Mono Bolts vs Hemlock Rivets: Comparisons and Recommendations

Introduction to Mono Bolts and Hemlock Rivets

When it comes to choosing fasteners for metal fabrication and construction projects, two popular options are mono bolts and hemlock rivets. Both provide secure fastening strength, though there are some key differences to understand when deciding which is best for a particular application.

What are Mono Bolts?

A mono bolt (also sometimes called a one-sided bolt) is a specialty fastener designed to be set from one side only, making them ideal for situations where you only have access to one side of what you are fastening. They work like a typical bolt and nut combination, except the nut is swaged permanently to the bolt mechanically with applied pressure.

What are Hemlock Rivets?

A hemlock rivet, also sometimes referred to as a blind rivet, is a mechanical fastener that also can be set from one side. However, unlike mono bolts, the hemlock rivet inserts into pre-drilled holes and then a tool pulls the stem, causing the rivet body to deform and clamp materials together from the backside.

Key Differences Between Mono Bolts and Hemlock Rivets

While both mono bolts and hemlock rivets share the advantage of single-sided assembly, there are some notable ways in which they differ:

Materials and Strength

Mono bolts are most commonly fabricated from steel alloys and therefore are generally stronger than hemlock rivets. They are capable of withstanding heavier shear and tensile loads without failing. Mono bolts range in size from 3mm to 30mm diameter to suit different load requirements.

Hemlock rivets are primarily made from softer aluminum alloys, with some higher-strength variants made from stainless steel, copper alloys, or specialty polymers. Pound for pound, mono bolts exceed the clamping capability of same-sized hemlock rivets.

Installation Differences

Installing mono bolts requires access to both sides of the materials at least initially, as the bolts must be inserted from one side and then a tool or press swages the nut from the opposite side. Holes generally need to be pre-drilled as well to accept the shank.

Hemlock rivets can be set entirely from one side using manual, air, or electric setting tools designed to pull and deform the rivet stem. No access to the backside or prep of holes is necessary prior to installation. This makes them ideal for blind or one-sided connections.

Cost Comparison

Per piece, mono bolts tend to cost more than same sized hemlock rivets. However, mono bolts may work out to be more cost effective in certain situations because fewer fasteners may be required to achieve the same holding strength. The type and size of materials being joined is also a factor.

Generally speaking, projects using heavier gauge metals favor mono bolts, while lighter sheet metals and plastics can be adequately fastened with hemlock rivets.

Corrosion Resistance

Stainless steel mono bolts match or slightly outperform stainless hemlock rivets when it comes to corrosion resistance. Mono bolts feature a press fit that helps minimize moisture ingress. Standard steel mono bolts require finishes like zinc plating if corrosion resistance is necessary.

Typical Applications for Each Fastener

Knowing typical applications for mono bolts vs hemlock rivets also helps make the best choice for your project:

Mono Bolt Uses

• Structural fabrication
• Machinery assembly
• Permanent scaffolding
• Conveyor systems
• Metal bridge construction

Essentially most applications where high shear or tensile loads need to be resisted favor the inherent strength of mono bolts.

Hemlock Rivet Uses

• HVAC ducting
• Electronic enclosures
• Truck and trailer bodies
• Temporary road signs
• Sheet metal cabinets & furniture

Hemlock rivets work well when lighter sheet metal assembly is involved or quick fastening is required during onsite construction activities.

Bottom Line Recommendations

While mono bolts are the clear choice when it comes strong, permanent structural connections, don't count out hemlock rivets for lighter fastening tasks where economy and ease of installation are beneficial.

Consider the expected loads, the materials being joined, cost constraints, the need for potential disassembly, and installation access limitations when deciding between these two popular single-sided fasteners.

Both mono bolts and hemlock rivets deliver secure, reliable fastening performance in a variety of construction and fabrication contexts. Understanding their comparative strengths and ideal uses enables matching the best fastening solution to the requirements of your next project.

FAQs

What is the main advantage of mono bolts and hemlock rivets over regular nuts and bolts?

Both mono bolts and hemlock rivets can be installed from one side only, making them ideal fasteners when you only have access to one side of the materials being joined. They do not require access to both sides like regular bolt and nut sets.

When should I choose a mono bolt over a hemlock rivet?

Mono bolts are usually the best choice when very high strength connections are needed, like in structural fabrication, heavy machinery, or permanent metal frameworks. Their high shear and tensile strength exceeds hemlock rivets.

What are some typical applications suitable for hemlock rivets?

Hemlock rivets work very well for joining thinner gauge metals, like in HVAC ductwork, electronic enclosures, sheet metal furniture and cabinets, temporary road signs, and trailer and truck bodies.

Can mono bolts and hemlock rivets be removed after installation if needed?

Hemlock rivets are designed as permanent fasteners and generally cannot be removed without destroying them. Mono bolts could potentially be ground off and replaced if access to both sides is available later on.