General Design Practice

Correct Assemblies
How They Work
Boss Diameters & Wall Thickness
Expansion Insert Installation
Expansion Insert Tooling
Expansion Insert Floor Thickness
Hole Depth - All Inserts
Hole Diameters - All Inserts
Insert Removal
Molding
Self Threading Insert Tooling
Rotational Torque & Tensile Strength
Ultrasonic And Thermal Installation

Correct Assemblies

When designing clearance diameters of component parts it is extremely important to assure that the insert and not the plastic carries the load. The correct assembly pictured is referred to as a "clamping" condition and the incorrect assembly is referred to as a "jack-out" condition.

Below are suggested maximum torque values for brass and low carbon steel screws.

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How They Work

Dodge® Inserts can be installed using ultrasonic equipment (moderate to high production) or thermal installation equipment (prototype work and low quantity production). Thermal equipment can be as simple as a soldering iron held by hand or mounted in an arbor or drill press. More refined equipment is available with adjustments and settings for precise, uniform installations.

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Boss Diameters & Wall Thickness

To obtain the maximum assembly strength, the wall thickness (see illustration) should be .5 to 1.0 times the insert outside diameter. If the insert application is in a circular boss, the boss diameter should be 2 to 3 times the insert diameter. Thinner walls and bosses may be used, however this may affect the assembly strength. This applies to all types of inserts.

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Expansion Insert Installation

Expansion inserts must be expanded by depressing the spreader plate prior to insertion of the screw. The screw will not expand the insert and lock it in place.

The Expansion Insert Tooling shown in this catalog provides an economical and efficient means of installing the inserts.

The Dodge Hand Tool works best in thermoset materials. Since the receiving hole diameter is .002 larger than the insert diameter, the insert drops freely into the hole and is ready to be expanded using this tool.

The Standard Model is best for thermoplastic materials. Since the receiving hole diameter is .003 smaller than the insert diameter, there is interference and the insert must be pressed to the bottom of the hole prior to expanding it. The shoulder on the tool installs the insert. Once it has bottomed, tension on an internal spring is overcome and the punch depresses the spreader plate permanently anchoring the insert in the hole.

DO NOT push the spreader plate too deep. This will reduce the holding strength of the insert.

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Semi-Automatic Model

May be used to install Dodge Standard and Flange Inserts. The tool consists essentially of a punch and spring loaded sleeve. It must be chucked in an arbor or foot press. It is not designed to be driven by a hammer.

Basic part number is 79005 for inch and 79027 for metric.

Hand Tool

May be used to install Dodge Standard and Flange Inserts. The tool may be used with hammer or chuck in an arbor sleeve. It must be chucked in an arbor press or foot press.

Basic part number is 79015 for inch and 79017 for metric.

Clinch Insert Model

Designed to install and crimp Dodge Clinch Inserts. The tool consists of a punch and a spring-loaded sleeve with a radius section which crimps the eyelet portion of the insert over the mating component. It must be chucked in an arbor press or foot press.

Basic part number is 79035 for inch and 79047 for metric.

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Expansion Insert Floor Thickness

Since the force required to install and expand Standard Expansion Inserts must be absorbed by the floor of the hole it should be flat and be at least 1/2 of the insert length (Dimension "L").

The force required to install and expand Flange and Clinch Inserts is absorbed by the flange of the insert and the work surface so floor thickness for these inserts can be minimized. DO NOT use through holes for these inserts - the spreader plate may fall out and will result in significantly lower holding strength.

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Hole Depth - All Inserts

Minimum hole depth for Ultraserts is equal to the insert length plus .030". Hole depth for Self Threading inserts is listed in the catalog.

Hole depth for Standard Expansion Inserts should be equal to the insert. Hole depth for Flange and Clinch Inserts is equal to the insert length if the flange is to be recessed. If the flange is not recessed, hole depth is equal to the insert length minus .030" (flange thickness).

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Hole Diameters - All Inserts

Hole sizes for Ultraserts and Self Threading Inserts are listed in the catalog. Expansion insert hole sizes vary with the material being used:

Thermoset Plastic - Insert body diameter "A" +.002" 
Thermoplastic - Insert body diameter "A" -.003" 
Foam Thermoplastic - Insert body diameter "A" -.006" 

The tolerance for the hole diameter is ±.001

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Insert Removal

If plastic parts must be recycled because of warping, discoloration or any other reason, removal of metal components in the plastic can be a major problem. Dodge has developed an inexpensive method for removing inserts using a standard soldering iron modified with a partially threaded tip. The special tip configuration engages the insert and rapidly transfers heat which melts the plastic, allowing quick and easy removal of the insert. Contact our Applications Engineering Department for a copy of the drawing of the extraction tips to be used with your standard soldering iron.

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Molding

A heavy wall section or tall bosses may cause undesirable sink marks on a surface. "Stepped" holes may be used to minimize this condition. The table below shows the maximum diameter of the "step" for Expansion Inserts. For Ultraserts I and II the maximum diameter of the "step" is Dimension "H" in the catalog - For Ultrasert IV the maximum diameter of the step is the dimension "B" shown in the catalog.

Expansion Inserts
Insert Size           Max. Step Hole Dia.
4-40                     .080
5-40                     .100
6-32                     .100
8-32                     .100
10-24                   .120
10-32                   .120
1/4-20                  .145

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Self Threading Installation Tools

Inch            Standard        Hand        Extension
2-56             5301-02           5311-02     5301-02-15
4-40             5301-04           5311-04     5301-04-15
6-32             5301-06           5311-06     5301-06-15
8-32             5301-2             5311-2       5301-2-15
10-24           5301-3             5311-3       5301-3-15
10-32           5302-3             5312-3       5302-3-15
1/4-20          5301-4             5311-4       5301-4-15
1/4-28          5302-4             5312-4       5302-4-15

Metric          Standard        Hand         Extension
M2x0.4         5370-2             5380-2        5370-2-15
M2.2x0.45    5370-2.2           5380-2.2     5370-2.2-15
M2.5x0.45    5370-2.5           5380-2.5     5370-2.5-15
M3x0.5         5370-3             5380-3        5370-3-15
M3.5x0.6      5370-3.5          5380-3.5     5370-3.5-15
M4x0.7         5370-4             5380-4        5370-4-15
M5x0.8         5370-5             5380-5        5370-5-15
M6x1            5370-6             5380-6        5370-6-15

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Rotational Torque & Tensile Strength

Rotational Torque - Rotational force required to turn the insert in the parent material. It is a good comparative measure of overall strength of assembly.

Tensile Strength - Axial force (in Pounds) required to pull the insert out of the material at least .020.

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Ultrasonic Installation

Ultrasonic installation is recommended for all but the largest insert sizes. Ultrasonic installation generally results in very consistent, stress free assemblies with very short cycle times. In ultrasonic insertion the metal insert is designed to partially enter (pilot) into a cored or drilled hole in the thermoplastic part. The vibrating ultrasonic horn contacts the insert causing the vibration to travel through the interface of the metal insert and the plastic part. Heat generated as a result of the vibration causes the plastic to effectively mold itself to the knurls and undercuts of the insert permanently locking the insert in place.

Thermal Installation

Inserts may be installed into thermoplastic materials using various sources of electrically generated energy to heat the insert above melting point of the thermoplastic part. Inserts may be preheated then pressed into the plastic part or the insert may be piloted into a cored or drilled hole in the plastic part then heated by conduction. Heated insert installation provides a stress free assembly and is recommended for very large insert sizes or when the required fixturing or noise levels associated with ultrasonic installation are prohibitive.

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