Inserts for Plastics

Threaded Inserts for Plastics provide reusable threads and secure tight threaded joints. An additional benefit is high load carrying capability. The objective is to design an Insert with sufficient torque resistance to accommodate the tightening torque necessary to achieve sufficient axial tension load on the threaded joint to keep it together and prevent loosening, while also achieving pull-out values necessary for the load conditions that the Insert will be exposed to while in service.

SPIROL’s Inserts are designed to maximize and balance rotational torque and tensile (pull-out) performance. We provide complimentary Application Engineering support to help you design in the most appropriate Insert for your plastic assembly.

SPIROL offers a variety of Threaded Inserts for Plastics to meet your performance and installation requirements including heat/ultrasonic, molded-in, press-in and self-tapping Inserts in standard thread sizes ranging from M2 (2-56) to M8 (5/16-18) – depending on Insert type.

SPIROL also designs and manufactures a standard line of Insert Installation Equipment, from manual to automatic modules. Learn more about SPIROL’s Insert Installation Equipment, or contact us for support in determining the best insert for your plastic assembly.

heat / ultrasonic inserts
Heat / Ultrasonic Inserts
Heat/Ultrasonic Inserts are designed for post-mold installation in thermoplastics. Heat and ultrasonic installation yield outstanding performance results. SPIROL offers several different series of Heat/Ultrasonic Inserts available in long and short variations, long for maximum torque and pull-out resistance; short for less stringent requirements with the benefits of lower cost and reduced installation time. SPIROL’s standard Heat/Ultrasonic Inserts includes the following series:

• Series 19 and Series 20 Flanged (Straight Hole): These Inserts have a slightly tapered body designed for use in straight holes to yield excellent performance with low radial stress. Seating and installation are facilitated with a pilot and a tapered knurl and groove design. The Series 20 has the same body style as the Series 19 Short with the addition of a head to provide more bearing surface for the mating component to prevent jack-out.

Series 29 Symmetrical and Series 30 Flanged (Straight Hole): These Inserts are designed with a wide center knurl coupled with two smaller knurls and deep undercuts on both ends to maximize torque and pull out performance. The Series 29 is symmetrical for ease of orientation, and the generous pilot facilitates installation into the hole. The Series 30 has the exact same body style as the Series 29 - with the addition of a head for more bearing surface for the mating component to prevent jack-out.

Series 14 (Tapered Hole): These Inserts are designed for use in tapered holes. The tapered hole facilitates proper seating and maximizes the surface contact between the Insert and hole wall prior to the application of heat or ultrasonic vibration.

SPIROL’s Heat / Ultrasonic Inserts are available in thread sizes ranging from M2 (2-56) up to M8 (5/16-18).

self-tapping inserts
Self-Tapping Inserts
Self-Tapping Inserts provide the best pull-out resistance for a post-mold installed Insert, yet generally cost more than their post-mold counterparts. The external threads are designed with a thin profile to minimize induced stress in the plastic and have a relative coarse pitch to provide the maximum plastic shear surface to resist pull-out.

SPIROL’s Series 10 Self-Tapping Insert is a thread-forming Insert for soft, flexible thermoplastics and is available in thread sizes ranging from M3 (4-40) up to M6 (1/4-20).

press in inserts
Press-In Inserts
Press-In Inserts are designed to be pressed into a plastic hole without melting the plastic prior to installation. They offer rapid installation with no specialized equipment and achieve good overall joint performance. The Series 50 is symmetrical with a generous pilot. Series 51 is the headed version which is also suitable for pull-through applications where high pull-out force is a requirement.

SPIROL’s Series 50 and Series 51 Press-In Inserts are available in thread sizes ranging from M2 (2-56) up to M8 (5/16-18).

molded-in inserts
Molded-In Inserts
Molded-In Inserts are designed for maximum pull-out and torque performance, and are often the Insert of choice for thermosets and engineered plastics with a high percentage of filler. The minor thread diameter tolerance is controlled to ensure positive positioning and perpendicularity of the Insert on the core pin during the molding process. Series 63 is symmetrical eliminating orientation and Series 65 is the same body style in a blind ended version. These Inserts are made from 2024 aluminum, a light-weight, lead-free grade.

SPIROL’s Series 63 and Series 65 Molded-In Inserts are available in thread sizes ranging from M4 (8-32) up to M8 (5/16-18).

Additional Information

Read How to Maintain Joint Integrity When Converting from Metal to Plastic and other White Papers on Threaded Inserts for Plastics.

Review our Application Stories for how SPIROL Engineers and Products have helped provide quality and cost saving solutions for fastening and joining problems.

SPIROL designs and builds a variety of Threaded Insert Installation Equipment with fixtures for your post mold Inserts for Plastic applications.

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    SPIROL offers complimentary Application Engineering support. We will assist on new designs as well as help resolve issues, and recommend cost savings on existing designs.