PSA Discs: Product Spotlight
PSA and Hook and Loop are fastening systems to allow cloth, paper and film abrasive discs to be quickly attached and removed from a backup pad. PSA discs are more common in the USA whilst Hook and Loop is popular in Europe and is becoming more popular in the USA.
Hook and loop discs are primarily used in 5” and 6” discs on orbital sanders, while PSA is used on all sizes of disc from ½” to 36”. ½” to 4½” discs are used with a shank mounted back up pads on an angle or straight-line grinder. 5” and 6” discs are almost exclusively used on orbital sanders. 8” and larger are used on stationary disc machines and pedestal machines with a metal platen.
5” and 6” Discs
Both PSA and Hook and Loop discs are used for medium stock removal to finishing applications. Cloth discs are suited to the more aggressive applications due to their higher tear resistance. Paper discs are used in finishing applications. Paper and film substrates are manufactured to be flatter than cloth substrates and for this reason are the best choice for finer grits where surface finish and maintaining flat surfaces during grinding is required.
In critical fine finishing applications with tight tolerances, film is the only product to use. To maintain a smooth finish the backing pads can have varying levels of cushioning to allow the discs to contour over a surface rather than gouge.
A common feature of 5” and 6” discs is the vacuum holes. The holes in the disc are connected through the back-up pad and tool to a vacuum line. This technology came from automotive body shops that required the dust created in the finishing process be sucked away from the surface to keep the area clean. 5 holes and 8 holes are the two formats.
7” and Larger Discs
These will always be PSA discs and will be used on stationary machines often found in maintenance and repair shops for odd jobs and repair jobs. The discs are mounted directly to a steel platen.
PSA Discs and PSA Disc Rolls
PSA 5” and 6” paper discs are available as individual discs with a liner or as a disc roll where the discs are attached to one another in roll form without a liner paper. The disc rolls are often more convenient for the end user as there is no liner to dispose of and the disc roll can be kept as a single unit. Individual discs need to be kept in a box to ensure the stack of discs stays together.
Note on PSA Adhesive
Regardless of the disc size, the PSA disc must securely hold to the pad or platen while being easy to remove after the disc is finished. The disc must not leave any residue on the pad or platen. Excess residue can cause an uneven grinding surface for the next disc. This presents a highly technical challenge to the disc manufacturer; one which ARC has mastered.