Weld Stud with 3 Projections on Top of Head: IFI-148 Type T3 Design, Welding and OEM Applications

Weld Stud with 3 Projections on Top of Head: IFI-148 Type T3 Design, Welding and OEM Applications

A weld stud with three projections on top of the head is an externally threaded fastener designed to be permanently attached to a suitable metal surface by resistance projection welding.

Its distinguishing feature is the location of three integrally formed welding projections on the top face of the stud head. 

During installation, this projection-bearing face contacts the parent metal, while the threaded shank remains available for subsequent assembly.

Unlike through-hole projection weld studs, the top-of-head configuration can be welded directly to a sheet metal surface without requiring a mounting hole for the stud shank.

This makes it a useful fastening option where the outside surface of a fabricated component should remain uninterrupted, where access is limited, 

or where a permanent threaded attachment point is required without conventional through-bolting.

In North American fastener terminology, certain configurations are identified as Type T3 threaded projection weld studs under IFI-148. 

The applicable type designation and dimensional conformity must be verified against the actual product drawing.

For automotive OEMs, Tier-1 and Tier-2 suppliers, sheet metal fabricators and industrial equipment manufacturers, 

successful application depends on the complete fastening system: stud geometry, material, parent sheet, electrode design, welding parameters and mechanical loading.

Juxin Fasteners supplies three-projection top-of-head weld studs and related industrial welding fasteners for standard and drawing-based OEM requirements.

What Is a Three-Projection Top-of-Head Weld Stud?

The fastener consists of a threaded shank and a formed head incorporating three welding projections.

The threaded shank provides the mechanical fastening interface.

The head transfers the loads from the threaded connection into the welded attachment.

The three projections establish localized electrical and mechanical contact with the workpiece during resistance welding.

As the welding cycle progresses, the projections heat and collapse under electrode force, allowing the welded interface to develop.

Principal Design Characteristics

• Three integrally formed projections on the top face of the head

• Externally threaded shank

• Resistance projection welding installation

• Direct surface attachment without a stud-shank clearance hole

• Potential suitability for concealed mounting locations

• Metric or Unified inch threads according to the product specification

• Material and dimensional options subject to drawing and supply confirmation

The number of projections is a design feature, not a universal mechanical strength rating.

IFI-148 and Type T3: Understanding the Product Designation

IFI-148, Threaded Projection Weld Studs, is an American fastener industry specification covering general 

and dimensional information for several types of weld studs with integrally formed projections.

These projections may be located on top of or beneath the stud head, depending on the design.

Type T3

Type T3 is associated with a top-of-head three-projection configuration.

For procurement purposes, the type designation should be accompanied by the applicable dimensions, material and thread specification.

Why the Drawing Remains Essential

The designation alone may not fully define:

• Thread size and class

• Stud length

• Head dimensions

• Projection geometry

• Material grade

• Surface finish

• Special dimensional tolerances

• Customer-specific performance requirements

The applicable IFI-148 edition and any customer deviations should be identified in the purchase specification.

Top-of-Head vs. Under-the-Head Projection Weld Studs

These two designs serve different sheet metal assembly requirements.

Why Top-of-Head Geometry Matters

A top-of-head stud can be positioned on the inner surface of a panel while leaving the opposite face without a fastener penetration.

This can be advantageous for:

• Concealed brackets

• Exterior-facing metal panels

• Equipment housings

• Sheet metal covers

• Blind mounting locations

However, the absence of a through-hole does not guarantee a completely mark-free exterior surface.

Welding conditions and sheet thickness may still produce local indentation, distortion or visible marking.

How Resistance Projection Welding Works

Resistance projection welding is a variation of resistance welding in which specially formed projections concentrate electrical contact and heat generation at selected locations.

For a three-projection head stud, the process generally includes:

1. Positioning the projection-bearing head against the parent sheet

2. Applying electrode force to establish contact

3. Passing welding current through the intended joint interface

4. Allowing localized heating and projection collapse

5. Maintaining suitable electrode force during weld formation and cooling

The final welded joint depends on the relationship between the stud, substrate and welding equipment.

Why This Is Not Conventional CD Stud Welding

Capacitor discharge stud welding, drawn-arc stud welding and resistance projection welding are different joining processes.

The three formed projections of a Type T3-style stud are intended for resistance projection welding.

