JIS vs DIN Core Pin Standards: Dimensions, Tolerances & Interchangeability

Standard Overview

Head Thickness: The Critical Difference

Head thickness (T) determines how the core pin seats in the mold plate counterbore. This is the most common source of cross-standard incompatibility:

• JIS: T = 4 mm is the default for shaft diameters from ø1.0 to ø10.0 mm. Larger diameters may use T = 6 mm.
• DIN: T varies proportionally with shaft diameter — typically T = shaft diameter × 0.5 to 0.8, with minimum T = 3 mm.

If you install a JIS pin (T = 4 mm) into a DIN mold base counterbored for T = 5 mm, the pin head sits 1 mm below the plate surface. This creates a gap that allows the pin to shift laterally under injection pressure, causing off-center holes in the molded part.

According to ISO 20457 (plastics molding tolerances), core pin head seating must be flush ±0.05 mm with the counterbore surface to maintain positional accuracy.

Taper Angle Differences

Both standards use a slight taper on the shaft for retention in the plate bore:

• JIS 1:100 taper — 0.01 mm diameter change per 1 mm of length (0.29° per side). This is a very gradual taper that provides firm retention with minimal shaft diameter variation.
• DIN 1:50 taper (some types) — 0.02 mm diameter change per 1 mm of length (0.57° per side). Steeper taper provides stronger retention but requires more precise reaming.

Installing a 1:100 taper pin in a 1:50 taper bore (or vice versa) results in point contact rather than full-length contact. The pin will either be loose (rattles) or bottoms out before fully seating.

Steel Grade Cross-Reference

The steels are metallurgically identical across standards — only the naming conventions differ. A JIS SKH51 core pin has the same composition, hardness, and performance as a DIN S 6-5-2 pin. According to JIS G 4403 and DIN EN ISO 4957, the chemical composition specifications overlap completely.

When Cross-Standard Substitution Works

• Same shaft diameter + same taper angle — If both the JIS and DIN pin have the same shaft ø and taper (1:100), the pin will fit. You only need to address the head thickness difference with a spacer washer or by re-machining the counterbore.
• Taperless core pins — Taperless core pins eliminate the taper variable entirely. A taperless pin from any standard fits any straight-bore plate bore of the same diameter. This is a key advantage for global supply chains using mixed mold base standards.

Specification Checklist

When ordering core pins for an existing mold, specify:

• Standard: JIS B 6131 or DIN 9861
• Shaft diameter: ø value in mm
• Overall length: L value in mm
• Head thickness: T value in mm (do not assume — measure)
• Taper angle: 1:100 or 1:50 (or "taperless")
• Material: SKH51 / SKD61 / STAVAX ESR
• Tolerance grade: Standard or high-precision