What Is Hot Melt Copper Nuts? | MachineMFG

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What Is Hot Melt Copper Nuts?


What is a hot melt copper nut? What are its advantages and applications?

Hot Melt Copper Nuts

Copper nuts can be embedded into plastic components through various methods such as mold pre-burial, hot pressing, ultrasonic insertion, and cold pressing. Among these, hot melt embedding is the most common and typical method, usually conducted using a hot melt machine or a manual soldering iron.

Hot Melt Copper Nuts

Hot Melt Copper Nut Process

The process involves heating the copper nut to a specific temperature to soften the plastic, then pressing it in. This method generates minimal internal stress and provides excellent torsional and pull-out strength for the nut.

Hot Melt Copper Nut Process

Hot Melt Nut Machine Welding Principle

Utilizing the principle of electric heat melting, the hot melt nut machine accurately controls temperature changes, combined with mechanical devices, to achieve product welding. This is particularly suitable for products that are difficult to weld, irregularly shaped, or large. Applications include plastic welding, nut embedding, riveting, and more.

Hot Melt Nut Machine Welding Process

  1. Vibratory Feeding Section:
    Operators only need to load the required number of copper nuts into the vibratory feeder each shift. The system automatically arranges the unordered parts in an orderly fashion. The maximum feeding speed is 200 pieces/minute.
  2. Heating and Feeding:
    The copper nuts from the vibratory feeder slide into a high-temperature tube (with adjustable temperature), enter the heating zone for preheating, and then are sent to the machine head for insertion.
  3. Embedding:
    The preheated copper nuts are pressed into the plastic case from the machine head. The insertion temperature is adjustable, and a limit device is added.
  4. Movement:
    Precision positioning is achieved through programmed control of the X, Y, and Z axes.

Selection of Plastic Holes and Nuts

  • D: Nut outer diameter
  • L: Nut length
  • d: Nut base diameter
  • C: Plastic hole diameter
  • W: Plastic hole wall thickness
  • Y: Plastic hole depth
  1. The d dimension represents the nut base, also known as the guiding and positioning part, which matches with the plastic C part before embedding. Therefore, the nut’s base end d should be smaller than the plastic BOSS inner hole diameter C for easy positioning.
  2. The D dimension is the nut’s outer diameter, which matches the plastic BOSS inner hole diameter C. Generally, the plastic inner hole diameter is about 0.25-0.3mm smaller than the nut’s outer diameter.
  3. The L dimension is the nut’s length, which matches the plastic BOSS hole depth Y. Typically, the plastic hole depth is 0.5-1.0mm greater than the nut’s height (length) to accommodate excess plastic.
  4. W is the plastic hole wall thickness. Generally, the plastic BOSS hole thickness is 0.8-1.0mm or more, and the larger the nut size, the thicker the wall.

Advantages and Applications of Hot Melt Copper Nuts


  1. Ease of assembly and disassembly.
  2. Provides high pull and torque strength.
  3. Reusable threads with high locking force.
  4. Reduces assembly operation skills, ensuring reliable fastening.
  5. Minimizes required length space.
  6. Simplifies hole design, etc.
  7. Applicable under certain high-temperature conditions.


Hot melt copper nuts are widely used in various industries, including electronics, hardware, plastics, lighting, toys, bathrooms, furniture, medical, sports equipment, and more. Examples include plastic casings for laptops, GPS devices, routers, mobile phones, wireless communication devices, home appliances, automotive parts, valves, electrical switches, and others.

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