Threaded Inserts for Telecom Equipment: Network Enclosures, Optical Systems and OEM Assembly

Threaded Inserts for Telecom Equipment: Network Enclosures, Optical Systems and OEM Assembly

Communication equipment manufacturing requires fastening solutions that support reliable assembly, dimensional stability, serviceability and long-term operation.

Telecom infrastructure, 5G radio equipment, network switches, routers, optical communication systems,

 industrial networking devices and data center equipment use a combination of engineered plastics, sheet-metal components, machined metal parts and electronic modules.

These assemblies have different fastening requirements.

A plastic network enclosure may require reusable metal threads for covers and internal brackets. 

An outdoor communication unit may need corrosion-resistant fastening components. A precision optical module may require controlled alignment.

 A sheet-metal telecom cabinet may be better served by self-clinching fasteners, cage nuts or blind rivet nuts.

Thread Insert Nuts for Communication Equipment, also known as Threaded Inserts for Plastics or Insert Nuts for Plastic Housings, 

provide a metallic internal thread within a suitably designed polymer component.

They can improve the durability of threaded interfaces and support repeatable assembly when the insert, surrounding plastic and mating components are correctly specified.

However, a threaded insert does not automatically prevent screw loosening, plastic creep, corrosion or mechanical failure.

For telecom OEMs and contract manufacturers, reliable fastening begins with the complete joint design, installation process and application-specific qualification.

Juxin Fasteners supplies industrial threaded inserts and custom fastening components for plastic and metal assemblies.

This guide explains how engineers, manufacturing teams and procurement specialists can evaluate threaded insert designs for communication equipment and prepare technical specifications for OEM sourcing.

Why Threaded Inserts Are Used in Communication Equipment

Telecommunication and networking products often combine lightweight polymer components with metallic brackets, printed circuit boards, connectors and serviceable electronic modules.

Threaded inserts can provide reusable internal threads in appropriate plastic structures.

Typical Engineering Requirements

• Durable threaded connections

• Repeatable screw assembly

• Serviceable equipment housings

• Defined internal thread geometry

• Resistance to insert rotation

• Resistance to axial pull-out

• Compatible installation processes

• Reliable performance under specified environmental conditions

Important Engineering Distinction

The metal insert provides the threaded interface.

The plastic boss transfers loads between the insert and the surrounding structure.

The mating screw and bracket determine how those loads enter the joint.

The complete assembly—not the insert alone—determines fastening reliability.

Telecom Applications: Where Threaded Inserts Are Appropriate

Network Switch and Router Housings

Network switches, routers, gateways and communication controllers may contain injection-molded plastic housings or plastic internal structures.

Potential threaded insert applications include:

• Removable housing covers

• Internal support brackets

• Serviceable electronic modules

• Selected connector support structures

• Auxiliary mounting components

Engineering Priorities

• Compact boss design

• Repeated assembly

• Thread engagement

• Installation depth

• Housing deformation

• Thermal exposure

• Assembly cost

5G and Wireless Communication Equipment

Wireless communication equipment may use plastic radomes, electronic housings and hybrid metal-plastic assemblies.

Selected plastic components may benefit from metallic threaded inserts.

Potential Applications

• Electronic control enclosures

• Plastic auxiliary covers

• Internal equipment brackets

• Serviceable modules

• Selected radome attachment features

Important RF Consideration

Metallic inserts are conductive components.

Their location near antennas or other RF-sensitive structures may affect electromagnetic performance.

A brass or stainless steel insert should not be described as improving signal transmission merely because it is metallic or conductive.

RF-sensitive fastening locations require validation by the equipment manufacturer.

Outdoor Telecom Equipment

Outdoor communication systems can experience:

• Humidity

• Rainwater exposure

• Temperature cycling

• UV exposure

• Salt-laden atmospheres

• Airborne contaminants

• Mechanical vibration

Threaded inserts may be used in suitable polymer enclosures and auxiliary components.

However, the environmental durability of the complete assembly depends on the polymer, insert material, screw, surface treatment, seals and enclosure design.

Fiber Optic and Optical Communication Equipment

Optical communication equipment may contain precision housings, connector supports, electronic modules and serviceable covers.

Potential applications include:

• Optical module support housings

• Internal electronic enclosures

• Fiber distribution equipment

• Connector mounting brackets

• Serviceable auxiliary components

Critical Distinction

A precision internal thread does not automatically establish optical alignment accuracy.

