EDM machine accuracy checks

⌖How to inspect

• Check the wire verticalityWire

  ToolsVerticality jig, flat reference plate

  ProcedurePlace the verticality jig on a plate verified to be ground flat, then check and adjust the wire verticality. When the workpiece is mounted tilted, some machines can correct the wire's vertical position with the machine's coordinate rotation function

  TolerancesMachine manufacturer's specification (no value in the published material)

  ^[14][15][16]

• Check the upper/lower guide distance setting before taper cuttingWire

  ToolsMachine setting screen, trial cut

  ProcedureTaper cutting is done by tilting the wire with the U and V axes. The upper/lower guide distance setting affects angular accuracy, together with the workpiece height

  Tolerances—

  ^[17](1 source, for reference)

• Check the offset with a trial cutWire

  ToolsTrial cut piece, micrometer, etc.

  ProcedureCheck the offset (the shift for the wire diameter and spark gap) with a trial cut. Once the actual contour cutting starts, do not change the cutting conditions. Finish the surface with multiple skim cuts, second cut onward

  TolerancesDimensional tolerance on the drawing

  ^[14][17]

• Stabilize the room temperature before working to accuracyWire

  ToolsThermometer

  ProcedureThermal displacement of the upper and lower arms and other parts changes the wire's attitude, so stabilize the temperature environment. Some machines have a function that compensates thermal displacement using multiple temperature sensors

  TolerancesFANUC example: ambient temperature 15–30 °C, and 20 ± 1 °C recommended for high-accuracy machining

  ^[17][16]

• Know how the accuracy test of a wire EDM machine is set upWire

  ToolsMeasuring instruments shown in the standard (5.6 Measuring instruments in the standard)

  ProcedureAfter leveling the machine, JIS B 6360 lists the tests in this order: geometric accuracy (linear axes, workpiece mounting table, motion of the U and V axes), positioning accuracy of numerically controlled axes (per JIS B 6190-2), machining accuracy, and circular motion accuracy (per JIS B 6190-4)

  TolerancesStandard tolerances (for each test such as G1–G4 and P1–P5)

  ^[2][3]

• Know how the accuracy test of a die-sinking EDM machine is set upDie-sinking

  ToolsMeasuring instruments shown in the standard

  ProcedureAfter leveling the machine, JIS B 6361-1 and -2 test geometric accuracy (linear axes, table, head/quill/spindle), positioning accuracy of numerically controlled axes (per JIS B 6190-2), and machining accuracy

  TolerancesStandard tolerances

  ^[5][8][6]

• Check the operating condition before measuring accuracyCommon

  ToolsEyes and ears (a vibration meter if needed)

  ProcedureCheck vibration, abnormal noise, stick-slip (running tests) and feed rates (characteristic tests) before the accuracy test

  Tolerances— (the accuracy test standards do not cover running tests or characteristic tests)

  The JIS accuracy test standards for wire and die-sinking EDM machines all state this in their scope

  ^[2][5][8](1 source, for reference)

≡Related standards

• WireJIS B 6360:2017 Wire electrical-discharge machines — Testing of the accuracy / ISO 14137:2015 (identical = IDT)Tests and tolerances for geometric accuracy, positioning accuracy, machining accuracy and circular motion accuracy of general-purpose wire EDM machines of normal accuracy (single-column and gantry types). The G1–G4 and P1–P5 tolerances changed from the 2006 edition. Draft prepared by the Japan Machine Tool Builders' Association and the Japanese Standards Association^[1][2][3]
• Die-sinkingJIS B 6361-1:2017 Die sinking electro-discharge machines — Testing of the accuracy — Part 1: Single-column machines / ISO 11090-1:2014 (IDT)Covers single-column machines with a compound table or a fixed table. Geometric accuracy (linear axes, table, head/quill/spindle), positioning accuracy and machining accuracy. Some tolerances changed from the 1999 edition, and the reference T-slot test was dropped^[4][5][6]
• Die-sinkingJIS B 6361-2:2017 Die sinking electro-discharge machines — Testing of the accuracy — Part 2: Double-column machines / ISO 11090-2:2014 (IDT)Covers double-column (gantry) machines of the slide-head type. The structure is the same as Part 1 (geometric accuracy, positioning accuracy and machining accuracy)^[7][8][9]
• CommonJIS B 6032:2025 Machine tools — Safety — Electrical discharge machines / ISO 28881:2022 (modified = MOD)Specifies safety requirements (for design and manufacture) for manual and numerically controlled die-sinking EDM machines, small-hole EDM machines and numerically controlled wire EDM machines, and the information the manufacturer must give to the user. A machine-specific safety standard (type C) whose content was changed from the ISO to suit Japanese fire prevention ordinances and the like. An annex contains fire protection rules for specific regions^[10][11][12]
• CommonTR B 0035:2019 Machine tools — Practical guidance and examples for risk assessment of electrical discharge machines (modified from ISO/TR 17529:2014)A Standard Technical Report (TR), not a JIS. Draft prepared by the Japan Machine Tool Builders' Association^[13](1 source, for reference)

The standard texts are paid, so tolerances are written from sources such as in-house standards published by machine manufacturers. For the correspondence between standards, see the standards correspondence table as well.