1. Plastic Overview

The two main categories of plastics where threaded inserts

are used:

a. Thermoset Plastics

Thermoset plastics cannot be re-melted using heat or pressure

once they are formed into their desired shape, These plastics tend

to be hard and brittle. Since they will not re-melt, inserts installed

by heat or ultrasonic can’t be used in these materials.

Recommended insert types include:

» Self-Threading » Expansion » Press-In designs

Thermoset Types

» Phenolic » Epoxies » Vulcanized rubber » Polyamide

b. Thermoplastics

Thermoplastic materials can be re-melted and re-formed once

formed into their desired shape.

Heat and Ultrasonically installed inserts perform best in

thermoplastic types of materials however Self-Threading, Expansion

and Press-in style inserts may also be utilized in these materials.

Thermoplastics Types

» ABS » PVC » Polycarbonate » Nylon

Fills (Additives)

Thermoplastic materials may be unfilled or may have a wide variety

of fillers added to them to increase the stiffness or toughness

properties of the material for specific applications. These fillers

may include nylon or carbon fiber, mineral or even metal.

2. Insert Characteristics

Dodge Inserts for Plastics are designed to provide the strength necessary

to allow bolts and screws to be tightened to the levels required to stretch

the fastener and maintain a sufficient bolted joint assembly.

The insert must also provide resistance to rotation and pull-out under

a wide variety of load and atmospheric conditions in a given assembly.

The optimum insert design depends on several factors including:

» Plastic resin

» Type and percentage of fill

» Preferred insert installation method

» Application strength requirements

» Environmental concerns

3. Material And Plating


Dodge inserts are traditionally made from 360 brass which falls

under the designation UNS C36000 ½ hard free-cutting brass.

The CDA specification is C360, ½ hard per ASTM B-16.

Dodge inserts are also available in alternate materials including

Steel and Aluminum. Contact Applications Engineering for further



Inserts and Compression

Limiters may be processed with

a variety of finishes from nickel

plates and automotive finishes

to colored dyes to distinguish

insert types or installations.

Please consult our Applications Engineering team for assistance with

your requirements.

a. Undercuts

To accommodate the best overall balance of rotational and pull-out

strength of an insert, the knurl bands are combined with undercuts,

fins or a combination of both.

b. Knurl Patterns

The most common design methods used to increase rotational

strength of an insert include increasing body diameter or increasing or

changing the knurl pattern on a given insert design. The rotational

resistance of an insert design can change dramatically by altering

the coarseness or fineness of a knurl.

Coarser knurl patterns can provide a significant increase in rotational

strength but can also induce significant stress into the insert/plastic

assembly which could ultimately lead to cracking and premature failure.

Straight Knurls

Effective in applications focused on high rotational strength.

» Multiple Knurls

It is common practice to utilize more than one knurl style

and direction on the same part to reach the most optimum

combination of rotational and torque resistance.

c. Tapers

To eliminate installation issues, many inserts are designed to

be installed into a tapered hole. This allows for the insert to

“self-align” during installation and requires less heat energy

as the mass of plastic resin that is required to melt is less than

with other hole designs. A tapered insert must always be

used in a tapered hole.

d. Flanges

In certain applications, it is advantageous to have a large

bearing surface to distribute the load applied when fastening

mating parts. A large flange not only increases the bearing

surface but also allows for adjustment of the mating part

without a negative effect on insert strength.

e. Custom Capabilities

Dodge Threaded Inserts can also be custom designed for specific

applications. Examples include undercut configurations, closed ends,

platings, flange modifications, etc. Contact your Sales Engineer

or Applications Engineering at (866) 364-2781 for assistance.

5. Best Practices

a. Hole Preparation Considerations

Each Style of insert listed throughout the catalogue

Straight vs. Tapered Holes - Straight hole preparation

allows for a taper that should not exceed a 1 degree included

angle. Tapered holes require an 8 degree included angle.

Tapering permits easy release of the core pin, aids in insert

alignment, which in turn reduces installation time.