Optical positioning should be controlled by suitable datums, locating features, structural components and the equipment's tolerance stack-up.

The threaded fastener may provide clamping, but it should not be assumed to perform every locating function.

Data Center and Network Infrastructure

Data centers use diverse fastening systems.

Threaded inserts for plastics may be appropriate for:

• Plastic equipment covers

• Electronic module housings

• Cable-management accessories

• Selected cooling-system auxiliary enclosures

• Network appliance components

However, server racks and metal cabinets frequently require different fasteners.

For sheet-metal structures, alternatives may include:

• Self-clinching nuts

• Self-clinching studs

• Self-clinching standoffs

• Cage nuts

• Clip-on nuts

• Blind rivet nuts

• Weld nuts or weld studs

These products serve different installation and structural requirements.

A plastic threaded insert should not be presented as a universal replacement for sheet-metal fastening hardware.

Types of Threaded Inserts for Telecom Plastic Assemblies

Heat-Set Threaded Inserts

Heat-set inserts are installed into suitable thermoplastics using controlled thermal energy.

A heated tool transfers heat into the metallic insert.

The surrounding polymer softens and flows into the insert's knurls, grooves and undercuts.

After cooling, the plastic provides mechanical retention.

Potential Advantages

• Reusable metallic threads

• Compatibility with selected thermoplastics

• Controlled post-mold installation

• Potential for automated assembly

Engineering Considerations

• Polymer grade

• Insert geometry

• Hole diameter

• Boss dimensions

• Tool temperature

• Installation speed

• Applied force

• Final seating depth

• Cooling conditions

Typical Applications

• Router plastic housings

• Communication controller enclosures

• Network device covers

• Selected electronic module supports

Ultrasonic Threaded Inserts

Ultrasonic insertion uses high-frequency vibration to generate localized heat at the insert-plastic interface.

The polymer softens and flows into the external retention geometry.

Potential Advantages

• Short cycle times in suitable applications

• Compatibility with automated installation

• Localized insertion

• Reusable metal threads

Engineering Considerations

• Vibration amplitude

• Installation force

• Process duration

• Tool alignment

• Polymer response

• Insert design

• Installation depth

Important Limitation

Ultrasonic insertion is not universally suitable for every thermoplastic or precision component.

Process conditions must be validated to avoid damage, inadequate retention or unwanted deformation.

Molded-In Threaded Inserts

Molded-in inserts are positioned inside the mold before plastic injection.

The polymer flows around the insert and retains it after solidification.

Potential Advantages

• Integration with molding

• Elimination of a separate insertion stage

• Compatibility with selected complex geometries

• Potentially strong mechanical engagement

Engineering Considerations

• Insert positioning

• Mold loading

• Core-pin geometry

• Thread protection

• Plastic flow

• Mold cycle time

• Tooling maintenance

• Scrap risk

Important Limitation

Molded-in installation should not automatically be described as the strongest or lowest-cost option.

Its suitability depends on the actual component and manufacturing process.

Press-In Threaded Inserts

Press-in inserts are installed mechanically into prepared plastic holes without intentionally melting the polymer.

They may use barbs, fins, knurls or other retention features.

Potential Advantages

• No thermal insertion step

• Relatively simple equipment

• Compatibility with selected automated presses

Engineering Considerations

• Hole diameter

• Interference

• Boss wall thickness

• Polymer stiffness

• Insertion force

• Alignment

• Retention performance

Excessive interference can create local stress and crack the plastic.

Self-Tapping Threaded Inserts

Self-tapping inserts are installed by rotation into a prepared hole.

Their external thread engages the surrounding plastic.

They may be suitable for selected thermoplastics or thermosets, depending on the design.

Engineering Considerations

• Installation torque

• Hole dimensions

• External thread geometry

• Material stiffness

• Boss strength

• Chip generation or material displacement

Installation Method Selection

The correct method should be selected through engineering evaluation rather than a universal ranking.

Material Selection for Communication Equipment Threaded Inserts

Brass Threaded Inserts

Brass is widely used for precision threaded inserts in plastic components.

