through a die to give it a specified inside diameter and wall thickness. The part would then be “cut” to a specified width (we call this the “cut thickness”). These parts have a square cross-section and are highly customizable with minimal capital costs. Parker specializes in custom precision cut lengths, and it is worth noting that TetraSeal® parts fall into this product category as well. If the ID and CS correspond to a standard AS568 size, these are sometimes referred to as a TS-xxx size (however, this will not be the final part number). The official Parker part number for both TetraSeals and custom precision cut parts cannot be determined prior to being quoted.
Another product that we often receive inquiries about is cord stock. This product line is manufactured by extrusion and the parts can have many different geometries. Cord stock is often used when a customer wants to create their own custom sized gaskets – doing a splice on their own. For extruded cord part numbers, Parker uses the below “smart” part numbering method:
Material – Profile – Packaging Method** – Material
Example: A spool of 500 feet of S7442 in the A002 profile would have the Parker part number S7442 A002 S S7442. The quantity would be 500.
With extruded/spliced parts, there is an additional step – splicing. When given “developed length” which is the total length of the part along its centerline, the part is cut to that length and then undergoes a hot vulcanization process using the same base polymer, creating a continuous part. This can be done for both hollow profiles and solid profiles. For extruded and spliced parts, the below “smart” part numbering method can be used:
Material – Profile – Packaging Method** – Developed Length (centerline length*, where xxx.xx corresponds to the length in inches)
Example: A 37” inside diameter x 0.139” cross section part, made from E7736-70 would have Parker part number E7736 A018 D 11668
*The centerline length is calculated by taking the desired ID (37”) and adding 1 cross section width to it and multiplying by Pi. (37” + 0.139”) * pi = 116.68”
** The different “packaging methods” are:
S: Spooled footage – This is a type of bulk packaging and the cord will come on a spool.
C: Coiled – This is another type of bulk packaging, and the cord will come coiled in a bag or box.
D: Developed Length (Spliced) – This type of package method is for spliced parts. The finished parts will be coiled in a bag or box.