PT Type DG
The PT Type DG is a direct screw fastener for use in light alloys.
The design incorporates many unique features which provide designers with a really effective direct screw fixing for these materials.
The profiled thread root gives low installation torque whilst the special thread form provides high stripping torque.
Advantages
- Thread forming - No debris
- Reliable & easy installation into punched, drilled, extruded & moulded holes
- Reusability of screw
Design Features
Special Profiled Root
The PT Type Screw is shaped to allow material flow, aiding in smooth formation and reduced stress.
- Reduces stress
- Allows material to flow during thread forming
- Reduces installation torque
- Increases pull-out load
Special Shaped Tooth
It provides low installation torque in light alloys while maintaining high stripping torque for reliability.
- Reduces radial stress
- Maximum surface bearing area
- High stripping torque
- High clamping force
- High back-off torque
PT Type DG Design Guide
Soft materials = ≤ 50 vpn
Medium soft materials = 51 to 75 vpn
Hard materials = 76 to 100 vpn
For specific application advice, contact PSM.
Hole & Boss Dimensions
- Use a slight taper (~1° inclusive) in the hole for smooth insertion.
- Optimize hole diameter at the mid-penetration point for effective thread forming.
- Minimum boss diameter is generally about 2.5 × d (nominal thread diameter).
- Recommended screw penetration ranges between 1.5 × d and 2.5 × d depending on material hardness.
Material & Load Factors
- For soft alloy castings or thin walls, ensure the boss and surrounding geometry can withstand stresses during installation.
- In plastic regions, include ribs or reinforcements to prevent deformation.
Installation & Torque Control
- Drive the screw gradually to allow proper thread forming without jamming.
- Avoid over-torquing to prevent stripping or cracking.
- Use torque-controlled drivers at recommended speeds to reduce heating or damage.
Hybrid Assembly Tips
- For plastic-metal assemblies, sequence screw insertion to suit structural needs.
- Validate that forming in one material doesn’t compromise performance in the other.
PT Type DG Dimensions
How to Specify
Applications & Advantages
PT Type DG is ideal for hybrid assemblies such as lighting housings, enclosures with metal frames and plastic covers, and brackets attached to die castings. Its advantages include:
- Unified fastening solution across metal and plastic
- Simplified inventory and assembly
- Strong thread performance in light alloy
- Resistance to vibration and relaxation
- Reduction in part count and assembly errors
Enhance Your Assembly with Our Precision PT Type DG Screws
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