Potential Advantages

• Good machinability

• Defined internal threads

• Thermal conductivity for heat insertion

• Availability of different retention geometries

• Corrosion resistance in many environments

Potential Applications

• Network equipment housings

• Router enclosures

• Communication controllers

• Selected electronic module supports

Material Considerations

The specific brass alloy should be defined by the drawing or purchasing specification.

Where lead restrictions or other material requirements apply, the alloy composition and supporting documentation must be confirmed.

Stainless Steel Threaded Inserts

Stainless steel may be appropriate for selected outdoor or corrosive environments.

304 Stainless Steel

May be suitable for many indoor and moderate outdoor conditions, subject to the actual environment.

316 or 316L Stainless Steel

May offer improved resistance in certain chloride-containing environments compared with common 304 grades.

Important Limitation

Neither 304 nor 316 stainless steel is universally corrosion-proof.

Crevice conditions, contamination, galvanic interaction and environmental exposure can still cause problems.

Carbon Steel Threaded Inserts

Carbon steel may be considered where cost and mechanical requirements justify its use.

Engineering Considerations

• Material grade

• Surface treatment

• Corrosion protection

• Thread strength

• Installation geometry

• Environmental exposure

Aluminum Threaded Inserts

Aluminum may be considered where low weight or specific material requirements are important.

Its thread performance, corrosion behavior and mating fastener compatibility require evaluation.

Material Selection Principle

The most expensive insert material is not necessarily the best.

Selection should be based on the complete fastening system and its service environment.

Outdoor Corrosion and Environmental Durability

Telecom equipment can remain outdoors for extended periods.

An insert's corrosion resistance must be evaluated together with the mating screw, surrounding structure and enclosure design.

Galvanic Corrosion

When dissimilar metals are electrically connected in the presence of an electrolyte, galvanic corrosion may occur.

The risk depends on the materials, exposed area relationship, electrical continuity and environment.

Crevice Corrosion

Moisture trapped around metallic interfaces may create localized corrosion conditions.

Plastic Aging

The polymer surrounding the insert may change under temperature, UV exposure, moisture or chemical contact.

Thermal Expansion

Metal and plastic generally have different thermal expansion behavior.

Temperature cycling can affect stress distribution, retention and joint preload.

Salt Spray Testing

ASTM B117 provides a method for operating salt spray apparatus.

It does not, by itself, establish a universal outdoor service-life prediction.

Test duration, acceptance criteria and correlation with service conditions must be defined by the customer.

Engineering Recommendation

For outdoor telecom equipment, evaluate the complete assembled joint under the intended environmental conditions.

Knurling, Grooves and Retention Geometry

The external geometry of a threaded insert determines how it engages the plastic.

Common features include:

• Straight knurls

• Helical knurls

• Diamond knurls

• Annular grooves

• Undercuts

• Barbs

• Flanges

Torque-Out Resistance

Torque-out resistance describes the insert's resistance to rotation within the plastic.

Pull-Out Resistance

Pull-out resistance describes the insert's resistance to axial extraction.

Why These Are Different

An insert may resist rotation effectively while having lower axial retention.

Another geometry may provide strong pull-out resistance but different rotational behavior.

Important Engineering Distinction

External knurls do not automatically prevent the mating screw from loosening under vibration.

Insert retention and screw locking are separate design functions.

Plastic Boss Design for Telecom Enclosures

The surrounding plastic boss is critical to insert performance.

Hole Diameter

An oversized hole may reduce retention.

An undersized hole may generate excessive installation stress.

The required diameter depends on the insert geometry, polymer and installation method.

Hole Depth

The hole must accommodate the insert and required clearance.

The mating screw should not bottom out and apply unintended axial force to the insert.

Boss Outside Diameter

The boss must provide sufficient surrounding material to support installation and service loads.

Boss Height

The boss must accommodate the insert length and required seating position.

Ribs and Reinforcement

Ribs may improve stiffness and load distribution when properly designed.

Edge Distance

An insert placed too close to a housing edge may create local cracking risk.

Molded Knit Lines

Weak knit lines near loaded bosses can reduce mechanical performance.

Glass-Filled Plastics

Glass-fiber reinforcement affects stiffness, shrinkage and local stress behavior.

Hole and installation recommendations for unfilled polymers should not automatically be applied to glass-filled grades.

No Universal Hole Tolerance

A single ±0.05 mm hole tolerance cannot be prescribed for every telecom insert.

