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
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.
