ISO 14744-6:2000

Overview

ISO 14744-6:2000 is Part 6 of the ISO 14744 series on acceptance inspection of electron beam welding machines. It provides procedures and measurement setups to evaluate the stability of the focal spot position (the impact point of the electron beam on the workpiece) during acceptance testing. The standard describes test fixturing, specimen preparation, measurement sequences and calculation methods used to determine positional drift and repeatability.

Key procedural elements described in the standard include the use of a heat sink block or a Faraday cage in the beam axis, a specially prepared specimen (piece B) for measuring spot position, and a third specimen (piece C) used to determine beam power needed for forming reproducible small melt points. The workpiece surface roughness is specified as Ra = 1.6 µm in accordance with ISO 1302.

Key Topics

• Test assembly: Use a dissipator (heat sink) or Faraday cage aligned in the beam axis and ensure thermal isolation between devices. Materials must be non-magnetic to avoid beam deflection.

• Specimen preparation: Piece B is prepared with a coordinate system and surface finish Ra 1.6 µm. Piece C (same height) is used to set beam power for melt spots or fusion lines.

• Measurement approaches:

  • Machines with optical viewing: procedures for CNC tables and non-CNC tables are described, including programmed melt points at coordinates (0,0), (5.000,0), (0,5.000) mm and a fourth measured point at (5.000,5.000) mm.
  • Machines without optical viewing: concentric fusion lines are used (before and after continuous operation) and measured for radial displacement.

• Instrumentation: Portable workshop microscope is used to read coordinates with about ±0.02 mm resolution.

• Calculation: Positional deviation is computed from measured coordinate differences using

  Δr' = sqrt(Δx^2 + Δy^2)

  where Δx and Δy are the differences between intended and measured coordinates. If a focal distance other than 300 mm is used, measured deviations are converted proportionally to a 300 mm reference.

Applications

• Acceptance testing of new or serviced electron beam welding machines.
• Verification for long-duration welding and processes requiring automatic part positioning where beam alignment must be reproducible over time.
• Quality assurance for applications demanding precise joint alignment and consistent weld quality.

Related Standards

• EN ISO 14744-1:2000 - Principles and acceptance conditions for electron beam welding machines (reference for test conditions).
• EN ISO 14744-3 - Measurement of beam current characteristics and use of Faraday cage or heat sink.
• ISO 1302 - Surface texture specification (used here for Ra = 1.6 µm).

This part of ISO 14744 focuses on practical test setup and measurement methods to quantify focal spot stability without prescribing specific acceptance limits (compare measured values with limits given in ISO 14744-1).