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Product Tutorials: Breakstem Rivets

What They Are

Blind fastening allows joining two or more materials together from one side of the application.

Breakstem fasteners and installation tools are a high performance blind fastening system. They consist of a mandrel and body which are combined into a single assembly. The term "Breakstem" refers to the end result of the placing process, when the fastener mandrel is gripped by the jaws in the tool nose piece and snaps off at a pre-determined load, sometimes flush with the fastener head. Used in all manufacturing industries throughout the world, there is a breakstem fastener and installation tool to suit virtually every assembly requirement.

Other names for rivet features:
• Mandrel (a.k.a. Stem, Nail, Pin)
• Body (a.k.a. Rivet, Shank)
• Head (a.k.a. Flange)



How They Work

View an interactive demo

  1. The rivet is placed in position and the installation tool pulls the mandrel.
  2. This action causes rivet deformation in two ways. Firstly, a bulbed tail is formed at the back of the rear sheet or the mandrel head pulls into the rivet body, which pulls the application together (clamp). Secondly, the rivet expands radially giving hole fill; this action compensates for any hole irregularity.
  3. At a pre-determined load the mandrel breaks leaving its tail (mandrel) locked into the body.



Head Styles

Dome Head
  • The most common and verstile head style
  • Twice the diameter of the rivet body
  • Sufficient bearing surface for all except extremely soft or brittle materials
  • Other names: Protruding, Button, Standard

Large Flange Head
  • Greater under head bearing surface
  • Designed fgor extremely soft or brittle materials
  • Other names: Mushroom, Brazier

Countersunk Head
  • Specified when a flush surface is required
  • Other names: Flat head



Rivet Styles

Non-Structural
The mandrel breaks within the rivet body, but is not designed to break flush with the rivet head. A short length of the mandrel is retained within the rivet body, but since the mandrel may not break within the shear plane, it is refered to as non-structural.
  • Non-critical applications
  • Low strength materials
  • Cost effectiveness

Structural
The mandrel breaks within the shear plane and for several products it is designed to break near flush with the rivet head.
  • Strength critical applications
  • Weather resistance
  • Sheet separation
  • Visual check for rivet placement



Body Types

Open End
The end of the rivet is open. The rivet body is hollow through its full length.

Closed End

The end of the rivet is solid and remains closed on the blind side after setting.

Large Blind Side Footprint
The shank of the rivet has one or more axial slots which extend from the underside of the head and terminate short of the open end. The remaining portion of the shank is a hollow cylinder similar to an open end type.

Peel Rivets
A portion of the rivet body is split axially into 2 or more segments.



Fasteners

Brand Material
(Rivet/Stem)
 Key Features
Aluminium/Aluminum
Aluminium/Steel
Steel/Steel

*Tubular component matches rivet
Avdelmate® (Non-Structural)
  • Two piece fastener
  • Extra wide grip range
  • Large bearing area against both sides of the application
  • Excellent hole fill

Aluminium/Steel
Aluminium/Stainless
Steel/Steel
Avex® (Non-Structural)
  • Multi-grip capability
  • Good hole fill
  • Retained stem
  • Large blind side bearing area

Steel/Steel Avibulb® (Non-Structural)
  • High shear and tensile strength
  • Good hole fill
  • Retained stem
  • Large blind side bearing area

Steel/Steel Avibulb® XT (Structural)
  • High shear and tensile strength
  • Multi-grip capability
  • High residual clamp load

Stainless/Stainless Avinox® XT (Structural)
  • High shear and tensile strength
  • High corrosion resistance
  • Ideal for applications requiring elevated temperatures
  • Multi-grip capability

Stainless/Stainless Avinox® (Non-Structural)
  • High shear and tensile strength
  • High corrosion resistance
  • Good hole fill
  • Retained stem
  • Large blind side bearing area

Aluminum/Steel Avseal® II (Structural)
  • Fully annealed sleeve
  • Excellent hole fill
  • Large hole tolerance
  • Internal lock

Aluminium/Aluminium Bulbex® (Non-Structural)
  • Split tail formation for thin sheet and low strength materials
  • Multi-grip capability
  • Retained stem

Aluminium/Aluminum
Steel/Steel
Hemlok® (Structural)
  • Very high shear and tensile strength
  • Large blind side bearing area
  • Interference lock via splined stem

Aluminium/Aluminum
Steel/Steel
Interlock® (Structural)
  • Multi-grip capability
  • Fully sealed fastener
  • Excellent hole fill
  • Mechanically locked stem
  • Good sheet take-up performance

Aluminium/Aluminium Klamp-Tite® (Non-Structural)
  • Split tail formation for soft and low strength materials
  • Multi-grip capability
  • Retained stem

