Resistance spot welding vs. clinching: What’s the better choice for metal joining in your shop? Both methods have pros and cons, and the decision between machines depends on several factors, such as material types, production requirements and cost.
To make an informed decision for your business, careful comparison and consideration is required.
- What is Spot Welding?
- What is Clinching?
- Spot Welding vs. Clinching: A side-by-side comparison.
- Spot Welding vs. Clinching: Cost overview and analysis.
What is Spot Welding?
Resistance spot welding is a process used to join two or more metal sheets by the heat obtained from resistance to electric current. One of the advantages of spot welding is its ability to produce rapid and reliable welds. The process can be easily automated for high-volume production if required. Although spot welding is an industry standard for metal joining, there are some drawbacks that can be addressed by using a clinching machine as an alternative option.
Pros of Spot Welding:
- High Joint Strength:
- When executed correctly, spot welding can produce strong and durable joints, making it suitable for various applications.
- Variety of Configurations:
- Spot welders come in different configurations, providing flexibility for various production requirements.
- Flush Surface Finish:
- Spot welding can create a flush surface on the finished piece, making it suitable for applications that require a smooth, flat surface.
Cons of Spot Welding:
- Testing Difficulty
- There’s no straightforward, non-destructive way to assess weld quality.
- Limited Material Compatibility
- Spot welding dissimilar metals, such as aluminum and steel, is difficult to impossible, limiting its application.
- Maintenance Requirements
- Spot welding machines require routine maintenance, including recirculating cooling water for copper tips, tip dressing, and filing.
What is Clinching?
Clinching is a mechanical process used to join metal sheets without the need for heat or additional materials like welding filler or fasteners. In clinching, the metal sheets are deformed and mechanically interlocked, creating a strong and permanent joint. This process is particularly useful for joining sheet metals in applications where welding might be challenging or impractical.
Pros of Clinching:
- Cost-Effective Operation:
- No consumables like welding electrodes or rivets are required.
- Reduced energy consumption as no heat is generated during the process.
- Versatility:
- Ideal for joining dissimilar metals.
- Suitable for thin and lightweight materials common in HVAC duct fabrication.
- Increased Productivity:
- High production rates due to rapid processing.
- Minimal setup and preparation time.
Cons of Clinching:
- Joint Appearance:
- Clinched joints may not have the same visual appeal as welded seams.
- Limited Thickness Range:
- Less suitable for very thick materials.
Spot Welding vs. Clinching: A side-by-side comparison
There are several factors to consider when comparing a spot welder and a clinching machine. To help determine which machine is the best option for your production, we’ve compiled the key differences between machines in the table below:
| Factor | Spot Welding | Clinching |
| Joining Method | Joins metal surfaces through the heat obtained from resistance to electric current. | Mechanical process of joining metal together. |
| Strength | Excellent strength when done correctly with optimal settings. | About 80% of the strength of an ideal spot weld. |
| Surface Appearance | Creates a flush surface if required. | Leaves an impression on one side and a button head on the other, resulting in a non-flush surface. |
| Materials Compatibility | Ideal for basic metals; challenging for dissimilar metals (eg: aluminum to steel). | Can join dissimilar metals. |
| Testing and Inspection | Difficult to test weld strength; relies on visual appearance or destructive testing. Additional testing equipment would be required. | Easy and non-destructive testing; quick measurement of the formed button. |
| Surface Damage | Intense heat may burn and make the metal porous, inviting rust. | Preserves galvanized, plastic, and pre-painted steel coatings. |
| Cooling and Maintenance | Requires circulating cooling water for copper tips and transformer, with tip dressing and filing maintenance on the electrodes. | No cooling water needed; not tip dressing, reducing downtime. |
| Safety Hazards | Involves electromagnetic fields, sparks, and fumes, requiring a clean work area and safety procedures. | No electromagnetic fields, sparks, or fumes. Norlok Clinching machines have an intelligent safety stroke to increase operator safety |
| Flexibility and Design | More flexible with various machine and arm configurations. | Requires a more rigid machine and tool design, with a higher initial investment. |