The correct dimensions must come from the approved insert design and validated plastic assembly.

Screw Jack-Out: A Frequently Overlooked Failure Mode

Jack-out occurs when the mating screw and joint geometry create an unintended force that displaces the insert from its plastic host.

Potential Causes

• Screw bottoming in a blind hole

• Incorrect screw length

• Incorrect insert seating

• Excessive clearance around the mating component

• Poorly designed load transfer

Engineering Controls

• Verify screw length

• Define thread engagement

• Confirm hole depth

• Control insert seating

• Evaluate the mating-part clearance hole

• Provide an appropriate bearing surface

• Validate the complete joint

Why Jack-Out Matters in Telecom Equipment

Network and telecom equipment may contain multiple screw lengths and different internal brackets.

A screw-length error can damage an otherwise correctly installed insert.

Plastic Creep and Clamp-Load Retention

A metal threaded insert provides a durable internal thread.

However, the surrounding plastic may deform under sustained compressive loading.

This can reduce the clamp load in the assembled joint.

Compression Limiters

Where appropriate, a separate compression limiter can help manage compressive loading through the plastic component.

The threaded insert provides the screw thread.

The compression limiter helps establish a suitable compressive load path.

These functions should not be confused.

Vibration, Shock and Mechanical Reliability

Communication equipment may experience vibration during transportation, installation or operation.

Outdoor units can also experience mechanical loading from wind or attached structures.

Insert Retention

The insert must resist rotation and axial extraction.

Screw Retention

The mating screw must maintain the required joint condition.

Plastic Structural Integrity

The surrounding boss must transfer loads without unacceptable damage.

Engineering Recommendation

Evaluate the complete joint under the actual loading conditions rather than relying on an unverified claim of vibration resistance.

Optical Equipment: Precision Fastening Versus Precision Location

Optical communication equipment may require tight positional control.

However, a threaded fastener is primarily a clamping or retention component unless the design explicitly assigns it another function.

Recommended Design Approach

Use appropriate locating features, datums and controlled tolerances for critical alignment.

Use the threaded insert and mating screw to provide the required fastening function.

This separation helps avoid relying on screw clearance or thread position as the sole optical alignment mechanism.

Automated Installation for Telecom OEM Manufacturing

High-volume communication equipment production may use automated threaded insert installation.

Potential equipment functions include:

• Automatic insert feeding

• Orientation control

• Robotic positioning

• Thermal insertion

• Ultrasonic insertion

• Servo-controlled pressing

• Force monitoring

• Position monitoring

• Installation-depth verification

• Process data recording

Manufacturing Engineer Priorities

• Process capability

• Tool alignment

• Resin variation

• Equipment maintenance

• Installation repeatability

• Defect detection

Production Manager Priorities

• Cycle time

• Accepted output

• Scrap

• Rework

• Changeover time

• Equipment uptime

• Labor requirements

• Cost per accepted assembly

Why Automated Tightening Is Different from Insert Installation

The insert is first secured within the plastic component.

The mating screw is then tightened into the insert.

These may be separate manufacturing operations.

Installation force, thermal insertion conditions, screw torque and tightening angle should not be treated as interchangeable process parameters.

Digital Traceability

Where required, production systems may record:

• Insert batch

• Installation equipment identification

• Installation parameters

• Inspection results

• Screw tightening data

• Assembly batch

The scope of traceability should be defined by the OEM's quality requirements and actual production system.

No Universal Equipment Performance Claim

Servo accuracy, cycle time, process capability, data-storage capacity and equipment reliability depend on the selected machinery and production conditions.

Such values should only be quoted when supported by actual equipment specifications and validation records.

Quality Control for Telecom Threaded Inserts

A suitable quality plan should address the insert, plastic host and completed joint.

Incoming Insert Inspection

Depending on the approved drawing:

• Internal thread size

• Thread pitch

• Thread tolerance

• Outside diameter

• Overall length

• Knurl geometry

• Material grade

• Surface treatment

• Burrs and visible defects

Plastic Component Inspection

• Hole diameter

• Hole depth

• Boss dimensions

• Hole position

• Molded defects

• Material identification

Installation Process Verification

• Insert orientation

• Tool alignment

• Installation force or temperature

• Final seating depth

• Equipment condition

• Process consistency

Mechanical Testing

As required by the application:

• Pull-out testing

• Torque-out testing

• Assembly torque evaluation

• Vibration testing

• Thermal cycling

• Environmental exposure testing

Acceptance Criteria

Test methods, sample quantities and acceptance limits should be agreed upon for the specific project.

