Plastic Moulding Hydraulic Systems Technical Transition Guide

This document outlines the technical considerations relevant to the use of ISO L-HM hydraulic oils in plastic moulding and injection moulding hydraulic systems. It is intended to support engineering, maintenance and procurement teams when assessing hydraulic oil suitability within existing operating and approval frameworks.

Equipment covered

  • Injection moulding machines
  • Extrusion and blow moulding equipment
  • Servo controlled and proportional valve hydraulic systems

Key operating risks addressed

  • Cycle time variation associated with viscosity instability
  • Valve response delay or control inconsistency
  • Thermal stress under continuous operation
  • Process variability linked to pressure control deviation

Hydraulic oil technical basis

Plastic moulding hydraulic systems typically operate under continuous duty with high demands on viscosity stability and valve response accuracy. Hydraulic oils used in these applications are commonly aligned with ISO 11158 L-HM and DIN 51524 Part 2 performance categories, which define requirements for antiwear protection, oxidation stability and hydraulic efficiency.

Hydraulic viscosity grade selection

Operating condition Typical viscosity grade Selection rationale
High response servo controlled systems ISO VG 32 Supports rapid valve response and consistent hydraulic control
General injection moulding duty ISO VG 46 Provides balanced viscosity for wear protection and thermal stability

Equivalency and approval position

Hydraulic oils aligned with ISO 11158 L-HM or DIN 51524 Part 2 are generally considered technically suitable for plastic moulding and injection moulding hydraulic systems when viscosity grades are selected in line with equipment manufacturer guidance and operating conditions.

Changeover guidance

  • Changeover is typically completed during planned maintenance activities
  • System flushing is not normally required when replacing lubricants of the same specification category
  • Existing filtration and cleanliness control practices are normally maintained

Glossary and reference

Definitions and reference material used across lubricant documentation, including abbreviations, standards terminology, test method references, and classification systems. These pages support consistent interpretation of specifications and data sheets.

Technical Transition Guides

Equipment and industry focused technical summaries covering common operating conditions, lubricant functions, and specification considerations used when reviewing or comparing existing lubricants.

Last reviewed: January 2026