Overview
EN ISO 8733:1997 (ISO 8733:1997) specifies the characteristics of parallel pins with internal thread made from unhardened steel or austenitic stainless steel. The standard covers nominal diameters from 6 mm to 50 mm and defines dimensional, material, surface and acceptance requirements for these cylindrical dowel-type fasteners used in precision assemblies.
Key topics and technical requirements
- Dimensions and tolerances: Nominal diameters d = 6–50 mm with specified nominal lengths and dimensional limits (see table in the standard). Metric screw threads for the internal bore follow ISO 965-2 with tolerance 6H.
- Materials and grades: Two main material categories are referenced: unhardened steel (St) and austenitic stainless steel (e.g., grade A1). Other materials may be agreed between customer and supplier.
- Hardness: The standard gives hardness ranges for the materials (document specifies hardness limits applicable to each material category).
- Surface finish and coatings: Pins are normally supplied in natural finish or with protective coatings by agreement. Preferred coatings listed include black oxide, phosphate conversion coatings and zinc plating with chromate conversion (see ISO 9717 and ISO 4042).
- Surface roughness and workmanship: Surface roughness requirement (Rz/Ra depending on measurement - document specifies R