Plastic fasteners are valued for their lightweight, low cost, and ease of use. They can be made from a variety of materials including polyolefins such as polyethylene, polypropylene or ethylene-vinyl acetate copolymer. In addition to PE-based products, PP-based products are also available on the market today. The most common types of plastic fasteners used for joining two surfaces together are those that have an interlocking design with male/female components. These designs generally involve mating threads formed at one end of each component which allow them to be joined by rotating the parts relative to each other until they become locked into place.
Plastic fastening systems may be classified according to several criteria:
- Type of material: Polymers, composites
- Shape: Round, square, rectangular, oval, triangular, etc.
- Threads: Single thread, double thread, multiple threads, self-locking, non-self locking, bi-directional, uni-directional, spiral, helical, etc.
- Insertion method: Push-fit, friction fit, interference fit, snap lock, etc.
- Surface treatment: Coated, plated, electroplating, hot dip coating, flame spraying, laser welding, plasma arc welding, adhesive bonding, solvent bonding, ultrasonic welding, etc.
- Manufacturing process: Molding, extrusion, injection molding, blow molding, thermoforming, compression molding, stamping, machining, cutting, punching, shearing, rolling, slitting, etc.
- Applications: Industrial applications, consumer goods and medical devices.
Types of Fasteners
Ball head: A ball head is a type of female connector having a spherical tip designed to mate with a corresponding male connector. It has been widely adopted in many industries due to its simplicity of operation and high reliability. They are commonly found in electrical connectors, plumbing fixtures, furniture assembly, appliance manufacture, tool handles, machine tools, and various industrial equipment.
Buttress head: A buttress head is a type of male connector having a pointed nose designed to mate with a correspondingly shaped socketed female connector. This style of connection allows greater surface area contact between the male and female connectors than do conventional round heads. Buttresses are typically used where there is limited space around the joint being connected.
Conventional screw: Screws are threaded connections used to join two objects using metal screws. Threaded joints are usually stronger than equivalent glue bonds but require more time and effort to assemble.
Female quick connect / disconnect: Quick connects are often referred to simply as “quick” because their female counterparts are so easy to install. Male quick connects are sometimes called “male quick”. Both terms refer to a device that uses a simple push-button mechanism to engage and disengage its counterpart quickly without requiring any special skills or tools. The term “disconnect” refers specifically to a device that can only be engaged when both halves are fully inserted; once the halves are completely separated, the unit becomes disconnected. Some examples of this kind of product would be water faucets, showerheads, toilets, urinals, and bidet seats.
Male quick connect / disconnect: Similar to female quick connects, these products use a simple push-button mechanism for engaging and disengaging them quickly. However, unlike most female quick connects, some male quick-connects also provide a means of preventing accidental separation while still allowing full insertion. Examples of this kind of product include toilet plungers and hand dryer attachments.
Hook & loop: Hook & loops are resiliently attached strips of fabric coated on one side with a pressure-sensitive adhesive. When pressed against each other, the hook portion will adhere to itself via the adhesive strip. In addition to joining clothing items such as shirts and pants, hooks & loops are frequently used to attach luggage tags and name badges to articles of apparel.
Lever action: Lever action connectors feature a lever arm mounted inside a housing. As the lever is rotated clockwise, the lever arm moves up towards the top of the housing causing the pin to move down through the hole. Conversely, counterclockwise rotation causes the pin to rise out of the bottom of the housing.
Magnetic: Magnetic connectors utilize magnetic forces to hold two surfaces securely together. The strength of the attraction varies depending upon how close they are held together. They have been used in many applications including aircraft maintenance kits, automotive parts, medical devices, toys, and security systems.
Mechanical interlock: Mechanical interlocks are similar to mechanical locks except that instead of locking by physically blocking access to an object, they lock by mechanically interfering with the movement of components within the system. For example, if you were trying to open your refrigerator door from the outside, the latch could prevent the door from opening until the latch was released.
Nylon thread: Nylons are polyamides made from polymerized fatty acids and diamines. These materials are strong and durable yet flexible enough to withstand repeated stretching and shrinking cycles. Nylons are commonly used in sewing threads, fishing line, rope, twine, shoelaces, electrical cord insulation, dental floss, surgical sutures, and bicycle spokes.
Permanent magnet: Permanent magnets are small pieces of ferromagnetic material that contain no internal electric current. Their attractive force depends solely on the size of the piece of permanent magnet relative to its distance from another like-polarity permanent magnet. If the distance between the magnets is less than about 1/4 inch then the resulting force may be sufficient to lift heavy loads. Because of their high mass density, they are useful for holding things together. The use of permanent magnets has become more common since the introduction of neodymium into industrial-grade magnets. Neodymium magnets are stronger than those containing iron or cobalt alone because it contains much higher concentrations of these elements. This allows them to produce greater amounts of energy per unit of volume.
Plastic snap fastener: Plastic snaps consist of a thin metal spring connected at both ends to a plastic body. A plastic tab can be inserted over the free end of the spring so that when the tab is pulled back, the spring opens and closes repeatedly. They are typically found on disposable diapers and children’s clothes where they allow easy removal without damaging garments.
Slide fastener: Slide fasteners are a type of zipper consisting of rows of teeth formed along opposing edges of mating fabrics. By sliding the row of teeth past each other, the zippers can be opened and closed. There are several different types of slide fasteners:
Velcro® hook and loop tape: Velcro® is manufactured under license from 3M Company, who originally developed the product in 1948. Invented by George de Mestral while working for Swiss textile company Novartis AG, he filed his patent application in Switzerland on September 23rd, 1949. He named the new invention velcro after the French verb croire. His initial idea was to create a fabric fastening device using hooks and loops, but early prototypes did not work reliably. De Mestral refined the concept and patented the method of attaching the hooks and loops in 1953. Today there are many different forms of velcro including specialized versions for medical applications, clothing, footwear, furniture, household goods, toys, sports equipment, and even cars.
Zippers: Zippers are one of the most common ways to close an item. They come in many different styles including button zips, slide zips, snap zips, hook and loop closures, etc. Zipper technology has advanced dramatically since the introduction of the zipper. Today’s modern zippers are much stronger than their older counterparts. In fact, today’s zippers are often rated with higher breaking strengths than other closure systems, allowing them to withstand greater forces without failure. These new high-strength zippers may not always look exactly like the old style but they offer the same functionality.