ISO 8606:1990

Overview

ISO 8606:1990 is an international standard developed by the International Organization for Standardization (ISO) that establishes a foundational specification basis for bulk moulding compound (BMC) and dough moulding compound (DMC) under the category of plastics prepregs. These materials are essential for manufacturing composite parts through moulding processes, particularly when textile glass serves as the primary reinforcement. This standard provides clear classification, definitions, physical and mechanical properties, sampling methods, shelf life, packaging, and marking requirements to ensure consistency and quality in BMC and DMC products.

Key Topics

Classification and Composition

ISO 8606 defines BMC and DMC by their composition and linear shrinkage characteristics:

• BMC: Homogeneous resin-fibre mixtures with chemical thickeners.
• DMC: Similar to BMC but without chemical thickeners.

Classification is further divided based on:

• Resin types including unsaturated polyester (UP), epoxy, polyurethane (PUR), vinyl ester (VE), and phenolic resins.
• Reinforcements, primarily textile glass strands of 3 mm to 25 mm length.
• Fillers, such as calcium carbonate and aluminium trihydrate, to reduce cost and improve surface finish, combustion resistance, and electrical properties.
• Additives like pigments, fire retardants, UV absorbers, low-shrink agents, and others to enhance performance.

Shrinkage Categories

Shrinkage during curing largely impacts the final product's quality. ISO 8606 categorizes materials based on linear shrinkage:

• General-purpose (0.2% to 0.5%)
• Low-shrink (0.05% to 0.2%)
• Very-low-shrink (less than 0.05%)
• Zero-shrink (no measurable shrinkage)

Properties and Testing

Key physical, mechanical, and electrical properties detailed in the standard include:

• Tensile, flexural, compressive, and shear strengths
• Impact resistance (Charpy and Izod tests)
• Temperature of deflection under load
• Density and molding shrinkage
• Fire hazard and oxygen index testing
• Water absorption
• Dielectric strength, surface and volume resistivity, and proof tracking index

Test methods correspond with existing ISO and IEC standards, ensuring reliable and repeatable property measurements.

Sampling and Quality Control

Sampling is governed by ISO 1886 to represent batch uniformity. Visual inspections define acceptable defect types such as resin patches, dry spots, contamination, color heterogeneity, and packaging damage. Manufacturers and purchasers agree on acceptable defect limits for quality assurance.

Shelf Life and Packaging

ISO 8606 specifies that manufacturers indicate maximum storage life and conditions, emphasizing preservation of molding properties by protecting against volatile component loss (e.g., styrene). Packaging materials must be impermeable to volatiles and secure for transport to avoid damage.

Marking Requirements

Each unit package must be clearly labeled with:

• Product designation and classification
• Manufacturer’s identity and batch number
• Color code and mass of compound
• Date of manufacture
• Shelf life and recommended storage conditions

Applications

ISO 8606:1990 is critical for industries utilizing composite plastics in manufacturing, offering a standardized approach to:

• Producing high-quality BMC and DMC compounds for automotive, electrical, aerospace, and consumer products.
• Enhancing material selection by providing clear property classifications tailored to application demands.
• Ensuring compatibility and interchangeability of materials across international markets.
• Facilitating quality control and inspection through uniform testing and sampling techniques.
• Optimizing shelf life management and packaging integrity for supply chain and warehouse environments.

Related Standards

ISO 8606 references and aligns with multiple other international standards to cover detailed testing and terminology aspects, including:

• ISO 472:1988 – Plastics vocabulary and definitions
• ISO 604:1973 – Compression properties
• ISO 178:1975 – Flexural properties
• ISO 291:1977 – Standard atmospheres for conditioning
• ISO 75:1987 – Temperature of deflection under load
• ISO 1172:1975 – Loss on ignition for textile glass reinforced plastics
• IEC 93:1980 – Electrical resistivity measurements
• ISO 3268:1978 – Tensile properties of glass-reinforced plastics
• IEC 695-2-1 – Fire hazard testing

Together, these references enhance the robustness of ISO 8606’s application and ensure comprehensive evaluation of bulk and dough moulding compounds.

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Keywords: ISO 8606, bulk moulding compound, dough moulding compound, BMC, DMC, plastics prepregs, composite materials, glass reinforcement, plastic moulding, material specification, shrinkage classification, physical properties, mechanical properties, electrical properties, sampling methods, shelf life, packaging standards, international standards for plastics.