A standard CD stud welding machine should not be assumed compatible with this fastener.

Likewise, CD welding times and drawn-arc welding current values should not be presented as operating specifications for this product.

The Three Projections: Geometry and Weld Formation

The projections are the principal functional features of the welding interface.

Their height, shape, spacing and material condition influence initial contact and subsequent weld formation.

Projection Height

When all three projections contact the workpiece appropriately, electrode force can be distributed through the intended contact regions.

If one projection is substantially higher, it may contact first and alter the initial force and current distribution.

The actual result depends on electrode compliance, surface flatness and welding parameters.

Projection Shape

Projection shape influences initial contact area and the rate at which the projection deforms during welding.

A projection that collapses prematurely may fail to develop the intended localized heating.

A projection that does not collapse appropriately may also produce an unacceptable joint.

Projection Position

Projection position influences the distribution of welding contact around the stud head.

The arrangement must be compatible with head geometry, electrode contact and the intended joint performance.

Projection Manufacturing Consistency

For repetitive production, dimensional variation in the projections can contribute to variation in weld formation.

The relevant tolerances should be established by the product drawing and application requirements.

Important Engineering Distinction

Three projections of nominally equal height do not guarantee three equally formed weld regions.

Actual welding performance also depends on the equipment, substrate and surface condition.

Electrode Force: Too Much and Too Little Can Both Cause Problems

Electrode force is a critical variable in resistance projection welding.

It establishes mechanical contact and influences the electrical resistance at the joint interface.

Excessive Initial Force

Excessive force or mechanical impact may flatten the projections before sufficient welding heat develops.

This can reduce the intended concentration of contact resistance.

Insufficient Force

Insufficient force may contribute to unstable contact, excessive expulsion or inadequate weld formation.

Electrode Follow-Up

As the projections heat and collapse, the welding head must be able to follow the changing joint thickness.

Poor mechanical follow-up may produce an unstable force condition during the welding cycle.

Why Machine Rigidity Matters

Excessive machine deflection or electrode misalignment can change how the three projections contact the parent sheet.

Therefore, a conforming weld stud cannot compensate for every welding-machine limitation.

Electrode Design and Accessibility

The welding electrodes must establish a suitable current path and apply force without damaging the threaded shank.

Electrode configuration depends on the stud geometry and assembly arrangement.

Important considerations include:

• Electrode material

• Contact surface geometry

• Alignment

• Mechanical support

• Cooling

• Wear

• Clearance around the threaded shank

The electrode contacting the stud must be compatible with the head and shank configuration.

Electrode Wear and Production Consistency

Electrode wear may alter contact conditions during repeated welding operations.

The effect can become significant in high-volume manufacturing.

Equipment maintenance and process monitoring should therefore be considered alongside stud dimensional consistency.

Weldable Materials: Why Steel Grade Matters

The material specification must satisfy both mechanical and welding requirements.

A higher-strength steel is not automatically more suitable for projection welding.

Low-Carbon Steel

Low-carbon steels are commonly used for resistance-welded fasteners because their composition can support suitable welding behavior.

American fastener specifications provide examples using welding-quality carbon steels such as C1008 and C1010.

These material designations are relevant references for product selection, but their use in a particular Juxin Fasteners product must be confirmed.

Higher-Carbon and Higher-Strength Steels

Higher carbon content and certain heat-treated conditions can increase the risk of undesirable microstructural changes in the heat-affected zone.

Depending on the material and cooling conditions, local hardening and brittleness may occur.

IFI-148 includes technical cautions concerning these risks.

Why This Matters to OEM Buyers

A fastener described as Grade 8.8 or 10.9 should not automatically be assumed to provide a superior welded joint.

The material, heat treatment, welding process and finished-joint requirements must be evaluated together.

Stainless Steel

Stainless steel may be relevant where corrosion resistance is required.

However, different stainless steel grades have different electrical, thermal and mechanical characteristics.

A welding schedule developed for low-carbon steel should not be transferred to stainless steel without evaluation.

Brass and Other Materials

Certain projection weld stud product families may include brass or other material options.

Their suitability depends on the stud and substrate combination.

Aluminum and Dissimilar Metals

Direct resistance welding of dissimilar metals introduces additional metallurgical and process challenges.

A conventional carbon steel Type T3-style stud should not be assumed suitable for direct welding to aluminum sheet.