| Material Warping | High heat may cause warping in some materials. | Generally avoids thermal stress, reducing the likelihood of material warping. |
| Power Requirements | Requires electricity, involving electromagnetic fields. | Mostly pneumatic, requiring an air compressor but avoiding electromagnetic fields. |
| Tooling Size | Requires smaller contact area for tooling. | Requires a larger contact area for tooling. |
| Production Process | May involve expensive secondary operations for pre-painted metal. | Cleaner production process, especially for pre-painted or dissimilar metals. |
Spot Welding vs. Clinching: Cost overview and analysis
Determining the exact cost of operating a spot welder or a clinching machine can be challenging, as it depends on several factors, including the specific type of machine, the cost of consumables, energy prices, labour costs, and other operational expenses. However, we can provide you with a general framework to help you estimate the operational costs:
| Factor | Spot Welder | Clinching Machine |
| Consumables | The cost of welding electrodes, required for the spot welder is a significant factor. Prices can vary based on the type and size of electrodes, as well as the material being welded. | Clinching machines typically have minimal consumables compared to welding or riveting machines. However, there might be costs associated with punches, dies and elastomers.
|
| Energy Costs | Spot welders typically require significant electrical power. Check the machine’s specifications for power requirements and estimate the energy usage based on your local energy rates.
| Clinching processes usually involve less energy consumption compared to welding. Some Clinching machines run on compressed air with minimal electrical power required. Other Clinching machines are mechanical and would require more electrical power. Check the machine’s specifications for power requirements and estimate the energy usage based on your local energy rates.
|
| Labour Costs | Consider labor costs associated with operating the spot welder, including setup, monitoring, and any necessary maintenance. Factor in the hourly wage of the operator.
| Consider labor costs associated with operating the clinching machine, including setup, monitoring, and any necessary maintenance. Factor in the hourly wage of the operator.
|
| Maintenance and Repairs | Include an estimate for routine maintenance and potential repairs. Regular maintenance is essential for the longevity and efficiency of the spot welder. | Include an estimate for routine maintenance and potential repairs. While clinching machines are often known for their reliability and low maintenance requirements, it’s essential to plan for occasional service needs.
|
| Machine Depreciation | If you want to factor in machine depreciation over 100,000 joints, divide the initial cost of the spot welder by its expected lifespan in joints. This will give you a per-joint depreciation cost.
| If you want to factor in machine depreciation over 100,000 joints, divide the initial cost of the clinching machine by its expected lifespan in joints. This will give you a per-joint depreciation cost.
|
| Miscellaneous Costs | Account for any other miscellaneous costs that might arise during the spot welder’s operation.
| Account for any other miscellaneous costs that might arise during the clinching machine’s operation.
|
Making the Right Machine Selection for your Shop
For shops that can afford the initial investment of a clinching machine (which is approximately 1.5x – 3x* more expensive than a spot welder), the lower operating costs make a clinching machine more affordable in the long run.
For shops that can’t justify the initial cost of a clinching machine, a spot welder is an excellent option that will keep production running efficiently, given the machine is serviced and given proper maintenance.
On paper, one is not necessarily better than the other. The choice between a spot welder and clinching machine really comes down to your individual needs, your short- and long-term budget, and the specific goals you have for your business.
*An entry-level clinching machine is about 1.5x the investment of a 25 KVA Foot Operated Spot Welder. A more versatile clinching machine, such as the Surelok III, is about 3x the investment.
Calculating the Estimated Cost per Joint
To calculate the estimated cost per joint, use the following formula:
Cost per Joint = (Total Cost / Number of Joints)
This formula provides an average cost per joint, considering all the factors mentioned above. Keep in mind that this is a rough estimate, and actual costs may vary based on specific circumstances and the efficiency of your operations.
For a more accurate estimate, consult Empire Machinery on the current cost of a resistance spot welder or a clinching machine. We can also help you consider your specific production process and any unique factors that may impact costs.