» Counterbores – Traditionally are not

recommended as they may interfere with

proper insert alignment. Self threading

inserts, or flanged inserts which should be

installed flush, are the exception to the rule.

» Recommended Hole Depth - Allows for proper insert

set down (flush to 0.005 inch below the surface), prevents

excessive flash, and prevents back filling of plastic from

entering bottom threads.

» Flanges

In some applications, a large flange insert is installed from

the opposite end of the part and when the screw or bolt is

assembled, the tensile load is applied to the flange, increasing

resistance to pull-out.

b. Boss Diameter/Wall Recommendations

Traditionally a boss diameter is two times the insert diameter for

inserts ¼” and under, 3mm wall thickness applies for all inserts

that are larger. Exceptions include applications incorporating

supported bosses, reinforced materials, and heat installation.

Special consideration should be given to cold press installations

where stress will be increased and will require larger boss diameters.

c. Assembly Guidelines For Mating Parts

Clearance Holes – It is important that the insert bear the load and

not the plastic to avoid jacking the insert out. The mating component hole

should be smaller than the face of the insert yet allow the connecting

threaded fastener ample space to function normally.

Strength – The head of the bolt being used in the assembly

must seat against the compression limiter to avoid potential

failure due to plastic creep.

Mating Components – The mating component must also

withstand the stress generated by the clamping force. In

instances where the mating component will also be plastic,

the use of a secondary insert should be considered.

Types of Applications


» Insert is equal to or larger than the flange

» Provides higher axial strength

» Failure mode is the bolt


» Insert is smaller than the flange

» Has simple OD configuration

» Applies to smaller inserts under ½” OD

a. Heat Installation

Heat installation involves positioning the insert into the molded or

drilled hole. A heated tip is then inserted into the inside diameter of

the threaded insert.

Localized melting begins to take place and with the downward

pressure, the insert begins to install. Plastic flows into the varying

undercuts and knurls.

Benefits of thermal installation include:

» installation of multiple inserts at a given time

» ability to install inserts beyond ¼”

» superior strength assemblies

b. Ultrasonic Installation

Ultrasonic Installation involves positioning the insert into a molded

or drilled hole.

An ultrasonic horn then contacts the insert and begins to vibrate

the insert. This vibration creates frictional heat which melts

the plastic allowing the horn to lower the insert into position.

Once installed to the appropriate depth, the cycle is repeated for

the next insert.

c. Self -Tapping/Self Threading, Spred-Lok,

Expansion Inserts and Mold-In

Designed for ease of installation. Primarily involves preparing straight

holes and driving the insert into place, pressing the insert into place,

or pressing and then expanding the insert into place. Minimal tooling

is required.

c1. Self Tapping

Economical and easy to install. Provides excellent pull out

resistance. Insert design features a cutting edge slot which

assists in installation.

Dodge Inserts are designed for post mold and molded-in installations.

Post molding is cost effective in that it generally shortens cycle time

of the molding process, reduces rejects and damage from inserts

that could potentially come loose and damage the mold.

Molded-In inserts offer higher torque and pull-out resistance.

Several Dodge insert designs are available for Post-Molding

using Ultrasonic installation or Heat installation.

c2. Spred-Lok Inserts

Economical and easy to install. Designed for non-critical applications.

Insert is pressed into a straight prepared hole, expansion of the insert

is accomplished through the installation of the mating fastener. Mating

bolt should be long enough to extend at least two full threads beyond

the insert length to ensure insert retention.

c3. Expansion Inserts

» Standard Expansion

Economical and easy to install. Expansion inserts feature

a two piece design consisting of a threaded insert and a

captivated spreader plate. The insert is installed into a

blind, straight hole and the spreader plate is then depressed.

As the spreader plate is engaged, the knurled portion of the

insert expands, anchoring the insert into place.

» Clinch Expansion

Clinch inserts feature a pilot and a flange and have the same

design characteristics as Standard Expansion Inserts. The

inserts are used extensively in the electrical industry.

The pilot can be clinched over a terminal connector with

the flange providing a large surface for electrical contact.

