Overview
ISO 8526-2:1990 defines dimensional and mounting features for workholding pallets used as modular units on machine tools, specifically for pallets of nominal size greater than 800 mm. The part covers square and rectangular pallets (including 1.25 length-to-width ratio) in nominal sizes 1000, 1250, 1600 and 2000 mm. Its primary aim is to facilitate interchangeability of pallets and fixtures between machines and manufacturers in modular manufacturing systems.
Key topics and technical requirements
- Scope and purpose: Standardizes the geometry and interface features of large workholding pallets to ensure cross‑manufacturer compatibility; it does not specify the positioning accuracy of the pallet.
- Top surface types: Six top-surface options are defined (type 1 to type 6) - threaded-hole patterns, T-slots, T-slots with cross‑tenons, plain surface, and radial/Twin radial T-slot variants (Annex A normative covers radial slots).
- Workpiece location methods: Multiple locating strategies are specified: edge locators, centre hole plus alignment hole or reference slot, cross tenon slots, and straight-through locating holes.
- Pallet-to-receiver location: Location on the machine receiver by cylindrical or tapered location holes/pins (details and tolerances illustrated in figures).
- Bottom-surface shape and fixing details: Standardized bottom geometry, fixing holes for latch mechanisms, and details to prevent swarf/coolant ingress.
- Dimensions, tolerancing and progressions: Tabled principal dimensions and tolerances for form, orientation and location; Annex B (informative) explains arithmetic vs geometric progressions for T-slot pitches.
- Designation format: Pallet identification includes the part number, nominal dimensions (e.g., 1000 x 1000), top-surface type, T-slot/thread pitch and locating methods - enabling unambiguous ordering and specification.
Practical applications and users
- Who uses it:
- Machine tool builders (pallet changers and receiver design)
- Tooling, jig & fixture designers and manufacturers
- Production and process engineers implementing palletized production
- System integrators for automated machining cells
- Procurement teams specifying interchangeable pallets and fixtures
- Typical uses:
- Implementing pallet-change systems on CNC machining centers
- Designing fixtures that fit standard pallet interfaces across vendors
- Enabling flexible, modular production layouts and quick changeover
- Reducing custom adapter work and improving spare/fixture reuse
Related standards
- ISO 299 (T‑slots and bolts), ISO 1101 (geometrical tolerancing), ISO 286‑2 (fits), ISO 2768‑1 (general tolerances) - these are referenced for complementary tolerance and interface rules.
Keywords: ISO 8526-2, workholding pallets, modular units, machine tools, T-slots, pallet interchangeability, pallet design, pallet changers.
Open preview (PDF)Modular units for machine tools — Workholding pallets — Part 2: Workholding pallets of nominal size greater than 800 mm