ISO 6751:2011 PDF

Overview

ISO 6751:2011 defines the dimensions, tolerances, material guidelines and hardness requirements for ejector pins with a cylindrical head, used in compression and injection moulds and in die‑casting dies. All sizes and tolerances are given in millimetres. This fourth edition (2011) is a minor revision of the 1998 edition and aligns surface‑texture indications with ISO 1302:2002.

Key topics and technical requirements

• Scope: Applies specifically to ejector pins with a cylindrical head for moulding and die‑casting applications.
• Dimensions and tolerances: Detailed dimensional specifications are provided in Figure 1 and Tables 1 and 2 of the standard. Sizes, lengths and permissible oversizes are listed for hot worked and alloyed cold worked steels.
• Units: All dimensions are specified in millimetres.
• Surface roughness: Recommended surface finishes are given (Figure 1):
  • Ra 0.8 μm for hot worked steel
  • Ra 0.4 μm for alloyed cold worked steel
• Materials: Ejector pins shall be made of either hot worked steel or alloyed cold worked steel.
• Hardness requirements (Table 3):
  • Hot worked steel: minimum 1 400 MPa core strength, min. 950 HV0.3 (approx. 45 ± 5 HRC)
  • Alloyed cold worked steel: approx. 60 ± 2 HRC
  • The exact point of hardness measurement is left to the manufacturer’s discretion.
• Designation: Standardizes how ejector pins are identified: name, reference to ISO 6751, diameter (D, mm), length (L, mm), and material. Example: Ejector pin with cylindrical head ISO 6751 - 2 - 100 - Hot worked steel

Applications and practical use

• Ensures interchangeability and consistent quality of ejector pins used in:
  • Injection moulding
  • Compression moulding
  • Die casting dies
• Useful for toolmakers, mould designers, quality engineers and buyers who need to:
  • Select pins with correct dimensions and surface finish
  • Specify material and hardness for wear resistance and ejection performance
  • Create procurement and inspection documentation consistent with international practice

Who should use this standard

• Tool and die manufacturers
• Mould designers and design engineers
• Procurement teams specifying mould components
• Quality control and metrology personnel verifying pin dimensions and hardness

Related standards

• ISO 1302:2002 - surface texture indication (referenced for surface finish)
• ISO 8693 - Flat ejector pins
• ISO 8694 - Shouldered ejector pins

Keywords: ISO 6751, ejector pins, cylindrical head, moulding tools, injection moulds, compression moulds, die casting, dimensions and tolerances, hardness requirements, material guidelines, surface roughness, ejector pin designation.