Many times, especially in steel erection, we need to mix welded and bolted (or riveted) connections.  It is very important for the design engineer to know the implications on mixing welds and bolts as it pertains to connection strength, fatigue life, manufacturing costs and the skill level required to make these connections. However, sometimes the design engineer, or simply the designer, has the option of choosing one over the other.  Peter Jacobs, Senior  of Marketing at CNC Masters, has been kind enough to contribute by providing the pros and cons of both joining methods…

Selecting the appropriate metal joining process is critical as it impacts the product’s structural and commercial viability. There are various aspects to consider while deciding on the best joining method. Welded joints and riveted joints are two popular methods of permanent metal joining. Depending on the project, both welding and riveting have their upsides and downsides.

How Does Riveting Work?

CNC riveting is a mechanical procedure that uses rivets to fasten geometric structures permanently, ranging from simple to complicated. A rivet is a type of mechanical fastener used for riveting. This rivet adheres to the components’ adjoining surfaces. So, the fundamental principle of riveting is that the rivet acts as a single component with both ends holding each metal piece.

A rivet is constructed of metal; one end consists of a head while the other has a cylindrical tail. The rivet gets driven through the holes in overlapped workpiece material during the riveting process, and the side of the rivet is bulged to develop a solid joint. When the rivet gets inserted into the hole, the rivet’s tail must be deformed with a rivet gun so that it extends and tightly fastens into a fit.

It forms a semi-permanent connection between the metals. Repeat the operation along the joint to meet the project’s required strength criteria.

Application

CNC riveting is employed for a wide range of projects, including airplanes, structural beams, compact electronics, RVs, automobile chassis, hanger straps, etc. Many CNC riveting machines are designed for manufacturing lines, allowing for shorter turn-around times and a higher level of automation.

Pros and Cons of Riveting

Pros

• Rivets are inexpensive when compared to welding equipment.
• Riveting can be performed in any position or place. 
• The shear strength and fatigue resistance achieved are exceptionally high.
• Removal of a rivet is less damaging than removing a welded junction.
• Some rivets offer resistance to environmental and chemical corrosion.
• No substantial damage is rendered to the protective coatings of the parts engaged.
• It can be performed on joint ferrous, nonferrous, and even nonmetals.

Cons

• Riveting takes considerable time and is labor-intensive.
• The pieces to be linked must overlap, or a cover plate needs to be added in the case of butt joints.
• Pre-drilling of holes is required.
• A noisy procedure and a non-leak-proof joint get established.
• Rivets increase weight, whereas holes decrease stability.
• Riveted joints are noticeably larger than welded connections.

How Does Welding Work?

Welding is a permanent fabrication process that leverages the thermo-softening property of materials. According to this property, any material softens on heating and hardens on cooling. It’s commonly used to join metals and thermoplastics. It melts the parts with intense heat and then fuses them to cool and solidify.

In this welding procedure, intense heat is applied initially to melt the base metal. Afterward, a filler material is applied to this joint to form a molten material known as the weld pool. This weld pool cools and creates the junction, which can be sturdier than the base or parent metal, depending on its design. Then, the weld pool is compressed, resulting in a tight, solid welded joint.

This process also necessitates some form of protection or shielding to ensure that the filler and melted components do not become contaminated by ambient conditions.

Application

Welding can be used on a broad range of materials, including stainless steel and titanium, and employed on smaller, giant, heavy, lightweight, spherical, or angular projects. Shipbuilding, industrial pipelines, railroads, manufacturing facilities, automobiles, aviation, aeronautical architecture, and mechanical industries all employ various types of welding.

Pros and Cons of Welding

Pros

• Welded joints are more lightweight than riveted joints.
• In comparison to riveting, alterations or adjustments are quite simple.
• Welded joints offer better durability in high stress and pressure conditions.
• Leak-proof joints get established.
• Both thin and thick materials with flexible structural designs can be used.

Cons

• It necessitates highly skilled personnel with supervision.
• Welding defects like porosity are difficult to detect and may necessitate extreme precautions.
• Uneven heating and cooling might cause distortion and crack development.
• More stringent inspection standards need to be met.

Welding or Riveting? Which Method Should You Choose?

In contrast to a weld, drilling holes, inserting rivets, and heating the protruding end take a significant amount of time. Welding is a faster and often less expensive procedure, whether done using CNC machines or by hand, due to the small iterations and parts required.

On the flip side, welding may not prove to be efficacious for thin sheet metal as it may burn through it. When welding isn’t the best option, rivet holes tend to extend and have a more calibrated clearance.

So the best piece of advice to pick the most suitable method for conjoining metals is to consider the project’s requirements and finished appearance desired by the end-user.

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Conclusion

Riveting and welding are critical to almost all manufacturing industries across the globe. Both have provided tremendous strength and have substantially aided in the structural development or foundation of modern advances. They’re both parts of the procedure for joining two or more metal surfaces and are commonly employed. The decision of which one to utilize depends on the individual’s objective.

About the Author:

Peter Jacobs

Peter Jacobs is the Senior Director of Marketing at CNC Masters. He is actively involved in manufacturing processes and regularly contributes his insights for various blogs in CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general.