For mixed-material automotive structures, alternative joining arrangements may be necessary.

Surface Finishes and Coating Selection

Surface finish affects both corrosion protection and the electrical contact conditions during welding.

Plain Steel Finish

Plain steel or lightly protected surfaces may be specified where the fastener is welded before the finished assembly receives corrosion protection.

Zinc-Plated Steel

Zinc coatings can affect contact resistance, electrode wear and welding behavior.

The welding procedure must account for the coating condition.

Stainless Steel Surface Condition

Surface contamination and oxide conditions can influence welding behavior.

Other Coatings

Special finishes should not be assumed suitable for projection welding without confirming the coating and process requirements.

Coating Sequence

OEM manufacturers should specify whether the fastener is supplied in a condition intended for welding before coating, or whether the welding process must accommodate an existing finish.

This decision can influence the finished assembly's corrosion protection and manufacturing cost.

Sheet Thickness and Substrate Design

A top-of-head projection weld stud can eliminate the need for a stud-shank mounting hole, but the parent sheet must still be suitable for the welding process.

Thin Sheet Considerations

Thin sheet applications may be sensitive to:

• Excessive heat input

• Local indentation

• Surface marking

• Distortion

• Burn-through

• Inadequate weld formation

Thicker Sheet Considerations

Thicker workpieces may require different welding energy, force and electrode arrangements.

Sheet Flatness

Local sheet flatness affects how the three projections contact the substrate.

Sheet Coating

The substrate coating may influence electrical resistance and weld formation.

No Universal Minimum Thickness

The appropriate minimum sheet thickness cannot be determined from the stud thread size alone.

It must be evaluated for the actual fastener, substrate and welding procedure.

Why Top-of-Head Weld Studs Are Useful for Concealed Attachments

One of the clearest application advantages identified by American fastener suppliers is the ability to create a permanent 

attachment point without penetrating the parent panel with the stud shank.

This can be useful where:

• The exterior surface should remain visually uninterrupted

• Through-bolting is undesirable

• Access is available from the welding side

• A permanent threaded mounting point is required

• A concealed bracket or support must be attached

Design Limitation

A concealed attachment is not automatically a structural, watertight or pressure-tight connection.

Those properties require separate design and validation.

Automotive Body-in-White and Component Manufacturing

Automotive manufacturing uses welded threaded attachment points in suitable stamped and fabricated metal components.

Potential applications include:

• Interior mounting brackets

• Wiring harness supports

• Heat-shield attachment points

• Auxiliary equipment brackets

• Fabricated steel panels

• Non-safety-critical mounting structures

The selected fastening method depends on the assembly's mechanical and manufacturing requirements.

Automotive Engineering Requirements

Relevant factors include:

• Material compatibility

• Welded joint strength

• Dimensional accuracy

• Corrosion protection

• Fatigue loading

• Installation repeatability

• Downstream assembly torque

• Production process validation

Safety-critical or crash-relevant applications require additional engineering approval and testing.

Electrical Enclosures and Power Distribution Equipment

Electrical equipment manufacturers use sheet metal cabinets, mounting panels and fabricated structures.

Top-of-head projection weld studs may provide permanent threaded attachment points for selected mechanical components.

Potential applications include:

• Equipment mounting brackets

• Cabinet panels

• Instrument supports

• Internal mounting structures

• Cable-management brackets

Where electrical grounding or bonding is required, the electrical connection must be evaluated separately from the mechanical weld.

Industrial Machinery and Equipment Housings

Industrial machinery manufacturers may use three-projection weld studs in fabricated:

• Machine covers

• Equipment panels

• Support brackets

• Mounting plates

• Auxiliary housings

• Serviceable assemblies

For these applications, the welded stud provides a fixed threaded point that can simplify subsequent mechanical assembly.

HVAC and Commercial Equipment

HVAC equipment and commercial machinery use fabricated sheet metal structures with repeated mounting locations.

Top-of-head projection weld studs may be considered for suitable brackets and housings.

Relevant engineering requirements include sheet thickness, vibration, corrosion exposure, welding access and production volume.

AI Data Center and Electronic Equipment Structures

Server racks, electrical cabinets, UPS enclosures and other data center infrastructure components may use permanent threaded attachment points in suitable metal structures.

