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D2562-94 – Standard Test Method Technical Guide
ASTM D2562-94 standard practice provides guidelines for classifying visual defects in reinforced thermosetting plastic parts molded via compression or transfer molding. It establishes acceptance criteria, defect descriptions, and inspection practices to ensure consistent quality control.
📋 Acceptance Criteria and Defect Types
The acceptance criteria cover dimensional conformance, insert integrity, and workmanship. Parts must meet specified dimensions and tolerances; inserts must be free from damage and flash. Molded-in threads should be clean and smooth. The following table lists common defects that are generally acceptable unless restricted on the product drawing.
| 🟦 Defect Type | 📏 Description | 🎯 Acceptance Status |
|---|---|---|
| Ripple Surface | A wavy surface from differential shrinkage between resin and reinforcement, typically in long glass-fiber-filled plastics. | Acceptable unless specifically prohibited. |
| Shrink-Mark | Dimple-like depression with rounded edges, occurring near bosses or ribs where section thickness changes. | Acceptable unless otherwise specified. |
| Resin Voids | Multiple blisters in surface; applicable only to chopped fabric-reinforced molding compounds. | Acceptable unless otherwise specified. |
🔬 Critical Areas and Inspection Practices
Critical areas are those where imperfections could harm structural, aerodynamic, or electrical function. They must be designated on drawings via encircling, cross-hatching, or word descriptions. In these areas, defects from Table 1 (such as nicks, cracks, shorts) are not acceptable if specified. Sampling frequency and allowable defects should be pre-agreed between buyer and seller.
💡 Tip: Clearly mark critical areas on product drawings. Use cross-hatching to indicate different quality levels for various zones of the part. This helps inspectors focus on key regions during visual inspection.
📊 Defect Classification and Quality Grades
This standard categorizes defect descriptions to support various quality requirements. By providing word descriptions of possible defects, it helps align expectations between manufacturers and inspectors for different product grades. Good commercial workmanship practices must always be followed.
⚠️ Important: All dimensions outside specified tolerances lead to rejection. Threaded inserts may be retapped for cleaning but not if they contain locking features. Always verify product drawing for critical area requirements.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D2562-94?
It covers acceptance criteria for visual inspection of parts molded from reinforced thermosetting plastics by compression and transfer molding, serving as a guide for contracts and final inspection.
💡 How are critical areas designated?
By encircling, cross-hatching, or word description on the product drawing. These areas require stricter defect tolerance due to functional importance.
⚡ Can inserts be retapped?
Yes, to clean threads or remove flash, unless threads contain locking features. Inserts must not be damaged or coated with molding material that impairs function.
📌 Are ripple surface and shrink-marks always acceptable?
They are generally acceptable unless otherwise specified in the product drawing or contract. They are common in certain materials like long glass-fiber-filled plastics.