How to Select Light, Medium, or Heavy Load Parting Lock Sets for Side Mounting
Understanding Load Ratings
`nSide mounting parting locks are used in injection molds to control the opening sequence from the mold exterior. Their load rating is governed by internal spring design conforming to standard mold construction practices.
Side mounting parting locks are available in three load configurations, each designed for a specific range of mold sizes and plate weights:
| Load Rating | Holding Force per Lock | Body Width | Typical Mold Size | Plate Weight Range |
|---|---|---|---|---|
| Light | 200-500 N | 30 mm | �?00 mm width | <50 kg per side |
| Medium | 500-1,500 N | 46 mm | 300-600 mm | 50-200 kg per side |
| Heavy | 1,500-3,000 N | 60 mm | >600 mm | >200 kg per side |
The load rating is determined by the internal spring configuration �?heavier springs produce greater holding force but require greater machine opening force to release the lock.
How to Calculate Required Load Rating
Follow this calculation to determine the minimum load rating:
- Step 1: Determine the plate weight on the heavier side of the parting surface (in kg).
- Step 2: Convert to force: Weight (N) = Mass (kg) × 9.81 m/s².
- Step 3: Apply a 2× safety factor for dynamic loads during mold opening.
- Step 4: Divide by the number of locks per parting line (minimum 2).
- Step 5: Each lock's rated holding force must exceed this value.
Example: 100 kg plate × 9.81 × 2.0 safety factor = 1,962 N total. With 4 locks: 1,962 ÷ 4 = 490 N per lock �?Medium load rating (500-1,500 N) is sufficient.
Compact (46 mm Width) Option
The compact 46 mm wide variant provides medium-range holding force in a narrower body. This is useful when:
- Mold side clearance in the press is limited (common in small-tonnage presses).
- Multiple locks are needed per side but total width is constrained.
- The mold runs on multiple presses with different platen widths.
PLOC: Bidirectional Control Variant
The PLOC (mold opening/closing control) variant provides bidirectional control �?it can both hold plates together (like a standard lock) and actively pull them apart during opening. This eliminates the need for separate puller bolts on molds where side access is available:
- During closing: Cam engages, holding plates at the parting surface.
- During opening: Internal mechanism reverses, creating active pull-apart force.
PLOC locks are ideal for molds with adhesion-prone resins (TPE, silicone) where plates resist separation despite lock release.
Mounting Considerations
- Position: Mount on the operator side and non-operator side of the mold, symmetrically. Never mount on top or bottom only �?gravity creates asymmetric loading.
- Clearance: Verify that the lock body does not interfere with the press platen, tie bars, or safety guarding.
- Surface preparation: Machine flat mounting pads on the mold exterior if the cast surface is not sufficiently flat.
- Bolt torque: Follow manufacturer-specified torque to prevent mounting bolt loosening under vibration. Use thread-locking compound.