Custom Dual-Head Resistance Spot Welding Machine for Piano Bracket Manufacturing

Application Industry: Musical Instrument Manufacturing

Workpiece: Galvanized steel sheet and rivets for piano brackets

In metal fabrication, workpieces vary in structure, joining methods, and welding positions. For metal components with specific structural requirements, standard welding equipment may not fully meet the needs of the actual production process. Customizing equipment to match the workpiece characteristics is therefore a practical solution.

This case features a customized welding machine supplied by PDKJ for musical instrument manufacturing: a pneumatic resistance spot welding machine with two cylinders and a single welding head.

The machine is designed for spot welding rivets to galvanized steel sheets used in metal bracket components. It demonstrates how PDKJ configures dedicated welding equipment according to specific workpiece and production requirements.

Ⅰ Project Background

The customer specializes in manufacturing metal components for musical instruments and supplies products to overseas markets. Its mass-production requirements include strict standards for weld strength, surface appearance, and batch-to-batch consistency.

The workpiece in this project is an external piano bracket component with the following specifications:

• Material: Galvanized steel sheet

• Sheet thickness: 1.0–1.2 mm

• Workpiece dimension: 13.30 mm

• Welding process: Resistance spot welding of galvanized steel sheet to rivets

For this type of metal component, the equipment must do more than provide a basic joining function. It must also accommodate the workpiece structure, electrode contact position, and actual assembly method. Equipment selection should therefore consider not only welding power but also the compatibility between the workpiece and the welding process.

Ⅱ Key Challenges in the Customer's Existing Production Process

When using general-purpose welding equipment, the customer encountered three major production challenges.

1. Insufficient and Unstable Electrode Force

Rivet spot welding requires sufficient and consistent electrode force throughout the welding process. A conventional single-cylinder welding machine may not provide adequate pressure for the application, and fluctuations in force can contribute to weak welds and weld pull-out strength below the required standard.

These defects may occur unpredictably, affecting the overall product acceptance rate.

2. Challenges in Galvanized Steel Welding and Increased Post-Weld Finishing Costs

The zinc coating on galvanized steel can be affected by welding heat. If the pressure and welding sequence are not properly matched, excessive spatter and coating damage may occur.

After welding, workpieces may require manual grinding or surface repair, increasing labor requirements and production costs.

3. Equipment Interference and Limited Production Efficiency

The workpiece dimensions and welding orientation can create clearance issues with the welding head or worktable of standard equipment. This makes fixture positioning more difficult and increases the time required to load, clamp, and align each workpiece, ultimately limiting production throughput.

The customer's key requirements were to obtain a dedicated resistance spot welding machine that could provide sufficient and stable electrode force, accommodate the workpiece structure and operating position, achieve reliable spot welding between galvanized sheet and rivets, reduce weak welds and spatter defects, minimize post-weld grinding, and support continuous, high-volume production.

Ⅲ PDKJ's Resistance Welding Solution and Equipment Advantages

To address these challenges, PDKJ adopted a dual-cylinder pressure-boosting structure with a single welding electrode head. The combined output of the two cylinders provides the required electrode force. The welding head and worktable layout were also optimized to accommodate the workpiece and its operating position.

Combined with a digital welding control system and customized fixtures, the solution addresses production challenges through mechanical design, welding process optimization, and simplified operation.

01. Dual-Cylinder Drive for Welding Pressure

The two cylinders apply force synchronously, directing their combined output to a single conductive welding electrode assembly.

The machine structure is designed around the actual welding motion and workpiece requirements. The specific force distribution and coordination of the cylinders depend on the machine's actual construction and commissioning results.

02. Multi-Stage Welding Sequence for Galvanized Sheet and Rivet Welding

The machine features a multi-stage welding sequence with a complete process cycle covering preheating, welding, and pressure holding.

The welding sequence and current output are controlled to help reduce spatter caused by zinc coating vaporization and limit excessive coating damage. The process is designed to achieve a reliable joint between the rivet and sheet metal while meeting the product's weld pull-out strength requirements, helping reduce manual grinding and rework.

03. Digital Welding Recipe Management to Reduce Operator-Related Variations

Welding parameters can be saved as individual production recipes and recalled when needed. This reduces dependence on operator experience and helps maintain consistent welding quality during continuous, multi-shift production.

Recipe-based parameter management also helps reduce variations between production batches.

04. Industrial-Grade Configuration and Complete Implementation Support

The conductive electrode assembly, cylinders, and cooling system are selected according to the demands of frequent industrial production. The equipment is designed to support extended operating periods under appropriate working conditions.

Adjustment provisions also allow the machine to accommodate certain similar workpieces through electrode fixture replacement and parameter adjustments, improving equipment versatility.

Before shipment, the machine undergoes preliminary acceptance inspection. After delivery to the customer's factory, PDKJ engineers provide on-site installation, commissioning, and process verification, together with operator training and routine maintenance guidance. This support helps the customer bring the equipment into stable production more efficiently.

Ⅳ Project Results

After the DTB-80S dual-cylinder pressure-boosting spot welding machine entered production at the customer's facility, the following improvements were achieved:

1. Improved welding consistency: Stable electrode force and a properly matched welding sequence helped reduce weak welds and spatter-related defects, controlling labor costs associated with grinding and rework.

2. More efficient workpiece positioning: The optimized welding head and worktable layout resolved workpiece clearance issues, improved loading and positioning efficiency, and better supported the customer's mass-production requirements.

3. More consistent batch quality: Recipe-based parameter management helped maintain stable weld quality across multiple shifts, supporting the quality control requirements of piano bracket orders for overseas markets.

This project demonstrates PDKJ's approach to customized resistance welding equipment: evaluating the actual workpiece, adapting the machine structure and welding process, and providing commissioning and technical support to help customers achieve reliable production.

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Professional Services by Guangdong Pudian Automation Technology Co., Ltd.

Guangdong Pudian Automation Technology Co., Ltd.

• 20 years of expertise in resistance welding, laser welding, and automated welding equipment

• Focus on high precision, high stability, and customized solutions

• Full coverage of processes including spot welding, projection welding, seam welding, rolling welding, laser welding, and automated production lines

• One-on-one customized welding solutions based on material, thickness, and production volume

• Serving multiple industries and solving complex welding challenges

Whether it involves joining galvanized sheets with rivets, welding metal brackets, or processing other metal components, PDKJ can evaluate the appropriate equipment solutions based on your specific workpieces and process requirements.

If your products require welding equipment, please get in touch with PDKJ! Providing photos of your workpieces, product drawings, details on material thickness, and specific welding requirements will help us understand your actual processing needs and assess the most suitable welding equipment and process solutions for you.

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If you have welding machine requirements, please contact Ms. Zhao

E-Mail: pdkj@gd-pw.com

Phone: +86-13631765713