Potential applications include:

• Equipment mounting brackets

• Cabinet components

• Auxiliary mechanical supports

• Fabricated steel panels

The selected stud must meet the mechanical, material and manufacturing requirements of the actual equipment.

Automated Projection Welding and Production Engineering

Top-of-head projection weld studs may be installed using suitable automated resistance welding equipment.

Automation may include:

• Component feeding

• Stud orientation

• Mechanical or robotic positioning

• Electrode movement

• Welding-current control

• Force control

• Process monitoring

• Part transfer

Automatic Feeding Compatibility

Not every stud geometry is suitable for every automatic feeder.

The head dimensions, shank length, thread geometry and part orientation characteristics must be compatible with the equipment.

Process Monitoring

Welding systems may monitor electrical and mechanical process variables.

Monitoring supports process control but does not automatically establish the mechanical strength of every finished joint.

Production Repeatability

Repeatability depends on the fastener, welding equipment, electrodes, fixtures, substrate and validated welding procedure.

Common Projection Weld Stud Failure Modes

These are possible causes rather than guaranteed diagnoses.

Weld Strength, Torque Resistance and Joint Validation

The finished welded joint must meet the application's mechanical requirements.

Potential evaluation methods include:

• Visual inspection

• Dimensional inspection

• Torque testing

• Axial pull-off testing

• Shear testing

• Destructive weld examination

• Metallographic examination

• Fatigue testing where relevant

• Corrosion testing where required

The applicable tests and acceptance criteria must be defined for the project.

Torque Resistance Is Not Tensile Strength

A stud that passes a specified torque test has not necessarily demonstrated adequate axial tensile or fatigue performance.

Different tests evaluate different failure mechanisms.

Weld Failure Location

Failure may occur in the stud, the weld interface or the parent sheet.

The significance of each failure mode depends on the design and acceptance criteria.

Three Projections Are Not a Guaranteed Strength Advantage

Three projections do not automatically produce a stronger joint than a different projection arrangement.

The final joint performance depends on the complete design and validated welding process.

Metric and Unified Inch Threads

Three-projection weld studs may be specified with metric or Unified inch-series threads according to the actual product configuration.

Examples appearing in Juxin Fasteners' existing product information include:

These are independent examples, not interchangeable size pairs or confirmed current stock.

Thread Standards

ISO 261 and ISO 965 are relevant to ISO metric thread dimensions and tolerances.

ASME B1.1 is relevant to Unified inch threads.

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

Selecting the Correct Weld Stud: Engineering Decision Framework

A useful selection process begins with the assembly requirements rather than the nominal stud diameter alone.

When an Alternative Fastener May Be Better

A top-of-head projection weld stud is not the correct choice for every sheet metal application.

Alternatives may include:

• Under-the-head projection weld studs

• CD weld studs

• Self-clinching studs

• Blind rivet nuts

• Weld nuts

• Through-bolted connections

The correct fastening method depends on access, material, load, installation equipment and production economics.

Manufacturing Quality and OEM Procurement

For repeat OEM supply, the product specification may need to define:

• Thread dimensions

• Overall length

• Head dimensions

• Projection geometry

• Material specification

• Surface condition

• Dimensional tolerances

• Inspection characteristics

• Lot identification

• Packaging requirements

Projection Geometry Inspection

Projection height, position and shape may be relevant characteristics where they influence welding performance.

Thread Inspection

The thread must satisfy the specified class and tolerance.

Material Verification

The material specification should be consistent with both mechanical and welding requirements.

Packaging and Handling

Packaging should help prevent component mixing and damage to the projections or threads.

100% Inspection Is Characteristic-Specific

If an OEM requires full inspection or sorting, the characteristics, methods and acceptance criteria should be defined.

A general claim of 100% inspection does not establish zero defects or guaranteed weld performance.

OEM Cost and Supply Chain Considerations

Purchasing teams should consider more than the individual stud price.

Relevant commercial factors include:

• Material cost

• Product geometry

• Tooling requirements

• Inspection and sorting

• Packaging

• Prototype quantities

• Production volumes

• MOQ

• Lead time

• Delivery planning

• Engineering change control

Total Installed Cost

The economic evaluation may also include welding equipment, electrode maintenance, installation cycle, rework and scrap.

A lower-priced stud is not necessarily less expensive in the finished assembly if it introduces verified manufacturing problems.

