Choosing the Right Adhesive

Because a strain sensor performs no better than the adhesive with which it is bonded to the test specimen, the adhesive is a vitally important component in every strain sensor installation. Although there is no single adhesive which is ideally suited to all applications, there is a wide selection of qualified and dedicated adhesives for strain gage sensors that cover the spectrum of stress analysis, force measurement testing, and for use in transducer manufacturing.  Micro-Measurements offers a host of adhesives which are specially formulated to meet the highest performance standards under a wide range of environmental conditions.  These adhesives and are packaged to ensure reliable and repeatable mixing and application results.

Each package contains specific instructions for its proper handling – storage, mixing, application, curing and if appropriate, post-curing.  Package labeling also shows manufacturing date and shelf life information.

Every adhesive system offered by Micro-Measurements has been formulated in-house or is sourced from a qualified third party and extensively tested to ensure it is suitable for strain measurement application.

Shelf life and storage condition requirements must be carefully followed.  It is usually misguided economy to attempt installing strain gage sensors with outdated adhesive or a product which has been sourced from an unqualified source such as the local hardware store.

Care must be taken in selecting the correct adhesive for the measurement task at hand.  All conditions must be considered including:

  • Strain gage type

  • Temperature range

  • Maximum strain limit

  • Fatigue life requirement

  • Duration of test / installation

  • Humidity

For the majority of applications, foil strain sensors will be installed with one of the six basic adhesives shown in the list below, with the choice depending primarily on the relative weights given to the ease and the speed of application versus performance and the resistance to environmental extremes. When the application requires it, selection can be made from among the six special purpose adhesive described.

Basic Strain Gage Sensor Adhesives:

  • M-Bond 200: This high performance Cyanoacrylate adhesive system is the most widely used general purpose stress analysis adhesive. Easiest to handle. Fast room-temperature curing.It is intended for short term (up to one year) applications.

  • M-Bond AE-10: This room temperature curing 100% solids epoxy adhesive system is for long term general-purpose adhesive that is highly resistant to moisture and most chemicals. Room temperature curing.

  • M-Bond AE-15: Similar to M-Bond AE-10. Recommended for more critical applications, including transducer applications. Elevated temperature curing is required.

  • M-Bond 610: Used primarily in applications with wide temperature range requirements. Widely used in high accuracy and high performance transducer applications as well as stress analysis applications with extreme temperature requirements including deep cryogenic applications. Elevated temperature curing is required.

  • M-Bond 600: Similar to M-Bond 610, but faster reacting. Can be cured at lower temperature than M-Bond 610.

  • M-Bond 43-B: Normally used in transducer gaging. Highly resistant to moisture and chemical attack. Elevated temperature curing.

Special-Purpose Adhesives:

  • M-Bond GA-2: General purpose adhesive primarily used on very rough or irregular surfaces. Room-temperature curing.

  • M-Bond GA-61: Similar to GA-2, but more viscous. Also used to fill irregular surfaces and to anchor lead wires. Elevated temperature curing.

  • M-Bond A-12: Very high-elongation adhesive. Used only when other adhesives cannot meet elongation requirements. Elevated-temperature curing.

  • M-Bond 300- Polyester adhesive used primarily when low temperature curing is required. Sensitive to solvents. Not recommended as a general purpose adhesive.

  • M-Bond 450: High-performance epoxy for high temperature transducer applications.

The two most important considerations for proper adhesive selection are:

  1. Compatibility with the backing materials of the strain gage sensor.

  2. Operating temperature range over which the bond is expected to perform.

 

The chart below is offered as a simple guide to adhesive selection. Adhesives are grouped based upon application type, environmental conditions and strain limit. When more than one adhesive is listed for a particular strain sensor and test condition, preference would be given to the adhesive which is easiest to apply while still meeting all of the other performance criteria.

Type of Test or Application

Operating Temperature Range

Strain Sensors Series

Adhesive

General Static or Static-Dynamic Stress Analysis

 

-50° to +150° F (-45° to +65°C)

CEA, EA

200, AE-10, AE-15

 

 

WA, SA, WK, SK

AE-15 or 610

 

-50° to +400° F (-45° to +205°C)

WA, SA, WK, SK

600 , 610

 

-452° to +450° F (-269° to +230°C)

WK, SK

610

 

< 600° F ( <315°C)

WK

610

High Elongation (Post-Yield)

-50° to +150° F (-45° to +65°C)

CEA, EA

200, AE-10

 

 

EP

AE-15, A-12

Dynamic (Cyclic) Stress Analysis

-100° to +150° F (-75° to +65°C)

ED

200, AE-10

 

 

WD

AE-10, AE-15

 

-320° to +500° F (-195° to +260°C)

WD

600 or 610

Transducer Gaging

-50° to +150° F (-45° to +65°C)

CEA, EA

AE-10, AE-15

 

-50° to +200° F (-45° to +95°C)

N2A, J2A

600, 610, 43-B

 

-50° to +300° F (-45° to +150°C)

WA, SA, TA, TK, J5K

610, 450

 

-320° to +350° F (-195° to +175°C)

WK, SK, TK, J5K

610, 450

 

Learn more about adhesives

jjohnson's picture

Jim Johnson

Technical Sales Manager

Comments

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