Aluminium/Aluminium Klamp-Tite® (Structural)
  • Split tail formation
  • Multi-grip capability
  • Optional underhead washer provides weather-proof seal
  • Mechanically locked stem for strong, vibration resistant joints

Aluminium/Aluminum
Steel/Steel
Stainless/Stainless
Monobolt® (Structural)
  • Multi-grip capability
  • Fully sealed fastener
  • Visible lock
  • Excellent hole fill
  • Mechanically locked stem
  • Good sheet take-up performance

Aluminium/Steel
Monel/Steel
Stainless/Stainless
Steel/Steel
Q Rivet (Structural)
  • Interference lock via a splined stem
  • Stem plugs entire shell length
  • Weatherproof

Steel/Steel
Stainless/Stainless
Stavex® (Non-Structural)
  • Multi-grip capability
  • Good hole fill
  • Retained stem
  • Large blind side bearing area

Aluminium/Aluminum
Aluminum/Steel
T Rivet (Structural)
  • Superior clamp for sheet separation
  • Strong, vibration resistant joint
  • Mechanically locked stem for vibration resistant joints

Steel/Steel T-Lok® (Non-Structural)
  • ‘Peel-type’ tail formation for joining wood to metal
  • Wide grip range
  • Retained stem



Rivet Selection

Grip Range
The thickness of the parent material(s) must fall within the grip range of the fastener.

Hole Size
It is important to control the hole size accurately in order to ensure optimum fastener performance.

Corrosion Resistance
Corrosion is best reduced by selecting a fastener material which is the same as the parent material(s). Stainless steel fasteners offer the best corrosion resistance.

Special Surface Coatings
For improved corrosion resistance or aesthetics, we can apply various finishes.

Strength Characteristics
Shear and tensile values for the selected fastener must fall within the application requirements.

Load Spreading
Select a fastener with a large blind side bearing area and/or large flange head for use in thin or low strength materials.



Application

Outlined below are some of the most popular fastening scenarios and the recommended fastening solution for these situations.



Soft Material to Hard
Soft-to-hard is sometimes assembled by using a backup washer. Preferred practice is to use a large-flange rivet and set the blind side footprint against the hard material.


Thick and Thin Sheets
Whenever possible, set the blind side footprint against the thicker, stronger material./ Where the head mist be set against thinner material, use of a backup washer is desirable.


Tubing
Setting the rivet against a flattened section © produces maximum rigidity. The joint shown in B is slightly less rigid, but entirely satisfactory. The rivet should not extend through both tube walls as shown in A.



Plastic and Brittle Materials
When the more fragile plastics are involved, large blind side footprint rivets should be specified. When the plastic is rigid enough to afford satisfactory clinching action, standard blind rivets can be set directly against plastics.



Installation Tools

  • 30% glass filled nylon
  • Durable and robust construction for a long working life
  • Comfortable to handle
  • Reduced operator fatigue and improved productivity
  • Reduced risk of RSI
  • High speed assembly
  • Ideal for high volume production
  • Quick and simple to operate
  • Integral stem collectors
  • Tamper-proof casings
  • Overheat protection
  • Portable and easy to handle
Tool Description
nG1 (Hydro-Pneumatic)
Places up to 4.8 mm (3/16") aluminium breakstem rivets and up to 4.0 mm (5/32") steel breakstem rivets produced by Avdel®. Can also place Avseal® II 4 and 5 mm sealing plugs.

nG2 (Hydro-Pneumatic)
Places up to 4.8mm (3/16") breakstem rivets produced by Avdel®. Can also place Avseal® II sealing plug up to 7 mm.

nG2S (Hydro-Pneumatic)
Places up to 4.8mm (3/16") breakstem rivets. Can also place Avseal® II sealing plugs up to 7 mm.

nG3 (Hydro-Pneumatic)
Places up to 6.4mm (1/4") breakstem rivets produced by Avdel®, except Hemlok® structural fasteners. Can also place Avseal® II sealing plugs up to 9 mm and Avtainer® lockbolts 9.5mm (3/8").

nG4 (Hydro-Pneumatic)
Places Up to 6.4mm (1/4") breakstem rivets produced by Avdel® except Monobolt® structural rivets. Can also place: Avseal® II sealing plugs, up to 12 mm Avtainer® lockbolts, 9.5mm (3/8") Avdelok® and Maxlok® lockbolts 4.8mm (3/16") and 6.4mm (1/4") Hemlok® structural rivets 6.4mm (1/4").

eRiv® (Battery)
Places fasteners to 4.8mm (3/16)







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