Conversely, a higher-priced stud does not automatically provide superior weld performance.

Custom Three-Projection Weld Studs for OEM Applications

Some OEM applications require dimensions or configurations that differ from standard catalog products.

Potential drawing-based requirements include:

• Custom stud length

• Metric or Unified inch threads

• Special head geometry

• Projection dimensions

• Material specification

• Surface finish

• Dimensional tolerances

• Inspection requirements

• Packaging and identification

Manufacturing feasibility, MOQ and delivery arrangements depend on the actual project.

Juxin Fasteners: Three-Projection Weld Stud Supply

Juxin Fasteners supplies industrial welding fasteners for international OEM manufacturing and sheet metal applications.

Relevant products include:

• Three-projection top-of-head weld studs

• Type T3-style projection weld studs

• Carbon steel projection weld studs

• Stainless steel projection weld studs

• Other projection weld stud configurations

• Weld nuts

• Drawing-based custom welding fasteners

Specific dimensions, materials, finishes and conformity to a particular product standard require confirmation against the applicable drawing and supply specification.

Related Juxin Fasteners Products

• Projection Weld Stud with 3 Formed Projections

• Carbon Steel Weld Stud with 3 Projections on Top of Head

• Projection Weld Studs: Engineering Design and OEM Sourcing

Frequently Asked Questions

What is a Type T3 projection weld stud?

Type T3 is a designation associated with a three-projection top-of-head threaded weld stud configuration under IFI-148.

The actual dimensions and conformity requirements must be confirmed against the product drawing.

Do three-projection top-of-head weld studs require a hole?

The surface-welding design does not inherently require a clearance hole for the threaded shank in the parent sheet.

Are top-of-head weld studs suitable for concealed mounting?

They can be useful where a permanent threaded attachment is required without penetrating the parent panel.

 Exterior appearance still depends on the sheet and welding process.

Can a Type T3 weld stud be installed using capacitor discharge welding?

Its formed projections are intended for resistance projection welding. CD stud welding uses a different process and fastener configuration.

What steel is suitable for projection weld studs?

Welding-quality low-carbon steels such as C1008 or C1010 are relevant industry examples. 

The actual material must satisfy the specified product and welding requirements.

Does a higher mechanical property class guarantee a stronger weld?

No. Mechanical property class and weldability are different considerations. 

Material composition, heat treatment and welding conditions influence the finished joint.

Can top-of-head projection weld studs be used on galvanized steel?

Potentially, subject to the fastener material, coating, substrate and validated welding process.

Can they be welded directly to aluminum?

A conventional steel projection weld stud should not be assumed suitable for direct welding to aluminum.

 Dissimilar-metal joining requires specific engineering evaluation.

Does the three-projection design guarantee equal weld strength at all three locations?

No. Projection geometry, surface condition, electrode alignment and welding parameters influence the resulting welds.

Are metric and UNC versions interchangeable?

No. Metric and Unified inch threads are separate thread systems and must be matched to the correct mating components.

What information is required for an OEM quotation?

The engineering drawing, material, thread specification, projection geometry, parent-sheet details, 

welding requirements and estimated purchasing volume are the most useful starting points.

OEM RFQ — Weld Stud with 3 Projections on Top of Head

Juxin Fasteners welcomes technical inquiries and sourcing projects from automotive OEMs, Tier-1 and Tier-2 suppliers, 

sheet metal manufacturers, industrial equipment companies and international purchasing organizations.

For technical review and quotation, please provide:

• 2D engineering drawing and revision

• 3D CAD model where available

• IFI-148 type designation where applicable

• Metric or Unified inch thread specification

• Thread diameter, pitch and class

• Overall stud length

• Head dimensions

• Three-projection geometry

• Material specification

• Mechanical property requirements

• Surface finish

• Parent-sheet material and thickness

• Resistance projection welding requirements

• Electrode and fixture constraints

• Required joint performance

• Inspection and testing requirements

• Packaging and lot identification

• Sample quantity

• Estimated annual demand

• Required delivery schedule

Company: Juxin Fasteners

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

Email: info@juxinfasteners.com

For three-projection top-of-head weld studs, IFI-148 Type T3-style threaded projection weld studs and drawing-based OEM 

welding fasteners, contact Juxin Fasteners with your technical drawings and purchasing requirements for product review and quotation.