RS PRO 4 Pair Parallel Set

Matched Sets

Sets contain matched pairs of parallels
All parallels are hardened and precision ground
Parallelism accuracy 0.0002in
Matched pair accuracy 0.0003in

Supplied with

Fitted polypropylene storage cases

Parallels, Surface Finish & Hardness

Surface Finish

Any machined component has a surface geometry which consists of three basic elements:

Form or Curvature - Whether the surface has irregular bumps or dimensional changes
Waviness - Whether the surface has regular repetitive ripples or patterns (e.g. milling patterns)
Roughness - The shapes or irregularities that are smaller than, and form part of the waviness pattern (e.g. material micro-structure)

Waviness and roughness are traditionally the most difficult elements to measure when comparing surface finish, however, they have a radical effect on the performance of the finished component. Variations will cause aesthetic appearance changes, component wear variations, oil retention variation etc. Many manufacturers therefore specify a range of roughness values which their components should be manufactured to, often expressed as: Ra, Rq (RMS), RzDIN, Ry, Sm,mm.

Datasheet