The installation and clinching operations are simultaneous

using a simple press-in type tool. Like the Flange Insert, much

of the installation force is absorbed by the flange allowing for

use in thin-section applications.

» Flange Expansion

The Flange Insert, in addition to having all of the design

features of the Standard Insert, has a flange with a large

bearing surface. The flange can be used to make an

electrical contact or to fasten a terminal connector. The flange

can also be used to join mating parts by inserting the body of

the insert through the mating part and into the receiving hole

in the parent material. The insert is excellent for use in thin

section applications since the flange absorbs much of the

installation force.

c4. Mold In Inserts

While the trend is to install inserts into Thermoplastics by post

mold, some highly filled plastics (above 35% fill) will benefit from

a mold-in insert design. The Dodge Ultramold insert is a unique

two-piece insert providing full thread to the bottom of the insert.

This design also features a controlled minor diameter and

innovative counterbore design to insure proper placement on

molding pins. This insert design provides optimum strength

in a space saving design.

» Ultra-Mold® Inserts

The unique two-piece concept allows full and complete threads

throughout the entire length of the insert. This saves space

and weight and reduces costs. Below is an image of a conventional

insert (on left) and the unique design of the Ultra-Mold (at right).

c5. Sealing Inserts

When an insert is heat or ultrasonically installed into a plastic

component, the difference in cooling rates of the metal and plastic

create a “stress relief zone” or microscopic void between the insert

external geometry and the plastic. While this is beneficial in reducing

the stress between the two materials, it can pose challenges to those

applications requiring a leak-proof interface between the insert and

the plastic.

Dodge has addressed this situation with the Ultraseal® insert. The

Ultraseal utilizes an O-ring as an integral component of the insert design.

When heat installed into the proper geometry hole, the O-ring seals

against the plastic and provides a leak-proof assembly.


» ISO/TS 16949: 2009 certified

» Lot control ensures product traceability

» Statistically controlled manufacturing processes

» PPAP, IMDS, Material Certifications

Sales & Applications Engineers

» Strategically located throughout North America

» Offer expertise in insert design, applications

engineering and current assembly technologies

» Offer cost effective fastening solutions; includes:

– Modifications to our standard products

– Custom solutions for your specific applications

– Conduct Line Walks, Value Analysis / Value Engineering

Product Development

» Our Technical Center offers review of your application,

product evaluation, analysis and recommendations to

help reduce your assembly costs

» Development support includes conceptual ideas,

preliminary designs and drawings

» Engineering prototypes and pre-production sampling

resources available

Technical Product Seminars

» Lunch and Learn Seminars offered to engineering,

manufacturing, purchasing and quality teams

» Instructors include representatives from our sales

engineering, applications engineering and/or

marketing teams

At STANLEY Engineered Fastening we believe in seeking ways to serve our customers better. We create the future by anticipating our

customers needs. Through diversifying our product lines, creating unique assembly technologies and offering a breadth of service to meet the

demands of industry worldwide, STANLEY Engineered Fastening provides technological solutions to over 100 different industries.


Avdel® has been producing assembly

systems since 1936 and offers a

comprehensive range of fasteners

and tooling.


With a focus on high-quality threaded

inserts for plastics products, Dodge has

been a leader in the fastening market

since the 1950s.


Gripco® has been providing quality nut and

threaded assembled products since 1904.


Based on a long history that began in

the aerospace industry, Heli-Coil offers a

vast range of high-quality.


iForm® continues a proud heritage since

1969 and represents over 40 years of

creative threaded fastener application



From 2mm micro rivets to 1/4"structural

rivets, POP blind rivets meet the needs of

multiple markets.

STANLEY Assembly


STANLEY Assembly Technologies supplies

production solutions to the global

assembly market.


Spiralock is a technologically superior

fastening system ideally suited for

threaded joint applications subjected to

heavy shock and vibration.


A one-sided drawn-arc welding process

is the foundation of the Tucker No-Hole

assembly solution.


Whether it's plastic, metal, or a

combination of the two, Warren can

design a product that will suit your