A universal statement of zero failures or a fixed PPM level is not a substitute for an approved quality plan.

Common Failure Modes in Telecom Threaded Insert Assemblies

International Thread Standards

Threaded inserts for plastics are normally defined through product drawings, internal thread standards and application-specific requirements.

ISO 261

General-purpose ISO metric screw thread series.

ISO 965 Series

ISO metric screw thread tolerances.

ASME B1.1

Unified inch screw threads, including UNC and UNF.

Example Metric Threads

• M2 × 0.4

• M2.5 × 0.45

• M3 × 0.5

• M4 × 0.7

• M5 × 0.8

• M6 × 1.0

• M8 × 1.25

Example Unified Inch Threads

• 2-56 UNC

• 4-40 UNC

• 6-32 UNC

• 8-32 UNC

• 10-24 UNC

• 10-32 UNF

• 1/4-20 UNC

These are examples of thread designations, not confirmation that every insert design is available in every size.

Metric, UNC, UNF, BSW and BSF threads are different systems and must not be treated as directly interchangeable.

Environmental and Industry Specifications

Communication equipment may be subject to application-specific requirements for environmental performance, enclosure protection, vibration and mechanical reliability.

The finished equipment manufacturer should define the applicable requirements.

A threaded insert should not be described as independently certified to a complete telecom equipment standard unless that specific claim is supported.

Custom Threaded Inserts for Telecom OEMs

Standard inserts may not fit every communication equipment design.

Juxin Fasteners accepts drawing-based inquiries for customized threaded inserts and related industrial fastening components.

Possible Custom Features

• Internal thread size and pitch

• Special outside diameter

• Custom overall length

• Knurl configuration

• Retention grooves

• Flanges

• Blind or through-thread design

• Lead-in geometry

• Material grade

• Surface treatment

• Critical tolerances

• Automatic feeding requirements

Why Custom Geometry May Be Required

A compact network enclosure may have limited boss space.

A glass-filled polymer may require a different retention profile.

An outdoor application may need a specific material or finish.

An automated assembly line may require a symmetrical insert that simplifies orientation.

An OEM may need a replacement component matching an existing approved drawing.

Supplier Development and Second-Source Qualification

Procurement teams should evaluate more than internal thread size and unit price.

Two M4 inserts can have the same internal thread but different external geometry and installation requirements.

Technical Qualification

• Approved drawing

• Thread specification

• Material grade

• External retention geometry

• Installation method

• Critical dimensions

• Mechanical performance

Quality Qualification

• Inspection methods

• Material documentation

• Traceability requirements

• Agreed testing

• Change-control requirements

• Packaging requirements

Commercial Qualification

• Prototype and sample quantities

• Minimum order quantity

• Volume pricing

• Production lead time

• Annual demand

• Delivery schedule

• Supply continuity

Second-Source Engineering Principle

A substitute insert must be evaluated in the actual plastic component and production process.

Matching the internal thread does not establish full interchangeability.

Total Installed Cost for Telecom Equipment

The insert's unit price is only one part of the manufacturing cost.

Other cost factors may include:

• Plastic molding

• Insert installation

• Feeding equipment

• Cycle time

• Scrap

• Rework

• Inspection

• Tooling maintenance

• Supplier qualification

• Packaging

• Logistics

The lowest-cost insert is not necessarily the lowest-cost fastening solution.

Juxin Fasteners: Related Fastening Solutions

Juxin Fasteners supplies threaded inserts for plastics and other industrial fastening components used in metal and plastic assemblies.

For telecom and network equipment, relevant product families may include:

• Brass threaded inserts for plastics

• Stainless steel threaded inserts

• Carbon steel threaded inserts

• Aluminum threaded inserts

• Heat-set threaded inserts

• Ultrasonic threaded inserts

• Molded-in threaded inserts

• Press-in threaded inserts

• Self-tapping threaded inserts

• Custom threaded bushings

• Self-clinching nuts and standoffs

• Cage nuts

• Clip-on nuts

• Blind rivet nuts

The correct product depends on whether the host component is plastic, sheet metal or another material.

