Technical Data Sheet

Magna-Tac E-645

Stack Lamination Adhesive 








Shelf Life

Part A:

Part B:

6000 cps

Water thin

Clear amber


Modified epoxy



77 %




1 year

1 year


Magna-Tac E645 is a two-part, thermosetting, formulated epoxy adhesive for bonding stack laminations used in stators, rotors, gyros, servomechanisms, synchros, transformers and magnetic amplifiers. It can also be used as an insulating varnish for impregnated coils and small electrical equipment. Bonding is achieved by heat. Only sufficient pressure to assure complete contact is needed.

Because so little adhesive is needed to accomplish a strong bond which resists shear stress, Magna-Tac E645 has proved practical as an adhesive/dielectric in the fabrication of magnetic accelerator units such as cyclotrons and cosmotrons.

Magna-Tac E645 is a strong metal-to-metal adhesive. Because of its excellent mechanical strength plus its resistance to many solvents, water, atmospheric conditions and temperature changes, this adhesive is adaptable to many industrial uses. It is particularly suited to the bonding of large surface areas and mass production processing.


Caution! Magna-Tac E645 contains a volatile, combustible solvent. Provide adequate ventilation. Avoid sparks. Do not use near open flame or spark-producing equipment. Flash point is 107 F.


Methods of Stack Lamination

 Most companies develop their own techniques to bond stack laminates most efficiently. The three most common are:


1. Coil or Stack, then Vacuum Impregnate

Stack cleaned metal in flat sheets separated on a mandrel or in coils. In a pot or kettle, under vacuum, remove all entrapped air. Pressure-force adhesive between layers.. Drain. Apply vacuum to remove solvent vapors. Heat cure. Cut to shape if required.


2. Precoat, then stack

Stack parts to shape and clean. Deposit a thin film of adhesive on each surface to be bonded. Dry. Store if necessary. Assemble into stack and heat cure.


3. Coat, Stamp & Stack

Spray or roll coat adhesive onto both sides of flat sheets. Dry. Stamp to shape. Lay up adhesive-coated laminates and heat cure.


Adhesive Preparation

In order to convert the basic formulation components into a tough, hard, strong adhesive film, thoroughly mix Magna-Tac E645 Part I with the Part II in the following proportions:


MagnaTac E645 Part 1 100 parts

MagnaTac E645 Part 2 30 parts


MagnaTac E645 Part 1 100 parts

MagnaTac E645 Part 2 35 parts


The tolerance of Part II is plus or minus 10 %.To assure optimum performance, mix thoroughly before using.

Reducing the viscosity of the mixed adhesive

While it is not mandatory, MagnaTac E-645 is commonly diluted with a solvent to reduce its viscosity. This allows for easier application of the adhesive.

Once part 1 and part 2 have been mixed, MagnaTac E-645 can be diluted with Cellosolve, methyl ethyl ketone (MEK), toluene, acetone, or a 50/50 mixture of acetone and isopropyl alcohol.

We recommend a mixture of 2 parts adhesive to 1 part solvent. If necessary the adhesive can be further diluted but do not exceed a 3:1 ratio.


Applying the adhesive


Mixed Magna-Tac E645 can be applied by brushing, spraying dipping or roller coating. For very small parts, it can be dispensed easily through a hypodermic needle.

For maximum adhesive, all surfaces must be perfectly clean and thoroughly degreased. For improved strength and chemical resistance, sandblast or treat the surfaces chemically. These treatments will vary according to the material, of course.

Operators' hands must be free from grease or oil while handling coated and uncoated parts.


  Cure Time


The adhesive must be thoroughly dried before curing. Drying may be accomplished at room temperature or by forced drying in a circulating air ovens. If all of the solvent is not removed before curing, blisters or weakening of the adhesive film will result. Thick or highly diluted films will take longer to dry.

At normal room temperatures, air drying may take 4-8 hours. For best results, force dry at 125F for 60 minutes or at 200F for 10 minutes. Do not dry at temperatures above 250F (the adhesive will start to cure at that temperature)

The adhesive dries to a tack free surface at room temperature. Coated parts may be stored before curing for periods of up to 6 months at room temperature. However, the adhesive film must be clean and dry.


Heat Curing

The hardening agent (Part II) of MagnaTac E645 is reactive above 250F. Normal cure temperatures at the glue line range from 265F to 400F. Curing temperature below 375F are recommended because it is practically impossible to degrade the adhesive in that range even if the recommended curing time is exceeded.

Before curing, Magna-Tac E645 is thermoplastic and flows freely as the temperature is raised. This allow the films to fuse to a stronger bond and assures complete "wetting" of the materials being bonded.

For certain specialized applications, however, some users prefer to retard the normal flowout. This can be done by partially curing the adhesive at contact pressure only for about 1/4 to 1/2 the "minimum gel time" shown in figure 1. Any of the normal time and temperature cycles listed may then be used for subsequent curing... but with slightly increased pressure.




Glue Line


Minimum Gel Time Minimum cure time Maximum Cure Time
266F or 130 C 40 Min. 14 Hours none
284F or 140C 32 Min 7 Hours none
302F or 150C 20 min 4 hours none
320F or 160C 15 min 2 hours none
338F or 170C 10 min 1.5 hours none
356F or 180C 8 min 1 hour none
374F or 190C 6 min 45 min none
392F or 200C 4 min 30 min 24 hours
428F or 220C 2 min 10 min 60 min.


The figures refer to the temperature of the adhesive film. Allow sufficient time for the stack to attain the correct temperature. The time required for cure depends on the temperature selected, on the mass of metal and on the heat capacity of the metal in the laminate. The temperature chosen depends on the heat sensitivity of the materials being bonded and time limitations in production scheduling.

If the maximum cure time is exceeded, over-curing which may caused failures - can results.

Curing Pressure

Pressure is not needed to effect the bond but is essential that the coated surfaces be in complete and intimate contact over the entire area of the materials being bonded. Accordingly, sufficient pressure must be applied to assure such contact. The specific amount of pressure needed will vary, depending upon the flatness of the components, porosity, resiliency, etc.

 Cured Properties


Fungus resistance

MagnaTac E-645 after cured is fungus inert and is not conducive to fungus growth. It is, however, necessary to conduct specific tests under service conditions to determine actual compatibility with end use application.


Typical lap shear values obtained when Magna-Tac E645 is used to bond 0.064" etched 2024T3 aluminum alloy to itself in a 1/2 overlap are as follows:


Test Temperature

Tensile Shear, psi

-67 F













Beacon Chemical Company

For Ordering & Technical Assistance

Tel: 914-699-3400

Fax: 914-699-2783




The information given and the recommendations made herein are based on our research and believed to be accurate but no guaranty of their accurate is made. The products discussed herein are sold without any warranty as to merchantability or fitness for a particular purpose or any other warranty, express or implied




BEACON ADHESIVES, Inc., 125 MacQuesten Parkway South, Mount Vernon, NY 10550, Tel: (914) 699-3405