What is Projection Welding?
Projection welding is a resistance welding process that concentrates electrical current at specific points through preformed protrusions on the workpiece. This allows high mechanical strength joints in critical automotive applications.
This process includes nut welding for M4-M12 nuts and stud welding for studs and threaded fasteners on automotive chassis. The electrodes require special materials that withstand repeated impact and high contact pressures.
Products for Automotive Projection
- Electrodes with CuW Insert (Elkonite Class 10-12) High-strength brazing with silver alloy for maximum conductivity and impact resistance. Elkonite inserts combine copper's conductivity with tungsten's hardness.
- Ceramic Guide Pins (Zirconia, Si₃N₄) and KCF Insulating materials for precise nut centering. Low spatter adhesion, maximum service life. Silicon nitride ceramics offer better thermal resistance.
- Stainless Steel Pins Economical option that absorbs impacts without breaking. Require electrode with insulating bushings to avoid short circuits.
- Threaded Electrodes and Bases In-house manufacturing of holders and bases for quick change in production lines. Standard and special threads as required.
- Shunts / Flexible Connectors Braided cables and flexible connectors for current bypass. High-purity electrolytic copper for minimum resistance.
Technical Differentiator – AWS J1.3
Superior Metallurgical Bond: Our Elkonite inserts (CuW Classes 10-12 per AWS J1.3) are joined to the electrode body through silver alloy brazing. This metallurgical bond ensures continuous electrical conductivity and mechanical resistance to repeated impact, outperforming conventional mechanical joints.
Typical Applications
Our projection electrodes are used in major automotive OEMs for:
- Weld Nuts M4 to M12 Component attachment on body-in-white, chassis and subframe
- Weld Studs Structural anchors on floors, roofs and side panels
- Brackets and Supports Attachment elements for harnesses, tubing and auxiliary components
Guide Pins for Nut Welding
The guide pin centers the nut on the stamping so the projections align correctly with the sheet metal. Available in Ceramic (Zirconia, Si₃N₄), KCF and Stainless Steel - each material with different advantages for your application.
Main Function: Centering
In projection nut welding, the nut has clearance - meaning it moves on the stamping. The guide pin has the diameter of the stamping hole and the nut's inside diameter, centering both parts so the projections align correctly.
The Problem: Weld Spatter
During projection welding (high amperage, low voltage), molten metal can spatter and adhere to the guide pin. These weld beads make centering the next nut difficult and can damage the threads.
When Do I Need an Insulating Pin?
- With insulating bushings (fiberglass + stainless): The electrode is already insulated, you can use stainless steel pins
- Without insulating bushings: You need insulating pins (ceramic or KCF) to prevent current from passing through the pin
Guide Pin Material Comparison
Ceramic (Zirconia, Si₃N₄)
Ideal for: High volume, 24/7 production
- Maximum operational life
- Total electrical insulation
- Easy cleaning - spatter doesn't stick
- Higher initial investment (better long-term ROI)
KCF (Potassium Titanate)
Ideal for: Medium volume, cost/life balance
- Balance hardness and mechanical strength
- Complete electrical insulation
- Less adhesion than stainless
- Moderate cost vs ceramic
Stainless Steel
Ideal for: Low volume, emergencies, impacts
- Absorbs impacts - doesn't break, only bends
- Easy to straighten or replace
- Immediate availability
- Requires electrode with insulating bushings
Available Sizes
| Metric Size | Pin Diameter (mm) | Typical Application |
|---|---|---|
| M4 | 3.2 - 3.5 | Electronic components, small brackets |
| M5 | 4.0 - 4.3 | Interior brackets, trim |
| M6 | 4.8 - 5.2 | Most common - BIW, brackets |
| M8 | 6.5 - 7.0 | Suspension, structural |
| M10 | 8.2 - 8.8 | Chassis, subframes |
| M12 | 10.0 - 10.5 | Heavy duty, structural applications |
Recommendation by Application
| Situation | Recommended Material | Reason |
|---|---|---|
| High volume 24/7, electrode without bushings | Ceramic (Zirconia) | Maximum life, total insulation, easy cleaning |
| Hot stamped / Laser cut | Ceramic (Zirconia) | Greater abrasive wear resistance |
| Medium volume, moderate budget | KCF | Good cost/performance balance |
| Application with frequent impacts | Stainless + bushings | Doesn't break, absorbs impacts, easy to straighten |
| Electrode already has insulating bushings | Stainless Steel | Economical, electrode already insulated |
| Special nuts, complex design | Consult | We evaluate design to prevent fractures |
Custom Designs: If your nut or stamping has special geometry, we manufacture custom guide pins per drawing. It's important that the design avoids forced corners or stress concentrators that can cause fractures in ceramics or KCF.