What is the definition of "cohesive failure"?
The inability of an adhesive to resist internal separation. During cohesive failure, the adhesive sticks to both surfaces, but cannot hold them together.

Learn more about cohesive failure in the class Intro to Adhesive Bonding 110 below.


Adhesives Training


Class Information
Adhesives Training Tooling U-SME classes are offered at the beginner, intermediate, and advanced levels. The typical class consists of 12 to 25 lessons and will take approximately one hour to complete.
Class Name:Intro to Adhesive Bonding 110
Description:This class describes adhesive bonding, adhesive classification, and the various factors that lead to a successful adhesive bond.
Prerequisites: none
Difficulty:Beginner
Number of Lessons:16
Language:English, Spanish
 
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Class Outline
  • Objectives
  • The Value of Adhesive Bonding
  • Pros and Cons of Adhesive Bonding
  • Adhesive Categories
  • Structural Adhesives
  • Nonstructural Adhesives
  • Wetting
  • Types of Joints
  • Types of Joint Stress
  • Surface Preparation
  • Adhesive Application
  • Failure and Inspection
  • Adhesive Removal
  • Safety
  • Adhesive Markets
  • Summary
  
Class Objectives
  • Describe the advantages of adhesive bonding.
  • Describe the characteristics of adhesive bonding.
  • Describe the types of adhesives.
  • Describe structural adhesives.
  • Describe nonstructural adhesives.
  • Define wetting.
  • List the different types of adhesive joints.
  • List adhesive bonding stresses.
  • Describe surface preparation.
  • Describe general steps for proper application of adhesives.
  • Describe potential bond failures to inspect.
  • Describe common methods for removing adhesives.
  • Describe safety issues and concerns relating to adhesives.
  • Describe the adhesive bonding markets.

Class Vocabulary

Vocabulary TermDefinition
acrylic adhesive A type of structural adhesive made from acrylic, a manufactured polymer. Acrylic adhesives set rapidly and are very strong due to heavy cross-linking.
adhesive A substance used to join two or more materials. The pros and cons of adhesives relate specifically to how adhesives differ from the materials used for welding and mechanical fastening.
adhesive bonding The process of binding materials together using any number of adhesive substances. Paste, glue, and tape are examples of common adhesives.
adhesive failure The inability of an adhesive to stick to a surface. During adhesive failure, the adhesive cannot bind two surfaces together and separates from the substrate.
anaerobic adhesive A type of structural adhesive that can cure and harden only in an environment absent of oxygen.
blueprint A document that contains the instructions necessary to manufacture and/or assemble a part.
butt joint A joint formed by two surfaces that meet without overlap or complex intersection. Butt joints are often combined with other joint designs.
carbon dioxide A heavy, colorless, odorless gas. Carbon dioxide can be used to extinguish fires fueled by adhesives or curing agents.
carrier The backing material to which pressure-sensitive adhesives stick. The carrier acts as a mode of transport for the adhesive.
cleavage strength A material's ability to resist forces that attempt to pull an adhesive apart by separating rigid surfaces.
cleavage stress A force that pulls an adhesive apart by separating two rigid surfaces.
cohesive failure The inability of an adhesive to resist internal separation. During cohesive failure, the adhesive sticks to both surfaces, but cannot hold them together.
cyanoacrylate A type of synthetic adhesive made from acrylic, a manufactured polymer. Cyanoacrylates bond with surfaces very quickly.
damping The ability to resist stresses and deformation caused by vibration. Adhesives have stronger damping capability than mechanical fasteners.
dispenser In adhesive bonding, a device that holds an adhesive and ejects the adhesive onto a surface. Dispensers can be handheld or attached to a robot.
dry powder A solid consisting of very small particles in large numbers. Dry powder can be used to extinguish fires fueled by adhesives or curing agents.
epoxy adhesive A type of structural adhesive made from epoxy, a manufactured polymer. Epoxy adhesives can bond with a variety of surfaces and are strong and resilient.
foam A material consisting of a mass of small bubbles formed together into a type of semi-liquid. Foam can be used to extinguish fires caused by adhesives or curing agents.
hot melt A type of adhesive that requires heat for application and strengthens as it solidifies.
joggle lap joint A variation of the lap joint design in which one surface area is straight, while the second forms an "S" shape.
joining The process of bringing and holding materials together by fastening, adhesive bonding, welding, or other similar processes.
joint The location at which an adhesive layer holds two surfaces together.
lap joint A joint formed when two surfaces overlap one another. Lap joints provide more stress resistance than butt joints.
machine vision A system of cameras and computers that can be programmed to complete tasks. Machine vision can be used to help assemblers locate defective products.
mechanical fastening The process of joining two materials through the physical interaction of a common device, or fastener. Common mechanical fastening processes include bolting and nailing.
natural adhesive An adhesive made from naturally occurring living sources, such as plants and animals. Natural adhesives are also called organic adhesives.
nonstructural adhesive A synthetic adhesive used for applications that do not require strong load-bearing capabilities. Nonstructural adhesives can be easily unbonded from surfaces.
organic adhesive An adhesive made from naturally occurring living sources, such as plants and animals. Organic adhesives are also called natural adhesives.
peel strength A material's ability to resist forces that attempt to pull an adhesive apart by separating flexible surfaces.
peel stress A force that pulls an adhesive apart by separating one flexible surface and one rigid surface.
pressure-sensitive adhesive PSA. An adhesive that needs only minimal pressure to stick to a surface.
shear strength A material's ability to resist forces that attempt to cause the internal structure of the material to slide against itself.
shear stress A force that attempts to cause the internal structure of a material to slide against itself.
silicone adhesive A type of structural adhesive made from silicone. Silicone adhesives set as soon as they contact air.
solvent A chemical material that attempts to dissolve another material. Solvents can be used to remove adhesives from a surface.
strap joint A joint design that combines the butt joint and lap joint. A butt joint is formed, and a third plank of material is then adhered to the area above the butt joint.
stress Any force that attempts to physically deform an object.
structural adhesive A synthetic adhesive with strong load-bearing capabilities. Structural adhesives are not easily unbonded from surfaces.
substrate The surface material upon which an adhesive is applied to form a bond or joint.
synthetic adhesive A chemically manufactured adhesive derived from either thermoplastics or thermosets. Synthetic adhesives are commonly used in industrial settings.
tensile strength A material's ability to resist forces that attempt to pull apart or stretch it.
tensile stress A force that attempts to pull apart or stretch a material.
tongue and groove joint A joint formed by inserting part of one surface material into a recessed area of a second surface. This joint design offers excellent stress resistance.
urethane adhesive A type of structural adhesive made from urethane, a manufactured polymer. Urethane adhesives form flexible joints.
viscosity A fluid's resistance to flow. An adhesive must have low viscosity in order to fill the crevices of a surface. However, if the viscosity is too low, the adhesive will run off the surface and form no bond at all.
welding A joining process that uses heat, pressure, and/or chemicals to fuse two materials together permanently.
wetting The process of spreading an adhesive over a surface. Proper wetting occurs when the adhesive fills all crevices of the surface.