Overview
ISO 8526-1:1990 defines dimensional and mounting details for modular workholding pallets used with machine tools - specifically square and rectangular pallets up to 800 mm nominal size. The standard is intended to promote interchangeability of pallets from different manufacturers in machine tools and manufacturing systems. It covers nominal sizes (320, 400, 500, 630 and 800 mm), top-surface types, location features and bottom-surface interfaces for pallet receivers. (Note: ISO 8526-1 does not specify pallet positioning accuracy.)
Key topics and technical requirements
- Scope and nominal sizes: Applies to pallets up to 800 mm nominal dimension (listed sizes include 320, 400, 500, 630, 800 mm).
- Top-surface types (1–6): Defines six top-surface options (threaded hole pattern, T-slots, T-slots with cross-tenons, plain, radial T-slots, twin radial T-slots) and associated hole/T‑slot pitches.
- Workpiece location features:
- Centre hole and optional alignment hole
- Edge locators and fixing hole patterns
- Reference slots and crossed-tenon slots
- Straight-through location holes (optional)
- Pallet-to-receiver location:
- Two cylindrical holes with pins or two tapered holes with tapered pins - positions and tolerances specified.
- Dimensions and tolerances:
- Detailed dimension tables for each nominal size and length (see Table 2 in the standard).
- References to geometrical tolerancing and fits: ISO 1101, ISO 286-2, ISO 2768-1, and ISO 299 are normative references used for tolerances, T-slot and threaded-hole dimensions.
- Annexes:
- Annex A (normative): radial T-slot top-surface dimensions (types 5 & 6).
- Annex B (informative): explanation of arithmetic (AP) and geometric (GP) progressions for T-slot pitches.
- Designation format: Example shown in the standard (ISO 8526-1 - 500 x 500 - 2 - 100 - c - a) encodes nominal size, top-surface type, T-slot pitch and location methods.
Applications and users
- Who uses it:
- Pallet and fixture manufacturers, machine-tool builders, tooling engineers, production planners, and procurement specialists.
- Systems integrators implementing pallet changers, flexible manufacturing cells, and automated machining lines.
- Practical applications:
- Standardized pallets for CNC machining, mass production lines, pallet-change systems, and modular tooling systems to ensure cross-vendor compatibility and simplify fixturing and setup.
- Helps reduce tooling changeover time and supports modular manufacturing strategies.
Related standards
- ISO 1101 - Geometrical tolerancing
- ISO 286-2 - Limits and fits (holes and shafts)
- ISO 2768-1 - General tolerances (linear/angular)
- ISO 299 - Machine tool table T-slots and bolts
ISO 8526-1 is a practical reference for anyone specifying or producing workholding pallets for machine-tool integration, ensuring consistent dimensions, mounting features and interchangeability across suppliers.
Open preview (PDF)Modular units for machine tools — Workholding pallets — Part 1: Workholding pallets up to 800 mm nominal size