For drawing-based custom insert requirements, see:

Custom Threaded Inserts for Plastic Components

For the wider industrial fastener range, visit:

Juxin Fasteners Official Website

Frequently Asked Questions

What threaded inserts are used in telecom equipment?

Heat-set, ultrasonic, molded-in, press-in and self-tapping inserts may be considered for suitable plastic components.

Are brass threaded inserts suitable for outdoor telecom equipment?

They may be suitable for selected applications, but material compatibility, corrosion exposure and the complete joint design must be evaluated.

Is 316 stainless steel always required for outdoor telecom equipment?

No. Material selection depends on the actual environmental exposure, customer requirements and joint design.

Can threaded inserts prevent vibration loosening?

Not automatically. Insert retention and mating screw loosening are separate engineering concerns.

Are threaded inserts suitable for fiber optic equipment?

They may be used for selected housings and brackets, but optical alignment requires appropriate locating features and structural validation.

Can threaded inserts be used in 5G antenna housings?

They may be suitable for selected structures, but metallic components near RF-sensitive areas require electromagnetic evaluation.

What is the best insert for glass-filled nylon?

There is no universal best insert. The specific resin, filler content, boss design and installation process must be evaluated.

What causes threaded inserts to pull out of plastic?

Possible causes include inadequate retention geometry, incorrect hole dimensions, weak plastic bosses or excessive axial loading.

What is the difference between a threaded insert and a compression limiter?

A threaded insert provides the internal metal thread. A compression limiter helps manage compressive loading in selected plastic joints.

Can plastic threaded inserts replace cage nuts in server racks?

Not as a direct substitution. Cage nuts are designed for particular sheet-metal rack interfaces, while plastic threaded inserts are intended for compatible polymer structures.

Can Juxin Fasteners supply custom telecom threaded inserts?

Juxin Fasteners accepts drawing-based OEM inquiries for custom threaded inserts and related industrial fastening components.

OEM RFQ — Threaded Inserts for Communication Equipment

Juxin Fasteners welcomes inquiries from telecom OEMs, network equipment manufacturers, optical communication companies,

 data center equipment suppliers, electronics contract manufacturers, structural engineers, design engineers, manufacturing engineers,

 production managers, procurement specialists and supplier development teams.

For technical review and quotation, please provide the following information where applicable.

Insert Specifications

• 2D engineering drawing

• 3D CAD model

• Internal thread size and pitch

• Outside diameter

• Overall length

• Knurl or retention geometry

• Head or flange design

• Material grade

• Surface treatment

• Critical tolerances

Host Component Information

• Plastic resin grade

• Filler content

• Hole diameter and depth

• Boss outside diameter

• Boss height

• Wall thickness

• Mating bracket geometry

• Sheet-metal thickness if a different fastener type is required

Installation Requirements

• Heat-set, ultrasonic, molded-in, press-in or self-tapping method

• Installation equipment

• Final seating depth

• Automatic feeding requirements

• Production cycle considerations

Mechanical and Environmental Requirements

• Pull-out resistance

• Torque-out resistance

• Screw tightening torque

• Static and dynamic loading

• Vibration exposure

• Temperature range

• Humidity

• Outdoor corrosion conditions

• Environmental testing

• RF or optical constraints where applicable

Quality Requirements

• Dimensional inspection

• Material documentation

• Traceability

• Test requirements

• Packaging

• Change-control requirements

Commercial Requirements

• Prototype quantity

• Sample quantity

• Initial order quantity

• Estimated annual demand

• MOQ expectations

• Delivery schedule

• Volume pricing requirements

Looking for Custom Threaded Inserts for Telecom Equipment?

Juxin Fasteners supplies industrial threaded inserts and custom fastening components for suitable plastic and metal assemblies.

Whether your project involves network equipment housings, optical communication modules, outdoor telecom enclosures or data center auxiliary equipment,

 our team can review your engineering drawings and purchasing requirements.

Company: Juxin Fasteners

Website: https://www.juxinfasteners.com/

Email: info@juxinfasteners.com

Send your drawings, material specifications, installation requirements and estimated purchasing quantities to request technical evaluation, samples or an OEM quotation.

Reliable communication equipment fastening depends on selecting the correct insert, plastic structure, installation process, environmental protection and complete joint design.